Patent Application
20230181564
This disclosure relates to compounds, pharmaceutical compositions comprising them, and methods of using the compounds and compositions for treating apicomplexan parasite infections. More particularly, this disclosure relates to tetrahydroquinolinone compounds and pharmaceutical compositions thereof, methods of selectively inhibiting cytochrome b with these compounds, and methods of treating diseases that benefit from selective cytochrome b inhibition, such as a T. gondii infection.
Malaria results in the death of about 0.5 million children a year, with drug resistance affecting the usefulness of successive generations of new medicines. The related apicomplexan parasite, Toxoplasma gondii, is the most frequent parasitic infection of humans in the world. It plays a significant role in food-born associated death in the USA, destruction of the human retina, and death and illness from recrudescent disease in the immune compromised or immunologically immature. It has been estimated that there are 1.9 million new cases of this congenital T. gondii infection globally over a ten-year period, causing 12 million disability adjusted life years from damage to the fetal brain and eye. Toxoplasmosis is an often neglected, untreated or mistreated disease. There are approximately 2 billion people throughout the world who have this parasite in their brain lifelong, some with known, severe, adverse consequences. There are possible additional, harmful effects for a substantial number of chronically infected people as this parasite modulates signature pathways of neurodegeneration, motor diseases, epilepsy, and malignancies. No medicine eliminates this chronic, encysted form of the parasite. New and improved medicines are greatly needed to cure Toxoplasma and Plasmodia infections. These parasites often share the same molecular targets for medicines due to a relatively close, apicomplexan, phylogenetic relationship. Thus, medicine development for each of these parasites can inform development of medicines that benefit treating the other.
One such shared molecular target is the mitochondrial cytochrome bc1 complex that is important for the survival of apicomplexan parasites such as Plasmodia and T gondii. Cytochrome b is a subunit of the cytochrome bc, complex, an inner mitochondrial membrane protein that is part of the electron transport chain. Activity of this complex is integral to oxidative phosphorylation and generation of ATP. Cytochrome b activity appears to be necessary for the replication and persistence of the parasite, and is the site of action of atovaquone. Cytochrome b is the target for quinolone-based compounds, but significant problems with solubility and toxicity have been noted with known cytochrome b inhibitors. Therefore, there remains a need for effective cytochrome b inhibitors that do not have the drawbacks of the currently known cytochrome b inhibitors.
The present disclosure is related to novel quinolone-like inhibitors, tetrahydroquinolinones (THQs). Thus, in one aspect, the disclosure provides compounds selected from:
or a pharmaceutically acceptable salt thereof.
Another aspect of the disclosure provides a pharmaceutical composition including one or more compounds of the disclosure as described herein (e.g., compounds provided above) and a pharmaceutically acceptable carrier, solvent, adjuvant or diluent.
Another aspect of the disclosure provides nanoparticle formulations comprising one or more tetrahydroquinolinones as disclosed herein. In one embodiment, the disclosure provides a nanoparticle formulation including:
Another aspect of the disclosure provides methods for treating an apicomplexan parasite infection. In certain embodiments, such methods include administering to a subject in need thereof an amount effective to treat the infection of one or more of modulators of one or more of the genes listed in
As used, modulators are any moiety that can increase or decrease and functional characteristics of the gene or gene product (RNA or protein), including but not limited to expression, stability, activity, or other characteristics of the gene or gene product (RNA or protein).
In certain embodiments, the apicomplexan parasite infection is a T. gondii infection.
Another aspect of the disclosure method for identifying test compounds for apicomplexan parasite therapy. Such methods include identifying one or more of test compounds that modulate activity of one or more of the genes listed in
Another aspect of the disclosure method for diagnosing an apicomplexan parasite infection (such as a T. gondii infection). Such methods include:
Other objects, features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The accompanying drawings are included to provide a further understanding of the systems and methods of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s) of the disclosure and, together with the description, serve to explain the principles and operation of the disclosure.
Before the disclosed methods and materials are described, it is to be understood that the aspects described herein are not limited to specific embodiments, and as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and, unless specifically defined herein, is not intended to be limiting.
In view of the present disclosure, the methods and systems described herein can be configured by the person of ordinary skill in the art to meet the desired need. As provided above, apicomplexan infections cause substantial morbidity and mortality, worldwide presenting urgent need for new and improved therapies. A markedly increased expression of cytochrome b in the currently untreatable T. gondii bradyzoite life-cycle stage was recently found (McPhillie et al. 2016). Thus, there is a great need for a compound that would inhibit tachyzoites, bradyzoites and three life cycle stages of even drug-resistant Plasmodia was developed, without a need for a pro-drug as has been needed in other attempts to target apicomplexan cytochrome b. The disclosure aimed to improve upon the physicochemical properties of napthoquinones and endochin-like quinolones (ELQs) targeting cytochrome b, including poor aqueous solubility and toxicity.
The disclosure provides novel quinolone-like inhibitors, THQs, with improved solubility, and lower toxicity, compared to known compounds in the literature. Without being bound by a theory, it is reasoned that the increased ‘sp3’ character of the THQs (i.e., moving from rod-like to sphere-like 3D space) could provide the required improvement in solubility that would allow for optimal pharmacokinetic properties. Molecules with an increased percentage of ‘sp3 character’ tend to be more three-dimensional than their planar (‘sp2-rich’) counterparts. The terms ‘sp2’ and ‘sp3’ refer to the shape of their hybridized atomic orbitals, which have trigonal planar and tetrahedral geometries respectively. Flat aromatic rings (‘sp2-rich’) are ubiquitous in drug discovery campaigns, but molecules with more ‘sp3 character’ are often more specific for their protein target and can have better physicochemical properties. Further, without being bound by a theory, it is reasoned that the larger binding pocket in the parasite enzymes, compared to their mammalian counterparts, would provide room for bulkier substituents to minimize effect on the human enzyme.
The disclosure in certain embodiments provides a preclinical lead candidate based on potent and selective inhibition of P. falciparum and P. berghei and T. gondii cytochrome bc1 for the treatment of malaria and toxoplasmosis. The candidate compound demonstrates high efficacy in relevant in vitro and in vivo models of the diseases, and has considerable potential for broad-spectrum use (i.e., against T. gondii tachyzoites and encysted bradyzoites and drug resistant Plasmodia). For example, in certain embodiments, the disclosure provides a next generation anti-apicomplexan lead compound, JAG21, a tetrahydroquinolone, with increased sp3-character to improve parasite selectivity. Relative to other cytochrome b inhibitors, JAG21 has improved solubility and ADMET properties, without need for pro-drug. JAG21 significantly reduces Toxoplasma gondii tachyzoites and encysted bradyzoites in vitro, and in primary and established chronic murine infections. Moreover, JAG21 treatment leads to 100% survival. Further, JAG21 is efficacious against drug-resistant Plasmodium falciparum in vitro. Causal prophylaxis and radical cure are achieved after P. berghei sporozoite infection with oral administration of a single dose (2.5 mg/kg) or three days treatment at reduced dose (0.625 mg/kg/day), eliminating parasitemia and leading to 100% survival. Enzymatic, binding, and co-crystallography/pharmacophore studies demonstrate selectivity for apicomplexan relative to mammalian enzymes. JAG21 has significant promise as a pre-clinical candidate for prevention, treatment and cure of toxoplasmosis and malaria.
The present disclosure is related to novel quinolone-like inhibitors, tetrahydroquinolinones (THQs) as provided above, or a pharmaceutically acceptable salt thereof.
Another aspect of the disclosure provides nanoparticle formulations comprising one or more tetrahydroquinolinones as disclosed herein. In one embodiment, the disclosure provides a nanoparticle formulation including:
In certain embodiments, the particle comprises one or more compounds of formula (I),
In certain embodiments, m is 0 or 1. In certain embodiments, m is 0.
In certain embodiments, n is 0, 1, or 2. In certain embodiments, n is 0 or 1.
In certain embodiments, R1 is hydrogen, methyl, or ethyl. In certain embodiments, R1 is hydrogen or methyl. In certain embodiments, R1 is hydrogen.
In certain embodiments, R2 is hydrogen, methyl, ethyl, or —CH2OH. In certain embodiments, R2 is hydrogen, methyl, or ethyl. In certain embodiments, R2 is methyl, ethyl, or —CH2OH. In certain embodiments, R2 is methyl or —CH2OH. In certain embodiments, R2 is methyl.
In certain embodiments, each R3 is independently halogen, C1-C3 haloalkyl, C1-C3 alkoxy, or C1-C3 haloalkoxy. In certain embodiments, each R3 is independently halogen, methyl, trifluoromethyl, methoxy, or trifluoromethoxy. In certain embodiments, each R3 is independently halogen, trifluoromethyl, methoxy, or trifluoromethoxy.
In certain embodiments, each R3 is independently methyl, ethyl, or C1-C3 haloalkyl. In certain embodiments, each R4 is independently methyl, ethyl, or trifluoromethyl.
In an example embodiment, the compound of formula (I) is wherein
In an example embodiment, the compound of formula (I) is JAG021.
In certain embodiments, the particle comprises one or more compounds that are listed in Table 1.
In certain embodiments, the particle comprises one or more compounds that are disclosed in International Patent Publication WO 2017/112678, published 29 Jun. 2017, and incorporated herein by reference in its entirety (such as the compounds disclosed in the table at pages 141-145, and claims 20 and 21).
As noted above, the nanoparticle formulation of the disclosure as provided herein includes a dispersion of particles within the aqueous carrier fluid, the particles comprising a hydrophobic material. In certain embodiments, the hydrophobic material is hydroxyethyl cellulose (HEC).
The hydrophobic material may be present in an amount sufficient to form the particle. For example, in certain embodiments, the hydrophobic material is present in an amount in a range of 3 mg/mL to 7 mg/mL. In certain embodiments, the hydrophobic material is present in an amount in a range of 4 mg/mL to 7 mg/mL. In certain embodiments, the hydrophobic material is present in an amount in a range of 3 mg/mL to 6 mg/mL. In certain embodiments, the hydrophobic material is present in an amount in a range of 4 mg/mL to 6 mg/mL. In certain embodiments, the hydrophobic material is present in an amount in a range of 3 mg/mL to 5 mg/mL. In certain embodiments, the hydrophobic material is present in an amount in a range of 5 mg/mL to 7 mg/mL. In certain embodiments, the hydrophobic material is present in an amount of about 5 mg/mL.
As noted above, the particle also comprises a surfactant. In certain embodiments, the surfactant is polyethylene glycol sorbitan monooleate (e.g., Tween® 80).
The surfactant may be present in an amount sufficient to form the particle. For example, in certain embodiments, the surfactant is present in an amount in a range of 1 mg/mL to 3 mg/mL. In certain embodiments, the surfactant is present in an amount in a range of 1.5 mg/mL to 3 mg/mL. In certain embodiments, the surfactant is present in an amount in a range of 1.5 mg/mL to 2.5 mg/mL. In certain embodiments, the surfactant is present in an amount in a range of 1 mg/mL to 2.5 mg/mL. In certain embodiments, the surfactant is present in an amount in a range of 1 mg/mL to 2 mg/mL. In certain embodiments, the surfactant is present in an amount in a range of 2 mg/mL to 3 mg/mL. In certain embodiments, the surfactant is present in an amount of about 2 mg/mL.
