Abstract: The crude polysaccharide JMBP-C was extracted from Mesona blumes with an alkaline solution. The neutral polysaccharide JMBP-N and the two acidic polysaccharides JMBP-A1 and JMBP-A2 were obtained by fractionating JMBP-C through ultrafiltration, ion exchange and gel column chromatography. Hydrogen peroxide was used to induce oxidative damage to human liver LO2 cells. The protective effects of JMBP-C, JMBP-A1 and JMBP-A2 on oxidative damage in cells were investigated by cell viability, the activities of lactate dehydrogenase (LDH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) and the content of malondialdehyde (MDA). The results showed that all three polysaccharides could significantly increase the survival rate of oxidatively damaged cells and effectively reduce the release of LDH. The LDH activity of damaged cells was significantly decreased by each of the polysaccharides at 2 mg/mL (P < 0.01). JMBP-A1 at 500 μg/mL increased the cell survival rate 49.47% compared with the model group. The three polysaccharides could improve the activities of GSH-Px, SOD and CAT in a dose-dependent manner. JMBP-A2 at 0.125 mg/mL increased GSH-Px activity to 69.20% of the normal level, which was higher than that of the positive control. JMBP-A1 at 2 mg/mL could restore the activity of SOD and CAT to 80.32% and 88.14% of the normal group respectively, which was significantly higher than those of the model group (P < 0.01), and the effect was close to that of the positive control group. Moreover, all three polysaccharides could effectively reduce MDA production. JMBP-A1 at 0.5 mg/mL reduced MDA content in damaged cells by 31.50%, and this effect was comparable to that of the positive control. In summary, the polysaccharides from Mesona blumes can increase the activity of antioxidant enzymes and decrease the production of lipid peroxides, suggesting a significant protective effect against oxidative stress-induced cellular damage.

Key words: polysaccharides from Mesona blumes, cell, oxidative damage, antioxidant enzyme