Phytochemical and antimicrobial studies on essential oils of some aromatic plants

The antimicrobial activity of the volatile constituents of five different plant essential oils, that is, Ocimum sanctum (leaves), Eucalyptus globulus (leaves), Mentha arvensis (leaves), Citrus lemon (fruit epicarp) and Citrus maxima (fruit epicarp) was evaluated in vitro against seven bacteria (Bacillus pumilus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella typhi), two filamentous fungi (Aspergillus niger and Aspergillus flavus) and a yeast (Candida albicans). The volatile constituents of O. sanctum, E. globulus and M. arvensis exhibited strong antimicrobial activities against test pathogenic fungi and bacteria (both gram-positive and  gram-negative). The chemical composition of essential oils determined by gas chromatograph (GC) and high performance thin layer chromatography (HPTLC) analysis consisted of eugenol (56.07%), 1, 8 cineole (17.34%) and menthol (43.45%) as the major chemical constituents in O.sanctum, E. globulus and M. arvensis, respectively. Limonene was the only major constituent present in the oil samples from C. lemon with the highest percentage (78.28%)