Chemical constituents from Bakeridesia pickelii Monteiro (Malvaceae) and the relaxant activity of kaempferol-3-O-β-D-(6″-E-p-coumaroyl) glucopyranoside on guinea-pig ileum

Abstract

The phytochemical investigation of Bakeridesia pickelii Monteiro led to the isolation of seven compounds: β-sitosterol, a mixture of sitosteryl-3-O-β-D-glucopyranoside and stigmasteryl-3-O-β-D- glucopyranoside, vanillic acid, p-coumaric acid, quercetin 3-O-β-D- glucopyranoside (isoquercitrin) and kaempferol-3-O-β-D-(6″-E-p- coumaroyl) glucopyranoside (tiliroside), which was isolated as the major component. Their structures were elucidated on the basis of spectroscopic data such as IR, 1H and 13C NMR, including two-dimensional techniques. Tiliroside relaxed the guinea-pig ileum pre-contracted with KCl 40 mM (EC50 = 9.5 ± 1.0 × 10-5 M), acetylcholine 10-6 M (EC50 = 2.3 ± 0.9 × 10-5 M) or histamine 10-6 M (EC50 = 4.1 ± 1.0 × 10-5 M) in a concentration-dependent manner.