The present disclosure relates in general to the use and synthesis of iminosugars for medical purposes and, in particular, to the use of iminosugars for inhibiting α-N-acetylgalactosaminidases (GalNAcases) or β-hexosaminidases, as well as treatments for diseases associated with these enzymes.
According to one embodiment, the current invention discloses a method for synthesizing DGJNAc or a DGJNAc derivative from D-glucuronolactone. Synthesis of DGJNAc comprises introducing nitrogen at C5 of glucuronolactone, inversion of configuration of the hydroxyl group at C3 and formation of the piperidine ring by introduction of nitrogen between C6 and C2.
According to another embodiment, numerous novel DGJNAc derivatives are disclosed. These compositions include a compound of the formula,
or a pharmaceutically acceptable salt thereof, wherein R is selected from the group consisting of substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted oxaalkyl groups; or wherein R is
In another embodiment, the current invention is drawn to a method of inhibiting α-N-acetylgalactosaminidases (GalNAcases) or β-hexosaminidases, comprising addition of a compound of the formula,
or a pharmaceutically acceptable salt thereof, wherein R is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted oxaalkyl groups; or wherein R is
In another embodiment, the current invention is drawn to a method of treating or preventing a disease associated with α-N-acetylgalactosaminidases (GalNAcases) or β-hexosaminidases activity comprising: administering to a subject in need thereof an effective amount of a compound of the formula,
or a pharmaceutically acceptable salt thereof, wherein R is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted oxaalkyl groups; or wherein R is
In a further embodiment, the subject is a human being and the disease is Schindler disease. In addition, R may be hydrogen and the compound DGJNAc
i. Iminosugars
Iminosugars, compounds in which the ring pyranose or furanose oxygen has been replaced by nitrogen, are the archetype for interaction with carbohydrate processing enzymes. (1). However, among the myriad of sugar mimics reported, there is not a single example of efficient inhibition of α-N-acetyl-galactosaminidases (GalNAcases).
ii. Overview
The current invention reports DGJNAc 1D and its derivatives as the first potent, specific and competitive inhibitors of GalNAcases. In addition,
iii. Synthesis of DGJNAc from Glucuronolactone
The synthesis of DGJNAc1D requires introduction of nitrogen at C5 of glucuronolactone (Scheme 1), inversion of configuration of the hydroxyl group at C3 and formation of the piperidine ring by introduction of nitrogen between C6 and C2 (with inversion of configuration).
iv. Schindler Disease
Schindler disease, a congenital metabolic disorder, is a lysosomal storage disorder caused by a deficiency in the alpha-NAGA (alpha-N-acetylgalactosaminidase) enzyme. This lysosomal storage disorder is also known as Kanzaki disease and Alpha-N-acetylgalactosaminidase deficiency. Mutations to the NAGA gene on chromosome 22 lead to a build up of glycoproteins in the lysosomes and an accumulation of glycosphingolipids throughout the body. This accumulation of sugars causes the clinical features associated with this disease. Schindler disease is an autonomic recessive disorder.
There are three main types of the disease. In the Type I infantile form, babies develop normally until about a year old. Afterwards, the child begins to lose previously acquired skills associated with the coordination of physical and mental behaviors. Additional neurological and neuromuscular symptoms including diminished muscle tone, weakness, involuntary rapid eye movements, vision loss, and seizures may be present. Over time symptoms worsen and children experience a decreased ability to move certain muscles due to muscle rigidity and the ability to respond to external stimuli decreases. Other symptoms include neuroaxonal dystrophy from birth, discoloration of skin, Telangiectasia or widening of blood vessels.
