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 -Glc p -(1→, →4)-β- d -Gal p -(1→, α-L-Ara f -(1→, →5)-α-L-Ara f -(1→, β- d -Glc p -(1→ and →4,6)-β- d -Glc p -(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.