V. Padmavathi

Synthesis, antimicrobial and cytotoxic activities of 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and 1,2,4-triazoles.

A new class of 1,3,4-oxadiazoles were prepared from acid hydrazides on treatment with different carboxylic acids in the presence of phosphorus oxychloride. Interconversion of oxadiazoles to thiadiazoles and triazoles was carried out with appropriate reagents. The antimicrobial and cytotoxic activities of compounds 7a-d to 12a-d were tested. Compounds 10d and 12d showed pronounced antimicrobial activity. Further, compound 10d exhibited maximum cytotoxicity.

Synthesis, antimicrobial and antioxidant activities of substituted pyrazoles, isoxazoles, pyrimidine and thioxopyrimidine derivatives

A new class of heterocycles, substituted pyrazoles, isoxazoles, pyrimidines, thioxopyrimidines were prepared from Michael adducts, 2-(1,2-diaroylethyl)malononitrile and 2-(1,2-diarylsulfonylethyl)malononitrile by cyclocondensation with appropriate nucleophiles. The lead compounds were screened for the antimicrobial and antioxidant activities.

Synthesis and antioxidant activity of oxazolyl/thiazolylsulfonylmethyl pyrazoles and isoxazoles.

A new class of oxazolyl/thiazolylsulfonylmethyl pyrazoles (10-13) and isoxazoles (14, 15) were prepared from the synthetically vulnerable intermediate E-styrylsulfonylacetic acid methyl ester (1) and studied their antioxidant activity.

Synthesis and antimicrobial activity of amido linked pyrrolyl and pyrazolyl-oxazoles, thiazoles and imidazoles.

A new class of amido linked bis heterocycles viz., pyrrolyl/pyrazolyl-oxazoles, thiazoles and imidazoles were prepared by 1,3-dipolar cycloaddition of TosMIC and diazomethane to the respective cinnamamide derivatives and screened for antimicrobial activity. The chlorosubstituted imidazolyl cinnamamide (6c) is the most potential antimicrobial agent as it displayed strong antibacterial activity against Bacillus subtilis and antifungal activity against Penicillium chrysogenum.

Synthesis, antimicrobial and cytotoxic activities of pyrimidinyl benzoxazole, benzothiazole and benzimidazole.

A variety of pyrimidinyl benzoxazoles, benzothiazoles and benzimidazoles linked by thio, methylthio and amino moieties were prepared and studied their antimicrobial and cytotoxic activities. The compound pyrimidinyl bis methylthio benzimidazole 22 was a potent antimicrobial agent particularly against Staphylococcus aureus (29 mm, MIC 12.5 μg/mL) and Penicillium chrysogenum (38 mm, MIC 12.5 μg/mL). The amino linked pyrimidinyl bis benzothiazole 24 exhibited cytotoxic activity on A549 cells with IC50 value of 10.5 μM.

Synthesis of Some Fused Pyrazoles and Isoxazoles

The α-keto methylene group in 3,5-diaryl-2-cyclohexenones 2 and 3,5-diarylcyclohexanones 8 have been used to obtain fused pyrazoles and isoxazoles. The new compounds were characterized by IR and 1H-NMR spectral data.

Synthesis and biological activity of 2-(bis((1,3,4-oxadiazolyl/1,3,4-thiadiazolyl)methylthio)methylene)malononitriles.

The reactivity of ketene dithiolates in the presence of different equivalents of sodium ethoxide was studied. 2-(Bis((5-aryl-1,3,4-oxadiazol-2-yl)methylthio)methylene)malononitriles 5 and 2-(bis((5-aryl-1,3,4-thiadiazol-2-yl)methylthio)methylene)malononitriles 6 were prepared by the reaction of malononitrile with carbon disulfide and 5-aryl-2-(chloromethyl)-1,3,4-oxadiazoles 3/5-aryl-2-(chloromethyl)-1,3,4-thiadiazoles 4. The preliminary antimicrobial and antioxidant activities of the lead compounds were assayed.

CYCLOHEXENONE CARBOXYLATES. A VERSATILE SOURCE FOR FUSED ISOXAZOLES AND PYRAZOLES

The 6-carbethoxy-3,5-diarylcyclohex-2-enone (1) was subjected to condensation and 1,3-dipolar cycloaddition reactions to get fused isoxazole and pyrazole derivatives.

Synthesis, antimicrobial and cytotoxic activities of sulfone linked bis heterocycles.

A new class of sulfone linked bis heterocycles viz., pyrrolyl/pyrazolyl arylaminosulfonylmethyl 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, and 1,2,4-triazoles were prepared and tested for antimicrobial activity and cytotoxicity. The chloro-substituted compounds 5c, 8c and 14c showed comparable antibacterial activity to chloramphenicol against Pseudomonasaeruginosa and compound 5c exhibited comparable antifungal activity to ketoconazole against Penicilliumchrysogenum. One of the compounds, vinylsulfonyl oxadiazole showed appreciably cytotoxic activity on A549 lung carcinoma cells with an IC(50) at a concentration of 31.7 μM.

Synthesis and bioassay of aminosulfonyl-1,3,4-oxadiazoles and their interconversion to 1,3,4-thiadiazoles

A new class of oxadiazoles is prepared by treating aminosulfonylacetic acids with different carboxylic acid hydrazides. Interconversion of oxadiazoles to thiadiazoles is carried out with thiourea. The compounds are screened for antimicrobial and antioxidant activities.