Four water-soluble polysaccharides fractions (ZSP1b, ZSP2, ZSP3c and ZSP4b) were isolated and purified from the fruiting bodies of Zizyphus Jujuba cv. Jinsixiaozao by DEAE-SepharoseCL-6B and SepharoseCL-6B column chromatography. Their chemical and physical characteristics were determined by chemical methods, gas chromatography (GC) and high-performance size-exclusion chromatography (HPSEC). Antioxidant activities of crude polysaccharide from the fruiting bodies of Zizyphus Jujuba cv. Jinsixiaozao (CZSP) and its purified fractions were investigated including superoxide anion, 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical-scavenging activity and reducing power. Antioxidant results showed that ZSP3c and ZSP4b containing more uronic acid had the stronger free radical scavenging activities than ZSP1b containing no uronic acid. Available data obtained with in vitro models suggested that uronic acid was an effective indicator of antioxidant activity of the samples.

A novel water-soluble polysaccharide (ZSP3c) was isolated from Zizyphus jujuba cv. Jinsixiaozao and its structure was investigated. ZSP3c was obtained by extraction with hot water followed by purification using DEAE-SepharoseCL-6B anion-exchange, SepharoseCL-6B and Sephadex G-200 column chromatography. It was eluted as a single symmetrical narrow peak on high-performance gel-permeation chromatography (HPGPC) and the average molecular weight (Mw) was estimated to be 1.4 × 105 Da. The ZSP3c was composed of l-rhamnose, d-arabinose and d-galactose in a molar ratio of 1:2:8. The structural features of ZSP3c were investigated by partial hydrolysis with acid, methylation analysis and NMR spectroscopy analysis. The results revealed that the main backbone chain of ZSP3c was (1 → 4)-d-galacturonopyranosyl residues interspersed with (1 → 2)-l-rhamnopyranosyl residues and (1 → 2,4)-l-rhamnopyranosyl residues. The neutral side chains of arabinofuranosyl residues and galactopyranosyl residues were attached to the backbone at the O-4 position of rhamnopyranosyl residues.