Recebido em 29/6/11; aceito em 14/1/12; publicado na web em 15/5/12In the search for new larvicides from plants, we have investigated the potential activity of the rotenoids deguelin (1), 12a-hydroxy-α-toxicarol (2) and tephrosin (3), isolated from the bioactive ethanol extract of roots of Tephrosia toxicaria Pers., against Aedes aegypti, the main vector of dengue. The absolute configuration of these compounds was determined by circular dichroism (CD) spectra. The LC 50 values of the compounds evaluated justify the potential of T. toxicaria as a new natural larvicide.

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The leaves and stems of Stemodia maritima, collected in the state of Ceara, Brazil, were subjected to hydrodistillation and their essential oils were analyzed by combined GC and GC/MS. The major components found in the leaf oil were β-caryophyllene and 14-hydroxy-9-epi-β-caryophyllene, while in the stem oil β-caryophyllene and caryophyllene oxide were the most abundant constituents. Furthermore, the oils were examined with respect to their larvicidal properties against the larvae of Aedes aegypti and showed LC 50 values of 55.4 ± 1.03 and 22.9 ± 0.85 ppm for the leaves and stems, respectively.

No presente trabalho descreve-se a composição química dos óleos essenciais de Rollinia leptopetala R.E. Fries (Annonaceae) e as atividades larvicidas dos óleos essenciais, do extrato metanólico das raízes desta espécie e do alcalóide oxoaporfinico, liriodenina (1), frente às larvas no terceiro estágio do mosquito Aedes aegypti. O extrato metanólico mostrou-se ativo com CL 50 64,6 ± 1,5 ppm e uma forte atividade foi exibida para o composto (1), CL 50 3,6 ± 0,4 ppm. Os óleos essenciais das folhas e galhos também mostraram atividade com CL 50 104,7 ± 0,2 and 34,7 ± 0,3 ppm, respectivamente. Estes dados sugerem que R. leptopetala é fonte potencial de larvicidas naturais. A composição química do óleo essencial e as atividades descritas são comunicadas pela primeira vez.The aim of present study was to describe the chemical composition of the essential oils from the leaf and stem of Rollinia leptopetala R. E. Fries (Annonaceae) and to evaluate the larvicidal activities of these essential oils, of the methanol extract from roots of this plant and of the oxoaporphine alkaloid, liriodenine (1) against the third-instar of Aedes aegypti larvae. The methanol extract from the roots showed larvicidal activity with LC 50 64.6 ± 1.5 ppm. Higher activity was observed for the isolated alkaloid liriodenine (1), LC 50 3.6 ± 0.4 ppm. The essential oils from the leaves and stems, also exhibited larvicidal activity with LC 50 104.7 ± 0.2 and 34.7 ± 0.3 ppm, respectively. These results suggest R. leptopetala as a source of natural larvicidal compounds. This is the first report about the chemical composition and larvicidal activity of the leaf and stem essential oils of R. leptopetala. Keywords: Rollinia leptopetala, Annonaceae, essential oils, liriodenine, Aedes aegypti IntroductionAedes aegypti is the principal mosquito vector of dengue fever, including the hemorrhagic form, which is endemic to South East Asia, Central and South America, and West Africa.1 Between 50 and 100 million of cases are registered each year, causing thousands of deaths. 2The disease has high levels of mortality, and also inflicts great economic losses and social disruption in Brazil. Although some viral diseases, such as yellow fever, have been brought reasonably under control with a vaccine, no vaccine is so far available for dengue. Today, the only way of decreasing the incidence of this disease is by controlling the Aedes aegypti proliferation. This is not an easy task because the mosquitoes have developed resistance to the current synthetic insecticides that, in addition, are toxic to humans and the environment. The mosquito population control in the larval stage is much easier than in the adult Chemical Composition and Larvicidal Activity of Rollinia leptopetala (Annonaceae) J. Braz. Chem. Soc. 376 stage, and then new strategies are needed for controlling the proliferation of the larvae of A. aegypti. Several studies have focused on natural products as insecticides for controlling A. aegypti larvae. Alkaloids and essential oils from herbal plants have ...

(1)H and (13)C NMR chemical shifts of praecansone B, pongaflavone and dehydrorotenone isolated from Tephrosia egregia Sandw and obovatin from T. toxicaria Pers. were unambiguously assigned by 1D and 2D NMR experiments including (1)H, (1)H COSY, gHMQC and gHMBC, allowing the correction of literature assignments.

