Identification and in vitro Characterization of Novel Antidiabetic Peptides Released Enzymatically from Peanut Protein.

Bioactive peptides derived from proteins found in various foods provide significant health benefits, including regulating blood sugar levels by inhibiting carbohydrate-hydrolyzing enzymes. Hydrolysates of peanut protein were prepared using alcalase (AH) or trypsin (TH) to generate antidiabetic peptides with high activity against α-amylase (IC₅₀ of 6.46 and 5.71 mg/mL) and α-glucosidase (IC₅₀ of 6.30 and 5.57 mg/mL), as well as antiradical activity to scavenge DPPH^• (IC₅₀ of 4.18 and 3.12 mg/mL) and ABTS^•+ (IC₅₀ of 2.87 and 2.56 mg/mL), respectively. The bioactivities of hydrolysates were greatest in the ultrafiltration-generated F3 fraction (< 3 kDa). The most active fraction was TH-F3, which was purified by gel filtration chromatography to generate sub-fractions (SF). With IC₅₀ values of 1.05 and 0.69 mg/mL, the F3-SF8 fraction was the most effective at inhibiting the activity of α-amylase and α-glucosidase, respectively. This fraction was further purified using RP-HPLC to generate sub-subfractions (SSF), the most active of which were F3-SF8-SSF9 and SSF10. The peptide sequences F3-SF8-SSF9 and SSF10 were determined using LC-MS/MS. Two novel antidiabetic peptides with the potential to inhibit α-amylase and α-glucosidase were identified, with the sequences Asp-Trp-Arg (476.22 Da, IC₅₀ of 0.78, and 0.35 mg/mL) and Phe-Tyr (329.15 Da, IC₅₀ of 0.91, and 0.41 mg/mL). These results suggest that peptides derived from peanut protein are attractive natural ingredients for diabetes management applications.