Isolation and structural characterization of a pectin from Lycium ruthenicum Murr and its anti-pancreatic ductal adenocarcinoma cell activity

Crude polysaccharides were obtained from fruits of Lycium ruthenicum Murr using hot water extraction followed by ethanol precipitation. A homogeneous polysaccharide, LRP3-S1 with a relative molecular weight of 114.8 kDa was purified by anion-exchange chromatography on DEAE Sepharose™Fast Flow and Sephacryl S-300 HR column. Monosaccharide composition analysis revealed that LRP3-S1 was composed of rhamnose, galacturonic acid, galactose, xylose and arabinose in a molar ratio of 14.4: 17.7: 26.6: 16.4: 24.9. LRP3-S1 contained a rhamnogalacturonan I (RG-I) backbone partially substituted at C-4 of rhamnose units by side chains, which included T-linked β-D-Galp, 1,3-linked β-D-Galp, 1,6-linked β-D-Galp, 1,3,6-linked β-D-Galp, 1,5-linked α-L-Araf, 1,3,5-linked α-L-Araf, T-linked α-L-Araf and T-linked β-D-Xylp. Biological activity tests showed that LRP3-S1 could inhibit the growth of pancreatic cancer cells. In addition, LRP3-S1 could attenuate invasion ability of BxPC-3 cells and down-regulate protein expression of p-FAK, p-AKT, p-GSK-3β and p-p38 MAP kinase.