A new α-amylase inhibitory peptide from Gynura medica extract

In this study, we discovered a novel peptide, Gymepeptide A, with alpha-amylase inhibitory activity in the water extract of Gynura medica. The structure of Gymepeptide A was determined as CGDREETR using HR-MS, H-1 NMR,C- 13 NMR, and 2D-NMR techniques. Notably, Gymepeptide A possesses a rare double arginine residue structure and exhibits strong alpha-amylase inhibitory activity. Enzyme dynamic assays, molecular docking experiments, and isothermal titration calorimetry indicated that the double arginine residue structure of Gymepeptide A interacts with amino acid residues in the nearby active site region of alpha-amylase through hydrogen bonds and van der Waals forces. This interaction effectively inhibits the hydrolysis activity of alpha-amylase. Furthermore, in vitro starch digestion tests revealed that Gymepeptide A significantly reduced the digestion rate of starch and the concentration of glucose produced after starch digestion. These findings highlight the great potential of Gymepeptide A in decreasing postprandial blood glucose levels.

Automated summary

In this study, a novel peptide called Gymepeptide A was discovered in the water extract of Gynura medica, which showed strong inhibitory activity against alpha-amylase. Gymepeptide A possesses a unique double arginine residue structure and interacts with the active site region of alpha-amylase through hydrogen bonds and van der Waals forces, effectively inhibiting its hydrolysis activity. In vitro digestion tests revealed that Gymepeptide A significantly reduced the digestion rate of starch and the concentration of glucose produced. This suggests that Gymepeptide A has the potential to decrease postprandial blood glucose levels.