Estudo fitoquímico e avaliação das atividades citotóxica e inibitória das cisteíno proteases de Vochysia thyrsoidea (Vochysiaceae)

Abstract

The genus Vochysia is a group of tropical trees with a very widely distributed species in cerrado and forests in Brazil. These plants have been tested in an effort to identify new and potentially useful chemistry compounds, and some works shown a diverse array of pharmacological activities, as well as antibacterial, antifungal, antiinflammatory and many others. Based on the ethnopharmacological literature the specie Vochysia thyrsoidea Pohl. (Vochysiaceae), used in folk medicine as an expectorant, was collected. This work presents the phytochemical study and biological tests performed with the organic extracts and secondary metabolites isolated from the leaves and of the stem bark of this plant. Six compounds were isolated using chromatographic techniques and the structural identification was carried out on the basis of 1D- and 2D-NMR experiments, IR spectrometry and comparison with literature data. The compounds identified were: catechin-3-O-ramno(3-cinnamoyl)pyranoside, catechin-3-O-ramnopyranoside, 2,4,6-trymetoxbenzoic acid, 3-oxo-urs-12-en-28-oic acid, 2-butyl D-fructofuranoside, 1-butyl D-fructofuranoside. The catechin and fructofuranosides are reported for the first time in the Vochysia genus. The average for all substances tested did not show considerable inhibition against cathepsin K, a cysteine protease that has been implicated in osteoporosis. However, in the enzyme inhibiton assay against cathepsin B, enzyme has been implicated in the cancer disease, showed considerable results and the most promising compound was the catechin-3-O-ramno(3-cynamoil)pyranoside (IC50= 65.12 μM). The citotoxic activities revealed the fructofuranoside (2-butyl D-fructofuranoside) as the most effective among all the substances tested, showed 100% (+/- 13.33) of inhibition in the cell lines of central nervous system tumor (SF-295). The substances submitted in reactions to structural changes didn´t have biological activities.