Structural characterization and functional evaluation of a heteropolysaccharide from large-fruited hawthorn (Malus...

This study explored the structural and functional properties of Malus doumeri polysaccharide (MDPS), an acidic heteropolysaccharide extracted from the large-fruited hawthorn (Malus doumeri (Bois) Chev.) by water extraction and alcohol precipitation methods. The weight-average molecular weight of MDPS was 110.114 kDa. It contained high levels of GalA, GlcA, Man, Xyl, Ara, and Gal, with molar ratios of 23.46:23.19:14.02:9.66:9.67:8.43. The results indicated that the polysaccharide might contain several typical pectic structural domains, including homogalacturonan and rhamnogalacturonan I. Scanning electron microscopy and atomic force microscope observations revealed that the MDPS exhibited irregular flakes, with molecular morphology aggregated particles and relatively rough surface. MDPS exhibited excellent bile acid-binding capacity, with its binding effects on the taurocholic acid being close to that of the positive control cholestyramine. Additionally, MDPS demonstrated strong α-glucosidase inhibitory activity. At the same concentration, the α-glucosidase inhibitory effect of MDPS was 1.6 times of commercial hawthorn polysaccharides (CHPS) and 3.7 times of commercial pectin (CP), respectively. Overall, MDPS possesses a unique chemical structure and exhibits excellent biological activities, including high bile acid binding capacity and α-glucosidase inhibitory activity, suggesting its potential for downregulating blood lipids and blood glucose. This study provides a theoretical and practical foundation for the utilization of Malus doumeri fruit resources and the development of high-value-added functional food ingredients.