Patent Application
20130203790
This invention is directed towards novel sulphur-containing compounds and pharmaceutically acceptable salts thereof, which have utility as anti-proliferative agents against mammalian cells. The invention provides a method for synthesizing the sulphur-containing compounds.
The present invention provides novel compounds, novel compositions, methods of their use and methods of their manufacture, such compounds being generally pharmacologically useful as anti-platelet aggregation agents in various vascular pathologies. The aforementioned pharmacologic activities are useful in the treatment of mammals. At the present time, there is a need in the area of vascular therapeutics for such a blocking agent. By interfering with hemostasis, such therapy would decrease the morbidity and mortality of thrombotic disease.
Hemostasis is the spontaneous process of stopping bleeding from damaged blood vessels. Precapillary vessels contract immediately when cut. Within seconds, thrombocytes, or blood platelets, are bound to the exposed matrix of the injured vessel by a process called platelet adhesion. Platelets also stick to each other in a phenomenon known as platelet aggregation to form a platelet plug. This platelet plug can stop bleeding quickly, but it must be reinforced by the protein fibrin for long-term effectiveness, until the blood vessel tear can be permanently repaired by growth of fibroblasts, which are specialized tissue repair cells.
An intravascular thrombus (clot) results from a pathological disturbance of hemostasis. The thrombus can grow to sufficient size to block off arterial blood vessels. Thrombi can also form in areas of stasis or slow blood flow in veins. Venous thrombi can easily detach portions of themselves called emboli that travel through the circulatory system and can result in blockade of other vessels, such as pulmonary arteries. Thus, arterial thrombi cause serious disease by local blockade, whereas venous thrombi do so primarily by distant blockade, or embolization. These diseases include venous thrombosis, thrombophlebitis, arterial embolism, coronary and cerebral arterial thrombosis and myocardial infarction, stroke, cerebral embolism, kidney embolisms and pulmonary embolisms.
There is a need in the area of cardiovascular and cerebrovascular therapeutics for an agent that can be used in the prevention and treatment of thrombi, with minimal side effects, including unwanted prolongation of bleeding in other parts of the circulation while preventing or treating target thrombi. The compounds of the present invention meet this need in the art by providing therapeutic agents for the prevention and treatment of thrombi.
The compounds of the present invention show efficacy as antithrombotic agents by virtue of their ability to block fibrinogen from acting at its platelet receptor site and thus prevent platelet aggregation.
The present invention relates to certain disuphides, and pharmaceutically acceptable salts thereof, having activity as anti-proliferative agents, to methods for their preparation, and to methods and pharmaceutical formulations for using these compounds in mammals (especially humans).
Because of their activity as anti-proliferative agents, the compounds of the present invention are useful for the treatment of a variety of conditions, including arterial or venous thrombosis, inflammation, bone degradation, malignancy (primary or secondary), cell aggregation-related conditions, thromboembolic disorders selected from thrombus or embolus formation, harmful platelet aggregation, re-occlusion following thrombolysis, reperfusion injury, restenosis, atherosclerosis, stroke, heart attack, peripheral arterial ischemia, myocardial infarction, and unstable angina.
a, 13b, 13c, 13d, 13e, 13f are clot formation and lysis profiles of various embodiments of the invention, hirudin and D-Phe-Pro-Arg chloromethylketone.
In one aspect, the invention provides novel disulphides of the general Formula I:
RSSR1 (I)
wherein R is pyridine, phenylamine or pyrimidine, and R1 is CH3.
In another aspect, the present invention provides a process from preparing a disulphide of the general Formula I as described above, which comprises reacting a corresponding thiol with S-methyl methanethiolsulfonate in MeOH to obtain the title compound.
In yet another aspect, the present invention provides an anti-proliferative agent active against mammalian cells comprising as active ingredient at least one compound selected from the group of compounds consisting of:
“Alkyl” means linear and branched structures, and combinations thereof, and extends to cover carbon fragments having up to 20 carbon atoms. Examples of alkyl groups include octyl, nonyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, eicosyl, 3,7-diethyl-2,2-dimethyl-4-propylnonyl, and the like.
“Lower alkyl” means alkyl groups of from 1 to 7 carbon atoms. Examples of lower alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, sec- and tert-butyl, pentyl, hexyl, heptyl, and the like.
“Cycloalkyl” means a hydrocarbon containing one or more rings having from 3 to 12 carbon atoms, with the hydrocarbon having up to a total of 20 carbon atoms. Examples of cycloalkyl groups are cyclopropyl, cyclopentyl, cycloheptyl, adamantyl, cyclododecylmethyl, 2-ethyl-1-bicyclo[4.4.0]decyl and the like.
“Lower alkenyl” means alkenyl groups of 2 to 7 carbon atoms. Examples of lower alkenyl groups include vinyl, allyl, isopropenyl, pentenyl, hexenyl, heptenyl, 1-propenyl, 2-butenyl, 2-methyl-2-butenyl and the like.
