Structural characteristics and immunopotentiation activity of two polysaccharides from the petal of Crocus sativus.

The current experiments were designed to explore the structural features and immunopotentiation activity of two homogeneous polysaccharides PCSPA and PCSPB prepared from Crocus sativus petals using DEAE-Sephadex A-50 and Sephadex G200 column chromatography. The structures of PCSPA and PCSPB were systematically characterized using extensive chemical and spectroscopic methods including colorimetry, HPGPC-RID, GC-MS, Smith degradations, methylation, solvolytic desulfation, UV, FT-IR, NMR, SEM, and AFM. The average molecular weights of PCSPA and PCSPB were 1.98 × 106 and 2.53 × 106 Da, respectively. PCSPA consisted of Gal, Rha, Ara, and Xyl in the molar ratio of 16:5:7:3, while PCSPB were composed of Gal, Glc, Man, Rha, Ara, and Xyl with molar ratio of 16:2:7:19:15:16. Both polysaccharides contained sulfonic and acetyl groups. PCSPA and PCSPB significantly activated RAW264.7 cells by enhancing the phagocytic activity, up-regulating the expression of surface molecules, promoting the production and mRNA expression of cytokines and chemokines via MAPK and NF-κB pathway.