251: Bioactivity Changes of ACE Inhibitory Peanut Protein Hydrolysate Due to Gastrointestinal Digestion

Introduction

Hypertension is a major public health concern globally. Due to the numerous side-effects of synthetic antihypertensive drugs, natural alternatives, such as food protein-derived bioactive peptides are gaining attention. In our previous study, the PPH produced through extensive enzymatic hydrolysis with Alcalase© showed significant ACE- and renin-inhibitory activities, suggesting their potential as antihypertensive agent. However, the bioactivity of PPH depends on its resistance to gastrointestinal degradation, and may be enhanced during digestion due to the formation of smaller and more effective peptides. This study evaluated the effects of in-vitro gastrointestinal digestion on the ACE-inhibitory activity of PPH and characterized the structural molecular weight changes of the peptides post-digestion.

Methods

PPH was produced through Alcalase© hydrolysis of peanut protein concentrate. The PPH samples were subjected to simulated gastric and intestinal digestions with pepsin and pancreatin at varying enzyme concentrations and digestion times. ACE inhibition was assessed using ACE derived from rabbit lungs and peptide FAPGG as substrate. The antihypertensive potential of each sample was expressed as IC50, the PPH concentration required to inhibit 50% of ACE activity. The changes in proteins and peptides due to digestion were visualized using SDS-PAGE. The quantitative data were analyzed using Nonlinear regression and post-hoc Tukey’s test.

Results

One-hour single-enzyme digestions of PPH produced samples with IC50 values similar to that of undigested PPH, indicating minimal change in ACE inhibition. However, increasing enzyme concentration and digestion time resulted in progressively lower IC50 values, suggesting enhanced ACE inhibition and the formation of smaller and more bioactive peptides. SDS-PAGE analysis revealed two proteins around 12kDa and 7.8kDa in PPH were resistant to single-enzyme digestion. In contrast, sequential digestion led to significant degradation of these proteins, which may explain the slightly higher IC50 values observed.

Significance

The gastrointestinal digestion of PPH could enhance its antihypertensive potential, which makes it possible to use PPH for blood pressure management.

Authors: Seyi D. Adebayo, Jianmei Yu