Synthesis and Biological Evaluation of New 3-Phenylthiazolidin-4-One and 3-Phenylthiazole Derivatives as Antimicrobial Agents
A new series of 3-phenylthiazolidin-4-ones 4a-h and 3-phenylthiazoles 6a-i were synthesized from the reaction of different 4-phenyl-3-thiosemicarbazone derivatives 3a-i with dimethyl acetylenedicarboxylate and 4-bromophenacyl bromide, respectively. Preparation of 3-phenylthiazoles 6a-i starting from 4-bromophenacyl bromide could be achieved through two pathways either directly or indirectly in which new intermediates 5a-i were isolated. The in vitro antibacterial activities of the newly synthesized compounds were tested versus two panels of Gram-positive bacteria; (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeuroginosa). Also, these compounds were tested for their activities as anti-fungal versus a panel of two fungi (Aspergillus flavus, Candida albicans). Compounds 4d, 6a, 6d, and 6f showed excellent antimicrobial activity exceeded 90%. Compound 6d had equivalent potency to Ampicillin in inhibiting the growth of (Bacillus subtilis) bacteria (% activity index= 100%). Most of the rest of compounds showed good antimicrobial activity (70–90%).