Antibacterial activity of flower of Melia azedarach Linn. and identification of its metabolites

Abstract

Constituents of eight different extracts and fractions, obtained from flowers of Melia azedarach, were identified by gas chromatography–mass spectrometry and mass spectral library search. Altogether, 38 phytochemicals were identified, all for the first time from the flowers. Only 14 of these were known from parts of M. azedarach other than flowers, while 24 are reported for the first time from any part of the plant. These metabolites included branched and n-hydrocarbons, aromatics, a polyisoprenoid, fatty acids, fatty acid methyl esters, and fatty alcohols, which were found to be different from its essential oil constituents. One major constituent 4-hydroxybenzoic acid (4) was not only identified but also isolated as a pure compound from ethyl acetate extract. Extracts, compound 4 and its derivatives gallic acid and methyl gallate were tested for antimicrobial potential. Gallic acid and methyl gallate exhibited antibacterial activity against Staphylococcus saprophyticus. Methyl gallate also showed some activity against Corynebacterium diphtheriae and Corynebacterium. hofmannii. Among the extracts, only methanol extract exhibited activity against Pseudomonas sp. The extracts only inhibited the growth of dermatophytic fungi.