“Lower alkoxy” means alkoxy groups of from 1 to 7 carbon atoms of a straight, branched, or cyclic configuration. Examples of lower alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, cyclopropyloxy, cyclohexyloxy, and the like.
“Alkylcarbonyl” means alkylcarbonyl groups of 1 to 20 carbon atoms of a straight, branched or cyclic configuration. Examples of alkylcarbonyl groups are 2-methylbutanoyl, octadecanoyl, 11-cyclohexylundecanoyl and the like. Thus, the 11-cyclohexylundecanoyl group is c-Hex-(CH2)10—C(O)—.
“Lower alkylcarbonyl” means alkylcarbonyl groups of from 1 to 8 carbon atoms of a straight, branched, or cyclic configuration. Examples of lower alkylcarbonyl group are formyl, 2-methylbutanoyl, cyclohexylacetyl, etc. By way of illustration, the 2-methylbutanoyl groups signifies —COCH(CH3)CH2CH3.
“Lower alkylsulfonyl” means alkylsulfonyl groups of from 1 to 7 carbon atoms of a straight, branched, or cyclic configuration. Examples of lower alkylsulfonyl groups are methylsulfonyl, 2-butylsulfonyl, cyclohexylmethylsulfonyl, etc. By way of illustration, the 2-butylsulfonyl group signifies —S(O)2CH(CH3)CH2CH3.
Halogen means F, Cl, Br, and I.
It is intended that the definitions of any substituent (e.g., R, R1, R2, R6, etc.) in a particular molecule be independent of its definitions elsewhere in the molecule. Thus, NR62 represents —NHH, —NHMe, —N(Me)(Et), etc.
The heterocycles formed when two R6 (or R20) groups join through N include pyrrolidine, piperidine, morpholine, thiamorpholine, piperazine, and N-methylpiperazine.
Optical Isomers—Diastereomers—Geometric Isomers
Some of the compounds described herein may contain one or more asymmetric centers and may thus give rise to diastereomers and optical isomers. The present invention is meant to comprehend such possible diastereomers as well as their racemic and resolved, enantiomerically pure forms and pharmaceutically acceptable salts thereof.
Salts
The pharmaceutical compositions of the present invention comprise a compound of Formula I as an active ingredient or a pharmaceutically acceptable salt, thereof, and may also contain a pharmaceutically acceptable carrier and optionally other therapeutic ingredients. The term “pharmaceutically acceptable salts” refers to salts prepared from pharmaceutically acceptable non-toxic bases including inorganic bases and organic bases. Salts derived from inorganic bases include aluminum, ammonium, calcium, copper, ferric, ferrous, lithium, magnesium, manganic salts, manganous, potassium, sodium, zinc and the like. Particularly preferred are the ammonium, calcium, magnesium, potassium and sodium salts. Salts derived from pharmaceutically acceptable organic non-toxic bases include salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as arginine, betaine, caffeine, choline, N,N1-dibenzylethylenediamine, diethylamine, 2-diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine, ethylenediamine, N-ethylmorpholine, N-ethylpiperidine, glucamine, glucosamine, histidine, hydrabamine, isopropylamine, lysine, methylglucamine, morpholine, piperazine, piperidine, polyamine resins, procaine, purines, theobromine, triethylamine, trimethylamine, tripropylamine, tromethamine and the like. Mixed salts may at times be advantageous.
When the compound of the present invention is basic, salts may be prepared from pharmaceutically acceptable non-toxic acids, including inorganic and organic acids. Such acids include acetic, benzenesulfonic, benzoic, camphorsulfonic, citric, ethanesulfonic, fumaric, gluconic, glutamic, hydrobromic, hydrochloric, isethionic, lactic, maleic, malic, mandelic, methanesulfonic, mucic, nitric, pamoic, pantothenic, phosphoric, succinic, sulfuric, tartaric, p-toluenesulfonic acid and the like. Particularly preferred are citric, hydrobromic, hydrochloric, maleic, phosphoric, sulfuric and tartaric acids.
It will be understood that in the discussion of methods of treatment which follows, references to the compounds of Formula I are meant to also include the pharmaceutically acceptable salts.
Compounds of Formula I of the present invention may be prepared according to the synthetic routes outlined in the Schemes 1 to 4 and by following the methods described herein. Following the schemata, Table 1 illustrates compounds representative of the present invention.
General Experimental Methods
Reagents were provided by Sigma-Aldrich Chemical Company and Oakwood Chemicals Company. Methanethiolsulfonates were provided by Toronto Research Chemicals. Reagents were used without further purification. Solvents were obtained from Aldrich and Caledon. Prior to the preparation of the disulphides, methanol was purged of oxygen by bubbling nitrogen an inert gas through it for several minutes. Thin-layer chromatography (TLC) was carried out using EM Reagent plates with fluorescence indicator (SiO2-60, F-254). Products were purified by flash chromatography, which were performed on silica gel H (200-300 mesh), and the solvent proportions were expressed on a volume/volume basis. 1H-NMR spectra were recorded using a Brucker 300 MHz in CDCl3 unless otherwise noted.
