Structural characterization and anti-inflammatory activity of a polysaccharide extracted from the root of Tripterygium wilfordii

Tripterygium wilfordii, a traditional Chinese medicine, is widely utilized in the treatment of rheumatoid arthritis; however, the anti-inflammatory activity and potential applications of its polysaccharides have been less explored. In the present study, a water-soluble polysaccharide, designated TWP, was extracted from the roots of T. wilfordii, and its structural features and anti-inflammatory activity were investigated. The yield of TWP was 3.91 % ± 0.24 %, with carbohydrate and protein contents of 90.77 % ± 2.06 % and 2.67 % ± 0.81 %, respectively. Monosaccharide analysis revealed that TWP comprised rhamnose, arabinose, galactose, glucose, xylose, mannose, and glucuronic acid in a molar ratio of 16.0967: 8.3376: 27.925: 16.378: 0.5017: 0.4017: 6.4507. The weight-averaged (Mw) and number-averaged (Mn) molecular weights of TWP were 6713.24 kDa and 3188.86 kDa, respectively, with a polydispersity index (PDI) of 2.105. In vitro antioxidant assays demonstrated that TWP could scavenge hydroxyl, superoxide, DPPH, and ABTS radicals. Furthermore, TWP significantly reduced the levels of inflammation-related factors (NO, TNF-α, IL-6, and IL-1β) and the expression of their corresponding genes in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages in a concentration-dependent manner. Additionally, TWP markedly enhanced the activities of SOD, CAT, and GSH-Px, while reducing MDA level in LPS-induced RAW 264.7 macrophages.