ACE inhibitory and DPP-IV inhibitory activity of collagen peptides derived from the snapper salmon (Otolithes ruber) skin collagen via papain and pepsin-trypsin hydrolysis

Abstract

Fish-based collagen supplements have potential health benefits, including antioxidant, ACE inhibitory, and DPP-IV inhibitory properties, which are expressed upon their digestion in the gastrointestinal system, thus releasing bioactive peptides (BPs). This study evaluated the pre-digestion of fish collagen using papain as a pre-digestive enzyme, which has broad specificity to enhance collagen breakdown and BPs release. Fish skin collagen was extracted via acid solubilisation, confirmed as type-I, and subsequently hydrolysed using two methods: pepsin-trypsin digestion (PTD) and pre-digestion with papain followed by PTD (PDPTD). The PDPTD–fish collagen hydrolysates (FCH) exhibited IC50 values (mg/mL) of 0.088 for ACE, 1.67 for DPP-IV, as well as 2.38 and 0.026 for antioxidant activities including DPPH and ABTS radicals scavenging, respectively, which were significantly lower than that of PTD-FCH. The FCH (PTD and PDPTD) were identified using LC-MS/MS analysis, and molecular docking studies showed lower binding energies for PDPTD–FCH peptides, particularly IGFPGFPG, against ACE (-11.2 kcal/mol) and DPP-IV (-9.1 kcal/mol), suggesting better inhibitory ability exhibited by BPs. This study highlighted fish collagen as a valuable source of BPs with enhanced bioactivity when pre-digested with papain, indicating its potential for functional foods and nutraceutical industries.