With reference to Scheme 1, to a solution of pyridine-4-thiol (VI) (700 mg, 6.296 mmol) in MeOH (4 ml) was added a solution of 1 equivalent of S-methyl methanethiolsulfonate (0.594 ml) in MeOH (1 ml). The yellow reaction mixture was stirred at room temperature under an argon atmosphere for 12 hrs. The mixture was then concentrated under reduced pressure to provide the crude product as yellow oil. The crude was taken up in ethyl acetate (2 ml), and passed through a column silica-gel chromatography using 100% ethyl acetate as eluant to give the desired product, 4-methyldisulfanyl-pyridine (II), 484 mg, 49% as light yellow oil. The 1H-NMR spectrum of the resulting compound, 4-methyldisulfanyl-pyridine (II), is shown in
In a similar manner, with reference to Scheme 2, compound 2-methyldisulfanyl-pyridine (III) was obtained from pyridine-2-thiol (VII) as yellow oil. The 1H-NMR spectrum of the resulting product, 2-methyldisulfanyl-pyridine (III), is shown in
In a similar manner, with reference to Scheme 3, compound 4-methyldisulfanyl-phenylamine (VI) was obtained from 4-amino-benzenethiol (VIII) as yellow oil. The 1H-NMR spectrum of the resulting product, 4-methyldisulfanyl-phenylamine (VI), is shown in
In a similar manner, with reference to Scheme 4, compound 2-methyldisulfanyl-pyrimidine (V) was obtained from pyrimidine-2-thiol (IX) as yellow oil. The 1H-NMR spectrum of the resulting product, 2-methyldisulfanyl-pyrimidine (V), is shown in
The potential platelet inhibitory activity of the compounds listed in Table 1 was assessed using in vitro tests of platelet function. Further, it was determined whether these compounds effect thrombin-mediated conversion of fibrinogen to fibrin and the subsequent degradation of a fibrin by tissue plasminogen activator (t-PA). Stock solutions of each compound were prepared in DMSO. Subsequent dilutions of drug were made in non-buffered saline containing 10% (v/v) DMSO.
Platelet Inhibition Assays
Platelet function studies were performed simultaneously in both whole blood (using whole blood impedance platelet aggregometry with a Multiplate System) and platelet rich plasma (light transmission aggregometry with a Chrono-Log System). Blood was collected from healthy individuals into vacutainers containing 3.2% (w/v) citrate and was used within 3 hours of collection. Platelet rich plasma (“PRP”) was prepared by centrifugation at 170 g for 15 minutes, and the platelet count measured and adjusted to 250×109/L for use in the light transmission aggregometry studies.
Each compound was tested at final concentrations of 10, 25, 50 and 100 μM. For each test, the compound was diluted 1/100 into the PRP or whole blood to obtain the final concentrations listed. The PRP or whole blood sample was allowed to stir in the aggregometer for 3 minutes prior to agonist addition. One compound was tested each day.
As a positive control to verify the sensitivity to inhibition of thrombin receptor agonist peptide (TRAP)-mediated aggregation, TRAP-induced aggregations were also done in the presence of eptifibatide, a glycoprotein IIb/IIIa inhibitor (final concentration of 77 μg/mL in PRP and 65 μg/mL in whole blood).
Materials used included:
Results for PRP aggregations are shown in
Referring to
Referring to
Referring to
Referring to
Referring to
Coagulation/Fibrinolysis Assays
Coagulation and fibrinolysis were studied simultaneously in a 96-well microtiter plate-based assay system. Varying concentrations of drug in 50 μl buffer or an equivalent volume of saline were added to the wells. To this was added 100 μl of 6 μM fibrinogen, 1 μM Glu-plasminogen and 4 mM CaCl2. Reactions were initiated by addition of 50 μl of buffer containing 2 nM t-PA and 20 nM thrombin. Final concentrations of reagents in the wells were 3 μM fibrinogen, 500 nM Glu-plasminogen, 2 mM CaCl2, 0.05 nM t-PA, 5 nM thrombin and compounds of Formulas (II), (Ill), (IV) or (V) (0-400 μM). As positive controls, hirudin or D-Phe-Pro-Arg chloromethylketone (PPACK) was used in place of the subject compounds. Plates were incubated at 23° C. for 1 h with constant shaking and turbidity was monitored continuously at 405 nm. Clot times and lysis times were determined using instrument soft wave as the times to half maximal increase and decrease in turbidity, respectively. Data are expressed as the mean±SEM of three experiments, each done in triplicate.
Materials used:
Results for clot formation and clot lysis are shown in
Referring to
Each compound of the present invention was tested at concentrations of 0-400 μM and was found to have no effect on the thrombin clotting time. In contrast, when hirudin or PPACK was tested at concentrations of 0-100 nM, it caused complete inhibition of clotting at 25 nM and 50 nM, respectively, with a measurable effect seen as low as 6.25 nM.
Referring to
| Number | Date | Country | |
|---|---|---|---|
| 61506202 | Jul 2011 | US |
