Isolation and structure determination of a new oligosaccharide from Blume riparia

A water-soluble oligosaccharide (BROS) was obtained from Blume riparia DC. by hot water extraction, ethanol precipitation, and fractionated by Sephadex G-50 and Sephadex G-25 column filtration chromatography. BROS is a homogenous composition. Its molecular weight was 1.314×103 Da by MALDI-TOF-MS accurate determination. It was composed of 8 monosaccharides, namely Glcp, Frup and Fruf in molar ratio of 1:1:6. The linkage type of all residues were determined by the means of methylation. A combination of 1H NMR and13C NMR spectroscopy analysis, the BROS structure was confirmed finally as: β-D-Frup-(2→1)-β-D-Fruf-1-(2→1)-β-D-Fruf-2-(2→1)-β-D-Fruf-3-(2→1)-β-D -Fruf-4-(2→1)-β-D-Fruf-5-(2→1)-β-D-Fruf-6-(2→1)-α-D-Glcp.   Key words: Blumea riparia (Blume) DC, oligosaccharide (BROS), purification, methylation, spectroscopy, structure.