Enzymic polypeptide antioxidant activity and inhibitory activity on α-glucosidase and α-amylase from Paeonia ostii cake

As a residue of oil processing, research about Paeonia ostii cake has not been reported. We used six enzymes to hydrolyze the Paeonia ostii cake and obtained six enzymatic polypeptides. The enzymatic polypeptide yields of the six methods were between 10.0 and 25.0 % and average molecular weight was between 3.0 and 10.0 kDa. The average particle size of six enzymatic polypeptides was less than 1000.0 nm. The enzymatic hydrolysis method had a significant effect on the surface morphology of the enzymatic residues. The enzymatic polypeptide from alkaline protease method had better thermal stability and stronger infrared absorption. The eight essential amino acid contents of six enzymatic polypeptides from pepsin, papain, neutral protease, protemax, trypsase and alkaline protease method were 14.7, 13.3, 14.2, 12.8, 13.8 and 15.0 %, and hydrophobic amino acid contents were 14.7, 14.2, 14.2, 13.9, 13.7 and 15.1 %, respectively. Among the 12 non-essential amino acids, only glutamine and asparagine were absent. In addition, the different amino acid increment in six enzymatic polypeptides was significantly different. Among them, cysteine had the largest increment, followed by glycine and glutamic acid. By 5-axe cobweb chart method, the enzymatic polypeptide from alkaline protease method was proved to have the strongest comprehensive antioxidant activity. The enzymatic polypeptides of alkaline protease and protemax method had stronger inhibition activity of alpha-glucosidase and alpha-amylase. In general, the enzymatic polypeptide from alkaline protease method had good antioxidant activity and physiological activity. Our research will provide basic data support for new potential applications of enzymatic polypeptide from peony cake and increase the added value of Paeonia ostii processing enterprises.