Recebido em 26/2/08; aceito em 10/9/08; publicado na web em 2/2/09 CHEMICAL CONSTITUENTS FROM Sebastiania macrocarpa MUELL. ARG. (EUPHORBIACEAE). The chemical investigation of the methanolic extract of the aerial part of Sebastiania macrocarpa allowed the isolation of the mixture of steroids β-sitosterol and stigmasterol, gallic acid, and scopoletin. The hexane extract of the roots allowed the isolation of the triterpene lupeol and of the macrociclic diterpene (+)-tonantzitlolone. The structures of all compounds isolated were identified on the basis of their spectral data and by comparison of their spectral data with values described in the literature. This is the first report involving the chemical investigation of this species.

Recebido em 27/3/08; aceito em 23/9/08; publicado na web em 2/2/09 CHEMICAL AND BIOLOGICAL STUDY OF THE Tephrosia toxicaria Pers. The ethanol extracts from leaves, stems, pods and roots were assayed against the 3 rd instar Aedes aegypti larvae and the highest activity was observed in the roots extracts (LC 50 47.86 ppm). This extract was submitted to partition with hexane, chloroform, ethyl acetate and methanol. The respective fractions were bioassayed and the best larvicidal activities were identified in the hexane (LC 50 23.99 ppm) and chloroform (LC 50 13.80 ppm) fractions. Antioxidant activity (DDPH method) was observed in the ethanol extract (IC 50 276 µg/mL) from roots of T. toxicaria. Fractions from this extract were also tested and the highest antioxidant activity (IC 50 89 µg/mL) was found in the methanol fraction. The flavonoids iso-obovatin (1), obovatin (2), 6a,12a-dehydro-β-toxicarol (3), 6a,12a-dehydro-α-toxicarol (4) and α-toxicarol (5) were isolated and bioassayed against A. aegypti. The flavonoid 5 showed the best larvicidal activity (LC 50 24.55 ppm). The antioxidant activity of 2 was investigated and showed IC 50 3.370 µg/mL. The antioxidant and larvicidal activities of Tephrosia toxicaria are reported for the first time.Keywords: Tephrosia toxicaria; flavonoids; biological activity. iNtRoduÇÃoO gênero Tephrosia, família Leguminoseae Papilionoideae (Fabaceae), possui aproximadamente trezentas espécies, distribuídas em regiões tropicais e subtropicais.1 Espécies deste gênero apresentam capacidade biogenética para produzir substâncias com grande diversidade estrutural, tais como esteróides, aminoácidos e flavonóides, incluindo os isoflavonóides rotenóides.2 Estes últimos são conhecidos por apresentarem as atividades ictiotóxica 3 e larvicida. 4 Outras atividades biológicas importantes, como anti-tumoral e antiviral, aparecem também descritas na literatura. 5,6Tephrosia toxicaria Pers., popularmente conhecida por "timbó de caiena" ou "anil", é utilizada para capturar peixes 7 e o extrato aquoso de suas raízes é aplicado como defensivo agrícola em hortas orgânicas na localidade de Guaraciaba do Norte -CE. A literatura relata o isolamento e atividade anticâncer de compostos isolados de T. toxicaria, 8,9 bem como a composição química e atividade larvicida de seu óleo essencial. 10A busca por substitutos para os inseticidas sintéticos tem produzido muitos trabalhos científicos, contemplando inclusive a utilização de extratos ou constituintes ativos provenientes de plantas.10-15 Esta procura pode ser justificada pela fácil degradação destes constituintes, menor toxicidade ao homem e, conseqüen-temente, representa uma alternativa mais segura para o meio ambiente.15 Estas observações, aliadas à crescente incidência da febre dengue -endêmica nas Américas, 16 sendo diagnosticados de 50 a 100 milhões de casos por ano 17 -nos estimularam adicionalmente para uma prospecção química em T. toxicaria, com o objetivo de encontrar compostos sucedâneos aos larvicidas sintéticos utilizados no combate ao Aedes aegypt...

The present work describes the isolation of dehydrodiscretamine, discretamine, liriodenine, lichexanthone, molvizarin, rolliniastatin-1, annonacin and bullatacin from roots of Rollinia leptopetala R E Fries. The structures were established after analysis of their NMR spectral data including 2D NMR experiments. With the exception of discretamine, the presence of these compounds in R. leptopetala and the NMR data of dehydrodiscretamine are reported for the first time. The CH 2 Cl 2 extract of the roots demonstrated high larvicidal activity against Aedes aegypti, with an LC 50 value of 1.44±2.0 ppm.