Fractionation and identification of bioactive peptides from red macroalgae protein hydrolysates: In silico analysis and in vitro bioactivities

Abstract

Recently, bioactive peptides derived from algae sources have gained significant recognition as vital functional ingredients in the development of health-enhancing foods and nutraceuticals. In this study, protein hydrolysates (SCPH and GSPH) derived from two red macroalgae (Sphaerococcus coronopifolius and Gelidium spinosum) were fractionated using semi-preparative-reversed phase high-performance liquid chromatography (RP-HPLC). Then, the peptides contained in the obtained fractions were identified by RP-HPLC coupled with tandem mass spectrometry (MS/MS). In silico analyzes of hydrophobicity, potential bioactivity using PeptideRanker, and toxicity of identified peptides were performed. Moreover, the prediction of Angiotensin-converting enzyme (ACE)- and Dipeptidyl-peptidase (DPP-IV)-inhibitory peptides using a quantitative structure-activity relationship (QSAR) was also carried out. Furthermore, in vitro evaluation of antioxidant and antibacterial activities, as well as ACE-, and DPP-IV-inhibitory properties was conducted for all peptide fractions. Our results showed that SCPH and GSPH fractions contain a large percentage of highly hydrophobic peptides with low molecular weight, and they exhibit no toxic effect. Among all identified peptides, 61 and 39 peptides, respectively from SCPH and GSPH fractions, presented a PeptideRanker score superior to 0.8. These peptide sequences exhibited a high proportion of potent predicted ACE- and DPP-IV-inhibitory peptides. Additionally, most of the peptide fractions exerted antioxidant, antibacterial, anti-ACE, and anti-DPP-IV inhibitory activities at different levels. Among them, F2 to F6 were the most active fractions. Overall, the results suggest that the bioactive peptide fractions separated from two red macroalgae protein hydrolysates could be considered as a beneficial ingredient for nutraceutical and functional food industries.