Another aspect of the disclosure provides methods for treating an apicomplexan parasite infection. In certain embodiments of the methods of the disclosure, the apicomplexan parasite infection is a T. gondii infection.
In certain embodiments, such methods include administering to a subject in need thereof an amount effective to treat the infection of one or more of modulators of one or more of the genes listed in
In certain embodiments, the one or more modulators comprises one or more inhibitors (of up-regulated genes) or one or more of activators (of down-regulated genes) of one or more of the genes listed in
In certain embodiments, the methods for treating an apicomplexan parasite infection include administering to the subject an amount effective to treat the infection of one or more of inhibitors of up-regulated genes listed in
In certain embodiments, the inhibitor comprises an inhibitor selected from the group consisting of an antibody selective for the expressed protein from the one or more genes, and an inhibitory nucleic acid selective for the one or more gene selected from the group consisting of aptamer, small interfering RNA, small internally segmented interfering RNA, short hairpin RNA, microRNA, and antisense oligonucleotides.
In certain embodiments of the methods of the disclosure, the one or more of inhibitors, or one or more of activators, comprises a compound as described herein. For example, in certain embodiments, the compound may be a compound of formula (I). In another embodiment, the compound may be any one of compounds listed in Table 1. In another embodiment, the compound may be any one of compounds as disclosed in International Patent Publication WO 2017/112678 as noted above. In another embodiment, the compound is an activator of Ribosomal protein RPS13 (Row 24, ID #TGME49_270380).
In certain embodiments, the methods for treating an apicomplexan parasite infection include administering to a subject in need thereof an amount effective to treat the infection (i) one or more of eukaryotic initiation factor-2a kinase (eif2k) inhibitors selected from the group consisting of anti-eif2k antibody, anti-eif2k aptamer, eif2k small interfering RNA, eif2k small internally segmented interfering RNA, eif2k short hairpin RNA, eif2k microRNA, and eif2k antisense oligonucleotides, and (ii) one or more compounds as described here, such as the compounds of formula (I) as described herein, or compounds listed in Table 1, or compounds as disclosed in International Patent Publication WO 2017/112678 as noted above.
For example, in certain embodiments, the compound in (ii) is JAG021. In certain embodiments, JAG021 is administered as a nanoparticle formulation according to the disclosure.
As noted above, the disclosure also provides a method for identifying test compounds for apicomplexan parasite therapy. Such methods include identifying one or more of test compounds that modulate activity of one or more of the genes listed in
In certain embodiments, the identifying one or more test compounds includes identifying those that reduce activity and/or expression (e.g., inhibitors for up-regulated genes) or those that increase expression (e.g., activators for down-regulated genes) of one or more of the genes listed in
For example, in certain embodiments, the method comprises identifying one or more test compounds that reduce activity and/or expression of one or more gene comprises the gene listed in Table 3 as entry No. 213-937. In certain embodiments, the method comprises identifying one or more test compounds that reduce activity and/or expression of one or more gene listed in
As noted above, the disclosure also provides a method for diagnosing an apicomplexan parasite infection (such as a T. gondii infection). Such methods include:
For example, in certain embodiment, the method includes determining the expression level of one or more gene listed in Table 3 as entry No. 213-937, and/or determining an activity level of the protein product of one or more gene listed in Table 3 as entry No. 213-937.
In certain other embodiment, the method includes determining the expression level of one or more gene listed in
In certain other embodiment, the method includes determining the expression level of one or more gene listed in
In certain other embodiment, the method includes determining the expression level of Ribosomal protein RPS13 (Row 24, ID #TGME49_270380), and/or determining an activity level of the protein product of Ribosomal protein RPS13 (Row 24, ID #TGME49_270380).
In another aspect, the present disclosure provides pharmaceutical compositions comprising one or more of compounds as described herein (e.g., listed in claim 1 and/or with respect to formula (I)) and an appropriate carrier, solvent, adjuvant, or diluent. The exact nature of the carrier, solvent, adjuvant, or diluent will depend upon the desired use for the composition, and may range from being suitable or acceptable for veterinary uses to being suitable or acceptable for human use. The composition may optionally include one or more secondary therapeutic agents. In certain embodiments, the composition may include one or more secondary apicomplexan parasite infection therapeutic agents.
When used to treat or prevent such diseases, the compounds described herein may be administered singly, as mixtures of one or more compounds or in mixture or combination with other agents useful for treating such diseases and/or the symptoms associated with such diseases. The compounds may also be administered in mixture or in combination with agents useful to treat other disorders, such as steroids, methotrexate, etc. The compounds may be administered in the form of compounds per se, or as pharmaceutical compositions comprising a compound.
Pharmaceutical compositions comprising the compound(s) may be manufactured by means of conventional mixing, dissolving, granulating, dragee-making levigating, emulsifying, encapsulating, entrapping or lyophilization processes. The compositions may be formulated in conventional manner using one or more physiologically acceptable carriers, diluents, excipients or auxiliaries, which facilitate processing of the compounds into preparations, which can be used pharmaceutically.
The compounds may be formulated in the pharmaceutical composition per se, or in the form of a hydrate, solvate, N-oxide or pharmaceutically acceptable salt. Typically, such salts are more soluble in aqueous solutions than the corresponding free acids and bases, but salts having lower solubility than the corresponding free acids and bases may also be formed.
Pharmaceutical compositions may take a form suitable for virtually any mode of administration, including, for example, topical, ocular, oral, buccal, systemic, nasal, injection, transdermal, rectal, vaginal, etc., or a form suitable for administration by inhalation or insufflation.
For prolonged delivery, the compound(s) can be formulated as a depot preparation for administration by implantation or intramuscular injection. The compound(s) may be formulated with suitable polymeric or hydrophobic materials (e.g., as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, e.g., as a sparingly soluble salt. Alternatively, transdermal delivery systems manufactured as an adhesive disc or patch, which slowly releases the compound(s) for percutaneous absorption may be used. To this end, permeation enhancers may be used to facilitate transdermal penetration of the compound(s).
Alternatively, other pharmaceutical delivery systems may be employed. Liposomes and emulsions are well-known examples of delivery vehicles that may be used to deliver compound(s). Certain organic solvents such as dimethyl sulfoxide (DMSO) may also be employed, although usually at the cost of greater toxicity.
The pharmaceutical compositions may, if desired, be presented in a pack or dispenser device, which may contain one or more unit dosage forms containing the compound(s). The pack may, for example, comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be accompanied by instructions for administration.
The compound(s) described herein, or compositions thereof, will generally be used in an amount effective to achieve the intended result, for example in an amount effective to treat or prevent the particular disease being treated. By therapeutic benefit is meant eradication or amelioration of the underlying disorder being treated and/or eradication or amelioration of one or more of the symptoms associated with the underlying disorder such that the patient reports an improvement in feeling or condition, notwithstanding that the patient may still be afflicted with the underlying disorder. Therapeutic benefit also generally includes halting or slowing the progression of the disease, regardless of whether improvement is realized.
The amount of compound(s) administered will depend upon a variety of factors, including, for example, the particular indication being treated, the mode of administration, whether the desired benefit is prophylactic or therapeutic, the severity of the indication being treated and the age and weight of the patient, the bioavailability of the particular compound(s) the conversation rate and efficiency into active drug compound under the selected route of administration, etc.
Determination of an effective dosage of compound(s) for a particular use and mode of administration is well within the capabilities of those skilled in the art. Effective dosages may be estimated initially from in vitro activity and metabolism assays. For example, an initial dosage of compound for use in animals may be formulated to achieve a circulating blood or serum concentration of the metabolite active compound that is at or above an IC50 of the particular compound as measured in as in vitro assay. Calculating dosages to achieve such circulating blood or serum concentrations taking into account the bioavailability of the particular compound via the desired route of administration is well within the capabilities of skilled artisans. Initial dosages of compound can also be estimated from in vivo data, such as animal models. Animal models useful for testing the efficacy of the active metabolites to treat or prevent the various diseases described above are well-known in the art. Animal models suitable for testing the bioavailability and/or metabolism of compounds into active metabolites are also well-known. Ordinarily skilled artisans can routinely adapt such information to determine dosages of particular compounds suitable for human administration.
Dosage amounts will typically be in the range of from about 0.0001 mg/kg/day, 0.001 mg/kg/day or 0.01 mg/kg/day to about 100 mg/kg/day, but may be higher or lower, depending upon, among other factors, the activity of the active compound, the bioavailability of the compound, its metabolism kinetics and other pharmacokinetic properties, the mode of administration and various other factors, discussed above. Dosage amount and interval may be adjusted individually to provide plasma levels of the compound(s) and/or active metabolite compound(s), which are sufficient to maintain therapeutic or prophylactic effect. For example, the compounds may be administered once per week, several times per week (e.g., every other day), once per day or multiple times per day, depending upon, among other things, the mode of administration, the specific indication being treated and the judgment of the prescribing physician. In cases of local administration or selective uptake, such as local topical administration, the effective local concentration of compound(s) and/or active metabolite compound(s) may not be related to plasma concentration. Skilled artisans will be able to optimize effective dosages without undue experimentation.
The following terms and expressions used herein have the indicated meanings.
Throughout this specification, unless the context requires otherwise, the word “comprise” and “include” and variations (e.g., “comprises,” “comprising,” “includes,” “including”) will be understood to imply the inclusion of a stated component, feature, element, or step or group of components, features, elements or steps but not the exclusion of any other integer or step or group of integers or steps.
As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
Terms used herein may be preceded and/or followed by a single dash, “—”, or a double dash, “=”, to indicate the bond order of the bond between the named substituent and its parent moiety; a single dash indicates a single bond and a double dash indicates a double bond or a pair of single bonds in the case of a spiro-substituent. In the absence of a single or double dash it is understood that a single bond is formed between the substituent and its parent moiety; further, substituents are intended to be read “left to right” unless a dash indicates otherwise. For example, alkyl, alkyl-, and -alkyl indicate the same functionality.
Further, certain terms herein may be used as both monovalent and divalent linking radicals as would be familiar to those skilled in the art, and by their presentation linking between two other moieties. For example, an alkyl group can be both a monovalent radical or divalent radical; in the latter case, it would be apparent to one skilled in the art that an additional hydrogen atom is removed from a monovalent alkyl radical to provide a suitable divalent moiety.
The term “alkoxy” as used herein, means an alkyl group, as defined herein, appended to the parent molecular moiety through an oxygen atom. Representative examples of alkoxy include, but are not limited to, methoxy, ethoxy, propoxy, 2-propoxy, butoxy, tert-butoxy, pentyloxy, and hexyloxy.
The term “alkyl” as used herein, means a straight or branched chain hydrocarbon containing from 1 to 10 carbon atoms, unless otherwise specified. Representative examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, n-octyl, n-nonyl, and n-decyl. When an “alkyl” group is a linking group between two other moieties, then it may also be a straight or branched chain; examples include, but are not limited to —CH2, —CH2CH2, —CH2CH2CHC(CH3)—, —CH2CH(CH2CH3)CH2—.
