Chemical constituents from Rhoicissus digitata and Rhoicissus tomentosa and their chemotaxonomic significance

Abstract

Rhoicissus species are indigenous to southern Africa and are commonly used in traditional medicine to treat gynaecological problems. A phytochemical investigation on the roots and fruits of Rhoicissus digitata led to the isolation of three triterpenes (12,13-dehydrolupeol, β-sitosterol, and oleanolic acid) and two flavonoids ((+)-catechin and quercetin). From the roots, leaves and fruits of Rhoicissus tomentosa, nine compounds were isolated including four terpenoids (3β-taraxerol, stigmasterol, oleanolic acid, and β-sitosterol), three flavonoids (quercetrin, (+)-catechin, and aromadendrin-7-O-β-glucopyranoside), and two pigment compounds (pheophytin a and lutein). The chemical structures of the compounds were elucidated based on nuclear magnetic resonance spectroscopy and mass spectroscopic data, and by comparison with literature values. The compound, 12,13-dehydrolupeol, was isolated from the Vitaceae for the first time. Findings from this study suggest a close chemotaxonomic similarity between the genus Rhoicissus and the genus Cissus.