Essential Oils of the Asteraceae Plants Blumea riparia DC. and Pluchea pteropoda Hemsl. ex Hemsl. Growing in Vietnam

Essential oils of two Asteraceae plants Blumea riparia DC. and Pluchea pteropoda Hemsl. ex Hemsl., collected from Vietnam, have been studied by hydro-distillation and GC/MS-FID (gas chromatography/mass spectrometry-flame ionization detector) analysis. Oil yields of B. riparia fresh leaves and twigs were in the range of 0.1–0.2%, whereas essential oil in the fresh aerial parts of P. pteropoda reached about 0.5%. Sesquiterpene hydrocarbons and oxygenated sesquiterpenes were the main chemical classes in the essential oils of B. riparia. The leaves and twigs of this species gave essential oils containing germacrene D (33.6-42.6%), ( E)-β-caryophyllene (11.2-11.6%), and bicyclogermacrene (9.3-12.1%) as the major components. Oxygenated monoterpenes and sesquiterpene hydrocarbons achieved the highest amounts in the essential oil of P. pteropoda aerial parts; 2,5-dimethoxy- p-cymene (43.5%), β-maaliene (14.0%), and α-isocomene (9.0%) were characteristic compounds. Particularly, as compared with related Blumea and Pluchea species, B. riparia and P. pteropoda, collected from Vietnam, might be good sources of germacrene D and 2,5-dimethoxy- p-cymene, respectively. The essential oil of B. riparia leaf successfully controlled the growth of the fungus Fusarium oxysporum, with an MIC value of 50.0 µg/mL, and the essential oil of P. pteropoda aerial parts showed significant antimicrobial activity against the Gram positive bacterium Bacillus subtilis and the yeast Candida albicans, with the same MIC value of 50.0 µg/mL.