Characterisation of a sugar fraction from Sarcocephalus latifolius stem bark extract

Abstract

The stem bark extract of the medicinal plant Sarcocephalus latifolius was analysed for its qualitative and quantitative carbohydrate content. Preparative high-performance liquid chromatography (HPLC) of the benzoylated sugar fraction, led to the isolation of d-fructose derivatives 1,2,3,4,6-penta-O-benzoyl-a-d-fructofuranose, 1,2,3,4,6-penta-O-benzoyl-b-d-fructofuranose, 1,2,3,4,5-penta-O-benzoyl-b-d- fructopyranose, and 1,3,4,5-tetra-O-benzoyl-b-d-fructopyranose, in addition to a- and b-d-pyranose forms of glucose, xylose, and arabinose perbenzoates, glycerol and d-erythriol perbenzoates, and an inseparable mixture of methyl 1,3,4,6-tetra-O-benzoyl-a,b-d-fructofuranoside, whose occurrence has never been previously reported from a natural source. The corresponding structures and conformations were fully characterised by extensive one and two-dimensional nuclear magnetic resonance (NMR) experiments. Quantification of the natural free sugars in the extract was achieved by HPLC using refractive-index detection.