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Antibacterial Activity and Chemical Composition of Essential Oils from Leaves of Some Aromatic Plants of Philippines

Abstract In this present study, the antibacterial activity and the chemical composition of essential oils from the leaves of ten aromatic plants growing in the Philippines were determined. Essential oils were isolated by steam distillation and their antibacterial activities against the gram-positive bacteria (S. aureus, S. epidermidis and E. faecalis) and gram-negative bacteria (P. aeruginosa and E. coli) were investigated using disc diffusion and broth micro-dilution methods. Chemical components of essential oils with most potent antibacterial activities were analyzed by gas chromatography/mass spectrometry (GC/MS). Less than 1% (w/w) essential oil was extracted from all plants. Curcuma longa produced the highest yield (0.77 %) among the studied plants. Among the ten essential oils, Lippia micromera, Plectranthus amboinicus, Cymbophogon citratus, and Ocimum tenuiflorum were the most effective in producing zones of inhibition greater than 15 mm. However, no significant differences were observed in their minimum inhibitory and bactericidal concentrations. The most abundant compounds in L. micromera, P. amboinicus, C. citratus, and O. tenuiflorum essential oils were γ-terpinene (25.6 %), carvacrol (51.3 %), citral (47.7 %), and m-eugenol (69.1 %) respectively. This study shows that the essential oils from L. micromera, P. amboinicus, C. citratus, and O. tenuiflorum cultivated in the Philippines exhibit potent antibacterial activity, which might be attributed to their high terpenoids or phenolic content.