Exploring the Antidiabetic and Antihypertensive Potential of Peptides Derived from Bitter Melon Seed Hydrolysate

Type 2 diabetes (T2D) has become a critical global health issue, with an increasing prevalence that contributes to significant morbidity and mortality. Inhibiting dipeptidyl peptidase-IV (DPP4) is a promising strategy for managing T2D. This study aimed to explore the DPP4 inhibitory peptide derived from bitter melon seed protein (BMSP) hydrolysate.

Reversed-phase high-performance liquid chromatography (RP-HPLC) was utilized to fractionate the hydrolysate. Peptide in the highest activity fraction was analyzed using liquid chromatography-mass spectrometry (LC-MS/MS). Peptide synthetic was used for further characterizations, such as bioactivity exploration, inhibition mechanism, molecular docking, and peptide stability against in vitro simulated gastrointestinal (SGI) digestion.

The BMSP hydrolysate was digested with gastrointestinal proteases (GP) and assessed for DPP4 inhibitory activity, yielding an IC₅₀ of 1448 ± 105 μg/mL. Following RP-HPLC fractionation, MPHW (MW4) and VPSGAPF (VF7) were identified from fraction F8 with DPP4 IC₅₀ values of 128.0 ± 1.3 µM and 150.6 ± 3.4 µM, respectively. Additionally, MW4 exhibited potential antihypertensive effects through ACE inhibition with an IC₅₀ of 172.2 ± 10.6 µM. The inhibitory kinetics and molecular docking simulations indicated that both MW4 and VF7 were competitive inhibitors of DPP4, while MW4 was also a competitive inhibitor of ACE. Importantly, both peptides remained stable during simulated gastrointestinal digestion, suggesting their resistance to human digestive processes and their capacity to maintain biological activity.

The findings suggest that BMSP-GP hydrolysate may have potential in terms of the development of health foods or therapeutic agents. However, in vivo studies are also essential for further confirmation of efficacy.