Antimicrobial activity of crude extracts from Oroxylum indicum leaves

Abstract

Oroxylum indicum (L.) Kurz is a traditional medicine used in Asia for the treatment and prevention of several diseases including respiratory diseases, diarrhea and dysentery. In this study, we investigated the antimicrobial activity of 4 crude extracts of O. indicum leaf, obtained using the solvents hexane, ethyl acetate, ethanol and methanol. Solutions containing 10 mg / ml of the crude extracts were dissolved in 50% (v/v) dimethyl sulfoxide (DMSO), and tested against 6 microorganisms by the agar well diffusion method. Methanol, ethanol and ethyl acetate extracts of O. indicum leaf were found to inhibit Bacillus cereus ATCC 11778, Staphylococcus epidermidis DMST 15505 and Candida albicans ATCC 10231, but were inactive against Pseudomonas aeruginosa ATCC 27853. The methanol and ethanol extracts generated the largest zones of inhibition, their mean sizes being 6.33±1.53 and 5.67±1.15 mm, respectively. Upon subsequent quantitative testing, the methanol extract of O. indicum leaf was found to completely inhibit microbial growth, its minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) values identified as being between 25 and 50 mg / ml. In conclusion, O. indicum leaf extract contains antimicrobial compounds that could be useful as pharmaceutical and cosmetic products.