A novel pentacyclic triterpene acid from the stem barks of Combretum fragrans F. Hoffm (Combretaceae)

Abstract

A phytochemical study was carried out on stem bark of Combretum fragrans F. Hoffm., a medicinal plant belonging to the Combretaceae family and used traditionally in the treatment of various ailments. Column chromatography separation on silica gel of the crude methanol extract from stem barks of C. fragrans led to the isolation of a new pentacyclic triterpene acid, with a 3,6-epoxide bridge and trivially named as fragransinic acid (1), along with four known compounds: betulin (2), betulinic acid (3), bellericagenin B (4) and a mixture of β-sitosterol (5) and stigmasterol (6). Structures were elucidated by extensive spectroscopic analyses including 1D and 2D NMR, mass spectrometry as well as by comparison with literature data. The above compounds were isolated for the first time from C. adenogonium. Implications for chemosystematics and traditional medicine were briefly discussed.

Keywords: Combretaceae; Combretum fragrans; fragransinic acid; pentacyclic triterpenes.