In Type II adult form, symptoms are milder and may not appear until the mid 30 s. Angiokeratomas, an increased coarsening of facial features, and mild intellectual impairment are typical symptoms. Type III form is considered an intermediate disorder with varying symptoms among patients. Severe symptoms include seizures and mental retardation. Less severe symptoms include delayed speech, mild autistic like presentation, and/or behavioral problems.
v. β-Hexosaminidases
Other lysosomal enzymes are also well known for their role in numerous diseases. One example of these enzymes are β-hexosaminidases. Selective inhibition of β-hexosaminidases are useful for the study of osteoarthritis, (8) allergy, (9) Alzheimer's disease, (10) O-GlcNAcase inhibition, (11) cancer metastasis, (12) type II diabetes, (13) genetic diseases such as Tay-Sachs and Sandhoff diseases, (14) and of plant regulation. (15) The synthetic piperidine analogue of N-acetylglucosamine DGJNAc 3 (16) and its N-alkyl derivatives (17) are potent inhibitors of β-hexosaminidases. The natural product nagstatin 4, (18) with a galacto-configuration, does not inhibit GalNAcases even though it is a potent inhibitor of β-hexosaminidases. (19) The synthetic analogue with a gluco-configuration 5 (20) together with PUG derivatives 6 (21) and GlcNAc-thiazolines 7 (22) are very potent inhibitors of β-hexosaminidases. A rare example of a pyrrolidine potent hexosaminidase inhibitor is LABNAc 8; (23) the first pyrrolizidine β-hexosaminidase inhibitor, pochonicine 9 [or its enantiomer], has been isolated from a fungal strain Pochonia suchlasporia var. suchlasporia TAMA 87. (24) Some seven membered-ring imino sugars also display potent inhibition. (25)
Unless otherwise specified “a” or “an” means one or more.
vi. DGJNAc and its DGJNAc Derivatives
The present inventors discovered that certain iminosugars, such as DGJNAc and DGJNAc derivatives, may be effective in the inhibition of GalNAcases or β-hexosaminidases. In particular, the DGJNAc and DGJNAc derivatives may be useful for treating or preventing a disease or condition caused by or associated with GalNAcases) or β-hexosaminidases.
In many embodiments, the iminosugar is DGJNAc or a DGJNAC derivative. DGJNAc (2-acetamido-1,2-dideoxy-
A “DGJNAc derivative” is a derivative of DGJNAc wherein the ring nitrogen is not substituted with a hydrogen atom.
In general, DGJNAc and DGJNAc derivatives can be represented by the formula
wherein R may be selected from hydrogen (for DGJNAc), substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted aryl groups, or substituted or unsubstituted oxaalkyl groups.
In some embodiments, R may be substituted or unsubstituted alkyl groups and/or substituted or unsubstituted oxaalkyl groups comprise from 1 to 16 carbon atoms, from 4 to 12 carbon atoms or from 8 to 10 carbon atoms. The term “oxaalkyl” refers to an alkyl derivative, which may contain from 1 to 5 or from 1 to 3 or from 1 to 2 oxygen atoms. The term “oxaalkyl” includes hydroxyterminated and methoxyterminated alkyl derivatives.
In some embodiments, R may be selected from, but is not limited to —(CH2)6OCH3, —(CH2)6OCH2CH3, —(CH2)6O(CH2)2CH3, —(CH2)6O(CH2)3CH3, —(CH2)2O(CH2)5CH3, —(CH2)2O(CH2)6CH3; —(CH2)2O(CH2)7CH3; —(CH2)9—OH; —(CH2)9OCH3.
In some embodiments, R may be an branched or unbranched, substituted or unsubstituted alkyl group, which may contain up 20 carbon atoms. In some embodiments, the alkyl group may C2-C12 or C3-C7 alkyl group.
In certain embodiments, the alkyl group may be a long chain alkyl group, which may be C6-C20 alkyl group; C8-C16 alkyl group; or C8-C10 alkyl group. In some embodiments, R may be a long chain oxaalkyl group, i.e., a long chain alkyl group, which may contain from 1 to 5 or from 1 to 3 or from 1 to 2 oxygen atoms.
In some embodiments, R may have the following formula
where R1 is a substituted or unsubstituted alkyl group;
In some embodiments, Z is NH and R1—Y is a substituted or unsubstituted alkyl group, such as C2-C20 alkyl group or C4-C12 alkyl group or C4-C10 alkyl group.
