Novel N-(1-thia-4-azaspiro[4.5]decan-4-yl)carboxamide derivatives as potent and selective influenza virus fusion inhibitors.

Hemagglutinin is the surface protein of the influenza virus that mediates both binding and penetration of the virus into host cells. We here report on the synthesis and structure-activity relationship of some novel N-(1-thia-4-azaspiro[4.5]decan-4-yl)-carboxamide compounds carrying the 5-chloro-2-methoxybenzamide structure, designed as influenza virus fusion inhibitors. The carboxamides (1a-h, 2a-h) have a similar backbone structure as the fusion inhibitors that we reported on previously. Compounds 2b and 2d displayed inhibitory activity against influenza A/H3N2 virus replication (average antiviral EC50 : 2.1 µM for 2b and 3.4 µM for 2d). Data obtained in the hemolysis inhibition assay supported that these compounds act as inhibitors of the influenza virus hemagglutinin-mediated fusion process.

Synthesis and anti-coronavirus activity of a series of 1-thia-4-azaspiro[4.5]decan-3-one derivatives.

A series of 1-thia-4-azaspiro[4.5]decan-3-ones bearing an amide group at C-4 and various substitutions at C-2 and C-8 were synthesized and evaluated against human coronavirus and influenza virus. Compounds 7m, 7n, 8k, 8l, 8m, 8n, and 8p were found to inhibit human coronavirus 229E replication. The most active compound was N-(2-methyl-8-tert-butyl-3-oxo-1-thia-4-azaspiro[4.5]decan-4-yl)-3-phenylpropanamide (8n), with an EC50 value of 5.5 µM, comparable to the known coronavirus inhibitor, (Z)-N-[3-[4-(4-bromophenyl)-4-hydroxypiperidin-1-yl]-3-oxo-1-phenylprop-1-en-2-yl]benzamide (K22). Compound 8n and structural analogs were devoid of anti-influenza virus activity, although their scaffold is shared with a previously discovered class of H3 hemagglutinin-specific influenza virus fusion inhibitors. These findings point to the 1-thia-4-azaspiro[4.5]decan-3-one scaffold as a versatile chemical structure with high relevance for antiviral drug development.

Microwave assisted synthesis and anti-influenza virus activity of 1-adamantyl substituted N-(1-thia-4-azaspiro[4.5]decan-4-yl)carboxamide derivatives.

A microwave-assisted three-component one-pot cyclocondensation method was applied for the synthesis of novel N-(1-thia-4-azaspiro[4.5]decan-4-yl)carboxamide compounds carrying an adamantyl moiety. The structures of the compounds were confirmed by spectral and elemental analysis. All compounds were evaluated for antiviral activity against influenza A (H1N1 and H3N2) and influenza B virus in MDCK cell cultures. The compounds displayed a confined structure-activity relationship. The N-(2,8-dimethyl-3-oxo-1-thia-4-azaspiro[4.5]dec-4-yl)adamantane-1-carboxamide 3b was the most potent inhibitor [antiviral EC(50): 1.4 µM against influenza A/H3N2 virus]. Its strong inhibitory effect in a virus hemolysis assay supports that 3b acts as an influenza virus fusion inhibitor by preventing the conformational change of the influenza virus hemagglutinin at low pH.

Novel inhibitors of influenza virus fusion: structure-activity relationship and interaction with the viral hemagglutinin.

A new class of N-(1-thia-4-azaspiro[4.5]decan-4-yl)carboxamide inhibitors of influenza virus hemagglutinin (HA)-mediated membrane fusion that has a narrow and defined structure-activity relationship was identified. In Madin-Darby canine kidney (MDCK) cells infected with different strains of human influenza virus A/H3N2, the lead compound, 4c, displayed a 50% effective concentration of 3 to 23 muM and an antiviral selectivity index of 10. No activity was observed for A/H1N1, A/H5N1, A/H7N2, and B viruses. The activity of 4c was reduced considerably when added 30 min or later postinfection, indicating that 4c inhibits an early step in virus replication. 4c and its congeners inhibited influenza A/H3N2 virus-induced erythrocyte hemolysis at low pH. 4c-resistant virus mutants, selected in MDCK cells, contained either a single D112N change in the HA2 subunit of the viral HA or a combination of three substitutions, i.e., R220S (in HA1) and E57K (in HA2) and an A-T substitution at position 43 or 96 of HA2. The mutants showed efficiency for receptor binding and replication similar to that of wild-type virus yet displayed an increased pH of erythrocyte hemolysis. In polykaryon assays with cells expressing single-mutant HA proteins, the E57K, A96T, and D112N mutations resulted in 4c resistance, and the HA proteins containing R220S, A96T, and D112N mutations displayed an increased fusion pH. Molecular modeling identified a binding cavity for 4c involving arginine-54 and glutamic acid-57 in the HA2 subunit. Our studies with the new fusion inhibitor 4c confirm the importance of this HA region in the development of influenza virus fusion inhibitors.

