Nesrin Cesur

Novel Inhibitors of Influenza Virus Fusion: Structure-Activity Relationship and Interaction with the Viral Hemagglutinin

ABSTRACT 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 μM 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 antimicrobial activity of some 5-aryl-2-[(N, N-disubstituted thiocarbamoylthio)acylamino]-1,3,4-oxadiazoles

In this study, a number of novel 5-aryl-2-[(N,N-disubstituted thiocarbamoylthio)acylamino]-1,3,4-oxadiazole derivatives were synthesized by the reaction of potassium salts of N,N-disubstituted dithiocarbamoic acids with 2-[(alpha-chloro-alpha-phenylacetyl/alpha-bromopropionyl)-amino]-5 -aryl-1, 3,4-oxadiazoles. Structures of the compounds were confirmed by the spectral data (IR, 1H NMR, EIMS) and elemental analyses. Most of the compounds were tested against various microorganisms and four of them were found to be weakly active against Staphylococcus aureus and Staphylococcus epidermidis.

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.

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.

FUSED HETEROCYCLES : SYNTHESIS OF SOME NEW IMIDAZOTHIAZOLES

Reaction of aldehyde-hydrazones or semicarbazones bearing an imidazo [2, 1-b] [1,3]thiazole ring system with mercaptoalkanoic acids were investigated. Antimycobacterial activities of compounds thus obtained were evaluated against Mycobacterium tuberculosis H37RV using rifampine as standard. Treatment of tuberculosis is still one of the major problems due to the rise of multidrug resistant tuberculosis in clinical practice. Since many years, isonicotinic acid hydrazide (isoniazide) has been used as a principal drug for the treatment of the desease. The effects of substituents and bioisosteric replacements on its antituberculous activity are still under investigation (1). This prompted us to synthesize 6-methylimidazo [2, l-£>] [1, 3] thiazole-5-carbohydrazide 2, a structural analog of isoniazide, and its hitherto unreported derivatives to screen their antituberculous properties. Ar: a,QH5; b,C,;H4F(4); C,QH4C1(4); d, QH4Br (4) ; e, QH4CH3 (4 ) ; f ,QH4OCH3(4) ; g,QH4N02(2) 6-Methylimidazo[2,1-b][l,3]thiazole-5-carbohydrazide was synthesized by the reaction of hydrazine with ethyl 6-methylimidazo [2 , l-£>] [1, 3] thiazole-5-carboxylate (2). 2 reacted with aromatic aldehydes to afford hydrazide-hydrazones 3 which furnished N-(2-aryl-

ENANTIOSELECTIVE QUANTIFICATION OF DOXYLAMINE IN HUMAN PLASMA BY HPLC

A high pressure liquid chromatography-diode array detector (HPLC-DAD) method using amylose tris(3,5-dimethylphenyl carbamate) chiral stationary phase (Chiralpak AD-H) is described for the determination of doxylamine enantiomers in human plasma. Doxylamine enantiomers were separated on a Chiralpak AD-H column using a mobile phase composed of n-hexane-2-propanol-diethylamine (98:2:0.025, v/v/v). Diphenhydramine was used as an internal Standard (IS). Doxylamine was extracted from plasma samples using dichloromethane:hexane (1:2 v/v), which yielded high extraction yields (87%), satisfactory precision (RSD < 1.05%), and good selectivity. Linearity was found in the 8–40 µg · mL−1 range with the limits of detection 0.13 µg · mL−1. Doxylamine enantiomers were well separated with no interference from endogenous plasma constituents. The method developed, showed a good linearity, sensitivity, and repeatability.

Synthesis and Structure-Activity Relationship of N-(3-Oxo-1-Thia-4-Azaspiro[4.5]Decan-4-Yl)Carboxamide Inhibitors of Influenza Virus Hemagglutinin Mediated Fusion

GRAPHICAL ABSTRACT Abstract We report on synthesis and the structure-activity relationship of carboxamide-derived inhibitors of the influenza virus fusion function of the viral hemagglutinin. The newly synthesized carboxamides have a backbone structure similar to reported fusion inhibitors, consisting of an aromatic ring system linked to a non-aromatic cyclic system via an amide bridge. Condensation of 2-hydroxybenzohydrazide, 5-chloro-2-hydroxybenzohydrazide or 3-hydroxynaphthalene-2-carbohydrazide, appropriate carbonyl compounds and sulfanyl acids yielded corresponding N-(3- oxo-1-thia-4-azaspiro[4.5]decan-4-yl)carboxamides, using a one-pot three-component cyclocondensation method. The compounds were characterized by IR, 1H-NMR,13C-NMR, and elemental analysis. All compounds were evaluated for antiviral activity against influenza A (H1N1, H3N2) and influenza B viruses in MDCK cell cultures. The contributions of different substituents on the antiinfluenza effect were discussed.

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, C19H24N4O2S2, inversion-related molecules 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 intermolecular C—H⋯O hydrogen bond connects the dimers to each other. An intramolecular C—H⋯O interaction 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).