In silico and in vitro assessment of bioactive peptides from Arthrospira platensis phycobiliproteins for DPP-IV inhibitory activity, ACE inhibitory activity, and antioxidant activity

Arthrospira platensis proteins are considered as viable ingredients for functional foods with nutraceutical properties and health-promoting effects. In this study, we used five different proteases including pepsin, trypsin, alcalase, papain, and bromelain to hydrolyze A. platensis phycobiliprotein. LC-MS/MS (liquid chromatography-tandem mass spectrometry) was used to determine the composition of the hydrolysates with thousands of bioactive peptides. Based on peptide sequencing, a candidate list of 1,333 bioactive peptides was constructed for the first time for which bioinformatics tools were used to assess the properties of the bioactive peptides. The inhibitory activity of dipeptidyl peptidase IV (DPP-IV) and angiotensin-converting enzyme (ACE), as well as the antioxidant activity of five phycobiliprotein hydrolysates (PBPHs), were verified in vitro. The IC50 values of PBPH-pepsin, PBPH-trypsin, PBPH-alcalase, PBPH-papain, and PBPH-bromelain for DPP-IV inhibited activity were determined to be 4.059, 5.603, 5.257, 3.819, and 4.195 mg mL(-1), respectively. All the above five PBPHs were also seen to significantly inhibit ACE activity (P < 0.0001) in the range of 0.1-1.0 mg mL(-1). The activity of five PBPHs fraction was found for the 2-azino-bis (3-ethylbenzothiazoline6-sulfonic acid) diammonium salt (ABTS) assay (the highest was 1.37 mM Trolox equivalent of 30 mg mL(-1) of PBPH-trypsin), 1,1diphenyl-2-picrylhydrazyl (DPPH) assay (the highest was 204.67 mu M Trolox equivalent of 10 mg mL(-1) of PBPH-pepsin), and Fe2+ chelating ability (the highest was 639.73 mu M FeSO4 equivalent of 10 mg mL(-1) of PBPH-trypsin). This study indicated that it was feasible to utilize A. platensis phycobiliprotein as a source of bioactive peptides which may be used as functional food and/or nutritional supplements for human health.