Synthesis and Biological Evaluation of some new Imidazo[1,2-a]pyridines.

A series of new 1-[(2,8-dimethylimidazo[1,2-a]pyridine-3-yl)carbonyl]-4-alkyl/arylthiosemicarbazides, 2-[(2,8-dimethylimidazo[1,2-a]pyridine-3-yl)carbonyl]hydrazono-3-alkyl thiazolidin-4-ones, 2-(2,8-dimethylimidazo[1,2-a]pyridine-3-yl)-5-arylamino-1,3,4-oxadiazoles and 4-alkyl/aryl-2,4-dihydro-5-(2,8-dimethylimidazo[1,2-a]pyridine-3-yl)-3H-1,2,4-triazole-3-thiones were synthesized. The structures of the compounds have been elucidated by IR, 1H NMR, EI mass spectra and elemental analysis. Antibacterial, antifungal and antimycobacterial activities of compounds were evaluated against various microorganisms and some of them were found to be active in varying degrees against Staphylococcus aureus, Staphylococcus epidermidis or Mycobacterium tuberculosis H37Rv.

2-[(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)amino]-1-methyl-2-oxoethyl pyrrolidine-1-carbodithio-ate.

In the title compound, C(19)H(24)N(4)O(2)S(2), inversion-related mol-ecules are linked together to form a dimer by N-H⋯O and C-H⋯O hydrogen bonds, generating two R(2) (1)(6) rings and one R(2) (2)(10) ring motif. An inter-molecular C-H⋯O hydrogen bond connects the dimers to each other. An intra-molecular C-H⋯O inter-action occurs. In the pyrrolidine ring, the two C atoms of the ring not bonded to the N atom displays positional disorder with site-occupation factors of 0.630 (18) and 0.370 (18).

Synthesis of some new 6-methylimidazo[2,1-b]thiazole-5-carbohydrazide derivatives and their antimicrobial activities.

In this study, 14 new compounds having 6-methyl-N2-(alkylidene/cycloalkylidene)imidazo[2,1-b]thiazole-5-carbohydrazide (3a-g), 3-[[(6-methylimidazo[2,1-b]thiazole-5-yl)carbonyl]amino]-4-thiazolidinone (4a-d) and 4-[[(6-methylimidazo[2,1-b]thiazole-5-yl)carbonyl]amino]-1-thia-4-azaspiro[4.4]nonan/[4.5]decan-3-one (4e-g) structures were synthesized. The structures of the compounds were elucidated by UV, IR, 1H-NMR, 13C-NMR, 1H-13C-COSY, mass spectra and elemental analysis. All compounds synthesized were tested for antimicrobial activity against Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Klebsiella pneumoniae ATCC 4352, Pseudomonas aeruginosa ATCC 1539, Salmonella typhi, Shigella flexneri, Proteus mirabilis ATCC 14153, Candida albicans ATCC 10231 and Mycobacterium tuberculosis H37Rv. Only 4d and 4f demonstrated antimicrobial activity against S. epidermidis ATCC 12228 (MIC: 19.5 microg/ml and 39 microg/ml, respectively).

LC determination of aminoglutethimide enantiomers as dansyl and fluorescamine derivatives in tablet formulations.

Determination of dansyl (AG-DNS) and fluorescamine (AG-F) derivatives of rac-aminoglutethimide in tablet formulation by HPLC has been achieved on a cellulose tris-(3,5-dimethylphenyl carbamate), known as Chiralcel OD and OD-R under normal and reversed phase columns, respectively, using a fluorescence detector (lambda(ex), 360 nm; lambda(em), 530 nm for AG-DNS derivatives; lambda(ex), 395 nm, lambda(em), 495 nm for fluorescamine derivatives (AG-F)). The best results were obtained with mobile phase ethanol:cyclohexane:methanol (95:5:2 v/v/v) for AG-DNS derivatives and acetonitrile:0.5% ortho-phosphoric acid (85:15 v/v) containing 0.26 mM 1-hexanesulfonic acid sodium salt (HSA) for AG-F, respectively. The lower limit of detection (signal to noise ratio of 3:1) were found to be 20 ng ml(-1) for each enantiomer for AG-DNS and 20.5 ng ml(-1) for each diastreoisomer for AG-F.