Structural Characterization and Anti-Inflammatory Activity of Novel Acidic Polysaccharides from Laoshan Black Tea

In LPS-stimulated mouse inflammation model, Laoshan black tea polysaccharides (BTPSs) showed significant anti-inflammatory activity. Three water-soluble acidic polysaccharides (BTPS 3-1, BTPS 3-2, and BTPS 3-3) were purified. They contained glucose (Glc), galactose (Gal), fucose (Fuc), rhamnose (Rha), glucuronic acid (GlcA), and mannose (Man) at molar ratios of 9.0 : 4.9 : 4.9 : 1.7 : 1.5 : 1.0, 9.5 : 5.3 : 4.9 : 1.7 : 1.6 : 1.0, and 5.3 : 3.5 : 2.0 : 2.1 : 0.9 : 1.0 with average molecular weights of 28.38, 14.39, and 11.00 kDa, respectively. Three polysaccharides reduced the levels of NO, TNF-α, and IL-6 in LPS-induced RAW 264.7 cells, and BTPS 3-2 had the strongest anti-inflammatory effects. Based on analyses of the monosaccharide composition, methylation, and NMR, the main chain of BTPS 3-2 was composed of ⟶4) -β-D-Glcp- (1⟶, ⟶2) -α-L-Fucp- (1⟶, and ⟶6) -β-D-Galp- (1⟶, and Rhap, GlcpA, and Manp units were attached as side chains to the backbone. BTPS 3-2 also downregulated the expression levels of p-NF-κB p65, p-IκBα, TLR4, MyD88, COX-2, TNF-α, and IL-6. BTPS 3-2 ameliorated LPS-induced inflammation by regulating the TLR4/MyD88/NF-κB signaling pathway.