Identification of three novel angiotensin-converting enzyme inhibitory peptides derived from cauliflower by-products by multidimensional liquid chromatography and bioinformatics

The aim of this paper was the development of an analytical strategy for the production of purified bioactive peptides from cauliflower waste proteins, by testing two different extraction protocols and screening different enzymes for protein hydrolysis. The purification of peptides was carried out by multidimensional liquid chromatography employing reversed phase chromatography and hydrophilic interaction chromatography; the resulting fractions were tested for antihypertensive and antioxidative activities. The most active ones were characterized by nano-liquid chromatography-tandem mass spectrometry and identified by database search. The identified peptides were further mined by in-silico analysis using PeptideRanker to ascribe a bioactivity rank to each peptide. Thus, six potential ACE-inhibitory peptides were synthesized and validated checking their retention times and fragmentation patterns for consistency. Pure peptide standards were finally in-vitro tested for the specific bioactivity. In this way, three novel ACE-inhibitory peptides were successfully identified and validated from cauliflower waste hydrolysate, showing good IC50 values.