In vitro antimicrobial and cytotoxicity screening of n-hexane, chloroform and ethyl acetate extracts of Lablab purpureus (L.) leaves

Abstract

In the present study the antimicrobial & cytotoxic activity of crude extracts (Chloroform, n-Hexane, Ethyl acetate) of leaves of Lablab purpureus L. were studied. Antimicrobial activity was tested against eleven important pathogenic bacteria including both gram positive and gram negative bacteria and three fungi. The bacteria are B. megaterium, B. subtilis, Staphylococcus aureus, Sarcina lutea, Escherichia coli, Salmonella paratyphi, S. typhi, Shigella boydii, S. dysenteriae and Vibrio mimicus & V. parahemolyticus. Disc diffusion technique was used for invitro antibacterial and antifungal screening. Here kanamycin disc (30g /disc) was used as standard for antibacterial study. The extracts showed antimicrobial activity against most of the bacterial strains with an average zone of inhibition of 8-20mm. The tested fungi are Saccharromyces cerevaceae, Candida albicans and Aspergillus niger. The extracts showed moderate to good antifungal activity with an average 9 -15 mm zone of inhibition. Among the three solvent extracts used, the most effective extract was found to be n-Hexane extract and maximum activity (20 mm, zone of inhibition) found against Staphylococcus aureus with Minimum inhibitory concentration (MIC) values of 64g/ml. The maximum zone of inhibition for chloroform extract showed 17mm against Bacillus subtilis and E.coli with MIC 128g/ml and 32g/ml respectively. The maximum zone of inhibition for Ethyl acetate extract showed 17mm against Vibrio mimicus with MIC values of 64g/ml .Cytotoxicity test was also studied by Brine Shrimp Lethality Bioassay and compare with LC50 values of standard Vincristin sulphate as a positive control. The results illustrated significant cytotoxicity against A. salina, with LC50 13.88µg/ml, 19.17µg/ml and 17.97µg/ml for n-Hexane, Chloroform and Ethyl acetate extracts respectively.