Separation Of Anthocyanins From Aronia Melanocarpa And Their Antioxidant Activity And Radioprotective Effect

In modern society,people are inevitably exposed to ionizing radiation from highly radioactive background materials.Ionizing radiation causes the body to produce a large number of free radicals,and free radicals can destroy biological macromolecules and biofilms,resulting in cell dysfunction and body damage.Therefore,the research on the prevention and treatment of radiation damage,and on the effective radiation protective agents become an urgent problem to be solved.At present,most synthetic radiation protectants have many disadvantages,such as high toxicity,side effects and high price.Therefore,the development of new natural radioprotectors with high potency and low toxicity has become the focus of modern medicine and health care industry.Aronia melanocarpa has attracted much attention due to its strong antioxidant activity and various health benefits based on its anthocyanin.In this paper we selected anthocyanin from Aronia melanocarpa?AAM?as the research object,optimizing its extraction process,investigating its antioxidant capacity and thermal degradation model,and studying its protective effect on oxidative damage in radiated mice.The main results are as follows:?1?Ultrasonic assisted solvent extraction method was used to separate AAM.The extraction conditions were optimized by response surface methodology.The results showed that the optimum extracting condition was:ethanol concentration 80%,extraction temperature 45?,ultrasonic time 20 min,solid-liquid ratio 1:32 and p H 2.2.The highest yield was 19.42 mg/g DW.The purity of AAM purified by macroporous resin chromatography and solid phase extraction reached 90.43%.?2?DPPH method and ABTS method were used to determine the antioxidant capacity.The results showed that the antioxidant capacity of AAM was the highest at p H 3.0-5.0,which equaled 6.55-6.83?mol TE/mg?DPPH method?or 7.89-8.20?mol TE/mg?ABTS method?,6-17%higher than that of other p H.The changes of AAM content and antioxidant capacity during6 h at different p H and temperature were monitored.The results showed that the thermal degradation of AAM solutions with different p H at 40-100?followed a first-order kinetic reaction,and the degradation rate constant grew with the increase of temperature.Moreover,the stability of AAM at p H 7.0 was significantly lower than that at p H 2.0.When AAM was p H2.0,the half-life under heat treatment at 60,80 and 100?was 20.33,3.09 and 1.23 h respectively,and the activation energy was 72.77 k J/mol.When AAM was p H 7.0,the half-life under heat treatment at 60,80 and 100?was 11.18,4.18,1.02 and 0.38 h,respectively,and the activation energy was 55.88 k J/mol.Under the heat treatment,the antioxidant capacity of AAM decreased with time,and the higher the temperature,the faster the decline.The antioxidant capacity retention was positively proportional to AAM retention.The antioxidant capacity of AAM pyrolysis product was 64.8%?DPPH method?and 42.1%?ABTS method?of that of AAM.?3?The ¹³⁷Cs?radiation-induced oxidative damage animal model was established to study the radioprotection effect of AAM.Results showed that the mice in the radiation control group had all died within the 15th day after exposure to 7 Gy?irradiation.On the 30th day,AAM dose of 25 mg,50 mg,and 100 mg/kg b.w.had survival rates of 10%,30%,and 20%,respectively,proving that AAM had a significant protective effect on mice exposed to lethal radiation dose,delaying the time of death and reducing mortality.The immune organs of the mice were atrophied by 5 Gy exposure,and the weight of thymus and spleen decreased by 72%and 61%,respectively.The dose of 50 mg/kg and 100 mg/kg b.w.AAM alleviated the loss of thymus and spleen of the mice after radiation,and there was no significant difference between the two group.The thymus of the mice returned to the normal level and thymus mass was 59-65%of the normal level.So AAM can effectively protect the immune organs of the irradiated mice.Compared with the normal control group,the white blood cell count,red blood cell count and platelet count of the radiation control group decreased by 70%,25%and 30%respectively.Administration of 50 mg/kg and 100 mg/kg b.w.AAM alleviated the reduction of white blood cells,red blood cells and platelets in peripheral blood of mice caused by radiation,and there was no significant difference between the two groups.The levels of white blood cells,red blood cells and platelets in the two groups were 57-61%,85-90%and 91-94%of those in the normal control group,respectively.The micronucleus rates of AAM low,medium and high dose groups were all significantly lower than those of the radiation control group,with a decrease of 31%,42%and 43%,respectively,indicating that AAM could reduce micronucleus formation and chromosome aberrations in the radiated mice.Non-lethal dose of radiation reduced the activity of SOD and CAT,two important antioxidant enzymes reduced GSH,the main antioxidant in serum,and increased MDA,the most important end product of lipid peroxidation in liver,kidney,testis and serum.The administration of 50 mg/kg and 100 mg/kg b.w.AAM could enhance the activity of SOD and CAT in the organs and serum of mice,increase GSH,reduce MDA,and protect the antioxidant system of mice.