Synthesis of new series of 5,6-dihydro-4H-1,2-oxazines via hetero Diels-Alder reaction and evaluation of antimicrobial activity.

A new series of 5,6-dihydro-4H-1,2-oxazines were synthesized via hetero Diels-Alder reaction of alpha-nitrosoolefins with alkenes. alpha-Nitrosoolefins were generated from ketoximes by the action of chloramine-T. The newly synthesized compounds were characterized with IR, NMR, elemental analysis and screened for their antimicrobial activity; they exhibited excellent antimicrobial activity. The minimal inhibitory concentration of the compounds was in the range of 10-35 microg ml(-1) for bacteria and 10-40 microg ml(-1) for fungi.

Antioxidant and Antimicrobial Activity of 5-methyl-2-(5-methyl-1,3-diphenyl-1H-pyrazole-4-carbonyl)-2,4-dihydro-pyrazol-3-one.

Cycloaddition of nitrile imines 4 generated in situ by the catalytic dehydrogenation of diphenyl hydrazones 3 using Chloramine-T (CAT) as oxidant in glacial acetic acid with enolic form of ethyl acetoacetate 5 afforded Ethyl 3-aryl-5-methyl-1-phenyl-1H-pyrazol-4-carboxylate 6 in 80% yield. The said pyrazoles 6 refluxed with 80% hydrazine hydrate using absolute alcohol as solvent for about 2-3 hours to produce the respective 5-methyl-1,3-diphenyl-1H-pyrazole-4-carboxylic acid hydrazide 7. The alcoholic solution of pyrazole acid hydrazides on heating with ethyl acetoacetate 5 to give the 5-methyl-2-(5-methyl-1,3-diphenyl-1H-pyrazole-4-carbonyl)-2,4-dihydro-pyrazol-3-one 8. The synthesized compounds were found to exhibit good antimicrobial and antioxidant activity as evaluated by 1,1-diphenyl-2-picryl Hydrazyl (DPPH) radical scavenging, reducing power and DNA protection assays.

Growth inhibition and induction of apoptosis in MCF-7 breast cancer cells by a new series of substituted-1,3,4-oxadiazole derivatives.

The multiple pharmacological actions of unique synthetic compounds are a prerequisite for classifying a drug as highly efficacious, because the multiple pharmacological actions offer the possibility of treating various diseases like cancer. 1,3,4-Oxadiazoles are an important class of heterocyclic compounds with broad spectrum of biological activities. In this study we focused on the ability of these derivatives to induce apoptosis in cultured MCF-7 breast cancer cells. Treatment of MCF-7 cells with varying concentrations of the different derivatives resulted in dose and time dependent sequence of events marked by apoptosis, as shown by loss of cell viability, chromatin condensation, internucleosomal DNA fragmentation and sub G(0) phase accumulation. Furthermore, apoptosis in MCF-7 cell was induced by upregulation of proto-oncoprotein Bax and activation of Caspase-3 activated DNase. Although the derivatives induced apoptosis was associated with Bax protein levels, negligible Bcl-2 reduction was observed. Analysis of the data suggests that the substituted oxadiazole derivatives exert antiproliferative action and growth inhibition on MCF-7 cells through apoptosis induction and that it may have anticancer properties valuable for application in drug products.

Synthesis and antimicrobial studies of a new series of 2-[4-[2-(5-ethylpyridin-2-yl)ethoxy]phenyl]-5-substituted-1,3,4-oxadiazoles.

A series of novel 2-[4-[2-(5-ethylpyridin-2-yl)ethoxy]phenyl]-5-substituted-1,3,4-oxadiazoles were synthesized by the oxidative cyclisation of hydrazones derived from 4-[2-(5-ethylpyridin-2-yl)ethoxy]benzaldehyde and aroylhydrazines using chloramine-T as oxidant. IR, NMR and elemental analysis characterized the newly synthesized compounds. The synthesized compounds were evaluated for their antimicrobial activity and were compared with standard drugs. The compounds demonstrated potent to weak antimicrobial activity. Out of the compounds studied, compounds 8c and 8d showed significant inhibition. Compounds 8b, 8f, 8k and 8e showed moderate activity. The minimum inhibitory concentration of the compounds was in the range of 8-26 microg ml(-1) against bacteria and 8-24 microg ml(-1) against fungi. The title compounds represent a novel class of potent antimicrobial agents.