Analytical Sciences

Analysis Method of the Angiotensin-I Converting Enzyme Inhibitory Activity Based on Micellar Electrokinetic Chromatography

Toshiro WATANABE,*^,**  Tapan Kumar MAZUMDER,* Shiro NAGAI,* Keisuke TSUJI,** and Shigeru TERABE***

*Yaegaki Technology Development Laboratories, Yaegaki Bio-industry, Inc., 681 Hayashida, Himeji, Hyogo 679-4298, Japan
**School of Humanities for Environmental Policy and Technology, Himeji Institute of Technology, Shinzaike-Honcho, Himeji, Hyogo 670-0092, Japan
***Faculty of Science, Himeji Institute of Technology, Kamigori, Hyogo 678-1297, Japan

A micellar electrokinetic chromatography (MEKC) method was developed for estimating the angiotensin-I converting enzyme (ACE) inhibitory activity by separating the hippuric acid liberated in the ACE reaction mixture in the presence of an inhibitor, captopril. The hippuric acid was successfully separated and detected by MEKC with a 25 mM sodium dodecyl sulfate solution in a 25 mM phosphate-50 mM borate buffer at pH 7.0; the total analysis took about 5 min. A good linear relationship was observed between the inhibitor and the peak area of hippuric acid release. No significant difference in the ACE inhibitory activity (IC₅₀) of captopril (an antihypertensive medicine) or autolyzed-mushrooms (functional foods) was observed between the conventional method and the MEKC method. The MEKC method was found to be a useful technique for a rapid assay of the ACE inhibitory activity.

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