ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Design and synthesis of novel thiopheno-4-thiazolidinylindoles as potent antioxidant and antimicrobial agents

Jaiprakash S. Biradar, Parveen Rajesab, and B. Somappa Sasidhar

Central Research Lab, Department of Chemistry, Gulbarga University, Gulbarga, 585 106, Karnataka State, India

E-mail: jsbiradar@yahoo.com

Abstract: A novel and convenient synthesis of thiopheno-4-thiazolidinyl indole analogues is presented (IVa-IVi), with the aim of obtaining biologically active compounds. 3,5-disubstituted indol-2-carboxyhydrazides (Ia-If) were allowed to react with 3-acetyl-2,5-dichlorothiophene (II) to yield the corresponding 3,5-disubstituted indol-2-carbohydrazides (IIIa-IIIf). The pre-formed indolecarbohydrazides (IIIa-IIIf) were allowed to react with 2-mercaptoacetic acid or 2-mercaptopropanoic acid to produce thiopheno-4-thiazolidinylindoles (IVa-IVi). This reaction protocol affords a simple, eco-friendly, non-hazardous, easier preparation and high yields. The antioxidant (free radical scavenging, total antioxidant capacity and ferric-reducing antioxidant power) and antimicrobial activities of the synthesised compounds were evaluated. The structures and purity of the products were confirmed by their IR, ¹H NMR, ¹³C NMR and mass spectral and analytical data. Most of the compounds tested showed very significant scavenging, antioxidant and antimicrobial activities. Compounds containing electron donor group (CH₃) at the fifth position of indole exhibit an excellent ferric-reducing activity. The present study suggests that compounds IIIa-IIIb, IIIf, IVa-IVc, IVf-IVi, may serve as promising lead scaffolds for antioxidant and antimicrobial agents.

Keywords: indole carboxyhydrazide – indole carbohydrazide – thiopheno thiazolidinylindoles – dichlorothiophene – antioxidant activity – antimicrobial activity

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0452-3

Chemical Papers 68 (3) 392–400 (2014)