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O óleo essencial obtido a partir das cascas do caule de Croton urucurana Baillon (Euphorbiaceae) foi analisado por CG e CG-EM. 83 compostos foram identificados, sendo borneol (14,7%), acetato de bornila (5,2%), 1-isopropil-7-metil-4-metileno-1,3,4,5,6,8-hexaidro-2H-naftalen-4a-ol (14,7%), sesquicineol (10,5%) e epóxido de γ-gurjuneno (5,4%) os principais componentes. Para o óleo essencial bruto, foi determinada em 3,21 mg mL -1 a EC 50 no ensaio de atividade antioxidante frente ao radical livre DPPH. A fração do óleo essencial bruto que apresentou atividade antioxidante foi purificada por CCD sobre sílica gel. Análises de CG e CG-EM revelaram que α-bisabolol (38,3%), α-eudesmol (9,3%) e guaiol (8,2%) são os principais componentes da fração antioxidante. A EC 50 medida no teste frente ao DPPH foi de 1,05 mg mL -1 para a fração bioativa. Foi determinada a atividade antimicrobiana do óleo essencial bruto frente a sete bactérias Gram-positivas e Gram-negativas e três fungos. Os valores de CIM medidos variaram de 1,25 a 10,00 mg mL -1 .The essential oil obtained from the stem bark of Croton urucurana Baillon (Euphorbiaceae) was analysed by GC and GC-MS. 83 compounds were identified and borneol (14.7%), bornyl acetate (5.2%), 1-isopropyl-7-methyl-4-methylene-1,3,4,5,6,8-hexahydro-2H-naphthalen-4a-ol (14.7%), sesquicineole (10.5%) and γ-gurjunene epoxide (5.4%) were the main components. The EC 50 value of the crude essential oil in the DPPH free radical scavenging assay was 3.21 mg mL -1 . The fraction of the crude essential oil that presented antioxidant activity was purified by prep-TLC on silica gel. GC and GC-MS analysis revealed that α-bisabolol (38.3%), α-eudesmol (9.3%) and guaiol (8.2%) were the main components of the antioxidant fraction. The EC 50 value measured for the bioactive oil fraction in the DPPH assay was 1.05 mg mL -1 . The antimicrobial activity of the crude essential oil was assayed against seven Gram-positive and Gram-negative bacteria and three yeasts. Measured MIC values ranged from 1.25 to 10.00 mg mL -1 . Keywords:Croton urucurana, essential oil, antioxidant, DPPH assay, antimicrobial acticity IntroductionCroton (Euphorbiaceae) is one of the largest genera of flowering plants, with nearly 1,300 species of herbs, shrubs, and trees that are ecologically prominent and often important elements of secondary vegetation in the tropics and subtropics worldwide. Previous works reported that the essential oils from northeastern Brazilian Croton species, C. zenhtneri, C. nepetaefolius and C. argyrophylloides, exhibited good antioxidant activities. 9 Croton urucurana Baillon (Euphorbiaceae) is a tree commonly found in Paraguay, northern Argentina, southern Brazil, and Uruguay. Three different products from this species are used primarily in folk medicine: the red sap, the stem bark, and the gum exudate. 10 Many pharmacological effects of Croton urucurana have been described in literature, which include wound and ulcer healing, antidiarrhoeic, anticancer, intestinal anti-inflammatory, antioxidant and an...

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Aerial parts of Elyonurus muticus were collected in the four seasons of the year in the Brazilian Pantanal and subjected to extractrion with cold ethanol and to hydrodistillation. Sesquiterpenoids (E)-caryophyllene, bicyclogermacrene, spathulenol and caryophyllene oxide were the main components identified in the essential oils and their concentrations varied according to the plant collection period. The essential oils and the ethanolic crude extracts were active against Bacillus cereus MIP 96016, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923 and were not active against Escherichia coli ATCC 25922. The antibacterial activities varied according to the plant collection period.

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