Biological Activities And Mechanisms Of Extracellular Polysaccharide From Lachnum Sp. And Its Selenium Nanoparticles

Our research group has already analyzed the structure of the extracellular polysaccharide?LEP-2b?from Lachnum YM405,and found that LEP-2b has antioxidant and anti-cancer activity in vitro.However,it is unclear whether LEP-2b has the protective effect on liver injury,whether it has the synergistic effect with silymarin,and whether it could be used to prepare nanoparticles.Therefore,this study investigated the synergistic hepatoprotective effect of LEP-2b and the anticancer activity of LEP-2b-selenium nanoparticles and also mechanisms.The effect of LEP-2b and its combination effect with silymarin were studied.LEP-2b and the combination treatment groups showed the reduction of the liver index in mice and alleviation of hepatic pathological changes.LEP-2b reduced serum enzymes?AST,ALT,AKP,and LDH?,increased hepatic antioxidant enzymes?SOD,CAT,GSH-Px,GSH,and T-AOC?,and reduced inflammatory cytokines?TNF-?,IL-6 and IL-1??levels dose-dependently.Combining high-dose LEP-2b with silymarin group?CH group?showed the significant effect on these indicators?p<0.01?.Western blot results showed that compared with the model group,p-p38/p38 level in the CH group was significantly elevated,and the p-JNK/JNK level was obviously decreased.The apoptosis rate of liver cells was detected by TUNEL staining.The results demonstrated that the apoptosis rate of CH group was significantly lower than that of the model group?p<0.01?.Immunohistochemistry results showed that CH treatment markedly reduced the expression of Caspase-3.Moreover,compared with the model group,CH treatment obviously down-regulated the expressions of Cleaved-caspase-3,Bax and Bak,and up-regulated the expression of Bcl-2.Therefore,compared with mono-therapy,high-dose LEP-2b combined with silymarin has the best protective effect against acute liver injury induced by CCl₄.The mechanism may be related to reduction of oxidative stress and inflammation,or the inhibition of hepatocyte apoptosis and apoptosis-related proteins.Therefore,the combination of high-dose LEP-2b with silymarin is an effective method to protect liver injury.LEP-2b-selenium nanoparticles?LEP2b-SeNPs?were prepared,and we found that the concentration of LEP-2b affects the particle size of SeNPs?selenium nanoparticles?.LEP2b-SeNPs are dispersed with smaller particle size than SeNPs under transmission electron microscopy.LEP2b-SeNPs has higher stability during storage.The results showed that LEP2b-SeNPs injection alone not significantly reduced the body weight of normal mice,which indicated that mice were well tolerated to the dose of LEP2b-SeNPs.H22 tumor-bearing mice model was established to explore the anti-cancer activity of LEP2b-SeNPs.The results showed that the tumor weight of the mice in the low-dose LEP2b-SeNPs and positive control groups were extremely significant compared with the model group?p<0.001?.The mice in the model group had larger body weight than the normal group,and the food intake decreased significantly with days.However,the LEP2b-SeNPs-treated mice had relatively stable body weight and food intake,indicating that LEP2b-SeNPs had great antitumor activity.Immunohistochemical results showed that the low-dose LEP2b-SeNPs inhibited the expression of Ki-67 in tumor tissues?p<0.01?,and the effect was better than the high-dose group?p<0.05?,indicating that low-dose LEP2b-SeNPs effectively inhibited cancer cell proliferation.The expression of angiogenesis biomarkers in mice was detected.The levels of tumor VEGF and CD31 in the low-dose LEP2b-SeNPs treatment group were significantly reduced.Western blot results showed that the low-dose LEP2b-SeNPs markedly decreased MMP-2 and MMP-9 expressions?p<0.01?when compared with the model group,suggesting the excellent anti-tumor effect of low-dose LEP2b-SeNPs may be related with the inhibition of tumor angiogenesis,thereby inhibiting tumor growth and metastasis.In addition,LEP2b-SeNPs treatment did not cause hematological toxicity to mice,and serum levels of IFN-?,IL-1?,IL-2 and TNF-?were significantly elevated?p<0.05 or p<0.01?.Hepatic CAT levels increased while MDA levels decreased,indicating that LEP2b-SeNPs can also significantly reduce oxidative stress in tumor-bearing mice.Therefore,LEP2b-SeNPs has great stability,biological safety and antitumor activity.