In some embodiments, X1 is NO2 and X3 is N3. In some embodiments, each of X2, X4 and X5 is hydrogen.
vii. Salts, Prodrugs, Pharmaceutical Compositions
In some embodiments, the iminosugar may be in a form of a salt derived from an inorganic or organic acid. Pharmaceutically acceptable salts and methods for preparing salt forms are disclosed, for example, in Berge et al. (J. Pharm. Sci. 66:1-18, 1977). Examples of appropriate salts include but are not limited to the following salts: acetate, adipate, alginate, citrate, aspartate, benzoate, benzenesulfonate, bisulfate, butyrate, camphorate, camphorsulfonate, digluconate, cyclopentanepropionate, dodecylsulfate, ethanesulfonate, glucoheptanoate, glycerophosphate, hemisulfate, heptanoate, hexanoate, fumarate, hydrochloride, hydrobromide, hydroiodide, 2-hydroxyethanesulfonate, lactate, maleate, methanesulfonate, nicotinate, 2-naphthalenesulfonate, oxalate, palmoate, pectinate, persulfate, 3-phenylpropionate, picrate, pivalate, propionate, succinate, tartrate, thiocyanate, tosylate, mesylate, and undecanoate.
In some embodiments, the iminosugar may also used in a form of a prodrug.
In some embodiments, the iminosugar may be used as a part of a composition, which further comprises a pharmaceutically acceptable carrier and/or a component useful for delivering the composition to an animal. Numerous pharmaceutically acceptable carriers useful for delivering the compositions to a human and components useful for delivering the composition to other animals such as cattle are known in the art. Addition of such carriers and components to the composition of the invention is well within the level of ordinary skill in the art.
In some embodiments, the pharmaceutical composition may consist essentially of DGJNAc or the DGJNAc derivative, indicating that the DGJNAc or the DGJNAc derivative is the only active ingredient in the composition.
Yet in some other embodiments, DGJNAc or the DGJNAc derivative may be administered with one or more additional compounds.
In some embodiments, the iminosugar may be used in a liposome composition, such as those disclosed in US publication 2008/0138351; U.S. application Ser. No. 12/410,750 filed Mar. 25, 2009 and U.S. provisional application No. 61/202,699 filed Mar. 27, 2009.
viii. Administration and Inhibition of GalNAcases or β-hexosaminidases
The iminosugar, such as a DGJNAc or the DGJNAc derivative, may be administered to a cell or an animal affected by disorders associated with GalNAcases or β-hexosaminidases activity. The iminosugar may inhibit GalNAcases or β-hexosaminidases and help reduce, abate, or diminish the disease in the animal.
In addition, DGJNAc or the DGJNAc derivative, may be used to study the inhibition of GalNAcases or β-hexosaminidases with in vitro or in vivo studies.
Animals suffering from the disease include primates including monkeys and humans.
The amount of iminosugar administered to an animal or to an animal cell to the methods of the invention can be an amount effective to inhibit the GalNAcases or β-hexosaminidases. The term “inhibit” as used herein may refer to the detectable reduction and/or elimination of a biological activity exhibited in the absence of the iminosugar. The term “effective amount” may refer to that amount of the iminosugar necessary to achieve the indicated effect. The term “treatment” as used herein may refer to reducing or alleviating symptoms in a subject, preventing symptoms from worsening or progressing, inhibition or elimination of the causative agent, or prevention of the disorder related to the GalNAcases or β-hexosaminidases activity in a subject.
The amount of the iminosugar which may be administered to the cell or animal is preferably an amount that does not induce toxic effects which outweigh the advantages which accompany its administration.
Actual dosage levels of active ingredients in the pharmaceutical compositions may vary so as to administer an amount of the active compound(s) that is effective to achieve the desired therapeutic response for a particular patient.
The selected dose level may depend on the activity of the iminosugar, the route of administration, the severity of the condition being treated, and the condition and prior medical history of the patient being treated. However, it is within the skill of the art to start doses of the compound(s) at levels lower than required to achieve the desired therapeutic effect and to gradually increase the dosage until the desired effect is achieved. If desired, the effective daily dose may be divided into multiple doses for purposes of administration, for example, two to four doses per day. It will be understood, however, that the specific dose level for any particular patient can depend on a variety of factors, including the body weight, general health, diet, time and route of administration and combination with other therapeutic agents and the severity of the condition or disease being treated. The adult human daily dosage may range from between about one microgram to about one gram, or from between about 10 mg and 100 mg, of the iminosugar per 10 kilogram body weight. Of course, the amount of the iminosugar which should be administered to a cell or animal may depend upon numerous factors well understood by one of skill in the art, such as the molecular weight of the iminosugar and the route of administration.
