Covalent/Noncovalent Binding Of Cyanidin-3-O-Glucoside To Bovine Serum Albumin Inhibits The Formation Of Advanced Glycation End Products And Its Application

Anthocyanins are secondary metabolites with a variety of physiological activities in plant derived foods.They usually have protein affinity.The interaction between food anthocyanins and proteins will change their nutritional characteristics and functional structure.In the process of food processing,amino compounds such as proteins and amino acids and carbonyl compounds such as reducing sugars will undergo Maillard reaction and inevitably produce some harmful substances such as AGEs.In this study,the model proteins bovine serum albumin(BSA)and cyanidin-3-O-glucoside(C3G)were used as raw materials to explore the interaction mechanism of covalent and noncovalent binding.By studying the amount of products produced in each stage of glycosylation reaction,as well as the physical and chemical properties,functional properties and structural changes of reaction products,as well as the structural changes and functional properties of proteins covalent and noncovalent with C3 G,This paper attempts to clarify the influence of the interaction between anthocyanins and proteins on advanced glycation end products through different ways,so as to provide a scientific basis for scientifically understanding the influence of the interaction between food proteins and anthocyanins on product quality and safety.The main results are as follows:(1)The effects of covalent binding of bovine serum albumin and C3 G on protein structure and function were studied by SDS-PAGE,UV-Vis,Fourier transform infrared,fluorescence and circular dichroism.In the BSA-C3 G covalent composite system,the formation of macromolecular derivatives was analyzed by SDS-PAGE,which shows that it forms a covalent crosslinking system.Fluorescence spectrum analysis showed that the covalent crosslinking of C3 G and BSA significantly reduced the fluorescence intensity of bovine serum albumin,and the structure and microenvironment of BSAC3 G covalent complex changed significantly.The content of α-helix increased gradually,while β-turn decreases gradually,which is mainly reflected in the higher stability of protein structure and the formation of more stable complexes.(2)The effects of noncovalent binding of bovine serum albumin and C3 G on protein structure and function were studied by SDS-PAGE,UV-Vis,fluorescence and circular dichroism.SDS-PAGE showed that there were no new bands in the noncovalent complex of BSA-C3 G,indicating that the noncovalent binding reaction between BSA and C3 G occurred.In BSA-C3 G non covalent composite system,the addition of C3 G changes the microenvironment of tyrosine residues and tryptophan residues,which changes the conformation of bovine serum albumin,resulting in the change of secondary structure of bovine serum albumin.Fluorescence spectrum analysis showed that the fluorescence intensity of noncovalent complexes decreased significantly with the increase of C3 G concentration.(3)The glycosylation model was constructed by using BSA-C3 G covalent complex and fructose to study the effects of covalent binding on the early product of nonenzymatic glycosylation,fructosamine,the end product of late glycosylation,AGEs,the sulfhydryl group of BSA,the crosslinking structure and conformation of BSA.The inhibition rates of BSA and C3 G covalent conjugate on fructosamine were 4.02%,11.84%,12.55% and 18.77%,respectively;The inhibition rates of fluorescent AGEs were 23.93%,42.82%,58.2% and 74.48%,respectively.The results showed that BSAC3 G covalent complex could inhibit the formation of stage products fructosamine and AGEs,and the activity of inhibiting AGEs was higher than that of fructosamine.It may be due to the covalent binding reaction between C3 G and bovine serum albumin and competitive binding of glycosylation sites,so as to further inhibit the production of AGEs.(4)The glycosylation model was constructed by using BSA-C3 G non covalent complex and fructose to study the effects of noncovalent binding on the early product of nonenzymatic glycosylation,fructosamine and the late glycosylation end product ages,the sulfhydryl group of BSA,the crosslinking structure and conformation of BSA.The inhibition rates of BSA-C3 G non covalent conjugate on fructosamine were 9.2%,13.28%,14.25% and 29.83%,respectively;The inhibition rates of AGEs were 42.51%,52.03%,58.4% and 65.14%,respectively.The results show that BSA-C3 G non covalent complex can inhibit the formation of stage products fructosamine and AGEs.C3 G non covalent binding has a higher inhibitory effect on fructosamine than C3 G covalent binding in the early stage,which may be because C3 G prevents the formation of AGEs by scavenging active free radical ions and carbonyls or reducing the reaction oxidation rate.(5)Taking grape and milk as raw materials,a grape milk compound beverage rich in anthocyanins was designed,and the inhibitory effect of anthocyanins on the formation of advanced glycation end products in the actual production of milk beverage was discussed.This anthocyanin milk compound beverage is delicious and nutritious.It can effectively inhibit the formation of advanced glycation end products during beverage processing.It has a good market prospect and provides a new idea for the development of new beverage products.