Identification and antidiabetic activity of peptides in protein Morus alba leaf proteolytic hydrolysates: A novel functional food ingredient for ameliorating type 2 diabetes mellitus

Abstract

Diabetes mellitus, a chronic metabolic disorder, has become a global health concern due to its increasing prevalence and associated complications. Mulberry (Morus alba), widely used in the food and nutraceutical industries, has shown potential in alleviating metabolic disorders through its protein. This study aimed to analyze the composition of the protease hydrolysate of a new resource species, the protein mulberry, and investigate its activity in ameliorating type 2 diabetes mellitus (T2DM). Proteolytic hydrolysis of protein mulberry leaf proteins increased total amino acid content (TAA) by 11.58%, with significant increases in 14 amino acids. Chromatography and mass spectrometry indicated that the main peptides in hydrolyzed proteins with molecular weight was less than 10 kDa and 802 bioactive peptides were identified. Moreover, this study constructed a mouse model of streptozotocin (STZ)/high-fat diet-induced T2DM.Two peptides showed tolerance to digestive enzymes. Protein mulberry leaf proteolytic hydrolysate (MLPH) effectively improved the blood sugar level and glucose tolerance of diabetic mice; increased the activities of serum C-peptide, liver glycogen, and antioxidant enzymes; reduced the indices of blood lipid and oxidative stress; and improved the morphology of liver and islet cells. Transcriptome analysis showed that the genes upregulated in the MLPH group were primarily involved in the synthesis and metabolism of sterols and cholesterol. These findings suggest that MLPH, rich in amino acids and bioactive peptides, holds promise as a functional food ingredient for managing T2DM and developing antidiabetic foods.