Antioxidant and Hypoglycemic Activity of Polysaccharides With Different Tissues From <i>Rosa roxburghii</i> f. eseiosa Ku

Rosa roxburghii f. eseiosa Ku, a thornless variety of Rosa roxburghii Tratt, remains underexplored regarding the tissue-specific functionality and structure-activity relationships of its polysaccharides. This study systematically investigated the composition and bioactivities of polysaccharides extracted from the fruit, root, stem, and thick stem of this variant. Using gradient ethanol precipitation (40%, 60%, and 80%), polysaccharides with distinct molecular weight (M_w) profiles were obtained. All isolates were identified as acidic heteropolysaccharides with complex and tissue-dependent monosaccharide compositions. Fractions precipitated with 60% and 80% ethanol exhibited lower M_ws and significantly enhanced bioactivities, including potent radical scavenging capacity and α-glucosidase inhibition. Notably, RREK-R60, the crude polysaccharide obtained from the roots of Rosa roxburghii f. eseiosa Ku via 60% ethanol precipitation, exhibited a notable α-glucosidase inhibition rate of 92.91%. Structural analysis revealed tissue-specific traits, such as the unique presence of N-acetylglucosamine in fruit and root samples, along with elevated uronic acid, galactose, and arabinose content, which correlated strongly with bioactivity. These findings underscore the potential of Rosa roxburghii f. eseiosa Ku polysaccharides as functional food ingredients or anti-diabetic agents. Further in vivo studies and detailed structural elucidation are warranted to fully establish their structure-activity relationships.