New Phenylthiazoles: Design, Synthesis, and Biological Evaluation as Antibacterial, Antifungal, and Anti‐COVID‐19 Candidates

Abstract

Abstract The combination of antibacterial and antiviral agents is becoming a very important aspect of dealing with resistant bacterial and viral infections. The N ‐phenylthiazole scaffold was found to possess significant anti‐MRSA, antifungal, and anti‐COVID‐19 activities as previously published; hence, a slight refinement was proposed to attach various alkyne lipophilic tails to this promising scaffold, to investigate their effects on the antimicrobial activity of the newly synthesized compounds and to provide a valuable structure–activity relationship. Phenylthiazole 4 m exhibited the most potent anti‐MRSA activity with 8 μg/mL MIC value. Compounds 4 k and 4 m demonstrated potent activity against Clostridium difficile with MIC values of 2 μg/mL and moderate activity against Candida albicans with MIC value of 4 μg/mL. When analyzed for their anti‐COVID‐19 inhibitory effect, compound 4 b emerged with IC 50 =1269 nM and the highest selectivity of 138.86 and this was supported by its binding score of −5.21 kcal mol −1 when docked against SARS‐CoV‐2 M pro . Two H‐bonds were formed, one with His164 and the other with Met49 stabilizing phenylthiazole derivative 4 b , inside the binding pocket. Additionally, it created two arene‐H bonds with Asn142 and Glu166, through the phenylthiazole scaffold and one arene‐H bond with Leu141 via the phenyl ring of the lipophilic tail.