Novel 2-indolinone derivatives as promising agents against respiratory syncytial and yellow fever viruses.

Background: A vaccine or antiviral drug for respiratory syncytial virus (RSV) infections and a specific antiviral drug for yellow fever virus (YFV) infections has not yet been developed. Method: In this study, 2-indolinone-based N-(4-sulfamoylphenyl)hydrazinecarbothioamides were synthesized. Along with these new compounds, previously synthesized 2-indolinone-based N-(3-sulfamoylphenyl)hydrazinecarbothioamides were evaluated against various DNA and RNA viruses. Results: Some 2-indolinone compounds exhibited nontoxic and selective antiviral activities against RSV and YFV. Halogen substitution at the indole ring increased the anti-RSV activities. Moreover, 1-benzyl and 5-halogen or nitro-substituted compounds were the most effective compounds against YFV. Conclusion: Generally, the 3-sulfonamide-substituted compounds were determined to be more effective than 4-sulfonamide-substituted compounds against RSV and YFV.

Design, synthesis and anti-influenza virus activity of furan-substituted spirothiazolidinones.

A new series of N-(3-oxo-1-thia-4-azaspiro[4.5]decan-4-yl)carboxamides have been designed, synthesized and evaluated as antiviral agents. The compounds were prepared by condensation of 2-methylfuran-3-carbohydrazide, appropriate carbonyl compounds and sulfanyl acids. The new molecules were characterized by IR, 1H NMR, 13C NMR, mass spectrometry and elemental analysis. Six analogues proved to be active against influenza A/H3N2 virus, the two most protent analogues, 3c and 3d, having an EC50 value of about 1 µM. These findings help to define the SAR of spirothiazolidinone-based inhibitors of the influenza virus membrane fusion process.

Synthesis, in vitro cytotoxic and apoptotic effects, and molecular docking study of novel adamantane derivatives.

[4-(Adamantane-1-carboxamido)-3-oxo-1-thia-4-azaspiro[4.4]nonan-2-yl]acetic acid (4a) and [4-(adamantane-1-carboxamido)-8-nonsubstituted/substituted-3-oxo-1-thia-4-azas-piro[4.5]decane-2-yl]acetic acid (4b-g) derivatives were synthesized; their structures were verified by elemental analysis, infrared spectroscopy, 1 H nuclear magnetic resonance (NMR), 13 C NMR, and mass spectroscopy data; and their in vitro cytotoxicity activities were investigated against human hepatocellular carcinoma, human prostate adenocarcinoma, and human lung carcinoma cell lines (HepG2, PC-3, and A549, respectively), and a mouse fibroblast cell line (NIH/3T3). All compounds, except compound 4e, were found as cytotoxic, especially on A549 cells as compared with the other cells (selectivity index = 2.01-11.6). As a further step, the effects of compounds 4a-c on apoptosis induction were tested and the expression of selected apoptosis genes was analyzed. Among the selected compounds, compound 4a induced apoptosis remarkably. Moreover, computational calculations of the binding of compounds 4a-c to the BIR3 domain of the human inhibitor of apoptosis protein revealed ligand-protein interactions at the atomistic level and emphasized the importance of a hydrophobic moiety on the ligands for better binding.

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.

Novel 2-indolinones containing a sulfonamide moiety as selective inhibitors of candida ß-carbonic anhydrase enzyme.

Inhibition of the ß-carbonic anhydrase (CA, EC 4.2.1.1) from pathogenic Candida glabrata (CgNce103) by 1H-indole-2,3-dione 3-[N-(4-sulfamoylphenyl)thiosemicarbazones] 4a-m was investigated. All the compounds were found to be potent inhibitors of CgNce103, with inhibition constants in the range of 6.4-63.9 nM. The 5,7-dichloro substituted derivative 4l showed the most effective inhibition (KI of 6.4 nM) as well as the highest selectivity for inhibiting CgNce103 over the cytosolic human (h) isoforms hCA I and II. A possible binding interaction of compound 4l within the active site of CgNce103 has been proposed based on docking studies.

Novel sulfonamide-containing 2-indolinones that selectively inhibit tumor-associated alpha carbonic anhydrases.

Human carbonic anhydrases IX and XII are upregulated in many tumors and form a novel target for new generation anticancer drugs. Here we report the synthesis of novel 2-indolinone derivatives with the sulfonamide group as a zinc binding moiety. Enzyme inhibition assays confirmed that the compounds showed selectivity against hCA IX and XII over the widely distributed off-targets hCA I and II. Molecular modelling studies were performed to suggest modes of binding for these compounds.

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.