Enhancement of the in Vitro Bioactivities of Limpet (Patella Vulgata) Proteins: Effect of Pre-Enzymatic Hydrolysis Followed by Simulated Gastrointestinal Digestion

Abstract

Bioactive hydrolysates were generated from limpet (Patella vulgata) protein concentrate (LPC) utilising Alcalase (TM) and Flavourzyme (TM) followed by simulated gastrointestinal digestion (SGID). Samples were analysed using gel electrophoresis (SDS-PAGE) and gel permeation chromatography (GP-HPLC), while in vitro antioxidant (FRAP, ORAC and ABTS(center dot+)) and angiotensin-converting enzyme (ACE) inhibitory activities were employed to evaluate bioactivity. Alcalase was more effective than Flavourzyme in hydrolysing LPC, achieving a significantly higher (p < 0.05) amino nitrogen content after digestion, i.e., 29.50 +/- 0.69 vs. 21.06 +/- 1.04 mg g(-1) protein, respectively. The hydrolysates exhibited enhancements in some biological activities following SGID, with significant (p < 0.05) increases in antioxidant (except for the ORAC and FRAP activities in the Alcalase hydrolysates) and ACE inhibitory activities. The antioxidant activity of Alcalase-generated hydrolysates declined significantly during gastric digestion but was subsequently enhanced in the intestinal digestion phase. In contrast, the Flavourzyme-generated hydrolysates exhibited a progressive increase in antioxidant activity throughout SGID, with the highest levels observed following pepsin and Pancreatin (TM) incubation. In comparison with digestion where only SGID was conducted, the inclusion of a pre-enzymatic hydrolysis step with Alcalase prior to SGID led to significant improvements in both antioxidant (as measured by the ABTS assay, 360.92 +/- 18.32 mu mol Trolox Equivalents g(-)(1) protein) and ACE inhibitory activity (81.5% inhibition, at a final sample concentration of 0.2 mg mL(-1)). These findings highlight the potential health benefits of protein hydrolysates from limpet and their applicability in the food and health industries, underscoring the value of marine-derived proteins in developing bioactive compounds.