Preparation, chemical composition, glycolipid-lowering activity and functional property of high-purity polysaccharide from Moringa oleifera Lam. leaf: A novel plant-based functional hydrophilic colloid

Natural functional hydrophilic colloids with glycolipid-lowering activities have remarkable application prospects but scarce. Moringa oleifera Lam. leaf (MOL) is a good candidate for novel plant-based functional hydrophilic colloid, but the development of high-purity MOL polysaccharide (MOLP) is limited due to high protein and pigment contents in MOL and bottleneck of green preparation. In this study, a green preparation strategy for high-purity MOLP as a functional hydrophilic colloid was established through comparative evaluation of different enzyme-assisted extraction and conventional/non-conventional purification methods on purity and function of MOLP. Liquid nitrogen pulverization coupled with cellulase enzymolysis, high-temperature treatment and yeast fermentation was optimal to extract MOLP. Dual protease enzymolysis in combination of dual resins absorption was screened out as the most efficient purification method for MOLP in comparison with TCA, sevage, enzymolysis, and chromatography methods. High-purity MOLP with high molecular weight exceeding 1000 kDa and high proportions of Ara and Gal showed strong glycolipid absorption inhibitory activity, prebiotic effect on human gut probiotics related to glycolipid metabolism, and good function property e.g. light color, viscoelasticity, emulsibility and water/oil holding capacity, which exceeded commercial pectin in bioactivity and resembled commercial pectin in functionality. The positive correlation between purity of MOLP and function was clarified in terms of correlation coefficients of total sugar content/molecular weight distribution and bioactivity/functionality. It offered theoretical direction for the development of high-purity polysaccharide as functional hydrophilic colloid from leaf-derived raw materials.