Fluorometric Assay of Angiotensin I-converting Enzyme Inhibitory Activity of Vinegars

Abstract

Angiotensin I-converting enzyme (ACE) inhibitory activities of the residues of 24 kinds of vinegars including 6 kinds of unpolished rice vinegars, 4 kinds of polished rice vinegars, 6 kinds of grain vinegars were determined fluorometrically. Among them, rice vinegars, especially unpolished rice vinegars, showed relatively stronger inhibitory activity for the enzyme. Amino acids and some related compounds in unpolished rice vinegars might affect the inhibitory activity, while organic acids were not related. However, the degree of inhibition of unpolished rice vinegar was stronger than that of glycine, which inhibits the ACE activity most strongly among amino acids. The results suggest that the ACE activity is inhibited not only by amino acids but by the other components in vinegars. Comparable study of the determination methods, colorimetry and fluorometry, was also done and showed that the fluorometric method was useful to assay of ACE in turbid sample solutions.