Structure characterization and antioxidant activity of a novel polysaccharide isolated from Ginkgo biloba

A novel polysaccharide (GBP5052) with antioxidant activity was isolated from Ginkgo biloba. The structure of GBP5052 was elucidated on the basis of physico-chemical and instrumental analyses, and its average molecular weight (Mw = 2 30 x 10(5)) was determined by gel permeation chromatography. The backbone of GBP5052 was composed of (1 -> 4)-linked alpha-D-mannopyranosyl residues which branched at O-3. The three branches consisted of beta-L-rhamnopyranosyl residues, (1 -> 4)-linked alpha-D-galactopyranosyl terminated with beta-L-rhamnopyranosyl residues, and (1 -> 3,4)-linked alpha-D-mannopyranosyl terminated with beta-L-rhamnopyranosyl residues, respectively. In the in vitro antioxidant assay, GBP5052 was found to possess DPPH radical-scavenging activity and hydroxyl radical-scavenging activity with an IC50 value of 0 412 mg/mL and 0.482 mg/mL, respectively. (C) 2010 Elsevier B V All rights reserved