Selective inhibition of thrombin by (2R,4R)-4-methyl-1-[N2-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl++ +) sulfonyl]-l-arginyl)]-2-piperidinecarboxylic acid

The potency of thrombin inhibition by 4-methyl-1-[N2-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl)-sulfony l]- L-arginyl]-2-piperidinecarboxylic acid (MQPA) depended on the stereoconformation of the 2-piperidinecarboxylic acid moiety. Ki values for bovine alpha-thrombin were 0.019 microM with (2R,4R)-MQPA, 0.24 microM with (2R,4S)-MQPA, 1.9 microM with (2S,4R)-MQPA, and 280 microM with (2S,4S)-MQPA. (2R,4R)-MQPA of the four stereoisomers of MQPA was also the most potent inhibitor for other trypsin-like serine proteases with Ki values of 5.0 microM for trypsin, 210 microM for factor Xa, 800 microM for plasmin, and 1500 microM for plasma kallikrein. Examination of the potency of thrombin inhibition by arginine derivatives related to MQPA in structure suggested the presence of a specific binding site for the carboxamide portion (C-terminal side). The relative inhibitory potency of the four stereoisomers of MQPA for trypsin was nearly identical with that for thrombin, suggesting that the specific binding site for the carboxamide portion is present in both enzymes. Modification of thrombin by phosphopyridoxylation or the presence of heparin did not significantly alter the binding of MQPA.     

Enantioselective synthesis of (R)- and (S)-2-methyl-[3,3,2-2H3] alanines

The synthesis of optically pure (R)- and (S)-2-methyl-[3,3,3-2H3] alanines of biological interest is described. The stereochemistry of the reaction of the lithio derivative of (R)-(-)-2,5-dimethoxy-3-benzyl-3-methyl-3,6-dihydropyrazine with alkyl and deuterated alkyl iodides is discussed. The configuration of the newly formed center of chirality in (R)- and (S)-2-methyl-[3,3,3-2H3] alanines is derived from 1H NMR.     

Discovery of (1R,2R)-N-(4-(6-isopropylpyridin-2-yl)-3-(2-methyl-2H-indazol-5-yl)isothiazol-5-yl)-2-methylcyclopropanecarboxamide,a potent and orally efficacious mGlu5 receptor negative allosteric modulator

A novel series of selective negative allosteric modulators (NAMs) for metabotropic glutamate receptor 5 (mGlu5) was discovered from an isothiazole scaffold. One compound of this series, (1R,2R)-N-(4-(6-isopropylpyridin-2-yl)-3-(2-methyl-2H-indazol-5-yl)isothiazol-5-yl)-2-methylcyclopropanecarboxamide (24), demonstrated satisfactory pharmacokinetic properties and, following oral dosing in rats, produced dose-dependent and long-lasting mGlu5 receptor occupancy. Consistent with the hypothesis that blockade of mGlu5 receptors will produce analgesic effects in mammals, compound 24 produced a dose-dependent reduction in paw licking responses in the formalin model of persistent pain.     

(R)-2-(4-Phenylbutyl)dihydrobenzofuran derivatives as melatoninergic agents

(R)-2-(4-Phenylbutyl)dihydrobenzofuran derivatives (e.g., 3 and 4) were synthesized as novel melatoninergic ligands with significantly lower vasoconstrictive activity in vitro in the rat tail artery. Binding affinity assays were performed on cloned human MT1 and MT2 receptors stably expressed in NIH3T3 cells.     

Nucleoside Analogues on the Basis of 4(R),5(R)-Dihydroxymethyl-2-methyl-1,3-dioxolane

Abstract

New nucleoside analogues on the basis of 4(R), 5(R)-dihydroxymethy1-2-methyl-1,3-dioxoiane have been prepared. Alkylation of thymine, adenine and N² -palmitoyl-guanine with 2-bromomethyl-4(R),5(R)-dibenzyloxymethyl-1,3-dioxolane followed by separation of regio isomers by adsorption chromatography and deprotection yielded the desired chiral nucleoside analogues. The structures of thus prepared compounds were confirmed by UV and PMR spectroscopy. The obtained compounds 11 have no anti-HIV and ant i herpetic activity and are not cytotoxic.     

