| At the moment,our oats are produced at a high level but at a low cost.Oat protein is a high-quality cereal protein with an excellent amino acid composition.Oats have been demonstrated in studies to be effective in avoiding diabetes mellitus type 2,and with the global population aging,it has become increasingly vital to take long-term,safe,and efficient strategies to control and prevent diabetes mellitus type 2.In this paper,the hypoglycemic effect of oat peptides on diabetic mice was investigated by hydrolyzing oat protein to obtain biologically active small molecule peptides and studying their inhibitory effect on α-amylase,which provides an important scientific basis for the deep processing of oats and the development and utilization of oat peptides.The specific experimental methods and results are as follows:(1)The oat protein was extracted from oats by alkali solubilization and acid precipitation methods,and the results showed that the content of oat protein was 86.36% by using the Komas Brilliant Blue method.The effects of liquid to material ratio,enzyme addition and enzymatic digestion time on oat peptides were investigated by using the peptide yield and α-amylase inhibition rate as indicators,and the optimal protease was determined as flavor protease.The enzymatic conditions were optimized on the basis of single-factor design response surface test,and finally we got better enzymatic conditions: 20:1 m L/g of liquid to material ratio,6000 U/g of enzyme addition,and 3 h of enzymatic time,under which the protease activity was effectively improved to achieve the best inhibition effect.The peptide yield reached 44.1% and theα-amylase inhibition rate reached 64.47% at this time.(2)Based on the optimal preparation process for oat peptides,four different peptides were separated from the oat proteolytic solution by ultrafiltration technique: <3 k Da,3-5 k Da,5-10 k Da and >10 k Da.81.37% inhibition of α-amylase was achieved in the <3 k Da fraction.For the<3 k Da fraction,Sephadex G-25 gel was used to purify the F1 and F2 fractions,and the highest inhibition rate of 88.62% was obtained for F2.The F2 fraction was further purified by RP-HPLC to obtain the F2-1 fraction.The inhibition kinetics of the purified oat peptide F2 fraction was found to be a reversible competitive inhibition of α-amylase,and the inhibition constant Ki = 21.13 mmol/L was calculated.(3)The in vivo hypoglycemic study of oat polypeptide F2 was performed by intra peritoneal injection of STZ to induce diabetes mellitus type 2,and the results showed that in mice treated with oat polypeptide F2,the treatment lasting 4 w could significantly improve the symptoms of diabetes(P<0.01),and the levels of TC,TG and LDL-C were increased.Compared with the model group,the mice in the oat polypeptide F2 treatment group had a decrease in HDL-C levels and INS levels were decreased in the oat po lypeptide F2-treated group compared with the model group.The results of oxidative stress showed that the SOD and CAT activities of oat polypeptide F2 high,medium and low dose groups were enhanced by 46.96%,24.09%,1.56% and 29.89%,20.68%,7.12%,respectively,compared with the model group,and the content of GSH increased by 83.56%,48.1%,21.48%,respectively,while there was a significant decrease in MDA content.Based on the results of HE staining of liver tissues,it was found that the degree of damage to liver sections of mice in the high and medium dose groups of oat polypeptide F2 was significantly reduced and the treatment effect was comparable to that of the acarbose group.Western blotting results indicated that the enzymatically prepared oat peptide F2 could improve the blood glucose level in mice with diabetes by regulating P-AK T and AMPK related signaling pathways.In summary,the enzymatic separation and purification of oat peptides can effectively alleviate the blood glucose level in diabetes mellitus type 2,which not only broadens the application field of natural resource peptide components,but also opens up the idea of diabetes drug research and expands the research direction of the biological activity of resource-rich oats in China,which provides a reference for the resource utilization of oats and the research and development of natural hypoglycemic components. |
