Study On Immunomodulatory And Anti-aging Effects Of LGP50 And LGP50S-1, Polysaccharides Extracted From Longan Pulp

Objective: This paper aims to study on the immunomodulatory effect of LGP50 and LGP50S-1, polysaccharides extracted from longan pulp and anti-aging activity of LGP50 in mice.Methods: MTT assay was used to evaluate the effects of LGP50 and LGP50S-1 on the proliferation of murine splenic lymphocytes and cytotoxicity of NK cells in vitro. The effect of LGP50 and LGP50S-1 was investigated on the level of IL-2 secreted by spleen lymphocytes using ELISA method; Griess reagents were used to detect NO generation in peritoneal macrophages; The influence of LGP50S-1 on the cell-cycle distribution of splenic lymphocytes was measured through flow cytometry; further, the effect of LGP50S-1 on MAPKs and NF-κB signaling pathways in murine lymphocytes was studied by Western blot method; The in vivo immunomodulatory effects of LGP50 were also investigated in immunosuppressive mice by carbon clearance assay and delayed type hypersensitivity test. In addition, the anti-aging effect of LGP50 was evaluated in the D-galactose-induced aging mouse model.Results: LGP50 and LGP50S-1( 25-400 μg/ml) promoted the proliferation of spleen lymphocytes; LGP50 and LGP50S-1( 25-200 μg/ml) boosted the secretion of IL-2 in a concentration-dependent manner. At the concentration of 200 μg/ml of LGP50 and LGP50S-1, the contents of IL-2 secreted by spleen lymphocytes reached 36.57 pg/ml, 26.31 pg/ml and 176.76 pg/ml, 69.46 pg/ml after 24 or 48 hours, respectively. LGP50 enhanced delayed-type hypersensitivity of immunosuppressive mice, which showed significant differences at the doses of 50, 100, and 200 mg/kg compared with normal control group.LGP50 and LGP50S-1( 25-400 μg/ml) significantly enhanced the cytotoxity of NK cells against YAC-1 cells in a concentration-dependent manner, and at the concentration of 400 μg/ml, the kill ratios are 33.74% and 51.08%, respectively; LGP50 and LGP50S-1( 3.1-400 μg/ml) significantly promoted the secretion of NO of peritoneal macrophages, and at the concentration of 200 μg/ml, the contents of NO secreted by peritoneal macrophages reached 73.50 μM, 28.58 μM and 99.67 μM, 33.17 μM after 24 or 48 hours, respectively; LGP50 enhanced the ability of carbon clearance of immunosuppressive mice, which showed significant differences at the doses of 50, 100, and 200 mg/kg compared with normal control group.LGP50S-1 promoted the development of spleen lymphocytes cycle towards S phase, at the concentration of 100 μg/ml, the percentage of cells in S phase reached 22.74%, while the normal group was only 15.72%; and at the concentration of 100 μg/ml, LGP50S-1 promoted phosphorylation of the signaling molecules of NF-κB and ERK1/2 in a time-dependent manner between 0 to 3 hours.At the doses of 100 and 200 mg/kg, LGP50 significantly increased the level of CAT, SOD and GSH-Px, and reduced the level of MDA in serum, liver and brain tissues in the D-galactose-induced aging mouse model.Conclusion: LGP50 and LGP50S-1 enhanced the non-specific immune function in mice through increasing activity of NK cells, the contents of NO of macrophages secreting and carbon clearance capacity, enhanced specific immune function in mice through promoting lymphocyte proliferation, the secretion of IL-2 and delayed-type hypersensitivity by activating NF-κB and MAPK signaling pathways; meanwhile, LGP50 had anti-aging effect.