The term “halo” or “halogen” as used herein, means —Cl, —Br, —I or —F.
The terms “haloalkyl” and “haloalkoxy” refer to an alkyl or alkoxy group, as the case may be, which is substituted with one or more halogen atoms.
The term “hydroxy” as used herein, means an —OH group.
The term “substituted”, as used herein, means that a hydrogen radical of the designated moiety is replaced with the radical of a specified substituent, provided that the substitution results in a stable or chemically feasible compound. The term “substitutable”, when used in reference to a designated atom, means that attached to the atom is a hydrogen radical, which can be replaced with the radical of a suitable substituent.
It will be apparent to one skilled in the art that certain compounds of this disclosure may exist in tautomeric forms, all such tautomeric forms of the compounds being within the scope of the disclosure. Unless otherwise stated, structures depicted herein are also meant to include all stereochemical forms of the structure; i.e., the R and S configurations for each asymmetric center. Therefore, single stereochemical isomers as well as enantiomeric and diastereomeric mixtures of the present compounds are within the scope of the disclosure. Both the R and the S stereochemical isomers, as well as all mixtures thereof, are included within the scope of the disclosure.
“Pharmaceutically acceptable” refers to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problems or complications commensurate with a reasonable benefit/risk ratio or which have otherwise been approved by the United States Food and Drug Administration as being acceptable for use in humans or domestic animals.
“Pharmaceutically acceptable salt” refers to both acid and base addition salts.
As used herein, the term “cell” is meant to refer to a cell that is in vitro, ex vivo or in vivo. In some embodiments, an ex vivo cell can be part of a tissue sample excised from an organism such as a mammal. In some embodiments, an in vitro cell can be a cell in a cell culture. In some embodiments, an in vivo cell is a cell living in an organism such as a mammal.
As used herein, the term “contacting” refers to the bringing together of indicated moieties in an in vitro system or an in vivo system. For example, “contacting” a parasite with a compound includes the administration of a compound described herein to an individual or patient, such as a human, infected with the parasite, as well as, for example, introducing a compound into a sample containing a cellular or purified preparation containing the parasite.
As used herein, the term “individual” or “patient,” or “subject” used interchangeably, refers to any animal, including mammals, preferably mice, rats, other rodents, rabbits, dogs, cats, swine, cattle, sheep, horses, or primates, and most preferably humans.
As used herein, the phrase “amount effective”, “therapeutically effective amount” or “effective to treat” refers to the amount of active compound or pharmaceutical agent that elicits the biological or medicinal response that is being sought in a tissue, system, animal, individual or human by a researcher, veterinarian, medical doctor or other clinician.
In certain embodiments, a therapeutically effective amount can be an amount suitable for
(1) preventing the disease; for example, preventing a disease, condition or disorder in an individual who may be predisposed to the disease, condition or disorder but does not yet experience or display the pathology or symptomatology of the disease;
(2) inhibiting the disease; for example, inhibiting a disease, condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder; or
(3) ameliorating the disease; for example, ameliorating a disease, condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder (i.e., reversing the pathology and/or symptomatology) such as decreasing the severity of disease.
Many general references providing commonly known chemical synthetic schemes and conditions useful for synthesizing the disclosed compounds are available (see, e.g., Smith and March, March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, Fifth Ed., Wiley-Interscience, 2001; or Vogel, A Textbook of Practical Organic Chemistry, Including Qualitative Organic Analysis, Fourth Ed., New York: Longman, 1978).
Compounds as described herein can be purified by any of the means known in the art, including chromatographic means, such as HPLC, preparative thin layer chromatography, flash column chromatography and ion exchange chromatography. Any suitable stationary phase can be used, including normal and reversed phases as well as ionic resins. Most typically, the disclosed compounds are purified via silica gel and/or alumina chromatography. See, e.g., Introduction to Modern Liquid Chromatography, 2nd Edition, ed. L. R. Snyder and J. J. Kirkland, John Wiley and Sons, 1979; and Thin Layer Chromatography, ed E. Stahl, Springer-Verlag, New York, 1969.
During any of the processes for preparation of the subject compounds, it may be necessary and/or desirable to protect sensitive or reactive groups on any of the molecules concerned. This may be achieved by means of conventional protecting groups as described in standard works, such as J. F. W. McOmie, “Protective Groups in Organic Chemistry,” Plenum Press, London and New York 1973, in T. W. Greene and P. G. M. Wuts, “Protective Groups in Organic Synthesis,” Third edition, Wiley, New York 1999, in “The Peptides”; Volume 3 (editors: E. Gross and J. Meienhofer), Academic Press, London and New York 1981, in “Methoden der organischen Chemie,” Houben-Weyl, 4.sup.th edition, Vol. 15/A, Georg Thieme Verlag, Stuttgart 1974, in H.-D. Jakubke and H. Jescheit, “Aminosauren, Peptide, Proteine,” Verlag Chemie, Weinheim, Deerfield Beach, and Basel 1982, and/or in Jochen Lehmann, “Chemie der Kohlenhydrate: Monosaccharide and Derivate,” Georg Thieme Verlag, Stuttgart 1974. The protecting groups may be removed at a convenient subsequent stage using methods known from the art.
The compounds disclosed herein can be made using procedures familiar to the person of ordinary skill in the art and as described herein. For example, compounds of structural formula (I) can be prepared according to general procedures (below), and/or analogous synthetic procedures. One of skill in the art can adapt the reaction sequences of Example 1 and general procedures to fit the desired target molecule. Of course, in certain situations one of skill in the art will use different reagents to affect one or more of the individual steps or to use protected versions of certain of the substituents. Additionally, one skilled in the art would recognize that compounds of the disclosure can be synthesized using different routes altogether.
The preparation and methods of use of the compounds of the disclosure are illustrated further by the following examples, which are not to be construed as limiting the disclosure in scope or spirit to the specific methods and compounds described in them.
The THQ compounds were synthesized as described below. 10 mM stock solutions were made with 100% Dimethyl Sulfoxide (DMSO) and working concentrations were made with IMDM-C(1×, [+] glutamine, [+] 25 mM HEPES, [−] Phenol red, 10% FBS)[Gibco, Denmark]). Final compounds had >95% purity determined by high performance liquid chromatography (HPLC), high resolution mass spectrometry and NMR spectrometry. Liquid chromatography-mass spectrometry (LC-MS) and NMR spectrometry were used to determine the integrity and purity of all intermediates. THQ compounds were synthesized as described in Schemes 1 and 2, which describe compounds MJM170 and JAG21 as exemplars.
Scheme 2 provides two different routes to analogues of 7, route A or route B. Route A is a linear route to analogues requiring a Suzuki step to intermediate 12 from intermediates 4 and 10. Route B allows quicker access to analogues from intermediate 15 and derivatives can be synthesised via the Chan-Lam reaction to give final intermediate 12 by varying the boronic acid 16.
Platinum oxide (0.100 g, 10 mol %) was added to a solution of 4-hydroxy-2-methylquinoline (1, 1.00 g, 6.28 mmol, 1.00 eq) in glacial N acetic acid (10.0 mL). The heterogeneous mixture was catalytically H hydrogenated under a balloon of hydrogen. After 22 hrs, TLC (10% MeOH-DCM) confirmed complete reaction. The mixture was filtered through celite under vacuum, washing thoroughly with EtOAc (50 mL). The filtrate was concentrated and the resulting residue purified by column chromatography (10% MeOH-DCM) to give the desired product as a pale yellow oil (0.917 g, 5.65 mmol, 89%); Rf 0.14 (10% MeOH-DCM); δH (300 MHz, CDCl3) 1.74-1.76 (4H, m, CH2), 2.29 (3H, s, Me), 2.49-2.52 (2H, m, CH2), 2.67-2.70 (2H, m, CH2), 6.16 (1H, s, Ar—H); bc (125 MHz, CDCl3) 19.0 (Me), 21.8 (CH2), 22.1 (CH2), 27.1 (CH2), 112.5 (CH), 122.4 (Cq), 146.4 (Cq), 147.0 (Cq), 178.3 (Cq); Spectroscopic data consistent with literature values (JMC, 1993, 36, 1245-54).
nButylamine (6.20 mL, 62.8 mmol, 10.0 eq) was added to a suspension of 2-methyl-5,6,7,8-tetrahydroquinolin-4-one (2, 1.02 g, 6.28 mmol, 1.00 eq) in DMF (10.0 mL). To this heterogeneous mixture was added I2 (1.60 g, 6.28 mmol, 1.00 eq) in a saturated solution of KI (6.00 mL). After 20 hrs stirring at R.T., a precipitate formed in the orange solution, excess iodine was quenched with 0.1 M sodium thiosulfate solution (10.0 mL). The precipitate was filtered by vacuum filtration, washed with distilled H2O and dried (Na2SO4) to give the desired product as a colorless solid (1.76 g, 6.09 mmol, quantative yield); δH (300 MHz, DMSO-de) 1.61-1.70 (4H, m, CH2), 2.29 (2H, t, J 6.0, CH2), 2.43 (2H, s, CH2), CH3 under DMSO peak.
Potassium carbonate (1.53 g, 11.1 mmol, 2.00 eq) was added to a heterogeneous mixture of 2-methyl-3-iodo-5,6,7,8-tetrahydroquinolin-4-one (3, 1.60 g, 5.56 mmol, 1.00 eq) in DMF (15.0 mL), and the reaction heated to 50° C. for 30 minutes. The R.B. flask was removed from the heating mantle and ethyl iodide (0.67 mL, 8.33 mmol, 1.50 eq) was added dropwise. The reaction was then heated at 50° C. for 18 hrs. The reaction was cooled to R.T., quenched with water (40 mL). The resulting emulsion formed which was extracted with EtOAc (50 mL). EtOAc layer were washed with water (3×30 mL), brine (3×30 mL), dried (Na2SO4) and concentrated to give a pale yellow oil (1.09 g, 3.44 mmol, 61%); Rf 0.88 (1:1 Pet-EtOAc); HPLC (RT=1.67 minutes); LCMS (Method A), (RT=1.6 min, m/z (ES) Found MH+ 318.0); δH (500 MHz, CDCl3) 1.49 (3H, t, J 7.0, ethoxy CH3), 1.73-1.78 (2H, m, CH2) 1.84-1.88 (2H, m, CH2), 2.78-2.69 (5H, m, CH2 & CH3), 2.84 (2H, t, J 6.5, CH2), 3.97 (2H, q, J 7.0, OCH2); bc (125 MHz, CDCl3) 15.6 (CH3), 22.3 (CH2), 22.8 (CH2), 23.6 (CH2), 29.3 (CH3), 32.0 (CH2), 68.4 (OCH2), 90.9 (Cq), 124.5 (Cq), 158.3 (Cq), 158.9 (Cq), 163.9 (Cq).
