CHEMICAL COMPOSITION AND ANTI-MICROBIAL ACTIVITY OF THE VOLATILE OILS OF AVERRHOA CARAMBOLA L. (STAR FRUIT) GROWN IN NIGERIA

Abstract

The chemical composition and antimicrobial activity of the essential oils extracted from the leaf and fruit of Averrhoa carambola L. (family Oxalidaceae) grown in Nigeria were evaluated. These extractions were carried out via hydrodistillation using a Clevenger apparatus. Essential oils from the leaf and fruit were analyzed using gas chromatography-mass spectrometry. The essential oil of the fruit revealed the presence of seventeen components, whose major compounds were estragole (62.312 %), trans-α-bisabolene (12.209 %) and pinene (8.246 %). Seven components from the essential oil of the leaf were identified; the major compounds were estragole (66.847 %), bis(2-ethylhexyl) phthalate (11.964 %) and α-ocimene (9.699 %). The volatile oil from the fruit showed antimicrobial activity against the test organisms (Escherichia coli, Bacillus subtilis, and Staphylococcus aureus) with minimum inhibitory concentrations ranging from 10 to 20 μg/ml; while that of the leaf inhibited the growth of only Staphylococcus aureus with minimum inhibitory concentration of 20 μg/ml. These results show that the plant, Averrhoa carambola, is a good antimicrobial agent. Keywords: Averrhoa carambola, volatile oil, hydrodistilation, antimicrobial activity, estragole, pinene, α-ocimene, star fruit