Analysis and Characterization of Novel Bioactive Peptides Derived from Red Macroalgae Protein Hydrolysis Using Peptidomics and Bioinformatics Approaches

Red macroalgae are a viable alternative source of proteins, essential nutrients, and bioactive peptides with potential biological activities. In this study, we used a peptidomics strategy to identify the bioactive peptides and bioinformatics tools to predict their bioactivities from two red macroalgae (Sphaerococcus coronopifolius and Gelidium spinosum) protein hydrolysates, named respectively SCPH and GSPH.

The extracted proteins from red macroalgae were first hydrolyzed by pepsin for 24 h at different enzyme/substrate (E/S) ratios and then characterized with reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to 214 nm detection. In silico analysis of hydrophobicity and toxicity of identified peptides were determined. The prediction of Angiotensin conversion enzyme (ACE)- and Dipeptidyl-peptidase-IV (DPP-IV)-inhibitory peptides using a quantitative structure-activity relationship (QSAR) was also performed.

Further characterization by RP-HPLC coupled with tandem mass spectrometry (MS/MS) of SCPH and GSPH, prepared at an E/S ratio of 1/10 (w/w), allowed the identification of 172 and 64 unique peptides, respectively. Additionally, both hydrolysates contain a large percentage of high hydrophobic (62.63% and 53.48%, respectively) and low molecular weight peptides with no toxic effects. Furthermore, the identified peptides showed a high proportion of potent predicted ACE-inhibitory peptides (IC₅₀ < 100 µM), in the range of 59.88% and 81.53% for SCPH and GSPH, respectively. Moreover, the potent predicted DPP-IV-inhibitory peptides were quantified as 92.98% and 91.30% for SCPH and GSPH, respectively.

These findings indicated that protein hydrolysates from these two red macroalgae present an attractive source of food-derived bioactive peptides with promising nutraceutical properties, especially antihypertensive and antidiabetic activities.