Synthesis, In Vitro Antimicrobial, and Antioxidant Activities of Novel Thiazole Derivatives

ABSTRACT In this study, new thiazole derivatives containing hydrazone and bromothiophene moieties were synthesized, and their structures were elucidated using 1 H NMR, 1 3 C NMR, and HRMS. Antimicrobial and antioxidant tests were conducted to assess their biological activities. In the antimicrobial section, compound 2e showed moderate activity on Gram‐positive ( Bacillus subtilis and Staphylococcus aureus ), Gram‐negative ( Pseudomonas aeruginosa and Escherichia coli ), and fungal strains ( Candida albicans and Candida krusei ) with minimum inhibitory concentration (MIC) values of 125, 250, and 500 µg/mL, respectively. Furthermore, according to the agar diffusion assay, compounds 2a and 2e showed the most significant antibacterial activity. Their antioxidant properties were investigated by the DPPH radical scavenging method, and among them, compound 2b showed the highest activity with an IC 50 value of 29.16 ± 0.009 µM. Compound 2e showed activity close to that of the reference drug, gallic acid (IC 50 of 29.48 ± 0.014 µM), with an IC 50 of 33.14 ± 0.002 µM. The structure–activity relationship (SAR) analysis revealed that electron‐donating substituents, particularly methoxy groups, enhance antimicrobial and antioxidant activity through improved molecular interactions. In silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) evaluation further indicated that compound 2e possesses favorable pharmacokinetic properties, including good membrane permeability and oral absorption, despite moderate solubility and predicted hERG liability.