| Summary: | The essential oil distilled from the leaves of Coleus parvifolius Benth. (Labiatae) was studied by gas chromatography and mass spectrometry (GC-MS). The main components were found to be (E)-phytol (42.77%), followed by eicosatrienoate (16.39%), n-tetradecanoic acid (14.42%), octoil (6.54%), 2-methyl-7- octadecyne (5.97%), nonadecane (3.25%), germacrene-D (2.19%) and α-humulene (1.42%), respectively. Regarding biological activities, the ethanolic extract of C. parvifolius showed potent antimicrobial activity against gram positive bacteria (Staphylococcus aureus, Bacillus subtilis and B. cereus) with inhibition zones of 7-11 mm at a concentration of 10 mg/disc and moderate activity against gram negative bacteria (Salmonella typhi, S. enteritidis and Escherichia coli) with inhibition zones of 9-11 mm at 100 mg/disc, whereas it was inactive against fungus, Candida albicans at a concentration of 100 mg/disc. The extract also exhibited strong antioxidant activity (ED50 = 5.87±0.03 μg/ml) three times higher than that of butylated hydroxytoluene (BHT, ED50 = 18.08±0.43 μg/ml). Moreover, it was non-toxic to brine shrimp with LC50 value > 1,000 μg/ml.
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