Synthesis and cholinergic affinity of diastereomeric and enantiomeric isomers of 1-methyl-2-(2-methyl-1,3-dioxolan-4-yl)- pyrrolidine, 1-methyl-2-(2-methyl-1,3-oxathiolan-5-yl)pyrrolidine and of Their iodomethylates

Four out of the eight possible stereoisomers of 1-methyl-2-(2-methyl-1,3-dioxolan-4-yl)pyrrolidine, 1-methyl-2-(2-methyl-1,3-oxathiolan-5-yl)pyrrolidine and the corresponding iodomethylates have been synthesised. They were formally derived from hybridisation of potent though unselective agonists studied before, such as 1,3-dioxolane 1 and 1,3-oxathiolane 2, with the structure of nicotine. It was expected that, by exalting the molecular complexity of the parent compounds, in particular through stereochemical complication in the proximity of the critical cationic head of the molecule, the chance to find agonists able to discriminate among cholinergic receptors subtypes would increase. The relative and absolute configuration of the compounds obtained has been established by means of NMR spectroscopy and X-ray crystallography. In preliminary studies, their binding affinity has been evaluated on rat brain nicotinic and muscarinic receptors. While none of the compounds showed any nicotinic affinity up to the dose of 10 microM, most of the iodomethylates were endowed with promising affinity for the muscarinic receptors.     

Selective inhibition of trypsin by (2R,4R)-4-phenyl-1-[Nalpha-(7- methoxy-2-naphthalenesulfonyl)-L-arginyl]-2-piperidinecarboxylic acid

Evidence is accumulating indicating that trypsin stimulates divergent cellular reactions through the proteinase-activated receptor, in addition to its role as the digestive enzyme. In this report, we introduce (2R,4R)- 4-phenyl-1-[N(alpha)-(7-methoxy-2-naphthalenesulfonyl)-l-arginyl]- 2-p iperidinecarboxylic acid as a potent and selective trypsin inhibitor. The agent inhibited trypsin competitively with the K(i) value of 0. 1 micrometer. It inhibited thrombin weakly (K(i) = 2 micrometer) and did not inhibit plasmin, plasma kallikrein, urokinase, and mast cell tryptase (K(i) values for these enzymes are >60 micrometer). Comparative studies with several established proteinase inhibitors revealed that the compound was the first small molecular weight trypsin inhibitor without tryptase inhibitory activity. A docking study has provided a plausible explanation for the molecular mechanism of the selective inhibition showing that the agent fits into the active site of trypsin without any severe collision but that it comes into clash at the 4-phenyl group of piperidine ring against the "60-insertion loop" of thrombin and at the 7-methoxy-2-naphthalenesulfonyl group against Gln(98) of tryptase.     

Crystal structures of (2R,4R)-2-(polyhydroxyalkyl)-1,3-thiazolidine-4-carboxylic acids: condensation products of l-cysteine with d-hexoses

We report herein the first crystal structures of (4-carboxy-1,3-thiazolidin-2-yl)pentitols [2-(polyhydroxyalkyl)thiazolidine-4-carboxylic acids], condensation products of l-cysteine with d-galactose and d-mannose: 2-(d-galacto-pentahydroxypentyl)thiazolidine-4-carboxylic acid hydrate, Gal-Cys·H(2)O (1), and 2-(d-manno-pentahydroxypentyl)thiazolidine-4-carboxylic acid hydrate, Man-Cys·H(2)O (2). In 1 and 2 the compounds crystallize as zwitterions, with the carboxylic groups deprotonated and the thiazolidine N atoms protonated. The sugar moiety and carboxylate group are in a cis configuration relative to the thiazolidinium ring, which adopts different conformation: twisted (T) on C(β)-S in 1, and S-puckered envelope (E) in 2. The carbon chain of the galactosyl/mannosyl moiety remains in an extended zig-zag conformation. The orientation of the sugar O2 atom with respect to the thiazolidinium S and N atoms is trans-gauche in 1 and gauche-gauche in 2. The molecular conformation is stabilized by the intramolecular N-H?O(Cys) contacts in both 1 and 2 and by the additional N-H?O(Man) interaction in 2. The crystal packing of orthorhombic 1 and monoclinic 2 is determined mainly by N/O/C-H?O hydrogen bonds forming ribbons linked to each other by direct and water-mediated O/C-H?O/S contacts.     

