A new colimetric assay for monoamine oxidase in serum and its clinical application.

A new colimetric assay for serum monoamine oxidase and clinical findings based on this method are described. This rapid, precise procedure employs 1-[(4-aminomethylphenyl)azol]-2-naphthol as a substrate. The enzymatically generated 1-[(4-formyl phenyl)azo]-2-naphthol is extracted into cyclohexane to form a colored solution whose absorbance is determined at 500 nm. The method proved to be extremely simple, and the results obtained correlated well with those given by the standard method of McEwen.