Effects Of Maillard Reaction On The Properties Of Superoxide Dismutase

Superoxide dismutase(SOD)plays an important role in the biological antioxidant system because it can catalyze superoxide free radical,the most basic free radicals in the body,into hydrogen peroxide and oxygen.Therefore,it's obvious that SOD has application potential in the field of medicine and health food.However,there is a widespread concern that SOD will lose their antioxidant activity during thermal processing and digestion.It is worth mentioning that the modification of Maillard reaction is an effective approach to improve the thermal stability and even gastrointestinal stability of proteins.Therefore,this paper investigated the effects of Maillard reaction on the properties of SOD.By the measurement of enzyme activity,SDS-PAGE,cell culture,the analysis of nanoparticles,field emission scanning electron microscopy,inductively coupled plasma atomic emission spectrometry and response surface optimization analysis,the following results were obtained:(1)The effect of co-existing glucose on the thermal stability of superoxide dismutase was analyzed during imitating conditions of the processing and decocting of Traditional Chinese Medicine.It showed that the co-existing glucose could improve the thermal stability of superoxide dismutase significantly by maillard reaction.(2)In the study of the thermal stability of superoxide dismutase,we found that the product of glucose modified SOD(G-SOD)generated during the maillard reaction is a kind of nanoparticles.It was found that the product can be stably stored at 4?environment through tracking and monitoring during a month,including the enzyme activity,particle size and Zeta potential.It showed that the active nanoparticles of superoxide dismutase can be prepared by maillard reaction.In another word,the existence form of SOD can be changed through maillard reaction.(3)In order to investigate the effects of maillard reaction on properties of SOD nanoparticles,we using design expert software and SAS statistical analysis software.Based on the Box-Benhnken central composite design principles,the conditions of maillard reaction optimized by the response surface analysis after single factor experiment were that the rate of SOD and Glucose was 1:2,the processing temperature was 60?,the processing time was 60 min,the decocting temperature was 75 ? and the decocting time was 45min.Under these condition,the enzyme activity of SOD was increased to more than 20 times than before(P<0.01),and the particle size decreased by 20%(P<0.05),which showed that the optimized product was a highly efficient SOD nanoparticles.(4)The activity and stability of G-SOD were detected.Compare native bovine SOD with G-SOD in stability by experiments of acid,alkali and proteinase.The stability of G-SOD improved significantly in acid,alkali and enzymolysis.These results suggested G-SOD may be more suitable for therapeutic use.(5)Compared the biological effects of native bovine SOD and G-SOD on cells,including NR8383(alveolar macrophages),Hep-G2(human hepatoma cells).The results showed that G-SOD can promote the proliferation of alveolar macrophages and increase their intracellular enzyme activity than native bovine SOD.Besides,the ability of G-SOD in inhibiting cancer cell proliferation and repairing damaged cells is better than native bovine SOD to some extent.In summary,the properties of G-SOD(glucose-modified SOD)including anti-heat,anti-acid,anti-alkali,anti-proteolysis,and the status of molecular existence all showed advantage over native SOD after Maillard reaction modification.Therefore,G-SOD might be a promising candidate for the development of new drug and health food.