In vitro evaluation of antimicrobial activity of crude extracts of Launaea pinnatifida cass leaves

Abstract

The aim of the study was to investigate the antimicrobial activity of various extracts of Launaea pinnatifida Cass leaves against some clinically isolated bacterial and fungal strains. Preliminary antimicrobial activity was evaluated by agar disc diffusion method. Minimum inhibitory concentration (MIC) was determined by tube dilution method, while minimum bactericidal concentration (MBC) and a minimum fungicidal concentration (MFC) were determined by agar diffusion method. Ethanolic extract (EE) exhibited highest sensitivity against Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi and moderate sensitivity against Bacillus subtilis and Vibrio cholera. While the distilled water extract (DWE) showed the maximum zone of inhibition against Pseudomonas aeruginosa compared to EE. Petroleum ether extract (PEE) exhibited the moderate inhibition while chloroform extract (CE) showed lowest inhibition. The DWE showed sensitivity against Aspergillus niger and Aspergillus flavus. The MIC and MFC values of 1000, 1200, 1400 and 1500 ?g/ml exhibited by different extracts showed the moderate sensitivity while the extracts that showed the MIC and MFC values of 1600, 1800 and 2000 ?g/ml was found to be the least sensitive against the fungi. The study confirmed that the EE possessed potential antimicrobial activity than the DWE when compared to other extracts. The differentiating activities of these extracts encourage to develop novel broad spectrum antimicrobial substances in future.