Chemical composition and antioxidant, antibacterial and antifungal activities of the essential oils from Bidens pilosa Linn. var. Radiata

The present study describes the chemical composition, antibacterial and antifungal activities of essential oils from Bidens pilosa, a traditional medicinal plant widely distributed in the subtropics and tropics. The essential oils from the fresh leaves and flowers of B. pilosa were analyzed by GC-MS. Forty-four components were identified, of which beta-caryophyllene (10.9% and 5.1%) and tau-cadinene (7.82% and 6.13%) were the main compounds in leaves and flowers, respectively. The oils and aqueous extracts of leaves and flowers were subjected to screening for their possible antioxidant activities by using 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and beta-carotene bleaching methods. In the former case, the essential oils from leaves and flowers were found to be superior to all aqueous extracts tested with an IC50 value of 47.5 and 49.7 mu g/ml, respectively, whereas all extracts and essential oils seemed to inhibit the oxidation of linoleic acid in the latter case. The oils from B. pilosa exerted significant antibacterial and antifungal activities against six bacteria and three fungal strains. The inhibitory activity of the flower essential oils in Gram-negative bacteria was significantly higher than in Gram-positive. Our findings demonstrate that the essential oils and aqueous extracts of B. pilosa possess antioxidant and antimicrobial activities that might be a natural potential source of preservative used in food and other allied industries. (c) 2007 Elsevier Ltd. All rights reserved.