Anti-inflammatory activity and structure-function analysis of degraded polysaccharide fragments from Tetrastigma hemsleyanum.

Tetrastigma hemsleyanum Diels et Gilg (T. hemsleyanum) is a medicinal plant with immunomodulatory activity. Its acidic glucuronic acid galactomannan (STHP5, 128 kDa) is degraded into fragments STHP5 DF-1 (78 kDa, helical, 2,3-Manp backbone, the main active fragment). STHP5 DF-1 inhibited NO and inflammatory cytokines, enhanced phagocytosis, reduced apoptosis and p65 nuclear translocation, and alleviated lung injury. Free Gal and Man pretreatment altered the immunomodulatory responses induced by HRDF-1, suggesting that Gal/Man-associated structural features may participate in its biological activity. Helix disruption was associated with enhanced anti-inflammatory activity; however, the underlying mechanism may involve multiple changes in molecular organization and cellular interactions rather than solely increased exposure of receptor-binding sites. These findings indicate that the observed immunomodulatory activity is related to differences in molecular size, glycosidic bond configuration, single sugar-related structural characteristics, and conformational coordination. This provides a theoretical basis for the targeted application of T. hemsleyanum polysaccharides.