Abstract

ULTRASOUND MEDIATED SYNTHESIS AND BIOLOGICAL ACTIVITY OF NEW THIAZOLES DERIVATIVE

Rohini N. Shelke, Dattatraya N. Pansare, Chandrakant D. Pawar, Devanand B. Shinde, Shivaji N. Thore, Umakant D. Pawar, Rajendra P. Pawar, Saroj R. Bembalkar*

Abstract

Objectives: A series of novel rhodanine derivatives 3, 4 and 6a-l were synthesized from 2-thioxothiazolidin-4-one and 2,4- dimethoxybenzaldehyde by Knoevenagel condensation an ultrasound irradiation and conventional technique. The compounds were synthesized with screening with various solvent, bases and characterized by spectral analysis. Method: The antibacterial activity was evaluated against two Gram-positive bacteria namely, Bacillus subtilis (NCIM-2063) and Staphylococcus aureus (NCIM-2901) and one Gram-negative bacterium Escherichia coli (NCIM-2256). The antibacterial activity of compounds was monitored by observing their Minimum Inhibitory Concentration (MIC, μg/mL) as previously mentioned by broth dilution method using Ciprofloxacin and Ampicillin as standard drugs. The antifungal activity was evaluated against three fungal strains; Candida albicans (NCIM-3471), Aspergillus flavus (NCIM-539) and Aspergillus niger (NCIM-1196). Result: The synthetic protocols employed for the synthesis of rhodanine derivatives 3 and 4 presented in Scheme 1 and the compounds 6a-l are presented in Scheme 3. The compound (Z)-5-(2,4- dimethoxybenzylidene)-2-thioxothiazolidin-4-one 3 was prepared via a Knoevenagel condensation. Conclusion: In comparison with conventional methods, our protocol is convenient and offers several advantages, such as shorter reaction time, higher yields, milder conditions and environmental friendliness. Amongst these synthesized compounds 6a, 6h, 6j, 6h were shows most antibacterial and antifungal activities.

Keywords: 2-thioxothiazolidin-4-one; knoevenagel condensation; ultrasonic irradiation; potassium carbonate.