2-Methyl-3-iodo-4-ethoxy-5,6,7,8-tetrahydroquinoline (4, 0.266 g, 0.839 mmol, 1.00 eq), Pd(PPh3)4 (0.048 g, 0.0419 mmol, 5 mol %) and 4-phenoxyphenylboronic acid (5, 0.270 g, 1.26 mmol, 1.50 eq) were charged to a R.B. flask under N2(g). Degassed DMF (10.0 mL) was added to the flask followed by 2M K2CO3 (1.60 mL). The flask was heated to 85° C. under N2(g). After 15 minutes, TLC (4:1 Pet-EtOAc) confirmed reaction was complete. The reaction was cooled and diluted with EtOAc (15 mL), filtered through celite and partitioned between EtOAc (10 mL) and H2O (25 mL). Combined organics were washed with H2O (3×30 mL), then brine (3×30 mL), dried (Na2SO4) and concentrated to give a red oil which was purified by column chromatography (3:1 Pet-EtOAc), to give the desired product as a pale yellow oil (0.235 g, 0.655 mmol, 78%); Rf 0.31 (3:1 Pet-EtOAc); HPLC (RT=3.08 minutes); bH (300 MHz, CDCl3) 1.04 (3H, t, J 7.0, ethoxy CH3), 1.76-1.93 (4H, m, 2×CH2), 2.32 (3H, s, CH3) 2.72 (2H, t, J 6.0, CH2), 2.91 (2H, t, J 6.5, CH2), 3.50 (2H, q, J 7.0, OCH2), 7.05-7.16 (5H, m, Ar—H), 7.20-7.29 (2H, m, Ar—H), 7.31-7.43 (2H, m, Ar—H); δc (125 MHz, CDCl3) 15.7 (CH3), 22.5 (CH2), 23.0 (CH3), 23.3 (CH2), 23.4 (CH2), 32.7 (CH2), 68.2 (OCH2), 118.6 (CH), 118.9 (CH), 123.4 (CH), 126.8 (Cq), 129.8 (CH), 131.5 (CH), 154.9 (Cq), 156.5 (Cq), 157.1 (Cq), 157.3 (Cq); m/z (ES) (Found: MH+, 360.1973. C24H2eNO2 requires MH, 360.1964).
Aqueous hydrobromic acid (>48%) (1.00 mL) was added to a solution of 2-methyl-3-(4-phenoxyphenyl)-4-ethoxy-5,6,7,8-tetrahydroquinoline (6, 0.226 g, 0.630 mmol, 1.00 eq) in glacial acetic acid (2 mL). The reaction was stirred at 90° C. for 5 days, monitoring by LMCS. The reaction was cooled to R.T. and the pH adjusted to pH 5 with 2M NaOH. The precipitate was collected by vacuum filtration and recrystallized from MeOH:H2O to give the desired product as an off-white solid (0.155 g, 0.467 mmol, 74%); HPLC (RT=2.56 minutes); δH (500 MHz, DMSO-de) 1.66-1.72 (4H, m, 2×CH2), 2.08 (3H, s, CH3) 2.31 (2H, t, J 6.0, CH2), 2.56 (2H, t, J 6.0, CH2), 6.99 (2H, d, J 8.5, Ar—H), 7.06 (2H, d, J 7.5, Ar—H), 7.14-7.18 (3H, m, Ar—H), 7.40-7.43 (2H, m, Ar—H), 11.0 (1H, s, NH); 6c (125 MHz, DMSO-de) 17.7 (CH3), 21.5 (CH2), 21.8 (CH2), 21.9 (CH2), 26.2 (CH2), 117.8 (CH), 118.6 (CH), 121.2 (Cq), 123.3 (CH), 123.7 (Cq), 130.0 (CH), 131.4 (Cq), 132.3 (CH), 142.3 (Cq), 143.2 (Cq), 155.0 (Cq), 156.8 (Cq), 175.4 (Cq); m/z (ES) (Found: MH, 332.1654. C22H22NO2 requires MH, 332.1645).
Copper (II) acetate (0.435 g, 2.39 mmol, 1.00 eq) was added to a suspension of 4-bromophenol (8, 0.414 g, 2.39 mmol, 1.00 eq), 4-trifluoromethoxybenzeneboronic acid (9, 0.983 g, 4.79 mmol, 2.00 eq) and 4 Å molecular sieves (0.566 g) in DCM (12 mL) at R.T. A solution of triethylamine (1.7 mL, 11.9 mmol, 5.00 eq) and pyridine (1 mL, 11.9 mmol, 5.00 eq) was added and the reaction was stirred for 16 hrs, open to the atmosphere. After 18 hrs, the reaction was quenched with 0.5 M HCl (20 mL) and the organic layer washed with water (20 mL), brine (20 mL), dried (Na2SO4) and concentrated to give a red oil which was purified by column chromatography (hexane) to give the desired product as a colorless oil (0.582 g, 1.75 mmol, 73%); Rr 0.58 (hexane).
2-Methyl-3-iodo-4-ethoxy-5,6,7,8-tetrahydroquinoline (4, 0.400 g, 1.26 mmol, 1.00 eq), Pd(PPh3)4(0.073 g, 0.06 mmol, 5 mol %) and 4-hydroxylphenylboronic acid (14, 0.260 g, 1.89 mmol, 1.50 eq) were charged to a R.B. flask under N2(g). Degassed DMF (10.0 mL) was added to the flask followed by 2M K2CO3 (3.00 mL). The flask was heated to 85° C. under N2(g). After 3 hrs, TLC (EtOAc) confirmed reaction was complete. The reaction was cooled to 50° C., diluted with EtOAc (15 mL) and activated charcoal was added. After stirring for 30 minutes, the mixture was filtered through celite and partitioned between EtOAc (10 mL) and H2O (25 mL). Combined organics were washed with H2O (3×30 mL), then brine (3×30 mL), dried (Na2SO4) and concentrated to give a brown solid which was triturated with diethyl ether to give the desired product as a pale red crystalline solid (0.220 g, 0.777 mmol, 60%); Rf 0.22 (EtOAc); m.p. 225-226° C. (EtOAc); 6H (500 MHz, MeOD-d4) 7.07 (d, J=8.6 Hz, 2H, H-3 & 5), 6.86 (d, J=8.6 Hz, 2H, H-2 & 6), 3.51 (q, J=7.0 Hz, 2H, CH3CH2O), 2.83 (t, J=6.3 Hz, 2H, H-8′), 2.72 (t, J=6.1 Hz, 2H, H-5′), 2.23 (s, 3H, Me), 1.95-1.72 (m, 4H, H-6′ & 7′), 1.00 (t, J=7.0 Hz, 3H, CH3CH2O); bc (125 MHz, MeOD-d4) 164.0 (Cq), 158.1 (C-1), 157.4 (Cq), 156.1 (Cq), 132.2 (C-3 & 5), 129.1 (Cq), 127.9 (Cq), 124.9 (Cq), 116.2 (CH), 69.1 (OCH2), 32.7 (CH2), 23.9 (CH2), 23.4 (CH3), 22.9 (CH2), 22.3 (CH2), 15.7 (CH3); m/z (ES) (Found MH+, 284.1664, C1eH21NO2 requires MH, 284.1651).
1-(4-bromophenyl)-4-(trifluoromethoxy) benzene (10, 0.100 g, 0.30 mmol, 1.00 eq), bis(pinacolato) diboron (1.10 eq), potassium acetate (3.00 eq) and Pd(dppf)Cl2 (0.03 eq) were added to a oven-dried flask under inert (N2) atmosphere. Anhydrous DMF (6 mL) was added and the reaction heated to 80° C. under N2 (g). After 22 hrs, the reaction was cooled to R.T., fresh Pd(dppf)Cl2 (0.03 eq) added, followed by 2-methyl-3-iodo-4-ethoxy-5,6,7,8-tetrahydroquinoline (4, 0.400 g, 1.26 mmol, 2.00 eq) and 2M Na2CO3 (2.9 mL). The reaction was heated to 80° C. for 20 hrs, cooled, diluted with EtOAc (20 mL), filtered through celite and partitioned between EtOAc (20 mL) and H2O (20 mL). Combined organics were washed with brine (3×20 mL), dried (Na2SO4) and concentrated to give a brown solid which was purified by column chromatography (3:1 Pet-EtOAc) to give the desired product as a colorless oil (30 mg, 0.07 mmol, 23%); HPLC (RT=2.41 minutes); 6H (500 MHz, acetone) 7.28 (d, J=8.7 Hz, 2H, H-2′ & 6′), 7.26 (d, J=9.1 Hz, 2H, H-2″ & 6″), 7.09 (d, J=9.1 Hz, 2H, H-3″ & 5″), 7.07 (d, J=8.7, 2H, H-3′ & 5′), 3.52 (q, J=7.0 Hz, 2H, CH3CH2O), 2.85 (t, J=6.5 Hz, 2H, H-8), 2.78 (t, J=6.2 Hz, 2H, H-5), 2.26 (s, 3H, Me), 1.89-1.81 (m, 2H, H-7), 1.81-1.72 (m, 2H, H-6), 0.93 (t, J=7.0 Hz, 3H, CH3CH2O); bc (125 MHz, acetone) δ 161.9 (Cq), 157.1 (Cq), 156.5 (Cq), 156.0 (Cq), 154.5 (Cq), 145.3 (Cq), 132.5 (Cq), 132.0 (CH), 126.7 (Cq), 123.0 (CH), 119.8 (CH), 119.0 (CH), 68.0 (OCH2), 32.5 (CH2), 23.0 (CH2), 22.9 (CH3), 22.7 (CH2), 22.5 (CH2), 15.05 (CH3); m/z (ES) (Found: MH*, 444.1792. C25H24F3NO3 requires MH, 444.1781).
Aqueous hydrobromic acid (>48%) (1.00 mL) was added to a solution of 2-methyl-3-(4-phenoxyphenyl)-4-ethoxy-5,6,7,8-tetrahydroquinoline (12, 30.0 mg, 0.07 mmol, 1.00 eq) in glacial acetic acid (2 mL). The reaction was stirred at 90° C. for 3 days, monitoring by LMCS. The reaction was cooled to R.T. and the pH adjusted to pH 5 with 2M NaOH. The precipitate was collected by vacuum filtration and recrystallized from MeOH:H2O to give the desired product as a colorless solid (25.0 mg, 0.06 mmol, 68%); m.p.>250° C.; HPLC (RT=2.78 minutes); δH (500 MHz, DMSO-de) 11.07 (s, 1H, NH), 7.40 (d, J=8.5 Hz, 2H, H-2′ & 6′), 7.19 (d, J=8.6 Hz, 2H, H-3″ & 5″), 7.13 (d, J=9.0 Hz, 2H, H-3′ & 5′), 7.02 (d, J=8.5 Hz, 2H, H-2″ & 6″), 2.54 (t, J=6.0 Hz, 2H, H-8), 2.28 (t, J=5.9 Hz, 2H, H-5), 2.07 (s, 3H, Me), 1.71 (m, 2H, H-7), 1.65 (m, 2H, H-6); δc (125 MHz, DMSO-do) 175.7 (Cq), 155.9 (Cq), 154.5 (Cq), 143.5 (Cq), 143.2 (Cq), 142.2 (Cq), 132.5 (CH), 132.2 (Cq), 123.6 (Cq), 123.0 (CH), 121.3 (Cq), 119.6 (CH), 118.2 (CH), 26.2 (CH2), 21.9 (CH2) 21.8 (CH2), 21.5 (CH2), 17.7 (CH3); m/z (ES) (Found: MH, 416.1492. C23H20F3NO3 requires MH, 416.1473).
