Synthesis and Biological Evaluation of 3-(2-Benzoyl-4-chlorophenyl)-4H-spiro [indole-3,2-[1,3]thiazolidine]-2,4(1H)- dione Derivatives for Anti-tubercular and Antimicrobial Activities

Objectives: To synthesize a new scaff fold of 3'-(2-Benzoyl-4-chlorophenyl)-4'H-spiro [indole-3,2'-[1,3] thiazolidine]-2,4'(1H)-dione derivatives and to assess the compounds for anti-tubercular and antimicrobial activities. Methods : A new series of 3'-(2-Benzoyl-4-chlorophenyl)-4'H-spiro [indole-3,2'- [1,3] thiazolidine]-2,4'(1H)-dione derivatives were prepared by synthesizing schiff’s bases followed by condensing schiff base with 2-mercaptopropanoic acid in the presence of zinc chloride. Synthesized compounds were characterized by IR, NMR and Mass spectral data. Their antimicrobial, antitubercular and also docking simulations were evaluated. Findings : Compound 3c (floro substituent) showed potent activity against Mycobacterium tuberculosis H37Rv with MIC value of 3.125 µg/ml when compared with standard Isoniazid. Compound 3c, 3d and 3f displayed better antimicrobial activity against used bacterial and fungal species with MIC range of 3-20µg/ml comparable to standard drugs ciprofloxacin and ketoconazole respectively. In silico studies revealed that compound 3c, 3f and 3d had a better binding affinity with M. tuberculosis enoyl-CoA hydratase EchA6 with ΔG values of -9.6kcal/mol, -9.4kcal/mol, and -8.6kcal/mol respectively comparable to isoniazid of -5.4kcal/mol. Compound 3c, 3f and 3d also displayed good binding affinity with DNA gyrase and lanosterol methylase. Novelty : Introducing benzoyl moiety to the thiazolidine ring potentiates the antitubercular and antimicrobial activity of spiro indole derivatives.