Peptide release, radical scavenging capacity, and antioxidant responses in intestinal cells are determined by soybean variety and gastrointestinal digestion under simulated conditions

This research evaluated the association between the different protein and peptide composition of seven soybean varieties and their radical scavenging and antioxidant properties throughout simulated gastrointestinal digestion. Glycinin and beta-conglycinin were the primary and more varying proteins among soybean varieties. Protein composition determined the degree of hydrolysis, which negatively correlated with glycinin concentration (r = -0.911). Peptide sequencing evidenced the diversity of released peptides among soybean varieties. Although potentially less absorbable in intestinal cells, bigger peptides exhibited a stronger in silico binding affinity with Keap1 (r = 0.806). Digested soybean radical scavenging and antioxidant properties were positively associated with protein (r = 0.900) and glycinin (r = 0.824) concentration. Soybean digested fractions reduced oxidative stress (21-118%) and cell death in intestinal epithelial cells by activating (1.2-3.6-fold) Nrf2-dependent antioxidant responses. Differences in the protein and peptide composition influence soybean health-promoting properties and will guide the production of healthier soybean-based products.

Automated summary

This study assessed the relationship between the protein and peptide composition of soybean varieties and their antioxidant properties during digestion. Glycinin and beta-conglycinin were the primary and most variable proteins among the different soybean varieties. Protein composition determined the extent of hydrolysis, which was negatively associated with glycinin concentration (r = -0.911). Peptide sequencing revealed the diversity of released peptides among the soybean varieties. Despite being less absorbable in intestinal cells, larger peptides showed a stronger affinity for Keap1 (r = 0.806). Digested soybean fractions exhibited radical scavenging and antioxidant properties, which were positively correlated with protein (r = 0.900) and glycinin (r = 0.824) concentration. These fractions reduced oxidative stress (21-118%) and cell death in intestinal epithelial cells by activating Nrf2-dependent antioxidant responses (1.2-3.6-fold). Differences in protein and peptide composition influence the health-promoting properties of soybeans and can guide the production of healthier soybean-based products.