Building blocks 1, 8, 9 and 14 were varied to create the complete series shown in Table 1, which provides characteristics and effects of compounds on inhibition of T.gondii replication and enzyme activity of the compounds of the disclosure (solubility in PBS 7.4, toxicity against HFF, predicted half-life, and inhibitory effect of compounds on RH strain tachyzoites and EGS strain bradyzoites in vitro and saffarine 0 assay enzyme activity). PBS Sol/Toxicity pH7.4 refers to solubility of the compound in Phosphate Buffered Saline (PBS) at pH7.4. Toxicity refers to the highest concentration tested that does not show toxicity to Human Foreskin Fibroblast (HFF) in tissue culture in WST assay; T1/2(H) refers to the predicted half-life in human liver microsomes; T12 (M) refers to the predicted half-life in mouse liver microsomes. Tachy/Brady IC50 was determined in studies in which cultures of parasites in HFF were treated with varying concentrations of the compound and there was 50% inhibition of the replication (number) of parasites. Parasites were RH-YFP expressing tachyzoites (Tachy) and EGS (Brady) strains. Studies of effects of inhibitors on HFF or on T.gondii tachyzoites were performed with triplicate wells in at least two biological replicate experiments. Studies of effects on bradyzoites were performed at least twice in at least two biological replicate experiments. Compounds with much less inhibition of mammalian than T. gondii cytochrome bc in the saffarine enzyme assay (indicated by **) provide potential to further develop compounds, if unanticipated toxicity occurs from JAG21.
Toxoplasma gondii:
Parasite Strains (Isolates). RH-YFP tachyzoites, (McPhillie et al, 2016; Fomovska et al, 2012; Gubbels et al, 2003), EGS strain (Vidigal et al 2015; Paredes-Santos et al 2012; McPhillie et al, 2016), Pru-luciferase, Me49, and RPS13Δ on the RH strain background (Hutson et al, 2010) were prepared and passaged in human foreskin fibroblasts [HFF] as described.
In Vitro Challenge Assay for T.gondii
RH strain YFP Tachyzoites. Protocol was adapted from Fomovska et al. (2012; 2012a) for HFF. HFF were cultured on a flat, clear-bottomed, black 96-well plate to 90%-100% confluence. IMDM (1×, [+] glutamine, [+] 25 mM HEPES, [+] Phenol red, 10% FBS [Gibco, Denmark]) was removed and replaced with IMDM-C(1×, [+] glutamine, [+] 25 mM HEPES, [−] Phenol red, 10% FBS)[Gibco, Denmark]). RH-YFP, lysed from host cells by passing twice through a 27-gauge needle, were counted, then diluted to 32,000/mL in IMDM-C. HFF were infected with 3200 RH-YFP, then returned to 37° C., CO2 (5%) incubator for 1-2 hours for infection. Various concentrations of the compounds in 20 μL IMDM-C were added to each well. There were triplicates for each condition. Controls were pyrimethamine/sulfadiazine (standard treatment), 0.1% DMSO only, HFF only, and untreated cultures of HFF infected with 2 fold dilutions of YFP expressing parasites (called “YFP gradient” to establish amount of color from known numbers of YFP expressing parasites). Cells were incubated at 37° C. for 72 hours. Plates were read using a fluorimeter (Synergy H4 Hybrid Reader, BioTek) to ascertain amount of relative fluorescence units (RFU) YFP, to measure parasite burden after treatment. Data were collected using Gen5 software with IC50 calculated by graphical analysis in Excel.
An initial screening assay of 10 μM, 1 μM, 100 nM, and 10 nM of the compounds was performed. Compounds were not considered effective or pursued for further analysis if there was no inhibition of tachyzoites at 1 μM. If compounds were effective at 1 μM, another experiment was performed to assess effect at 1 μM, 500 nM, 250 nM, 125 nM, 62.5 nM, and 31.25 nM.
Cytotoxicity Assays in parallel with RH Strain T.gondii in vitro studies. Toxicity assays used WST-1 cell proliferation reagent (Roche) as in Fomovska et al. (2012). HFF were grown on a flat, clear-bottomed, black 96-well plate. Confluent HFF were treated with inhibitory compounds at concentrations of 10 μM and 50 μM. Compounds were diluted in IMDM-C, and 20 μL were added to each designated well, with triplicates for each condition. A gradient with 2 fold-decreasing concentrations of DMSO from 10% to 0% in colorless, translucent IMDM-C was used as a control. The plate was incubated for 72 hours at 37° C. 10 μL WST-1 reagent (Roche) were added to each well. Cells were incubated for 30-60 minutes. Absorbance was read using a fluorimeter at 420 nm. A higher degree of color change (and absorbance) indicated mitochondrial activity and cell viability.
In vitro Challenge Assay for EGS strain Bradyzoites. HFF cells were grown in IMDM on removable, sterile glass cover slips in the bottom of a clear, flat-bottomed 24-well plate. Cultures were infected with 3×104 EGS strain parasites per well, in 0.5 mL media. The plate was returned to incubator at 37° C. overnight. The following day, the media was removed. Colorless IMDM and compounds were added to make various concentrations of the drug. Total volume was 0.5 mL 2 wells had media only, as a control. Plates were returned to the 37° C. incubator for 72 hours, checked once each 24 hours. If tachyzoites were visible in the control before 72 hours, cells were fixed and stained.
Cells were fixed using 4% paraformaldehyde and stained with Fluorescein-labeled Dolichos Biflorus Agglutinin, DAPI, and BAG1. Disks were removed, mounted on glass slides, and visualized using microscopy (Nikon T17). Slides were scanned using a CRi Panoramic Scan Whole Slide Scanner and viewed using Panoramic Viewer Software. Effects of compounds were quantitated by counting cysts in controls and treated cultures. Dolichos staining delimited structures and single organisms that remained were counted in a representative field of view. This was then multiplied by a factor determined by the total area of the cover slip in order to estimate the number of cysts and organisms in each condition. When the following forms were observed: “true cysts” with a dolichos-staining wall, “pseudocysts” or tight clusters of parasites, and small organisms, if there were fewer than four parasites visible in a cluster, organisms were counted individually (as “small organisms”). The entire scanned coverslip with all fields was also reviewed by 3 observers to confirm consistency.
Synergy studies with RH strain YFP Tachyzoites. Atovaquone and pyrimethamine were used to test whether they are synergistic with JAG21. Serial dilutions of the combination of JAG21 and either atovaquone or pyrimethamine were used in an in vitro challenge assay as described above. The EC50 of each compound and the combination of two compounds were determined. The effect of the combination of drugs was calculated with the following formula: C=[A]c/[A]a+[B]c/[B]a. If C is lower than 1, the two compounds tested have synergistic effect; if C is greater than 1, the two compounds tested have antagonist effect and if C is 1 they are additive.
T.gondii and HFF Mitochondrial Membrane Potential Measurements—the mitochondrial membrane potential was measured by the safranine method according to Vercesi et al, 1998). Freshly egressed T. gondii tachyzoites were filtered and washed twice with intracellular buffer (125 mM sucrose, 65 mM KCl, 10 mM HEPES-KOH buffer, pH 7.2, 1 mM MgCl2 and 2.5 mM potassium phosphate). After washing, the parasites were resuspended in the same buffer at 109/ml. An aliquot of 50 μL of this suspension was added to a cuvette containing Safranin 0, 2.5 μM and Succinate 1 mM in final volume of 2 mL of the intracellular buffer. The fluorescence was measured with a Hitachi 7000 spectrofluorometer with setting Ex. 495/Em. 586. Once the baseline fluorescence is testable, 30 μM digitonin was added to permeabilize the parasites. 85 seconds after permeabilization, the THQ derivatives, dissolved in DMSO, were added. 5 μM of FCCP (Carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone) was used as an uncoupler reference for calculations and its effect was considered 100%. Similar conditions for measuring the mitochondrial potential of mammalian cells were used with the following changes: the mammalian cells were re-suspended at 108/ml. 50 μl of mammalian cells was also used for each run in a cuvette with 2 μl solutions. The substrate used for mammalian cells was 5 mM glutamate and 5 mM malate. A higher concentration of digitonin (50 μM) was used to permeabilize the mammalian cells. The compounds were added at about 400 seconds after permeabilization. Each experiment was repeated at least three times in duplicates. Statistical analysis, unpaired student t test, was performed using GraphPad Prism 8.0 (GraphPad Software, Inc., San Diego, Calif.).
Structure Activity Relationship (SAR) and comparison of effect on T.gondii and HFF enzyme activity. The effects of changing R1 as 7-Et, 7-Me, 6-CF3, or 6-Me on activity against RH strain tachyzoites, kinetic solubility, and metabolic stability were compared. Kinetic solubility and metabolic stability in human or murine liver microsomes were measured. The hERG (human Ether-à-go-go-Related) liability was also determined. The hERG gene (KCNH2) encodes a protein Kv11.1, the alpha subunit of a potassium ion channel. This channel conducts the rapid component of the delayed rectifier potassium current, IKr, which is critical for repolarization of cardiac action potentials. A reduction in hERG currents from adverse drug effects can lead to long QT interval syndromes. These syndromes are characterized by action potential prolongation, lengthening of the QT interval on surface EKG, and an increased risk for “torsade de pointes” arrhythmias and sudden death. The MDCK-MDR1 Permeability Assay was also performed. MDCK-MDR1 refers to the ability of a compound to permeate across membranes of MDCK-MDR1 (Madin Darby canine kidney [MDCK] cells with the MDR1 gene [ABCB1], the gene encoding for the efflux protein, P-glycoprotein (P-gp)) in vitro. Assessing transport in both directions (apical to basolateral and basolateral to apical across the cell monolayers enables an efflux ratio to be determined. This provides an indication as to whether a compound undergoes active efflux (mediated by P-gp). This provides a prediction of blood brain barrier (BBB) penetration potential/permeability and efflux ratio. Effect in CACO-2 (Colon Adenocarcinoma cells) as a permeability assay and on cytochrome P450 CYP 450 were also determined. CYP enzymes catalyze oxidative biotransformation (phase 1 metabolism) of most drugs—CYP enzymes, bind to membranes in a cell (cyto) and contain a heme pigment (chrome and P) that absorbs light at a wavelength of 450 nm when exposed to carbon monoxide. Metabolism of a drug by CYP enzymes is a major source of variability in drug effect. These were measured by Chem Partners. The relative effect on HFF and parasite enzymes also were compared.
