Angiotensin-Converting Enzyme (ACE)-Inhibitor Activity of Novel Peptides Derived from Porcine Liver and Placenta

Peptides isolated from various biological materials are potential sources for novel angiotensin-converting enzyme (ACE) inhibitors. Here, the ACE-inhibitory activity of peptides derived from papain-digested hydrolysates of porcine liver and placenta were investigated. A high-throughput method was developed to identify potential bioactive peptides from the hydrolysates using in silico enzymatic cleavage, HPLC-MS/MS, and bioinformatics tools. Four peptides (FWG, MFLG, SDPPLVFVG, and FFNDA) were selected based on their predicted bioactivity, then synthesised and tested for ACE inhibition. All samples demonstrated ACE-inhibitory activity, with FWG and MFLG showing greater potency than SDPPLVFVG and FFNDA. The placenta hydrolysate outperformed both the liver hydrolysate and synthetic peptides in ACE inhibition, possibly due to it containing a higher proportion of dipeptides. The synthetic peptides' IC50 values were comparable to those reported for porcine muscle-derived peptides in previous studies. While less potent than the commercial ACE inhibitor captopril, the identified peptides showed promising ACE-inhibitory activity. This research demonstrates the potential of porcine liver and placenta as sources of novel ACE-inhibitory peptides and highlights the effectiveness of the developed high-throughput method for identifying bioactive peptides; this method could subsequently be adapted to other peptide sources, facilitating the development of innovative functional foods or nutraceuticals.