ANTIMICROBIAL AND ANTIINFLAMMATORY ACTIVITIES OF EXTRACTS AND CONSTITUENTS OF OROXYLUM-INDICUM (L.) VENT

Dichloromethane extracts of the stembark and root of Oroxylum indicum were found to have antimicrobial activities against Gram positive bact eria (Bacillus subtilis and Staphylococcus aureus), Gramnegative bacte ria (Escherichia coli and Pseudomonas aeruginosa) and a yeast (Candida albicans). Bioassay-guided chromatographic fractionation led to the i solation of flavonoids (bacailein and chrysin) and a naphthoquinone, l apachol. Lapachol was found active against the Gram-positive bacteria, 5 mu g giving a zone of inhibition equivalent to that shown by 5 mu g streptomycin, whereas 5 mu g chrysin gave inhibition zones of equal s ize to 5 mu g streptomycin against Candida albicans and Pseudomonas ae ruginosa. The inhibitory activity of lapachol from O. indicum root aga inst soya 5-lipoxygenase (IC50 0.79 mu g/ml) was equivalent to that of the positive control fisetin (IC50 0.97 mu g/ml) and 50 mu g/ml of th e dichloromethane extract of the rootbark gave 100% inhibition of leuk ocyte lipoxygenase. These activities might indicate an antiinflammator y effect for the dichloromethane extract, mainly due to the lapachol c ontent.