Os óleos essenciais da planta sub-aquática Conobea scoparioides (fresca e previamente seca) apresentaram rendimentos de 3,4 e 3,3%, respectivamente. Os principais constituintes identificados foram o éter metílico do timol (39,6 e 47,7%), timol (40,0 e 26,4%), α-felandreno (12,1 e 14,3%) e p-cimeno (1,5 e 1,7%), totalizando mais de 90% nos referidos óleos. A concentração de seqüestro do radical DPPH (CE 50 ) dos óleos e extrato foi de 46,7 ± 3,6 µg mL -1 para a planta fresca (CsO-f), de 56,1 ± 2,4 µg mL -1 para a planta seca (CsO-d), e de 23,0 ± 2,2 µg mL -1 para o extrato metanólico (CsE-d). O valor do extrato é comparável ao BHT (19,8 ± 0,5 µg mL -1 ), usado como padrão antioxidante. O valor médio dos óleos é duas vezes menor, mas igualmente importante como agente antioxidante. O teor de Fenólicos Totais (TP, 124,6 ± 8,7 mg GAE per g) e o Trolox Equivalente (TEAC, 144,1 ± 4,9 mg TE per g) do extrato metanólico confirmaram a significativa atividade antioxidante de C. scoparioides. Da mesma forma, nos bioensaios com larva de camarão (Artemia salina) o valor médio da concentração letal dos óleos (CL 50 , 7,7 ± 0,3 µg mL -1 ) foi dez vezes maior que no extrato metanólico (CL 50 , 77,6 ± 7,1 µg mL -1 ) mostrando importante atividade biológica.The essential oils of the sub-aquatic plant Conobea scoparioides (fresh and dried previously) showed yields of 3.4 and 3.3%, respectively. The main identified constituents were thymol methyl ether (39.6 and 47.7%), thymol (40.0 and 26.4%), α-phellandrene (12.1 and 14.3%) and p-cymene (1.5 and 1.7%), totalizing more than 90% of the oils. The DPPH radical scavenging activity (EC 50 ) of the oils and extract was 46.7 ± 3.6 µg mL -1 in the fresh plant (CsO-f), 56.1 ± 2.4 µg mL -1 in the dried plant (CsO-d), and 23.0 ± 2.2 µg mL -1 in the methanol extract. The extract (CsE-d)value is comparable to BHT (19.8 ± 0.5 µg mL -1 ) used as antioxidant standard. The mean value of the oils is twice smaller but equally important as antioxidant agent. The mean amount of Total Phenolics (TP, 124.6 ± 8.7 mg GAE per g) and the Trolox Equivalent (TEAC, 144.1 ± 4.9 mg TE per g) of the methanol extract confirmed the significant antioxidant activity of C. scoparioides. Similarly, in the brine shrimp bioassay (Artemia salina) the mean value of the lethal concentration for the oils (LC 50 , 7.7 ± 0.3 µg mL -1 ) was ten times higher than the methanol extract (LC 50 , 77.6 ± 7.1 µg mL -1 ) showing important biological activity.Keywords: Conobea scoparioides, Scrophulariaceae, pataqueira, thymol and thymol methyl ether, antioxidant capacity, cytotoxicity
IntroductionThe Scrophulariaceae is a cosmopolitan family comprising nearly 400 genera and 4,500 species, with their dispersion centre in the temperate regions of the north hemisphere. There are few species occurring in the Amazon. is a native erect herb called "pataqueira" or "vassourinhado-brejo", growing wild in seasonally inundated areas, with opposite leaves, sometimes alternate, deltoid, ovalate or lanceolate, with serrate or crenate margins. The who...