Synthesis and microbiological activity of some novel N-(2-hydroxyl-5-substitutedphenyl)benzacetamides, phenoxyacetamides and thiophenoxyacetamides as the possible metabolites of antimicrobial active benzoxazoles.

Synthesis of some novel N-(2-hydroxyl-5-substitutedphenyl)benzacetamides, phenoxyacetamides and thiophenoxyacetamides (5a-k) were described in order to determine their in vitro antimicrobial activity against 3 Gram-positive, 3 Gram-negative bacteria and the fungus Candida albicans comparing with several control drugs. The derivative 5e was found active at a MIC value of 25 micrograms/ml against the whole tested Gram-positive bacteria strains and the Gram-negative microorganism Klebsiella pneumoniae. Moreover, the synthesized compounds 5a-k exhibited significant antibacterial activity against the enterobacter Pseudomonas aureginosae when compared to the control drugs. For the antifungal avtivity against C. albicans, the compound 5k was found more active than the other synthesized derivatives. On the other hand, the antimicrobial activity of some of these acetamide derivatives (5c, 5d, 5e, 5j and 5k) which are the possible metabolites of benzoxazoles, were also compared with their cyclic analogues 6-10. However, most of the MIC values of the benzoxazole derivatives provided better activity than the compared acetamides, while some others of the acetamide derivatives possessed either one fold improved (5d, 5e and 5j) or the same potency (5c, 5d, 5e, 5j and 5k) against the tested microorganisms.