Structure and chain conformation of a (1 → 6)-α-D-glucan from the root of Pueraria lobata (Willd.) Ohwi and the antioxidant activity of its sulfated derivative

A water soluble glucan, PLB-2C, was isolated from the water extract of the root of Pueraria lobota (Willd) Ohwi using anion-exchange and gel permeation chromatography. Its structure was investigated by gas chromatography (GC) gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectra, and nuclear magnetic resonance (NMR) spectroscopy of heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) techniques. The results indicated that PLB-2C was a linear glucan composed of (1 -> 6)-alpha-D-Glcp. Chain conformation study showed that the polysaccharide took random coil compact conformation. In vitro cell viability assay by MTT method, its sulfated derivative PLB-2CS which was substituted at 2-0, 3-0, 4-0 positions, at 0.1, 1, and 5 mg/ml, could attenuate PC12 cell damage significantly caused by hydrogen peroxide. (C) 2008 Elsevier Ltd. All rights reserved.