Angiotensin I Converting Enzyme Inhibitory Peptides from Simulated in Vitro Gastrointestinal Digestion of Cooked Eggs

Egg proteins are an excellent source of bioactive peptides. The purpose of this work was to study the effect of cooking methods on the production of angiotensin converting enzyme (ACE) inhibitory peptides. Boiled or fried eggs (in the forms of whites, yolks, and whole eggs) were digested by gastrointestinal tract proteases at simulated gut conditions. Fried egg digests showed more potent activity than those of boiled egg digests; the fried whole egg digest had an IC50 value of 0.009 mg protein/mL. This hydrolysate was further purified by cation exchange chromatography and gel filtration chromatography. Seven peptides, Val-Asp-Phe (IC50: 6.59 mu M), Leu-Pro-Phe (10.59 mu M), Met-Pro-Phe (17.98 mu M), Tyr-Thr-Ala-Gly-Val (23.38 mu M), Glu-Arg-Tyr-Pro-Ile (8.76 mu M), Ile-Pro-Phe (8.78 mu M), and Thr-Thr-Ile (24.94 mu M), were identified by liquid chromatography-mass spectrometry (LC-MS/MS), and their IC50 values were predicted by using our previously reported structure and activity models. The presence of several tripeptides from in vitro simulated gastrointestinal egg digest indicates that these peptides may be absorbed into the body and exert an in vivo anti hypertensive activity, although in vivo study is needed to confirm this assumption. Our results showed that in vitro digestion of cooked eggs could generate a number of potent ACE inhibitory peptides which may have implications for cardiovascular disease prevention, including hypertension.