Metabolite profiling of the leaves of the Brazilian folk medicine Sideroxylon obtusifolium

Abstract

Sideroxylon obtusifolium (Roem. & Schult.) T. D. Penn. (family Sapotaceae) is a tree native to Central and South America. Infusions of the bark and the leaves are used in Brazilian folk medicine as an anti-inflammatory remedy. However, information on the constituents of S. obtusifolium remains scarce, and only common pentacyclic triterpenoids have been previously reported. HPLC-DAD/MS analyses revealed that saponins and flavonoids were the main constituents of the leaves. From the butanol-soluble fraction of an ethanolic extract, a total of four saponins and ten flavonol glycosides were isolated by a combination of chromatographic methods including Sephadex LH-20, MPLC, and HPLC. Their structures were established by acid hydrolysis and spectroscopic methods, mainly MS (n), 1D and 2D NMR experiments. The compounds include the new triterpene glycoside 3-O-( β-D-glucopyranosyl)-protobassic acid 28-O- β-D-apiofuranosyl-(1 → 3)-O-[O- β-D-apiofuranosyl-(1 → 3)- β-D-xylopyranosyl-(1 → 4)]-O- α-L-rhamnopyranosyl-(1 → 2)- α-L-arabinopyranosyl ester ( 1), as well as the new flavonol glycosides, quercetin-3-O-(O- α-L-rhamnopyranosyl-(1→ 2)-O-[ β-D-glucopyranosyl-(1 → 3)]- β-D-galactopyranoside) ( 6) and kaempferol-3-O-(O- α-L-rhamnopyranosyl-(1 → 2)-O-[ β-D-glucopyranosyl-(1 → 3)]- β-D-galactopyranoside) ( 8). In addition, catechin and a glycerogalactolipid, gingerglycolipid A, were obtained from the ethyl acetate-soluble fraction. The isolated compounds could be used in the future as chemical markers for quality control of this herbal drug.