RPS13Δ Tachyzoites in Human Primary Brain Neuronal Stem Cells in vitro for transcriptomics and transcriptomics analyses. Culture of Human Primary Brain Neuronal Stem Cells (NSC) was as described (McPhillie et al, 2016; Ngo et al, 2017); T. gondii RPS13Δ on RH strain background (Hutson et al, 2010) was used to infect the NSC as described (McPhillie et al, 2016; Ngo et al, 2017). RNA was isolated and prepared and used for transcriptomic experiments as described (McPhillie et al, 2016; Ngo et al, 2017). Briefly, NSC, initially isolated from a temporal lobe biopsy (Walton et a, 2006) were infected with either wild-type or RPS13Δ RH tachyzoites using biological duplicates at a multiplicity of infection of 2:1 and incubated as previously described (Ngo et al, 2017). Eighteen hours post-infection, extracellular parasites were washed out with cold PBS before total RNA extraction. Further isolation of the mRNA fraction was carried out with miRNeasy Mini Kit columns (Qiagen) following manufacturer instructions and Illumina barcoded mRNA sequencing libraries were constructed with TruSeq RNA Sample Preparation Kits v2 (Illumina). Libraries were sequenced as 100 bp single reads with Illumina HiSeq 2000 apparatus at a sequencing depth of about 3 Gbp per sample. Sequencing reads were mapped to the human (release GRCh38) and T. gondii ME49 strain (ToxoDB release 13.0) reference genome assemblies with hisat2 (Kim et al, 2015) and raw read counts were per gene were estimated with HTSeq (Anders et al, 2015). Identification of parasite genes that were differentially expressed between wild-type and RPS13Δ parasites was performed with the R package DESeq2 (Love et al, 2014) using a generalized linear model likelihood ratio test. Identification of orthologous genes between T. gondii and P. cynomolgi was carried out by best-reciprocal matches between T. gondii and P. cynomolgi proteomes using Blastp and a e-value cutoff of 1×104. The list of Genes that are differentially expressed between P. cynomolgi hypnozoites and the liver-schizont stage was extracted from a previously published study by Cubi R. et al (Cubi et al, 20171). Gene set enrichment analysis was carried out with the GSEA tool (Subramanian et al, 2005) using T. gondii Gene Ontology and cell cycle gene sets developed by Croken M et al (Croken et al, 20141) and visualized with the Enrichment Map application in Cytoscape (Su et al, 2014).
IVIS. Balb/C mice were infected intraperitoneally (IP) with 20×103 T. gondii (Prugneaud strain expressing luciferase) tachyzoites. Treatment began 2 hours later with JAG21 (5 mg/kg) which was dissolved in DMSO, administered IP in a total volume of 0.05 ml. Mice were imaged every second day starting on day 4 post infection using an IVIS Spectrum (Caliper Life Sciences) for minute exposures, with medium binning, 20 minutes post injection with 150 mg/kg of D-luciferin potassium salt solution.
Brain cysts. Brain cysts were searched for in paraffin imbedded tissue of the surviving Prugneaud strain infected treated Balb/C mice in the IVIS study, 30 days after infection which was 16 days after treatment had been discontinued. All treated mice had survived. There were no surviving untreated mice in those experiments.
In separate experiments, Balb/C mice were infected IP with 20×103 T. gondii Me49 strain tachyzoites. In these separate studies of mice with established chronic infection, after 30 days, IP treatment with JAG21 was begun each day for 14 days. JAG21 was dissolved in DMSO and administered IP in a total volume of 0.05 mL. In experiments when tafenoquine was administered alone or with JAG21 in some groups 3 mg/kg tafenoquine was administered once on day −1 from when JAG21 treatment was initiated. Cysts in brain were quantitated on day 30, 16 days after discontinuing JAG21. Immunoperoxidase staining was performed. Parasite burden was quantitated in two ways. The first was using a positive pixel count algorithm of Aperio ImageScope software. Positive pixels were normalized to tissue area (mm2). Briefly, automated quantitation was done by counting positive pixels per square area. The entire brain in one section was scanned for each mouse. The Cyst burden was quantitated as units of positive pixels per mm2. The average±S.E.M. numbers of mm2 per slide quantitated was 30.2±1.6 square mm per mouse for this quantification. Each highpower field of view shown in
RPS13 Δ In vivo. This G1 arrested parasite persists in tissue culture for prolonged times in the absence of tetracycline (Hutson et al 2010), but in immune competent mice it cannot be rescued with teteracycline, or LNAME (L-NG-Nitro arginine methyl ester, an analog of arginine) used as an antagonist of nitric oxide synthase (NOS) that inhibits NO production, or both together (Hutson et al. 2010).
In pilot studies, herein, interferon α receptor knockout mice that were not treated were observed following infection. At 7 and at 14 days following infection, spleen and liver were removed and immune peroxidase stained. At 14 days a group of mice were treated with anhydrotetracycline and when a subset of these mice died their spleen and liver were removed and immune peroxidase stained.
As in the pilot studies, this RPS13 Δ parasite also was used to infect interferon α receptor knockout mice in a treatment study. The design of this experiment with these immune compromised mice is shown in
RH Challenge in a Study of Oral Administration of a Novel Nanoformulation of JAG21:
Nanoformulation of JAG21 for oral administration in T.gondii studies. JAG21 was prepared using hydroxyethyl cellulose (HEC) and Tween 80. Briefly, this dispersant solution containing 5 mg/mL HEC and 2 mg/mL Tween 80 in water was prepared. Solid JAG21 was added to 20 mg/mL, and the dispersion was sonicated for 60 seconds using a Sonics vc50 probe-tip sonicator set to 20 kHz to homogenize. Sonication was performed at room temperature. Aliquots of the homogeneous dispersion were frozen and lyophilized using a VirTis AdVantage freeze drier. These aliquots were stored at room temperature for 5-6 months. Prior to dosing, aliquots were reconstituted using water. Controls containing no JAG21 were also prepared. Following reconstitution with water, the dispersion was imaged using a Nikon ECLIPSE E200 optical microscope set to 40× magnification. The average particle size of the JAG21 dispersion in HEC/Tween 80 was determined using an in-house image analysis program This novel method to stably formulate JAG21 was discovered after all other studies were completed and this was the last experiment in this manuscript performed as a consequence.
RH YFP challenge. For studies of the nano formulated JAG 21, this was administered for one or three days by gavage in the doses shown in the results section. These C57BL6 background mice received 2000 RH tachyzoites IP on day the first day of the experiment and peritoneal fluid was collected 5 days later to quantitate filuorescence and numbers of parasites.
Enzyme assays. P. falciparum 3D7 strain were obtained from the Liverpool School of Tropical Medicine. Protease cocktail inhibitor was obtained from Roche. Bradford protein assay dye reagent was obtained from Bio-Rad. All other reagents were obtained from Sigma-Aldrich. Decylubiquinol was produced as per Fisher et al. (2009). In brief, 25 mg of decylubiquinone were dissolved in 400 μl of nitrogen-saturated hexane. An equal volume of aqueous 1 M sodium dithionite was added, and the mixture vortexed until colorless. The organic phase containing the decylubiquinol was collected, the solvent was evaporated under N2 and the decylubiquinol finally dissolved in 100 μl of 96% ethanol (acidified with 10 mM HCl). Concentrations of decylubiquinol was determined spectrophotometrically on a Cary 300 Bio UV/visible spectrophotometer (Varian, UK) from absolute spectra, using ε288-320=8.1 mM-1·cm−1. Decylubiquinol was stored at −80° C. and used within two weeks.
P. falciparum culture and extract preparation. P. falciparum strain 3D7 blood-stage cultures were contained a 2% suspension of O+ human erythrocytes in RPMI 1640 medium containing L-glutamine and sodium carbonate, and supplemented with 10% pooled human AB+ serum, 25 mM HEPES (pH 7.4) and 20 μM gentamicin sulphate. Cultures were grown under a gaseous headspace of 4% O2 and 3% CO2 in N2 at 37° C. Cultures were grown to a parasitemia of 5% before use.
The protocol for the preparation of parasite extract was adapted from Fisher et al. Free parasites were prepared from infected erythrocytes pooled from five T75 flasks, by adding 5 volumes of 0.15% (w/v) saponin in phosphate-buffered saline (137 mM NaCl, 2.7 mM KCl, 1.76 mM K2HPO4, 8.0 mM Na2HPO4, 5.5 mM D-glucose, pH 7.4) for 5 min, followed by three washes by centrifugation in RPMI containing HEPES (25 mM), and a final resuspension in potassium phosphate buffer (50 mM K2HPO4, 50 mM KH2PO4, 2 mM EDTA, pH7.4) containing a protease inhibitor cocktail (Complete Mini; Roche). Parasite extract was then prepared by disruption with a sonicating probe for 5 s, followed by a 1 min rest period on ice to prevent the sample overheating. This process was performed three times. The parasite extract was used immediately. The protein concentration of the parasite extract was determined by Bradford protein assay (Bio-Rad).
Pfbc1 native assay. P. falciparum bc1 complex cytochrome c reductase (Pfbc1) activity was measured by monitoring cytochrome c reduction at 550 versus 542 nm using a Cary 300 Bio UV-Visible Spectrophotometer (Varian, UK), using a protocol adapted from Fisher et al. (2009). The assay was performed in potassium phosphate buffer in a quartz cuvette and in a final volume of 700 μL. Potassium cyanide (10 μM), oxidized cytochrome c (30 μM), parasite extract (100 μg protein) and compound/DMSO were added sequentially to the cuvette, with mixing between each addition. Test compounds were added to a final concentration of 1 μM. DMSO (0.1% v/v) and atovaquone (1 μM), a known malarial cytochrome bc1 complex inhibitor, were used as negative and positive controls respectively. The reaction was initiated by the addition of 50 μM decylubiquinol and allowed to proceed for 3 min.
Malaria parasite In vitro studies. Malaria potency testing in vitro was performed using 4 different P. falciparum strains, D6, TM91-C235, W2, and C2B. The D6 strain is a drug sensitive strain from Sierra Leone, the TM91-C235 strain is a multi-drug resistant strain from Thailand, the W2 strain is a chloroquine resistant strain from Thailand, and the C2B strain is a multi-drug resistant strain with resistance against atovaquone. These assays were performed as described below.
Compound Activity against Plasmodlum falciparum. Compound activity against P. falciparum, was tested using the Malaria SYBR Green I-Based Fluorescence (MSF) Assay. The complete method for performing this microtiter assay is described in previous work published by Plouffe et al. (2008) and Johnson et al (2007). In brief, this assay uses the binding of the fluorescent dye SYBR Green I to malaria DNA to measure parasite growth in the presence of two-fold diluted experimental or control. The relative fluorescence of the intercalated SYBR Green I proportional to parasite growth, and inhibitory compounds will result in lower observed fluorescence compared to untreated parasites.
Cytotoxicity assays in parallel with P.falclpaum assays In vitro. Toxicity studies also were performed with HepG2 cells (human liver cancer immortal cell line derived from the liver tissue of a 15-year-old African American, ATCC® HB-8065™) in parallel with the studies of P.falciparum, with inhibitors in vitro, as described in McPhillie et al (2016).