Pharmaceutical compositions that are useful in the methods of the invention may be administered systemically in oral solid formulations, ophthalmic, suppository, aerosol, topical or other similar formulations. For example, it may be in the physical form of a powder, tablet, capsule, lozenge, gel, solution, suspension, syrup, or the like. In addition to the active agent, such pharmaceutical compositions may contain pharmaceutically-acceptable carriers and other ingredients known to enhance and facilitate drug administration. Other possible formulations, such as nanoparticles, liposomes resealed erythrocytes, and immunologically based systems may also be used to administer the agent. Such pharmaceutical compositions may be administered by a number of routes. The term “parenteral” used herein includes subcutaneous, intravenous, intraarterial, intrathecal, and injection and infusion techniques, without limitation. By way of example, the pharmaceutical compositions may be administered orally, topically, parenterally, systemically, or by a pulmonary route.
These compositions may be administered in a single dose or in multiple doses which are administered at different times.
The present invention can be illustrated in more details by the following example, however, it should be understood that the present invention is not limited thereto.
Embodiments described herein are further illustrated by, though in no way limited to, the following working examples.
For the synthesis of DJGNAc 1D from D-glucuronolactone 2D, the acetonide 10 was esterified with trifluoromethanesulfonic(triflic)anhydride in dichloromethane in the presence of pyridine and the resulting crude triflate was treated with sodium azide in DMF to give the ido-azide 11 {mp. 112-114° C.; [α]D25+261.4 (c 1.0, CHCl3) [lit. (29) mp. 114-116+ C., [α]D20 +243 (c 1.1, CHCl3)]} in 97% yield. Direct conversion of the azidolactone 11 by a number of hydrides to the diol 12 gave only low yields; such α-azidolactones are extremely sensitive to base and commonly a two step reduction is necessary with initial reduction to the lactol. Accordingly DIBALH reduction of the azidolactone 11 in dichloromethane gave the corresponding lactol which was further reduced by sodium borohydride in methanol to afford the diol 12 mp. 120-122° C., [α]D25−69.6 (c 0.94, CHCl3) in 72% yield. Selective protection of the primary alcohol in 12 by reaction with tert-butyldimethylsilyl (TBDMS) chloride gave the corresponding TBDMS ether 13, oil, [α]D25−12.7 (c 1.1, CHCl3) in 99% yield; the overall yield of 13 from glucuronolactone 2D was 72% on a multigram scale and without any need for chromatographic purification until the final stage.
The synthesis of DGJNAc 1D required inversion and subsequent protection of the remaining unprotected C3 OH in the silyl ether 13. Oxidation of 13 with pyridinium chlorochromate in dichloromethane in the presence of molecular sieve afforded the corresponding ketone which on reduction from the least hindered face of the carbonyl gave the inverted alcohol 14, oil, [α]D25+74.9 (c 0.94, CHCl3), in 79% yield. Treatment of 14 with benzyl bromide and sodium hydride in DMF formed the fully protected benzyl ether 15, oil, [α]D25+101.5 (c 0.56, CHCl3) in 97% yield. Both the acetonide and silyl protecting groups in 15 were removed by treatment with HCl in methanol to give a 5:1 mixture of anomers of the methyl furanoside 16 (97%); reaction of 16 with triflic anhydride in dichloromethane in the presence of pyridine gave the ditriflate 17 which, with benzylamine in THF, gave the bicyclic pyrrolidine 18, oil, [α]D25+22.8 (c 1.11, CHCl3), as a single anomer in an overall yield of 61%. Formation of a piperidine ring by cyclization of a ditriflate was thus efficient; examples of successful cyclizations of a ditriflate, such as the formation of a pyrrolidine, (30) are very rare.
