Bioactive peptides have been extensively applied for developing health-promoting foods. To improve the value of Laminaria japonica proteins (LJPs), anti-hypertensive peptides were prepared by using controlled enzymatic hydrolysis along with response surface methodology to improve their yields. Eight anti-hypertensive peptides with tyrosine (Tyr) at the C-terminal were determined through an efficient RP-HPLC method and molecular docking was performed to reveal the underlying mechanisms behind their effectiveness of anti-hypertension. According to the results, the strongest activity of hydrolysates was achieved under enzyme ratio (papain: alcalase: trypsin) 1:2:1, pH 8.0, temperature 60°C, substrate concentration 1.7%, enzyme addition 4.4%, and hydrolysis time 5.1 h. Furthermore, molecular docking results displayed that anti-hypertensive peptides could bind with ACE active sites through forming a stable composite structure, thus causing a significant reduction to activities. These results demonstrated the potential applications of LJPs as a source of anti-hypertensive peptides and provided a reference for the industrialized anti-hypertensive productions.

Food-derived angiotensin-I-converting enzyme (ACE)-inhibitory peptides have gained attention for their potent and safe treatment of hypertensive disorders. However, there are some limitations of conventional methods for preparing ACE-inhibitory peptides. In this study, in silico hydrolysis, the quantitative structure–activity relationship (QSAR) model, LC-MS/MS, inhibition kinetics, and molecular docking were used to investigate the stability, hydrolyzability, in vitro activity, and inhibition mechanism of bioactive peptides during the actual hydrolysis process. Six novel ACE-inhibitory peptides were screened from the Larimichthys crocea protein (LCP) and had low IC₅₀ values (from 0.63 ± 0.09 µM to 10.26 ± 0.21 µM), which were close to the results of the QSAR model. After in vitro gastrointestinal simulated digestion activity of IPYADFK, FYEPFM and NWPWMK were found to remain almost unchanged, whereas LYDHLGK, INEMLDTK, and IHFGTTGK were affected by gastrointestinal digestion. Meanwhile, the inhibition kinetics and molecular docking results were consistent in that ACE-inhibitory peptides of different inhibition forms could effectively bind to the active or non-central active centers of ACE through hydrogen bonding. Our proposed method has better reproducibility, accuracy, and higher directivity than previous methods. This study can provide new approaches for the deep processing, identification, and preparation of Larimichthys crocea.