Properties of Novel Components of Polysaccharides Isolated From Lycium barbarum Fruits

This study has established structure-function relationships of Lycium barbarum polysaccharides (LBPs) relevant to antioxidant and tyrosinase-inhibitory functions in food systems by integrating optimized extraction, stepwise purification, comprehensive structural analysis, and functional verification, offering a novel multimethod approach to explore structure-based mechanisms of bioactivity. Firstly, hot-water extraction optimized at 30 mL/g, 90°C, and 5 h yielded 7.44% ± 0.17% crude LBPs. Secondly, ion-exchange followed by gel-filtration chromatography separated two purified fractions: LBP-1 (115.1 kDa) and LBP-2 (73.5 kDa). LBP-1 exhibited a compact morphology and featured spectral characteristics indicative of a triple-helix structure, along with both α- and β-glycosidic linkages. In contrast, LBP-2 showed a more amorphous configuration without triple-helix features and predominantly β-linkages. Their monosaccharide profiles also differed, with LBP-1 enriched in glucose, mannuronic acid, galacturonic acid, and glucuronic acid, while LBP-2 contained glucose, galacturonic acid, mannuronic acid, and arabinose. Both fractions exhibited in vitro antioxidant and tyrosinase-inhibitory activities, with LBP-2 demonstrating relatively stronger effects. The enhanced performance of LBP-2 may be associated with its dispersed structure and uronic acid-rich β-linked motifs, which increase the accessibility of functional sites. These insights support the potential application of both LBP-1 and LBP-2 in functional foods, with LBP-2 showing greater promise for use in beverages and fresh-cut fruit products requiring natural antibrowning and antioxidant solutions.