"Metabólitos Especiais Isolados de Raízes e Folhas de Brachiaria humidicola"

Abstract

The species of Brachiaria genus are originally from Africa, they are typically of tropi-cal climate that had excellent adaptation in different kinds of Brazilian soil. They have great importance in the country for agricultural use in the extensive production of cattle cutting or milk. The species of the genus Brachiaria are known for their high allelopathic effect owing to the presence of cinnamic acid derivatives, and the production of steroidal saponins that cause photosensitivity hepatotoxic in ruminant. This study aimed to identify special metabo-lites produced by the leaves and roots of B. humidicola. It was made by the analysis of ex-tracts obtained by maceration at room temperature, and fractionation by solvent partition and chromatographic techniques including open column of adsorption and exclusion, high-performance liquid chromatography, and gas chromatography. The identification of com-pounds was done by 1H and 13C NMR, and mass spectrometry and comparison with literature data. From the leaves extracts of B. humidicola were identified 2-hydroxy-3-methoxy-benzoic acid, trans-4-hydroxycinnamic acid, p-hydroxybenzoic acid, 2,3-dihydrobenzofurane, besides the flavonoids isorhamnetin-3-O-β-D-glucoside, quercetin-3-O- β-D-glucuronic acid methyl ester, quercetin-3-O- β-D-glucopyranoside and tricin (5,7,4’-trihydroxy-3’,5’-dimethoxy fla-vone). From the extract from the roots were isolated two steroidal saponins, 3-O-α-L-rhamnopyranosyl-(4’-1”)-α-L-rhamnopyranosyl-(2’-1’”)-β-D-glucopyranosyl-25(S)-spirost-5-en and penogenin-3-O-α-L-rhamnopyranosil (4’-1”)-α-L-rhamnopyranosil-(2’-1’”)-β-D-glucopyranoside, and the flavanol 7-O-β-D-glucopyranosil-catechin. The identified com-pounds, such as acids and steroidal saponins, belong to special metabolites classes that have been identified in Brachiaria genus, however flavonoids and saponin type penogenin are be-ing reported for the first time in this genus.