The essential oil obtained from leaves and flowers of Eupatorium polystachyum DC. (Asteraceae) collected in Rio Grande do Sul State, Brazil, was characterized by GC-MS and its antioxidant activity was assessed by DPPH assay. The yield of essential oil, relative to fresh material, was 1.6 and 0.9% for leaves and flowers, respectively. Both oils are constituted exclusively by terpenic compounds. Leaf oil contains great quantity of monoterpenes (66.4%); on the other hand, inflorescence oil contains comparable quantities of mono- and sesquiterpenes (51.8 and 47.7%, respectively). The same compounds are majority in both oils: beta-pinene (14.7 and 9.8%), beta-myrcene (15.3 and 10.8%) and limonene (22.8 and 20.5%) among monoterpenes and beta-caryophyllene (10.4 and 15.4%), germacrene D (7.2 and 9.4%) and bicyclogermacrene (12.0 and 19.2%) among sesquiterpenes. The oils had antioxidant activity by DPPH assay in 1:10 dilution in ethyl ether (v/v).
Eupatorium polystachyum; essential oils; antioxidant activity; DPPH
