RESUMO:Os óleos essenciais obtidos de plantas nativas de Baccharis dracunculifolia e Baccharis uncinella, também conhecido como óleo-de-vassoura, é utilizado na indústria de perfumaria, proporcionando um aroma exótico a diversos perfumes, além de muitos estudos sobre atividades biológicas dessas espécies destacam os efeitos alelopáticos, antioxidante, antimicrobianos, citotóxicos e antiinfl amatórios. A vassoura é uma planta arbustiva de ocorrência espontânea no Brasil, assim como nos demais países do Mercosul. A composição do óleo depende da região geográfi ca e do processo de extração utilizado e a importância comercial está diretamente relacionada com a concentração de compostos oxigenados, destacando o nerolidol e o espatulenol. Óleos essenciais obtidos dessas duas espécies pelo processo de hidrodestilação, foram avaliados pelo método de difusão em disco de papel, em placas de Petri contendo meio de Müeller-Hinton, semeadas com suspensões bacterianas previamente ajustadas ao tubo 0,5 da escala de Mac Farland de quatro cepas provenientes da American Type Culture Colection: Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 e Pseudomonas aeruginosa ATCC 27853. Discos contendo diferentes volumes dos óleos essenciais sem qualquer diluição (1, 3, 5 e 10 μL/disco) foram adicionadas às placas e incubadas a 36 o C por 24 a 48 horas. Discos de cloranfenicol (CLO) e amoxicilina (AMO) com volumes de 50 e 10 μg/disco respectivamente, foram utilizados como controle. Os resultados apresentados revelam que ambos os óleos avaliados apresentam atividade antimicrobiana sobre S. aureus, E. coli e P. aeruginosa. Unitermos:Baccharis, Asteraceae, atividade antimicrobiana, óleo essencial. ABSTRACT: "Antimicrobial activity of essential oils produced by Baccharis dracunculifolia D.C. and Baccharis uncinella D.C. (Asteraceae)". Essential oils obtained from the native plantsBaccharis dracunculifolia and Baccharis uncinella, known also as "óleo de vassoura", are used in the perfumery industry, providing diverse perfumes with exotic aromas. Besides several studies about the biological activities of these species highlight the allelopathic, antioxidant, antimicrobial, cytotoxic and antiinfl ammatory effects. The broom is a bushy plant which occurs spontaneously in Brazil as well as in the other countries from Mercosul. The oil composition depends on the geographical region and on the concentration of oxygenated blends, highlighting the nerolidol and the sphatulenol. Essential oils obtained from these two species by the hydrodistillation process were assessed by the diffusion method in paper disc, in Petri plaques containing Müeller-Hinton agar, with bacteria suspensions, previously adjusted to the tube 0,5 of Mac Farland scale of four strains which came from the American Type Culture Collection: Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853. Discs containing different volumes of the essential oils (1, 3, 5 and 10 (μL/disc) were added to plaques and incubated at 36 ºC for 24...

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The chemical composition of the essential oil obtained from the leaves of Helietta apiculata collected in different seasons in southern Brazil, was analyzed by gas chromatography (GC) and gas chromatography/mass spectometry (GC/MS). Twenty-eight compounds were identified and limonene was the major compound found for all seasons, 29.1% (spring), 24.8% (summer), 30.2% (autumn) and 28.5% (winter). The essential oil obtained in summer and autumn yielded higher concentrations of monoterpenes, winter and spring yielded the highest concentrations of sesquiterpenes. The essential oil collected in summer and autumn showed higher activity against the bacteria tested, and the oil collected in spring was effective only against E. coli.