H-Ile-Pro-Pro-OH (IPP) is a peptide inhibitor of angiotensin converting enzyme (ACE; IC50 = 5 μM).1 It inhibits acetylcholine-induced nitric oxide (NO) production in human umbilical vein endothelial cells (HUVECs) when used at a concentration of 1 μM and induces vasorelaxation in precontracted isolated rat aortic rings.2 IPP (0.3 mg/kg) decreases systolic blood pressure in spontaneously hypertensive, but not normotensive, rats.3 Dietary administration of IPP reduces plasma levels of total cholesterol, HDL-cholesterol, and triglycerides, mRNA expression of IL-6 and IL-1β, and aortic arch intimal thickening and atherosclerotic plaque formation in ApoE-/- mice.4
|1. Y., N., Yamamoto, N., Sakai, K., et al. Purification and characterization of angiotensin I-converting enzyme inhibitors from sour milk. J. Dairy Sci. 78(4), 777-783 (1995).|2. Hirota, T., Nonaka, A., Matsushita, A., et al. Milk casein-derived tripeptides, VPP and IPP induced NO production in cultured endothelial cells and endothelium-dependent relaxation of isolated aortic rings. Heart Vessels 26(5), 549-556 (2011).|3. Nakamura, Y., Yamamoto, N., Sakai, K., et al. Antihypertensive effect of sour milk and peptides isolated from it that are inhibitors to angiotensin I-converting enzyme. J. Dairy Sci. 78(6), 1253-1257 (1995).|4. Nakamura, T., Hirota, T., Mizushima, K., et al. Milk-derived peptides, Val-Pro-Pro and Ile-Pro-Pro, attenuate atherosclerosis development in apolipoprotein e-deficient mice: A preliminary study. J. Med. Food. 16(5), 396-403 (2013).