Isolation and structure characterization of a polysaccharide from Crataegus pinnatifida and its bioactivity on gut microbiota.

A glucose rich heteroglycan named HAW1-2 was isolated and purified from fruit of Crataegus pinnatifida by hot-water extraction, ethanol precipitation, DEAE-cellulose anion exchange and gel permeation chromatography. HAW1-2 was proved as a homogenous polysaccharide with a molecular weight (Mw) of 8.94 kDa. Monosaccharide composition results indicated that HAW1-2 was composed of arabinose, galactose and glucose. Methylation analysis and NMR spectrum showed that HAW1-2 contained →4)-β-d-Glcp-(1→, →4)-β-d-Galp-(1→, α-L-Araf-(1→, →5)-α-L-Araf-(1→, β-d-Glcp-(1→ and →4,6)-β-d-Glcp-(1→. Bioactivity test showed that HAW1-2 could significantly promote the growth of Bacteroides thetaiotamicron (BT), Bacteroides ovatus (BO) and Bifidobacterium longum (BL), which showed competition with the Bacteroides spp. under co-culture. Interestingly, Bacteroides spp. generated more acetic acids and propionic acids while BL only generated acetic acids. These results imply that polysaccharide HAW1-2 may be useful for human by modulating intestinal bacteria and producing short chain fatty acids.