Synergistic Protective Effect On Radiation Induced Oxidative Damage Of Polysaccharides AAP-4 Form Auricularia Auricular With Procyanidins

Ionizing radiation damage in the body via the primary role of direct and indirect effect causes the change of the biological molecular structures and properties, which can lead to a corresponding biochemical metabolic disorder and result in a variety of chronic diseases. Screening a kind of radioprotectant with the properties of high-efficiency and low-toxicity has been a hot area for the science researcher. A new radioprotectant consisting of two or more pathways of natural products is considered to be a better method of delay radiation injury. Recently research suggests that multi-targets or combination of different targeting agents both have many radiation-protective effect and will not cause any toxic. This advantage is conducive to the prevention or treatment of ionizing radiation injury. Therefore, studying the interaction effect of the in vitro antioxidant and screening proanthocyanidins（GSP） which has the strongest synergistic antioxidant activity via the interaction of six kind of polyphenol and Auricularia auriculajudae polysaccharides（AAP） can as a follow-up study. To reveal the mechanism of action, the composition and structure of the AAP are analyzed, as well as the radiation-induced oxidative damage synergistic protective effect of AAP-4 and GSP are researched.The research of eliminating 50% ABTS^+· and DPPH^· free radical through polyphenol and APP indicated that the combination of the GSP and AAP had good synergistic antioxidant effect for eliminating ABTS^+·（CI 0.41±0.06） and DPPH^·（CI 0.91±0.09） free radical. The in vitro antioxidant effect of the interaction between AAP and GSP was analyzed by Compusyn software. The results indicated that APP and GSP had an obvious synergistic effect for eliminating ABTS^+·, O₂^-·, DPPH^· and OH^· free radicals, hence and the drug dosage can be reduced. The synergistic effect was observed for the total reduction capacity. But it was not displayed for inhibition of lipid peroxidation.The APP was purified by DEAE-52 and Sephadex G-200, then obtained the main ingredients which was called AAP-4. The structure of the AAP-4 was characterized by FT-IR, HP-GPC and GC-MS. The results showed that the molecular weight of AAP-4 was 3.30×105 and was composed by D-xylose : Dmannose : D-glucose : D-galactose（molar ratio 1.97 : 4.67 : 9.91 : 0.31）. Then methylation and NMR were used for further characterized and the results revealed that the main configuration of sugar residues was α-D-Xylp-)1â†' and3,6â†')-α-D-Manp-（1â†' and 4â†'）-β-D-Glcp-（1â†', the backbone of AAP-4 was dew glucan which was composed by Glcp and Manp, and the terminal residue wasα-D-Xylp-）1â†'.The synergistic radiation protection function of AAP-4 and GSP to splenocyte was researched by the radiation induced oxidative damage model using cell and mouse. The data showed that the composition of AAP-4 and GSP increased the survival ability and multiplication capacity of splenocyte, and further increased the immunocompetence of body. The results also indicated that the effective coordination of radiation protection can be achieved by reducing the oxidation product quantity and increasing the contents of antioxidants and then reducing radiation on splenocyte DNA injury.60Co-γ rays can induce the stasis of splenocyte in G0/G1 mouse. Analyzing the cell cycle, the composition of AAP-4 and GSP could inhibit the stasis and coordinated protect the splenocyte apoptosis. Using immunohistochemical method to analyze the mitochondrial pathway of apoptosis, the results showed that AAP-4 and GSP could promote the expression of Bcl-2 by inhibiting the expression of Bax, cytochrome c and Caspase-3. Finally, the splenocyte apoptosis was suppressed.This research found that the combination of AAP-4 and GSP had two important functions. One of them was that it could improve the antioxidant status and immunocompetence in the body. Another function was that it had synergistic protective effect for the radiation-induced oxidative injury by the mitochondrial pathway of apoptosis which can inhibit the spleen apoptosis. This study had great theoretical value in revealing the radiation protection mechanism of 60Co-γ rays and practical significance for the further development of compound radiation protection agent.