Bioactive Peptides from Germinated Soybean with Anti-Diabetic Potential by Inhibition of Dipeptidyl Peptidase-IV, α-Amylase, and α-Glucosidase Enzymes

Abstract

Functional foods containing peptides offer the possibility to modulate the absorption of sugars and insulin levels to prevent diabetes. This study investigates the potential of germinated soybean peptides to modulate postprandial glycaemic response through inhibition of dipeptidyl peptidase IV (DPP-IV), salivary α-amylase, and intestinal α-glucosidases. A protein isolate from soybean sprouts was digested by pepsin and pancreatin. Protein digest and peptide fractions obtained by ultrafiltration (<5, 5–10 and >10 kDa) and subsequent semipreparative reverse phase liquid chromatography (F1, F2, F3, and F4) were screened for in vitro inhibition of DPP-IV, α-amylase, maltase, and sucrase activities. Protein digest inhibited DPP-IV (IC50 = 1.49 mg/mL), α-amylase (IC50 = 1.70 mg/mL), maltase, and sucrase activities of α-glucosidases (IC50 = 3.73 and 2.90 mg/mL, respectively). Peptides of 5–10 and >10 kDa were more effective at inhibiting DPP-IV (IC50 = 0.91 and 1.18 mg/mL, respectively), while peptides of 5–10 and <5 kDa showed a higher potency to inhibit α-amylase and α-glucosidases. Peptides in F1, F2, and F3 were mainly fragments from β-conglycinin, glycinin, and P34 thiol protease. The analysis of structural features of peptides in F1–F3 allowed the tentative identification of potential antidiabetic peptides. Germinated soybean protein showed a promising potential to be used as a nutraceutical or functional ingredient for diabetes prevention.

Bioactive Constituents of F. esculentum Bee Pollen and Quantitative Analysis of Samples Collected from Seven Areas by HPLC

“…Glucosidase is an important member of the sugar metabolism pathway in vivo, and α-glucosidase is directly involved in the metabolic pathways of starch and glycogen [36]. By inhibiting α-glucosidase, the chemical metabolism of sugar can be reduced, thereby achieving a hypoglycemic effect [37].…”

Gastrointestinal Digestion of Food Proteins under the Effects of Released Bioactive Peptides on Digestive Health

“…[33] Likewise, peptides from digests of germinated soybean recently showed inhibition of dipeptidyl peptidase-IV, -amylase, and -glucosidase enzymes, and thus may modulate the postprandial glycemic response. [34] Amigo-Benavent et al [35] described peptides with antioxidant activity in the digests of -conglycin and glycosylated -conglycin, some of them were not only resistant to gastrointestinal digestion but also transepithelially absorbed through Caco-2 monolayers. By using this cell model, it has been also confirmed that hydrolyzed soy proteins delivers an enhanced intestinal transport of dietary amino acids in comparison to intact protein.…”

A Novel Dipeptidyl Peptidase IV Inhibitory Tea Peptide Improves Pancreatic β-Cell Function and Reduces α-Cell Proliferation in Streptozotocin-Induced Diabetic Mice

“…DPP-IV inhibitory peptides derived from food proteins have attracted particular attention for their ability to prevent hyperglycemia. Hydrolysates approximately 1 kDa in size have been isolated from various natural sources, such as milk proteins, rice bran, amaranth proteins, ham, soybean, and fish proteins, and these hydrolysates display in vitro DPP-IV inhibitory activity [19,20]. Several animal studies have reported the in vivo antidiabetic effects of peptides, but the mechanisms have not been completely elucidated.…”