Metabólitos especiais isolados dos galhos e folhas de Piptadenia gonoacantha (Mart.) J. F. Macbr. (Leguminosae) e das flores de Laseguea erecta Mull. Arg (Apocynaceae)

Abstract

This is the first work concerning to the isolation and identification of special metabolites from the branches and leaves of Piptadenia gonoacantha (Mart.) J.F. Macbr. (Leguminosae-Mimosoideae), commonly known as "Pau Jacaré". Another part of this work describes the phytochemical study of the flowers of Laseguea erecta Mull. Arg. (Apocynaceae). The different parts of the plants were extracted by cold methanol and fractionated through solvents partition and chromatographic techniques. This procedure, besides the analysis of the fractions by TLC and spectrometric methods afforded the chemical constituents. From the branches of Piptadenia gonoacantha were obtained β-sitosterol, stigmasterol, the ester N-benzoylphenylalaninyl-2-benzoylamide-3-phenylpropil ester, the sitosterol-3-O-β-D-glucopiranoside, besides the flavonoids apigenin (5,7,4 -trihydroxyflavone), apigenin-5-methyl ether and 7,4 -dihydroxy-3 ,5-dimethoxyflavone. The leaves of this plant afforded the methyl gallate and the flavonoids, 8-C-glucopyranosyl-5,7,4 -trihydroxyflavone and 6-C-glucopyranosyl-5,7,4 -trihydroxyflavone, know respectively, as vitexin and isovitexin. The ester and the flavonoids are being registered by first time in the genus Piptadenia. From the flowers of Laseguea erecta were isolated the lupeol, ursolic acid, quercetin (3,5,7,3',4'-pentahydroxyflavone) and 3-O-α-arabinopyranosyl-quercetin. This is the first information about identification of special constituents in flowers of this specie. The structures were established by the IR, NMR 113H (1D, 2D), NMR C (BBD and DEPT) analysis and by comparison with literature data. In some cases, it was used mass spectral data analysis and derivatives preparation.