Structural elucidation and immunomodulatory activity of a neutral polysaccharide from the Kushui Rose (Rosa setate x Rosa rugosa) waste.

In this present study, the structure and immunomodulatory activity of a novel polysaccharide (WSRP-1b) from Kushui rose (Rosa setate x Rosa rugosa) waste were investigated. Structure characterization demonstrated that WSRP-1b had a weight-average molecular weight of 1.11 × 104 Da and consisted of glucose (42.6 %), mannose (21.4 %), arabinose (9.9 %), xylose (2.2 %), and galactose (23.9 %). Its backbone was composed of 1, 4-linked α-Glcp, 1, 4-linked ß-Glcp, and 1, 4-linked ß-Manp, with branches of 1, 4-linked α-Glcp and 1, 4-linked ß-Manp substituted at C-6 by 1, 6-linked ß-Galp. The branches mainly contained 1, 5-linked Araf, terminal arabinose and terminal glucose. Bioactivity assays showed that WSRP-1b had immunomodulatory activity by enhancing phagocytosis of macrophages, increasing production of ROS, NO, cytokines (IL-6, TNF-α), and activating NF-κB signaling pathway. These results suggested that it could be developed as a potential and safe immunomodulatory agent in fields of pharmacological or functional foods.