Abstract

The aim of this study was to investigate antibacterial activity of essential oils and different organic extractives extracted from the medicinal plant Lippia alba. The chemical composition of the hydrodistilled oil was determined by GC-MS spectroscopy. Typical eighty eight components representing 96.14% of the total oil was identified of which spathulenol (3.03%), caryophyllene oxide (6.39%), aromadendrene oxide-(2) (2.82%), alloaromadendrene oxide-(1) (2.46%), ledene oxide-(ii) (2.8%), α-caryophyllene, (1R)-(-)-myrtenal, 1-octen-3-ol (2.77 at.%), 1H-cyclopenta[1,3] cycloprop[1,2]benzene and myrtenyl acetates (3.29%) were the major components. The antibacterial activity was determined in vitro using agar diffusion method and the MIC determination test against six pathogenic bacteria. The essential oils and different extracts (5.0 μL disc^–1 correspond to 500 and 250 μg disc^–1) displayed a great potential of antibacterial activity against Gram-positive (Sarcina lutea, Bacillus subtilis) and Gram-negative bacteria (Xanthomonas campestries, Escherichia coli, Pseudomonas sp. and Klebsiella preumoniae). The zones of inhibition of different concentrations of the essential oils and the extracts against the tested bacteria were found in the range of 6~23 mm and the minimum inhibitory concentrations (MIC) were recorded between 1.95~500 μg disc^–1. The results obtained from this study demonstrated that the natural product derived from Lippia alba might be used in pharmaceutical, cosmetic and agro-industries as natural preservatives or flavoring to control pathogenic microbes.

Keywords: Lippia alba; Essential oils; Organic extracts; Antibacterial activity; GC-MS spectroscopy