In vitro gastrointestinal digestion study and identification of novel angiotensin i-converting enzyme inhibitory peptide from broccoli (brassica oleracea)

Due to the side effects of synthetic ACE inhibitors like captopril used for the treatment of hypertension, ACE inhibitory peptides derived from natural sources have attracted increasing attention in recent years. The aim of this work was to screen the vegetable with the highest angiotensin I-converting enzyme (ACE) inhibitory activity from 50 kinds of vegetables by using three different extraction methods, and to purify and identify the novel peptides from broccoli protein hydrolysates and evaluated the ACE inhibitory activity in vitro. Through centrifugation, ultrafltration, gel chromatography and high performance liquid chromatography (HPLC), the fraction BHs-IV-I-IV of the enzyme hydrolysate of broccoli with 100% ACE inhibitory activity was obtained. The novel ACE inhibitory peptide (KSVLLKF, KF-7) was identifed from fraction BHs-IV-I-IV by ultra-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS). ACE inhibition rate of 0.05 mg of KF-7 reached 42.86%, whereas 12.48 mg of pepsin hydrolysate of broccoli crude extract only exhibited 55.29% of ACE inhibition rate, indicating the low content of KF-7 in the protein hydrolysates of broccoli. These results suggested that KF-7 has a potential application in functional foods/pharmaceutical agents against hypertension and protein from broccoli may constitute a potential antihypertensive peptide source.