Peptidomic profile and α-glucosidase inhibitory activity of cooked and gastrointestinal digested legumes

Legumes are a good source of bioactive compounds, including peptides with antidiabetic potential. The α-glucosidase inhibitory activity of simulated gastrointestinal digested (GID) soybean, chickpea, green pea, and navy bean was determined after using three different household cooking methods (conventional, pressure, and microwave cooking). Samples were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC), and the fractions responsible for the α-glucosidase inhibitory activity were isolated. Lastly, peptides were identified by mass spectrometry in tandem (MS/MS) and in silico analyses were done to hypothesise potentially bioactive sequences. The results indicated that all legume extracts exert α-glucosidase inhibitory activity after thermal treatment and GID. Peptide profiles obtained by RP-HPLC showed the highest generation of peptides after the intestinal digestion phase, with small changes between thermal treatments. Best α-glucosidase inhibitory activity was observed in fraction 2 of all gastrointestinal digested samples, with values between 40 % and 62 % inhibition. In soybean, green pea, and navy bean, conventional-cooked samples showed the highest activity, while the pressure-cooked treatment resulted in significantly higher activity in chickpea samples. Finally, 48 peptides were identified by MS/MS and 13 were found as potentially bioactive using in silico tools, expanding previous knowledge on antidiabetic peptides derived from legumes.