A novel phycoerythrin-derived peptide from Colaconema formosanum: Synthesis, in vitro, and in silico study on angiotensin-converting enzyme (ACE) inhibitory activity

Abstract

Colaconema formosanum, the red algae used in this study, has never been documented for its bioactivities as an angiotensin-converting enzyme inhibitor (ACEI). This study aims to discover ACEI derived from C. formosanum with a mixture of enzymes and orthogonal bioassay-guided fractionation through in vitro and in silico approaches. LRDGEIILR (LR-9) was isolated from the protein hydrolysate of C. formosanum digested by a combination of proteases (pepsin and thermolysin). It is derived from phycoerythrin, a protein abundant in most red algae. The LR-9 has an IC50 value of 94.28 +/- 1.84 mu M. The kinetics of inhibition revealed LR-9 to be a competitive inhibitor. The results of kinetic studies were rationalized further using molecular docking, which showed that LR-9 interacts preferentially with critical residues in the ACE active site. Based on the toxicity prediction, LR-9 was non-toxic. This study suggests that ACEI peptides extracted from C. formosanum could be an alternative source for developing hypertension-treating functional foods.