SYNTHESIS AND MICROBIOLOGICAL ACTIVITY OF SOME NOVEL 5-METHYL-2-(2,4-DISUBSTITUTED OR 6-METHYL-2-(2,4-DISUBSTITUTED PHENYL) BENZOXAZOLE DERIVATIVES

The synthesis of a new series of 5- or 6-methyl-2-(2,4-disubstituted p henyl)benzoxazoles (4, 5) is described in order to determine their ant imicrobial activities and feasible structure-activity relationships. T he synthesized compounds were tested in vitro against three Grampositi ve bacteria, three Gram-negative bacteria and the yeast Candida albica ns, in comparison with several control drugs. Microbiological results exhibited that the synthesized compounds possess a broad spectrum of a ntibacterial activity against the tested microorganisms. The compounds 4b and 4c indicated some antibacterial activity against Staphylococcu s aureus having a minimum inhibitory concentration (MIC) of 12.5 mu g/ ml. Moreover, the compound 5a revealed a significant antibacterial act ivity against the enterobacter Pseudomonas aeruginosa showing a MIC va lue of 25 mu g/ml, i.e. more potent than the control drugs tetracyclin e and streptomycin. For the antimycotic activity against the yeast C. albicuns, the derivative 4c was found to be more active than the other synthesized compounds with a MIC value of 12.5 mu g/ml, but one-fold less potent than the control drugs oxiconazole and haloprogin. (C) 199 8 Elsevier Science S.A. All rights reserved.