Acetolysis of the furanoside 18 with boron trifluoride etherate in acetic anhydride gave a 4:1 mixture of the epimers 19 in 93% yield. The OMe group in 19 was reductively removed by sequential treatment with DIBALH in dichloromethane followed by sodium borohydride in methanol; acetylation of the resulting diol allowed easy isolation of the diacetate 20, oil, [α]D25+79.8 (c 0.43, CHCl3), in 83% overall yield from 19. Rapid reduction of the azide in XK by zinc dust in the presence of copper(II) sulfate in acetic acid-acetic anhydride-THF (31) with subsequent acylation of the corresponding amine gave the crystalline triacetate 21, mp. 112-114° C., [α]D25+26.2 (c 1.1, Me2CO) in 79% yield. Removal of the acetate protecting groups by treatment of 21 with sodium methoxide in methanol followed by hydrogenolysis of the benzyl groups by palladium (10% on carbon) in dioxane: aqueous hydrochloric acid gave DGJNAc 1D,mp. 150-154° C., [α]D25+41.9 (c 0.67, H2O)) [lit.6 oil, [α]D20+37 (c 1, MeOH)], in 98% yield. Unlike many iminosugars, the free base DGJNAc is readily crystallized; the overall yield of DGJNAc 1D from D-glucuronolactone 2D was 20%.
Selected data for DGJNAc 1D: HRMS (ESI+ve): C8H16N2NaO4 found 227.1001; (M+Na+) requires 227.1002; +41.9 (c 0.67, H2O); m.p. 150-154° C.; νmax (thin film, Ge): 3287 (br, s, OH/NH), 1637 (s, amide I), 1561 (s, amide II); δH (D2O, 400 MHz): 2.00 (3H, s, Me), 2.37 (1H, dd, H1a Jgem 12.9, J1a,2 11.6), 2.76 (1H, dt, H5 J5,4 1.3, , J5,6a=J5,6b 6.6), 3.08 (1H, dd, H1b Jgem 12.9, J1b,2 5.1), 3.58 (1H, dd, H3 J3,2 10.6, J3,4 3.0), 3.61 (1H, dd, H6a Jgem 11.1, J6a,5 6.3), 3.65 (1H, dd, H6b Jgem 11.1, J6b,5 6.6), 3.96 (1H, dt, H2 J2,1a 11.1, J2,1b 5.1, J2,3 11.1), 4.01 (1H, dd, H4 J4,3 3.0, J4,5 1.4); δC (D2O, 100 MHz): 22.7 (Me), 47.7 (Cl), 49.1 (C2), 59.4 (C5), 61.9 (C6), 68.9 (C4), 73.2 (C3), 175.2 (COMe); LRMS (ESI+ve): 205 (77%, M+H+), 431 (100%, 2M+Na+).
The enantiomer
DGJNAc 1D was a highly potent competitive inhibitor of GalNAcases (Ki 0.081 μM from chicken liver, Ki 0.136 μM from Charonia lampas); DGJNAc 1D was a good but much less potent competitive inhibitor of β-hexosaminidases (IC50 1.8 μM from Jack bean, IC50 1.8 μM from Jack bean, IC50 4.2 μM from bovine kidney, IC50 8.3 μM from human placenta, IC50 2.2 μM from HL-60).
The enantiomer L-DGJNAc 1L, showed no inhibition of α-N-acetylgalactosaminidases but was a very weak but non-competitive inhibitor of β-hexosaminidases [Ki 1100 μM—compared with Ki 2.2 μM for DGJNAc 1D—from human placenta]. This result was in accord with Asano's hypothesis (32) that
DGJNAc 1D showed modest inhibition of coffee bean α-galactosidase (IC50 64 μM) whereas
Both enantiomers of DGJNAc 1 were screened as inhibitors of a number of other glycosidases and neither enantiomer showed any significant inhibition [less than 50% inhibition at 1000 mM) against α-glucosidases (rice, yeast), β-glucosidases (almond, bovine liver), β-galactosidase (bovine liver), α-mannosidase (Jack bean), β-glucuronidases (E. coli, bovine liver), α-
Although the foregoing refers to particular preferred embodiments, it will be understood that the present invention is not so limited. It will occur to those of ordinary skill in the art that various modifications may be made to the disclosed embodiments and that such modifications are intended to be within the scope of the present invention.
All of the publications, patent applications and patents cited in this specification are incorporated herein by reference in their entirety.
This application claims the benefit of U.S. Provisional Patent Application No. 61/282,393, filed Feb. 2, 2010, the entire disclosures of which are incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB2011/000380 | 1/28/2011 | WO | 00 | 10/19/2012 |
Number | Date | Country | |
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61282393 | Feb 2010 | US |