P. berghei causal prophylaxis In vivo model. P. berghei sporozoites were obtained from laboratory-reared female Anopheles stephensi mosquitoes which were maintained at 18 degrees C. for 17-22 days after feeding on a luciferase expressing P. berghei infected Swiss CD11CR Using a dissecting microscope, the salivary glands were extracted from malaria-infected mosquitoes and sporozoites were obtained. Briefly, mosquitoes were separated into head/thorax and abdomen. Thoraxes and heads were triturated with a mortar and pestle and suspended in medium RPMI 1640 containing 1% C57BL/6 mouse serum (Rockland Co, Gilbertsville, Pa., USA). 50-80 heads with salivary glands were placed into a 0.5 ml Osaki tube on top of glass wool with enough dissection media to cover the heads. Until all mosquitoes had been dissected, the Osaki tube was kept on ice. Sporozoites that were isolated from the same batch of mosquitoes were inoculated into C57BLJ 6, 2D knock-out and 2D knock-out/2D6 knock-in C57BL/6 mice on the same day to control for biological variability in sporozoite preparations. On day 0, each mouse was inoculated intravenously in the tail vein with approximately 10,000 sporozoites suspended in 0.1 ml volume. They were stained with a vital dye containing fluorescein diacetate (50 mg/ml in acetone) and ethidium bromide (20 μg/ml in phosphate buffered saline; Sigma Chemical Co, St. Louis, Mo., USA) and counted in a hemocytometer to ensure that inoculated sporozoites were viable following the isolation procedure. Viability of the sporozoites ranged from 90 to 100%.
Animals. The mice used in these experiments were albino C57BL/6 female mice, which were housed in accordance with the current Guide for the Care and Use of Laboratory Animals (1996) under an IACUC approved protocol. All animals were quarantined for 7 days upon arrival, and the animals were fed standard rodent maintenance food throughout the study.
Test compounds, homogenization of JAG21 creating a nanoformulation, and administration. Animals were dosed with experimental compounds based on body weight. The suspension solution of orally administered drugs were conducted in 0.5% (w/v) hydroxyethyl cellulose and 0.2% Tween 80 in distilled water. To insure the size of the compounds in the dosing solution were under 50 μM (measured they were 4-6 p), the suspension was homogenized using a homogenizer (PRO Scientific Inc., Monroe, Conn., USA) with a 10 mm open-slotted generator running at 20,000-22,000 rpm for 5 min in an ice bath. The compounds were made fresh each day and used immediately (always in <½ hour). Stability beyond that time was not determined. It was not anticipated that they would be stable beyond that time.
Compounds were administered on three consecutive days (−1, 0, +1) relative to sporozoite infection or a single dose on day 0. Drug suspensions were administered to mice by oral gavage using an 18 gauge intragastric feeder. For the 3-day dosing regimen, compounds were administered at 0.625 mg/kg and for the single dose regimen administered on day 0, compounds were administered at 2.5 mg/kg.
In vivo imaging. All of the in vivo bioluminescent imaging methods utilized have been described previously. Briefly, JAG21 was administered orally on days −1, 0 and 1 with respect to sporozoite inoculation. All inoculated mice were imaged using the Xenogen IVIS-200 Spectrum (Caliper Life Sciences, Hopkinton, Mass., USA) IVIS instrument at 24, 48 and 72 hours post-sporozoite infection. The bioluminescent imaging experiments were conducted by IP injection of the luciferase substrate, D-Luciferin potassium salt, (Xenogen, Calif. and Goldbio, St Louis, Mo., USA), into mice at a concentration of 200 mg/kg 15 min before bioluminescent images were obtained. Three minutes after luciferin administration the mice were anesthetized using isoflurane, and the mice were positioned ventral side up on a 37° C. platform with continual anesthesia provided through nose cone delivery of isoflurane. All bioluminescent images were obtained using 5 minute exposures with f-stop=1 and large binning setting. Photon emission from specific regions was quantified using Living Image®3.0 software (Perkin Elmer),
Additionally, blood stage parasitemia was assessed 3 days after imaging was completed by treating small quantities of blood obtained from tail bleeds with the fluorescent dye Yoyo-1 measured by using a flow cytometry system (FC500 MPL, Beckman Coulter, Miami, Fla., USA), (Pybus et al, 2013; Marcissin et al, 2014)
Bovine cytochrome bc1 activity assays. Bovine cytochrome bc, inhibition assay was carried out in 50 mM KPi pH 7.5, 2 mM EDTA, 10 mM KCN, 30 μM equine heart cytochrome c (Sigma Aldrich), and 2.5 nM bovine cytochrome bc, at room temperature. 20 mM inhibitors dissolved in DMSO were added to the assay at a desired concentration without prior incubation. The working concentration of DMSO in the assay did not exceed 0.3% v/v. The reaction was initiated by the addition of 50 μM decylubiquinol (Abcam). The reduced cytochrome c was monitored by the different absorption between 550 and 542 nm using extinction coefficient of 18.1 mM−1 cm−1 in a SPECTRAmax Plus 384 UV-visible Spectrometer. The initial kinetic rate is determined as a zero-order reaction and used as the specific activity of cytochrome bc1.
Preparation of crude mitochondria: Whole fresh bovine heart was collected after slaughter and transported in ice. All work was carried out at 4° C. Lean heart muscle was cut into small cubes and homogenized in the buffer composed from 250 mM sucrose; 20 mM K2HPO4; 2 mM succinic acid; 0.5 mM EDTA. Buffer was added at a ratio of 2.5 L per 1 kg of muscle tissue. pH of resulting homogenate was adjusted to 7.8 using 2 M Tris and PMSF protease inhibitor was added to 0.1 mM concentration. The homogenate was then centrifuged in a Sorvall GS-3 rotor at 5000 g for 20 minutes. The resulting supernatant was then transferred to a Sorvall GSA rotor and centrifuged at 20,000 g for 20 minutes. Obtained mitochondrial pellet was washed in 50 mM KPi (pH 7.5); 0.1 mM PMSF buffer before second centrifugation under the same condition. The pellet was collected and sored at −80° C. for further use.
Solubilization of membrane proteins. The frozen mitochondria were thawed and re-suspended in 50 mM KPi (pH 7.5); 250 mM NaCl; 0.5 mM EDTA; 0.1 mM PMSF buffer; a small sample was taken for quantification of total mitochondrial proteins by BCA assay. The remaining sample was centrifuged at 180,000 g in Beckman Ti70 rotor for 60 minutes. The pellet was re-suspended in the same wash buffer with the addition 1 mg DDM per 1 mg of protein and then centrifuged under the same conditions for 60 minutes. The pellet was discarded and the supernatant was collected for ion exchange chromatography.
Purification of cytochrome bc1. During purification the presence of protein was detected using 280 nm absorbance and the presence of heme was detected using 415 nm Soret band peak and 562 nm absorbance. The solubilized protein solution was applied on DEAE-Sepharose CL-6B column (ca. 50 ml, GE Healthcare) pre-equilibrated with buffer A (50 mM KPi (pH 7.5); 250 mM NaCl; 0.01% w/v DDM; 0.5 mM EDTA) and washed with 3 CV of buffer A. The protein was eluted by linear gradient with buffer B (50 mM KPi (pH 7.5); 500 mM NaCl; 0.01% w/v DDM; 0.5 mM EDTA). Fractions containing cytochrome bc1 were pooled and concentrated to 0.5 ml using an Amicon Ultra-15 (Amicon, MWCO 100,000) concentrator. Concentrated sample was applied to a Sephacryl-S300 gel filtration column (ca. 120 ml) pre-equilibrated in buffer C (20 mM KMOPS (pH 7.2); 100 mM NaCl; 0.01% w/v DDM; 0.5 mM EDTA) and eluted at a flow rate of 0.5 ml/min. Purified cytochrome bc1 fractions were collected and concentrated to 40 mg/m. PEG fractionation with increasing concentration of PEG4000 was used to precipitate cytochrome bc. Precipitating solution (100 mM KMES pH 6.4; 10% PEG4000; 0.5 mM EDTA) was mixed with the protein to a desired PEG concentration. The precipitated protein pellet was re-solubilized in buffer D (25 mM KPi pH 7.5, 100 mM NaCl, 0.5 mM EDTA, 0.015% DDM) and dialyzed in the same buffer in a centrifugal ultrafilter to remove residual PEG. 5 μM cytochrome bc, was incubated at 4° C. for 12 hours with 50 μM JAC021 (10-fold molar excess) diluted from 20 mM solution stock in DMSO.
Crystallization, data collection and refinement of Cytochrome bc1-JAG021 complex. The inhibitor-bound cytochrome bc, was mixed with 1.6% HECAMEG to the final protein concentration of 40 mg/mL. Hanging drop methods was used for crystallisation. 2 μL of final protein solution with 2 μL of reservoir solution (50 mM KPi pH 6.8, 100 mM NaCl, 3 mM NaN3, 10-12% PEG4000) was equilibrated over reservoir solution at 4° C. The crystals were grown to 100 μm within four days. The single crystal was transferred in reservoir solution containing increasing to 50% concentrations of ethylene glycol prior to cryo-cooling in liquid nitrogen. X-ray data were collected from single crystal PROXIMA2 beamline, SOLEIL light source, France using DECTRIS EIGER X 9M detector at 0.9801 Å wavelength up to 3.45 Å resolution. Data were indexed and integrated using iMosflm (Battye et al, 2011), and scaled using Aimless (Evans, 2011). The starting model for refinement was 5OKD. All ligands except co-factors were removed from the model prior to refinement. Jelly-body refinement was carried out with Refmac5 (Murshudov et al, 2011). The inhibitor model was generated by Jligand (Lebedev et al, 2012). The model was manually edited in COOT (between cycle refinements. Data collection and refinement statistics are shown in Table 2A.
Electron microscopy and image processing. Cryo-EM was carried out as described in Ampomdanai et al. (2018). Briefly, 3 μL of sample at 5 mg/mL concentration were applied to Quantifoil Cu R1.2/1.3, 300 mesh holey carbon grids and plunge frozen using an FEI Vitribot (blot time 6 seconds, blot force 6). Data were collected on an FEI Titan Krios with a Falcon III direct electron detector operated in integrating mode at 300 kV Automated data collection was carried out using EPU software with a defocus range of ˜1 to ˜3.5 Nm, and a magnification of 75,000× which yielded a pixel size of 1.065 Å. Data were collected for 72 hours resulting in 5,356 micrographs. The total dose was 66.4 e−/Å over a 1.5 second exposure which was split into 59 frames. All of the processing was performed in RELION 2.1 unless otherwise stated. The initial drift and CTF correction was carried out using MOTIONCORR2 (Zheng et al. 2017) and Gctf (Zhang et al. 2016), respectively. The micrographs were examined and those with crystalline ice were initially removed resulting in 2,960 micrographs. A subset of about 2,000 particles were manually picked to generate 2D references to facilitate auto-picking resulting in 439,009 particles. These particles underwent an initial round of 2D classification with those classes that displayed clear secondary structure detail being taken forward to 3D classification and split into three classes. Two of the three classes generated a high-quality cytochrome bc, reconstruction with secondary structure information clearly visible. The particles from these two classes were recombined to form the final datasets consisting of 211,916 particles in the final reconstruction. The particles were 3D refined using C2 symmetry to produce a map with resolution 3.8 Å. The particles also underwent movie refinement and particle polishing which further improved the resolution of the map to 3.7 Å. A previously refined EM structure for SCR0911 (pdb 6FO6) was fit into the map using UCSF chimera and subsequently refined using phenix with the correct ligand. The maps were then inspected manually in COOT (Emsley et al 2004) and the model corrected for any errors in refinement and placement of residues. Statistics are in Table 2B.
