Proteomic profiling of Monascus-fermented djulis (Chenopodium formosanum) identifies ACE-inhibitory peptides through integrated in silico and in vitro approaches.

This study identified angiotensin-converting enzyme (ACE) inhibitory peptides generated during Monascus purpureus fermentation of djulis (Chenopodium formosanum). Protein hydrolysates from fermented dehulled djulis showed the highest ACE inhibition, reaching 40.71 ± 2.95 % on day 8 (captopril: 43.33 ± 3.53 %). In silico screening (BIOPEP database) and proteomics highlighted DAAGYVADK (DK9) as a potential candidate. Molecular docking indicated a binding affinity of -9.174 kcal/mol (captopril: -5.77). The binding was mainly stabilized by 7 hydrogen bonds with ACE active site residues Glu384, His353, Lys511, Gln281, Asn277, Ala354, and Arg522. Moreover, enzyme-kinetic analysis indicated competitive inhibition by increased Km with unchanged Vmax. Furthermore, absorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions suggested low toxicity and favorable pharmacokinetic properties for DK9. These findings support Monascus-fermented dehulled djulis as a promising substrate to generate natural ACE-inhibitory peptides and identify DK9 as a lead peptide for further development.