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  3. Screening assay of angiotensin-converting enzyme inhibitory activity from complex natural colourants and foods using high-throughput LC-MS/MS

Screening assay of angiotensin-converting enzyme inhibitory activity from complex natural colourants and foods using high-throughput LC-MS/MS

  • Food Chem. 2011 Jun 15;126(4):1909-15. doi: 10.1016/j.foodchem.2010.12.019.
Koichi Inoue 1,  Marie Kitade 2,  Tomoaki Hino 3,  Hisao Oka 3
Affiliations

Affiliations

  • 1 Department of Physical and Analytical Chemistry, School of Pharmacy, Kinjo Gakuin University, 2-1723 Omori, Moriyama-ku, Nagoya 463-8521, Japan. Electronic address: [email protected].
  • 2 Department of Physical and Analytical Chemistry, School of Pharmacy, Kinjo Gakuin University, 2-1723 Omori, Moriyama-ku, Nagoya 463-8521, Japan.
  • 3 Department of Physical and Analytical Chemistry, School of Pharmacy, Kinjo Gakuin University, 2-1723 Omori, Moriyama-ku, Nagoya 463-8521, Japan; Graduate School of Human Ecology, Human Ecology Major, Kinjo Gakuin University, Japan.
PMID: 25213976 DOI: 10.1016/j.foodchem.2010.12.019
Abstract

Inhibition of angiotensin-converting enzyme (ACE) by various foods decreases the blood pressure. ACE inhibitors derived from natural components may be of therapeutic value in preventive medicine. In this study, we report a novel screening assay of ACE inhibitors from complex natural colourants and foods that employ solid phase extraction (SPE), high-throughput liquid chromatography (LC) separation, and stable isotope dilution electrospray tandem mass spectrometry (SID-ESI-MS/MS). When a target sample was subjected to N-Hippuryl-His-Leu (HHL) and ACE in phosphate buffer (pH 7.4), generated hippuric acid (HA) was extracted by SPE. LC/SID-ESI-MS/MS detection of HA allowed us to accurately identify the effects of complex substances such natural colourants and foods that inhibit the ACE of HHL. The major HA and HA-d5 fragment ions at m/z 180→105 and 185→110 in the multiple reaction monitoring (MRM) mode can quantify levels that are lower than Other methods. The LC/SID-ESI-MS/MS method described here is a rapid, selective, sensitive, and highly reproducible method for the determination of HA in various samples. Based on the assay developed, all samples such as natural colourants, infant formula, soy paste, ketchup, mayonnaise, wheat flour, orange juice, supplement drink, tea, and coffee could be accurately measured for ACE inhibition in various matrices. High-throughput LC/SID-ESI-MS/MS assay has no limitations in the evaluation of inhibition activity in various natural samples such as colour, high-matrix, and processed foods.

Keywords

Angiotensin-converting enzyme; Inhibitors; Liquid chromatography mass spectrometry; Stable isotope dilution.

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