Synthesis and evaluation of N-[(1S,2S)-3-(4-chlorophenyl)-2-(3-cyanophenyl)-1-methylpropyl]-2-methyl-2-aminopropanamide as human cannabinoid-1 receptor (CB1R) inverse agonists

Obesity is a chronic medical condition that is affecting large population throughout the world. CB1 as a target for treatment of obesity has been under intensive studies. Taranabant was discovered and then developed by Merck as the 1st generation CB1R inverse agonist. Reported here is part of our effort on the 2nd generation of CB1R inverse agonist from the acyclic amide scaffold. We replaced the oxygen linker in taranabant with nitrogen and prepared a series of amino heterocyclic analogs through a divergent synthesis. Although in general, the amine linker gave reduced binding affinity, potent and selective CB1R inverse agonist was identified from the amino heterocycle series. Molecular modeling was applied to study the binding of the amino heterocycle series at CB1 binding site. The in vitro metabolism of representative members was studied and only trace glucuronidation was found. Thus, it suggests that the right hand side of the molecule may not be the appropriate site for glucuronidation.     

Discovery of (2S)-N-[(1R)-2-[4-cyclohexyl-4-[[(1,1-dimethylethyl)amino]carbonyl]-1-piperidinyl]-1-[(4-fluorophenyl)methyl]-2-oxoethyl]-4-methyl-2-piperazinecarboxamide (MB243), a potent and selective melanocortin subtype-4 receptor agonist

We report the discovery and optimization of substituted 2-piperazinecarboxamides as potent and selective agonists of the melanocortin subtype-4 receptor. Further in vivo development of lead agonist, MB243, is disclosed.     

Cytotoxic and antivascular 1-methyl-4-(3-fluoro-4-methoxyphenyl)-5-(halophenyl)-imidazoles

A series of 1-methyl-4,5-diphenylimidazoles 6 with various patterns of m-halogen substitution at the 5-phenyl ring were tested for cytotoxicity in cancer and nonmalignant cell lines and for their capacity to prevent tube formation in HUVEC cultures. Unlike the monofluoro and difluoro derivatives 6a and 6e, the monobromo and diiodo analogs 6c and 6h were strongly cytotoxic and inhibited the polymerization of tubulin and the tube formation by HUVEC. The dibromo derivative 6g displayed a unique selectivity for KB-3-1 cervix and PC-3 prostate cancer cells. It also inhibited the tube formation by HUVEC and the polymerization of tubulin which is indicative of its potential antiangiogenic activity in solid tumors.     

Genetic and phenotypic diversity of (R/S)-mecoprop [2-(2-methyl-4-chlorophenoxy)propionic acid]-degrading bacteria isolated from soils

Twelve mecoprop-degrading bacteria were isolated from soil samples, and their genetic and phenotypic characteristics were investigated. Analysis of 16S rDNA sequences indicated that the isolates were related to members of the genus Sphingomonas. Ten different chromosomal DNA patterns were obtained by polymerase-chain-reaction (PCR) amplification of repetitive extragenic palindromic (REP) sequences from the 12 isolates. The isolates were found to be able to utilize the chiral herbicide mecoprop as a sole source of carbon and energy. While seven of the isolates were able to degrade both (R)- and (S)-mecoprop, four isolates exhibited enantioselective degradation of the (S)-type and one isolate could degrade only the (R)-enantiomer. All of the isolates were observed to possess plasmid DNAs. When certain plasmids were removed from isolates MP11, MP15, and MP23, those strains could no longer degrade mecoprop. This compelling result suggests that plasmid DNAs, in this case, conferred the ability to degrade the herbicide. The isolates MP13, MP15, and MP24 were identified as the same strain; however, they exhibited different plasmid profiles. This indicates that these isolates acquired different mecoprop-degradative plasmids in different soils through natural gene transfer.     

