Rapid determination of the angiotensin I-converting enzyme inhibitory activity of peptide by HPLC method: A simulated gastrointestinal digestion study

Angiotensin I-converting enzyme (ACE) plays a vital role in blood pressure regulation. In vitro ACE inhibitory activity assays are commonly used for evaluating the activity of inhibitors in many researches. In the present study, a rapid, sensitive, simple, and accurate HPLC method for ACE inhibitory activity determination using chicken meat as a model was developed. Specific attention was paid to assess the ACE inhibitory activity of peptides released during simulated gastrointestinal digestion. Using hippuryl–histidyl–leucine as the substrate, ACE can catalyze it into hippuric acid, which is rapidly and sensitively detected by the HPLC at the retention time of 8–10 min. The ACE inhibitory activity of each digestion solution can be rapidly determined every 15 min or less. The model protein displayed a high ACE inhibitory activity during simulated gastrointestinal digestion, but the digestion solution in the stomach showed stronger activity than in the intestine.