Structural elucidation and anti-psoriasis activity of a novel polysaccharide from Saussurea Costus

PSCP, a novel water-soluble polysaccharide, was extracted from the root of Saussurea costus and subsequently purified using DEAE-52 cellulose and Sephadax G-50 columns. The elucidation of its structure involved various techniques including HPGPC, FT-IR, HPLC-ELSD, GC–MS, NMR, AFM, and SEM. The results show that PSCP was a homogeneous heteropoly saccharide having molecular weight of 4131 Da and mainly composed of 1-α-D-Glcp-(-2-β-D-Fruf-1-)23-2-β-D-Fruf. The anti-psoriasis activity of PSCP was evaluated in imiquimod-induced psoriasis in Balb/C mice. This study revealed that treatment with PSCP resulted in a significant improvement in the pathological morphology of the skin and a reduction in the PASI score. Analysis of liver RNA-Seq data indicated that the MAPK signaling pathway may play a crucial role in the ability of PSCP to ameliorate psoriasis. PSCP was found to effectively inhibit the phosphorylation of JNK, ERK, and p38, as well as down-regulate the expression of the transcription factor AP-1 (c-fos and c-jun) in the nucleus, thereby reducing the expression of inflammatory factors. These findings suggest that PSCP holds promise as a novel therapeutic approach for the treatment of psoriasis.