Chemical composition analysis and antioxidant activity evaluation of essential oil from Orthosiphon thymiflorus (Roth) Sleesen

Abstract Objective Orthosiphon thymiflorus (Roth) Sleesen (O. thymiflorus) is an aromatic plant widely distributed in the Western Ghats of South India. The present study investigates the chemical composition and antioxidant activities of O. thymiflorus essential oil isolated from the leaves. Methods The essential oil was hydrodistilled from the leaves by using Clevenger apparatus. Isolated essential oil was chemically analyzed by gas chromatography (GC) and gas chromatography- mass spectrometry (GC-MS). In vitro antioxidant activity of the isolated essential oil was determined. Results Chemical composition analysis of essential oil reported to the presence of thirty three compounds. The major compound was 2-isopropyl-5-methyl-9-methylene-bicyclo-1-decene (4.4.0) (42.62%) followed by carotol (16.48%), α -cadinol (6.14%) and δ-3-carene (5.15%). In vitro antioxidant activity of the isolated oil showed dose dependent free radical scavenging activity against DPPH (IC50 437.12±0.02 ?g/mL) and hydroxyl radicals (IC50 317.88±0.02 μg/mL). Metal chelating and prevention of deoxyribose degradation activities of the oil was observed with the IC50 of 339.78±0.01 μg/mL and 158.33±0.02 μg/mL respectively. Antioxidant activity of the oil was low when compared with the positive controls such as BHT and ascorbic acid. Conclusions The present study shows various chemical components present in the O. thymiflorus essential oil and with it's significant antioxidant activity thus has great potential to be used as natural food supplement.