Chemical Composition, Antioxidant and Antibacterial Properties of the Essential Oils of Shorea acuminata (Dipterocarpaceae)

Chemical composition, antioxidant and antibacterial properties of the essential oils from the stem and leaves of Shorea acuminata Dyer were investigated. The yield of the hydro-distilled essential oils obtained from stem and leaves were 0.40 % and 0.02 %, respectively. The main groups of compound found in the essential oils were sesquiterpene hydrocarbons (64.8 % and 33.4 %) and oxygenated sesquiterpenes (19.2 % and 51.7 %), which accounted for 85.6 % of the stem oil and 85.8 % of the leaf oil. Caryophyllene oxide (36.0 %) and beta-caryophyllene (13.9 %) were found to be the major constituents in the leaves, whereas germacrene D (35.0 %) was the major constituent in the stem. The essential oils from the stem and leaves exhibited good antioxidant activity as measured by DPPH free radical-scavenging ability with EC50 of 0.72 mg/ml and 0.64 mg/ml respectively. In beta-carotene/linoleic acid assay, the stem and leaves essential oil exhibited 88.78 % and 89.27 % antioxidant activity respectively at 9 mg/ml which was comparable to that of BHT (98.31 %). The antibacterial test results showed that the leaf oil of S. acuminata had low antibacterial activity against MRSA and S. aureus and no antibacterial activity against S. typhimurium and E. coli. The stem oil was inactive against all bacteria tested.