Discovery and activity of (1R,4S,6R)-N-[(1R)-2-[4-cyclohexyl-4-[[(1,1-dimethylethyl)amino]carbonyl]-1-piperidinyl]-1-[(4-fluorophenyl)methyl]-2-oxoethyl]-2-methyl-2-azabicyclo[2.2.2]octane-6-carboxamide (3, RY764), a potent and selective melanocortin subtype-4 receptor agonist

A novel isoquinuclidine containing selective melanocortin subtype-4 receptor small molecule agonist, 3 (RY764), is reported. Its in vivo characterization revealed mechanism-based food intake reduction and erectile activity augmentation in rodents.     

Novel (E)-1-(4-methyl-2-(alkylamino)thiazol-5-yl)-3-arylprop-2-en-1-ones as potent antimicrobial agents

New (E)-1-(4-methyl-2-(alkylamino)thiazol-5-yl)-3-arylprop-2-en-1-ones, unsubstituted or carrying fluoro, bromo, methoxy, nitro, methyl and chloro groups on the benzene ring, were synthesized and assayed in vitro for their antimicrobial activity against Gram positive and Gram negative bacteria and fungi. The compounds were very potent towards all tested microorganisms and in most cases their activity was better than that of reference drugs.     

Metathesis-mediated synthesis of (R)-10-methyl-2-tridecanone, the southern corn rootworm pheromone

(R)-10-Methyl-2-tridecanone, the female sex pheromone of the southern corn rootworm (Diabrotica undecimpunctata howardi Barber), was synthesized in 9 steps from methyl (S)-3-hydroxy-2-methylpropanoate in a 15.7% overall yield. Olefin cross metathesis between (R)-6-methyl-1-nonene and 5-hexen-2-one employing Grubbs' first-generation catalyst was the key step of the synthesis.     

2-(4-methyl-1-piperazinylmethyl) acrylophenone dihydrochloride: a new antimicrotubular drug

With the relation between chemical structure and pharmacological activity as a guide, we have been for some time synthetizing a wide range of beta-amino-ketone derivatives. One of them, 2-(4-methyl-1-piperazinylmethyl) acrylophenone, MPMAP, possesses antimicrotubular activities. This product inhibits 50% of the microtubule polymerization at a 3.10(-5) M concentration. It does not prevent tubulin paracrystal formation induced by vinblastine, and binding experiments reveal that this product is a weak inhibitor of colchicine binding. The structure of this compound is different from the other antimicrotubular agents and has the advantage of being far less complex, highly soluble and easy to synthesize. Thus, this product and related compounds should be a new tool for the study of antimicrotubular activities and tubulin assembly.     

Enantioselective metabolism of (R)- and (S)-4-hydroxy-2-nonenal in rat

4-Hydroxy-2-nonenal (HNE) is an endogenous product of lipid peroxidation, which is believed to play a biological role in the pathogenesis of various diseases. HNE is formed as a racemic mixture of (R)- and (S)- enantiomers. These enantiomers differ in their biological properties. The aim of this study was to investigate separately the in vivo metabolism of the two HNE enantiomers in male rats after intravenous administration of the corresponding radiolabeled compounds and to compare the results with those obtained with the racemic mixture. Although the difference in the excretion rates was not statistically significant, the HPLC profiles of urinary metabolites showed qualitative and quantitative differences between the two enantiomers. The level of 3-mercapturic acid-1,4-dihydroxynonane, which is considered as the major urinary metabolite of HNE, was significantly lower in the case of (S)-HNE injected rats. In vitro studies using rat liver cytosolic incubations and HNE-glutathione conjugate as substrate were performed to clarify the intermediate pathways involved in their metabolism. Large differences were obtained in the reduction and retro-Michael conversion steps of the metabolism between the conjugates originating from the two enantiomers.