Structural characterization and hepatoprotective activities of polysaccharides from the leaves of Toona sinensis (A. Juss) Roem.

Two polysaccharide fractions (TSP-1 and TSP-2) with molecular weights of 833.6 kDa and 81.6 kDa were isolated from Toona sinensis leaves (Meliaceae) by hot water extraction, DEAE Cellulose-52 chromatography and Sephacryl S-400 gel permeation chromatography. Structural analysis indicated that TSP-1 and TSP-2 consisted of Manp, GlcpA, Glcp, Galp, Xylp and Araf with different molar ratios. Methylation and NMR analysis revealed that the backbone of TSP-1 might consist of 1,6-linked-Glcp, 1,3,6-linked-Manp and 1,6-linked-Galp, while TSP-2 was mainly composed of 1,3,5-linked-Araf, 1,6-linked-Glcp, 1,4-linked-Xylp and 1,6-linked-Galp. Congo red assay indicated that TSP-1 and TSP-2 had no triple-helix structure, which was consistent with the results of AFM. In vivo hepatoprotective activity showed that TSP-1 and TSP-2 could improve CCl4-induced mice liver injury by reducing the activities of AST, ALT and the level of MDA, increasing the activities of SOD, GSH-Px, and CAT and the level of GSH in liver and decreasing the expression levels of TNF-α and IL-6 in liver. These results suggest that TSP-1 and TSP-2 have promising potential to serve as hepatoprotective agents.