Angiotensin I-converting enzyme inhibitory peptides: Inhibition mode, bioavailability, and antihypertensive effects

Bioactive peptides within the original food-derived proteins are inactive but can be activated by releasing them during food processing (by enzymatic hydrolysis or fermentation) or during gastrointestinal (GI) digestion. Among all the bioactive peptides, the antihypertensive peptides attract particular attention owing to the prevalence of high blood pressure, which plays an important role in cardiovascular diseases. These peptides have the ability to act as angiotensin I-converting enzyme (ACE) inhibitors. Previous studies have shown that the ACE inhibitory peptides functioned as competitive, noncompetitive, or uncompetitive inhibitors, and therefore, the structure-activity relationship of the peptides with various inhibition modes needs to be clarified. Besides, the ACE inhibitory activity of these peptides in vitro does not always suggest its antihypertensive effect in vivo, which is based on its fate to encounter GI enzymes and brush-border membrane peptidases, after oral administration. This paper reviews the current literature on ACE inhibitory peptides, focusing on the structure-activity relationship and inhibition mechanisms due to their inhibition modes. In addition, the in vitro-simulated GI digestion for assessing bioavailability and in vivo antihypertensive effects of the peptides are also summarized.