ABSTRACT
A series of 23 new 2-[p-substituted-benzyl]-5-[p-substituted-phenyl/benzyl-carbonylamino]benzoxazole derivatives has been synthesized by reacting 5-amino-2-[p-substituted-benzyl]benzoxazoles with the appropriate carboxylic acid chlorides. The structures of the synthesized compounds were confirmed by IR and (1)H-NMR spectral data. Antimicrobial activities of the compounds were investigated using the twofold serial dilution technique against two gram-positive and two gram-negative bacteria and three Candida species in comparison with standard drugs. Microbiological results indicated that the newly synthesized 2-[p-substituted-benzyl]-5-[p-substituted-phenyl/benzyl-carbonylamino]benzoxazole derivatives (3-25) possessed a broad spectrum of activity, showing MIC values of 6.25-200 microg/mL against the gram-positive and gram-negative microorganisms tested. Moreover, they showed significant antifungal activity with MIC values of 3.12-100 microg/mL against the Candida species tested. Especially, with a MIC value of 3.12 microg/mL, 2-benzyl-5-[p-bromobenzyl-carbonylamino]benzoxazole 9 displayed the same activity against C. glabrata as the standard drug myconazol.
Subject(s)
Anti-Bacterial Agents/chemical synthesis , Antifungal Agents/chemical synthesis , Benzoxazoles/chemical synthesis , Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Benzoxazoles/pharmacology , Candida/drug effects , Drug Design , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests , Structure-Activity RelationshipABSTRACT
A series of multisubstituted benzoxazoles, benzimidazoles, and benzothiazoles (5-7) as non-nucleoside fused isosteric heterocyclic compounds was synthesized and tested for their antibacterial activities against various Gram-positive and Gram-negative bacteria and antifungal activity against the fungus Candida albicans. Microbiological results indicated that the synthesized compounds possessed a broad spectrum of activity against the tested microorganisms at MIC values between 100 and 3.12 microg/ml. Structure-activity relationships (SAR) studies revealed that benzothiazole ring system enhanced the antimicrobial activity against Staphylococcus aureus. In these sets of non-nucleoside fused heterocyclic compounds electron withdrawing groups at position 5 of the benzazoles increased the activity against C. albicans.
