Proteome composition and profiling of bioactive peptides of edible Antheraea assamensis pupae by sequential enzymatic digestion and kinetic modeling of in vitro gastrointestinal digestion

Among several foods-derived peptides/protein hydrolysates tested to treat fluctuation in oxidative stress, Angiotensin-I converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) activities linked with physiological complications of type II diabetes and hypertension, only limited numbers sourced from insects have been implemented. Aim of this study is to profile the indigenous Muga (Antheraea assamensis) pupae proteome and evaluate the suitable parameters to procure ACE inhibitory, DPP-IV inhibitory and antioxidative peptide mix with suitable enzymatic interventions. Total 72 distinct proteins distributed in 22 insect protein families were identified through MS/MS analysis. Aldehyde dehydrogenase (6.79%), pupae cuticle protein (17.02%) and haemolymph protein (9.03%) were the most abundant enzymatic and non-enzymatic protein families. The highest ACE inhibition and DPPH scavenging activities were demonstrated by Alcalase (H1) and Papain (H3) hydrolysates at 3.0% enzyme–substrate (E/S) ratio with incubation of 3 and 5 h, respectively. The Flavourzyme (H5) and Papain (H6) hydrolysates at 2.3% E/S for 5 and 3 h incubations resulted in the best DPP-IV inhibition activity. Further, Flavourzyme (H2) and Thermolysin (H4) hydrolysates with 3.0 E/S for 5 and 2 h incubation resulted in higher ABTS scavenging activity. The respective potential activities of H1 and H3 increased while H4 and H5 were retained after simulated gastrointestinal digestion. Liquid chromatography, free amino acids and molecular mass analysis further supported variation between the profiles of non-hydrolysed and hydrolysed samples under enzymatic and simulated gastrointestional conditions. Gastrointestinal digests of protein extract, H1 and H3 displayed an uncompetitive, mixed and competitive inhibiting pattern towards ACE. While gastrointestinal digests of H5 and H6 revealed an uncompetitive and non-competitive DPP-IV inhibition. The bioactive protein hydrolysates from edible A. assamensis pupae generated using enzymatic digestion can be an effective supplement for functional or nutraceutical food formulations. Graphic abstract: [Figure not available: see fulltext.].