Abstract:Based on the hydrolysis specificity of ginger protease, highly bioactive peptide segments were virtually screened from the hydrolysates, followed by validation of in vitro activity and investigation of in vivo absorption into blood. First, highly active peptide segments were virtually screened through Peptide Ranker and molecular docking. Next, an in vitro enzyme-catalyzed reaction system was established to determine the inhibitory activity (IC50) of active peptides against dipeptidyl peptidase-IV (DPP-IV). Based on this, surface plasmon resonance (SPR) was introduced to investigate the interactions between DPP-IV and active peptides. Finally, oral administration experiments in rats were conducted to study the stability of active peptides in the gastrointestinal tract. Through computer simulation, the DPP-IV inhibitory peptide Gly-Pro-Ser-Gly-Pro-Hyp-Gly-Pro-Hyp-Gly-Pro-Hyp-Gly (GPSGPXGPXGPXG) was obtained via virtual screening. Moreover, the in vitro enzyme-catalyzed experiments showed that GPSGPXGPXGPXG has strong inhibitory effects against DPP-IV, with an IC50 of 457.3 μmol/L. SPR experiments further revealed fast binding and dissociation kinetics between the two peptides. However, in vivo experiments in rats suggested that GPSGPXGPXGPXG is not stable in the gastrointestinal tract and it is not absorbed intact, but it is partially absorbed into the circulatory system in the form of dipeptides and tripeptides, including oligopeptides like Pro-Hyp, Gly-Pro-Hyp, and Pro-Hyp-Gly. This study demonstrates that the bioactive peptides obtained via screening cannot maintain their structural integrity after oral absorption through the digestive tract and are hydrolyzed by peptidases in the body. The findings provide theoretical support for subsequent pharmacokinetic and pharmacodynamics studies in vivo.