Statistical Analysis. A Pearson test was used to confirm a correlation between increasing dose and increasing inhibition. An ANOVA and subsequent pairwise comparison with Dunnett correction was used to determine whether or not inhibition or toxicity at a given concentration was statistically significant. Stata/SE 12.1 was used for this analysis.
Initially, a small library of seven compounds (
A representative graph of these in vitro data is shown in
Cytotoxicity assays performed in parallel using HFF, WST-1 (Fomovska et al. 2012; Fomovska et al. 2012a), and HEP G2 cells demonstrated a lack of toxicity at concentrations substantially in excess of the concentrations effective against tachyzoites. Because T. gondii grows inside cells, if a compound were toxic to host HFF then it would make the compound appear to be spuriously effective (Fomovska et al. 2012; Fomovska et al. 2012a), when in actuality only toxicity for the host cell would be measured. Cytotoxicity to HFF was therefore assessed for all compounds at 10 μM. Results of this experiment are in Table 1, toxicity column. A two-way ANOVA and subsequent pairwise comparison found none of the differences in absorbance, compared to the media-DMSO vehicle controls, to be statistically significant (p>0.05). Most of these compounds are not toxic at 10 μM (the limit of solubility) and that cytotoxicity to cells can be attributed to DMSO in the solution, not the compound. Dose response testing (IC50) was performed with HEP G2 cells as described and the observed toxicity was: HEP G2 IC50 17.70 μM (r2=0.97) for JAG021; 7.1 μM (r2=0.98) for JAG050.
Lead compounds JAG050, JAG021 and others were tested against EGS strain (McPhillie et al, 2016; Vidigal et al, 2015; Paredes-Santos et al 2013; Paredes-Santos et al, 2018) tachyzoites and encysted bradyzoites using methods described earlier (McPhillie et al, 2016). A number of these compounds, including JAG21, were highly effective against tachyzoites (RH-YFP; Fomovska et al. 2012) (Table 1,
Results against P. falciparum using methodology described earlier (McPhillie et al, 2016, Trager et al, 2005, Ploufe et al, 2008, Johnson et al, 2007) also are shown in
In vitro absorption, distribution, metabolism, excretion, and toxicity (ADMET) analyses of the THQ compounds were outsourced to ChemPartner Shanghai Ltd. ELQ-271 (synthesized in-house) was tested as a comparison. THQs which were potent inhibitors of T. gondii tachyzoites were assessed for their kinetic solubility, metabolic stability in human and mouse liver microsomes (
JAG21 is the most active of the initially tested THQs against T. gondii Cytbc1, which also showed selectivity for the parasite over the mammalian mitochondrial membrane potential (
Mitochondrial membrane potential measurements were performed with permeabilized T.gondii tachyzoites in suspension using safranin O, which loads into polarized membranes. T. gondii tachyzoites were permeabilized with digitonin to allow the mitochondrial substrate succinate to cross the membrane and energize the mitochondrion. The fluorescence of safranin O, which loads into energized mitochondria was used to measure the membrane potential. The energized state of the mitochondrion is observed by a decrease in fluorescence (
Enzyme reduction of cytochrome c by P. falciparum parasite extract (Fisher et al, 2004, 2009) is mediated by P. falciparum bc1 complex cytochrome c reductase (Pfbc1) enzyme. All three compounds tested (1 μM) significantly inhibited the reduction of cytochrome c by the P. falciparum parasite extract, (JAG021=86.4±3.2; JAG099=81.3±6.0; MJM170=69.7±11.3% of the atovaquone response,
In binding assays and in co-crystallography (McPhillie et al, 2016; Capper et al, 2015; Ampomdanai et al, 2018; Battye et al, 2011; Emsley et al, 2010; Laskowski and Swindells, 2011; Lbebedev et al, 2012; Murshudov et al, 2011; Emsley et al, 2004; Zheng et al, 2017; Zhang et al, 2016), JAG021 has lower binding affinity to bovine cytochrome bc in comparison with previous compounds that have not been tested. JAG 21 ‘inhibits’ Cytbc1 but not fully, indicating that it will be less toxic for mammalian (bovine/human) cyt bc1 than the apicomplexan enzymes (
In vivo studies of JAG21 against T. gondii demonstrated high efficacy in a variety of settings. JAG21 at 5 mg/kg/day administered IP improves well-being and eliminates illness and T. gondii Type II Prugneaud luciferase tachyzoites completely in luminescence studies (
A nano formulation homogenized (<6 μM) was used effectively orally for the P.bergheii experiments, further, importantly, was effective in the single oral dose causal prophylaxis in 5 C57BL/6 albino mice at 2.5 mg/kg dosed on day 0, 1 hour after intravenous administration of 10,000 P. berghei sporozoites was completely protective. In addition, 3 dose causal prophylaxis treatment in 5 C57BL/6 albino mice at 0.625 mg/kg dosed on days −1, 0, and +1 also was completely protective. A representative experiment at a higher dose (5 mg/kg) is shown, but all experiments with the oral dosing regimen with the nanoformulation specified above showed 100% survival 30 days post infection with P. berghei, where all liver and blood stage parasites were eliminated (
In mice that were treated with JAG21 early after infection (
Sinai et al have demonstrated heterogeneity in the phenotypes of organisms within established cysts. Their work found bradyzoites within cysts are not uniform with regard to their replication potential (Watts et al, 2015), mitochondrial activity (Sinai, unpublished), and levels of the glucose storage polymer amylopectin (Sinai, unpublished). These properties of bradyzoites within (Watts, et al, 2015), and properties of tissue cysts vary during the course of infection with unappreciated levels of complexity in the progression of chronic toxoplasmosis (Watts et al, 2015). The analysis (
To further develop JAG21 for practical and clinical use, the next step was to make a formulation that is stable at room temperature, and would be effective when administered orally: Following a number of unsuccessful alternative methods (data not shown, a dispersion of JAG21 was prepared using hydroxyethyl cellulose (HEC) and Tween 80. This new formulation method is described in the Materials and Methods. When this dispersion was imaged using a Nikon ECLIPSE E200 optical microscope set to 40× magnification, the average particle size of the JAG21 dispersion in HEC/Tween 80 was determined using an in-house image analysis program and was found to be 2.85 μm (
T.gondii infections are highly prevalent and the impact of this disease can be devastatingly severe. Current treatments have toxicity or hypersensitivity side effects. New compounds that are without toxicity or hypersensitivity, and that are highly active against tachyzoites would be of considerable clinical usefulness. Further, no medicines are active against the encysted stage or definitively curative. In addition, malaria is lethal for one child every eleven seconds and a threat to travelers going to endemic areas. Development of drug resistance also increases the need for new anti-malarial compounds. The disclosure herein identified compounds highly effective against T.gondii and P. falciparum with dual activity.
To further develop the THQ series, 54 compounds were synthesized to improve kinetic solubility, solubility in physiologically-relevant media (FaSSIF, FeSSIF), and metabolic stability (microsomes and hepatocytes), and other ADMET properties. Compounds JAG050 and JAG021 were identified as lead compounds, demonstrating potent inhibition on both tachyzoites and bradyzoites life stages and were not toxic to human cells in the in vitro model (HFF). In addition, both compounds displayed low nanomolar efficacy against multiple drug resistant strains of P. falciparum in vitro. JAG050 and JAG021 demonstrate promising ADMET properties, with JAG21 slight superior due to the compound's longer metabolic stability in human and mouse microsomes.
A striking result with JAG21 in the in vivo parasite studies is the compound's high efficacy against T.gondii tachyzoites and bradyzoites. In the P. berghei in vivo model for malaria, a single dose causal prophylaxis in 5 C57BL6 albino mice at 2.5 mpk dosed on day 0, 1 hour after intravenous administration of 10,000 P. berghei sporozoites was achieved. Causal prophylaxis was also observed after a 3-dose treatment in 5 C57BL/6 albino mice at 0.6 mpk dosed on days −1, 0, and +1. A representative figure at a higher dose (5 mg/kg) is shown, and all experiments with the amounts mentioned above demonstrated identical high efficacy in luminescence, parasitemia, and survival results. This demonstrates that JAG21 functions better in this in vivo model than the ELQ 300 series where prodrug formulation is required to achieve solubility and efficacy. In contrast to the efficacy of JAG21, at 2.5 mg/kg in a single oral dose model resulted in cure without a prodrug. ELQ 300 (not the prodrug) was not effective at doses between 1 and 20 mg/kg although the prodrug was more effective.
JAG050 and JAG021 are lead compounds, with JAG21 being a superior compound due to its favorable predicted ADMET properties, potency, efficacy and lack of toxicity. JAG021 demonstrates increased solubility and potential for advanced formulation. There also is potential for improving solubility and reducing toxicity further because of the larger binding pocket in the apicomplexan Cytbc1 enzyme compared with the mammalian Cytbc1 enzyme, determined by modeling occupancy of the structure, enzyme assays and empirically, if it were needed. At present, JAG21 has sufficient drug like properties to move to advanced formulations, suggesting increased bulk will not be needed to reduce toxicity. It has selectivity as demonstrated by the enzymatic, binding and structure studies, although there are additional compounds that show even greater selectivity. It is highly effective in an oral nano preparation against P. berghei three life cycle stages, and with early treatment appears to be capable of curing toxoplasmosis in immunocompetent mice. This work demonstrates the promising nature of this novel tetrahydroquinolone scaffold and mature lead compound. JAG21 has the potential to become an orally administered medicine or with partners, part of a medicine combination that is curative for toxoplasmosis and is a single dose cure for malaria. It is suitable for partnering with other compounds to obviate problems with selection of resistant mutants. In certain embodiments, the compounds of the disclosure may be combined with atovaquone and/or cycloguanil (in proguanil) against P. falciparum. The compounds of the disclosure are suitable for treatment of T. gondii or P. falciparum infections.
JAG21 treats both T.gondii and Plasmodium species infections, demonstrated in vitro and in vivo. It has high efficacy against T.gondii tachyzoites and bradyzoites, and established encysted organisms. Treatment with a single low oral dose is effective for causal prophylaxis and radical cure of P.berghei infections. JAG 21 has complete efficacy against three life cycle stages of P.berghei. In terms of companion inhibitors, JAG21, a Qi inhibitor, synergizes against tachyzoites with atovaquone (a Qo inhibitor) in vitro. It appears able to contribute modestly to protection of immune compromised mice in conjunction with tafenoquine against an initially replicating, then G1 arrested, T.gondii parasite that shares key transcriptomic components with P. cynomolgi hypnozoites.
Some embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be incorporated within the spirit and purview of this application and scope of the appended claims. All publications, patents, and patent applications cited herein are hereby incorporated herein by reference for all purposes.
This application claims the benefit of priority of U.S. Provisional Patent Application No. 63/026,415, filed May 18, 2020, all of which is incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/033019 | 5/18/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63026415 | May 2020 | US |
