Development, validation, and application of a fast, simple, and robust SPE-based LC-MS/MS method for quantification of angiotensin I-converting enzyme inhibiting tripeptides Val-Pro-Pro, Ile-Pro-Pro, and Leu-Pro-Pro in yoghurt and other fermented dairy products

Abstract

Dairy products are an important part of a nutritionally balanced diet as their constituents can affect the human state of health. By inhibiting the angiotensin I-converting enzyme, the tripeptides Val-Pro-Pro, Ile-Pro-Pro, and Leu-Pro-Pro can lower blood pressure. As these peptides are produced during fermentation, they are found in various dairy products like cheese, yoghurt, etc., but except for cheese only little is known about their content. To investigate how other dairy products contribute to a supply of these antihypertensive peptides, we developed and validated a fast and sensitive assay for quantification of the three tripeptides with LC-MS/MS combined with a simple protocol for extraction and SPE-purification from yoghurt, curd, or other products. Finally, the entire method was successfully applied to survey peptide concentrations in samples from local dairies and thus expands our awareness on the content of antihypertensive peptides in our food.

Release of Leu‐Pro‐Pro from corn gluten meal by fermentation with a Lactobacillus helveticus strain

“…Although IPP, VPP, and LPP have been proved clinically effective in reducing the blood pressure of antihypertensive patients and several functional foods have been developed based on them, IPP and VPP are often designated as the major bioactive agents and LPP is often not detected or detected at a low level. A survey of 49 dietary products revealed that LPP was present only in few curds and was not found in the selected sour cream, crème fraiche, sour milk, or yoghurt products 41 ; Evolus® milk, however, which is the first product sold in Europe with a scientifically established claim to control blood pressure, contains only 0.8 mg L −1 LPP, which is much lower than the 6.9 mg L −1 of VPP and 6.1 mg L −1 of IPP 42 . Hence the current hydrolysate might be used as a novel antihypertensive ingredient, with LPP as the major bioactive ingredient.…”