In an effort to find effective and affordable ways to control of Aedes aegypti L. (Diptera: Culicidae), the larvicidal activities of 94 extracts from ten plant species belonging to eight families [Guettarda grazielae and Spermacoce verticillata (Rubiaceae), Coccoloba mollis and Triplaris americana (Polygonaceae), Eschweilera ovata (Lecytidaceae), Merremia aegyptia (Convolvulaceae), Ouratea nitida (Ochnnaceae), Protium heptaphyllum (Burseraceae), Rourea doniana (Connaraceae), and Tovomita brevistaminea (Guttiferae)], widely found in the northeast of Brazil, were initially screened at 250 microg/mL. Nineteen of the 94 extracts from six plant species (C. mollis, G. grazielae, M. aegyptia, R. doniana, S. verticillata, and T. americana) showed significant activity (>75% mortality) against the fourth instar larvae. Some of these extracts showed 100% mosquito larvae mortality, with LD(50) values lower 200 microg/mL. When compared to synthetic insecticide Temephos (LD(50) 8.7 microg/mL), two of them, hexane (LD(50) 12.1 microg/mL) and ethyl acetate (LD(50) 51.6 microg/mL) extracts from stems of R. doniana and G. grazielae, respectively, were the most effective. The isolation and purification of these extracts are in progress and evaluation of these compounds will be needed to identify the active component.

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Abstract:The chromatography fractionation of the hexane, chloroform and ethyl acetate extracts from the leaves and stems of Rourea doniana Baker, Connaraceae, resulted in the isolation of five triterpenes (lupeol, lupenone, α-amyrenone, β-amyrenone, and taraxerol), a flavonol (7,4'-dimethylkaempferol), a coumarin (scopoletin) and four phytosteroids (β-sitosterol, stigmasterol, β-sitosteryl-3-O-β-D-glucopyranoside and stigmasteryl-3-O-β-D-glucopyranoside). All compounds are being for the first time in this species and all triterpenes and the flavonol are being described for the first time in the family Connaraceae. These compounds were identified on basis of their IR and NMR ( 1 H, 13 C, DEPT, HSQC, HMBC, and NOESY) spectral data and by comparison with literature data.