APPLICATION OF LIQUID CHROMATOGRAPHY AND ELECTROCHEMISTRY TO THE STUDY OF THE METABOLISM AND KINETICS OF THE HYDROXYACETANILIDES

ANTHONY EUGENE ROTTERO, Purdue University

Abstract

The common analgesic, acetaminophen, has been extensively studied for many years. Acetaminophen has the chemical name $4\sp\prime$-Hydroxyacetanilide. Very little research has been done concerning the biological fate and activity of the two structural isomers of acetaminophen, namely, $2\sp\prime$-hydroxyacetanilide and $3\sp\prime$-hydroxyacetanilide. The oxidation of acetaminophen by cytochrome P-450 to a reactive intermediate has been well studied by this laboratory. The fate of the isomers was largely unknown. Liquid chromatography and electrochemistry provided a sensitive analytical means of determining the type of products formed in biological systems with measurements in the picomole range. The formation of thioether conjugates from the oxidized form of $2\sp\prime$-hydroxyacetanilide showed a close similarity to acetaminophen itself. Three such thioether conjugates were detected in microsomal incubations of the $2\sp\prime$-hydroxyacetanilide with mercaptoethanol. Identification of the three products was accomplished via differences in their electrochemical behavior. The hydroxylation of these isomers to the dihydroxy species was investigated using microsomal incubations and an iron-EDTA complex which mimicked the enzyme. The kinetic rate of production of the dihydroxy species from both $2\sp\prime$- and $3\sp\prime$-hydroxyacetanilide showed considerable differences in the rate of their metabolic transformations. The reaction between benzoquinone and the therapeutic drug, WR-1065, was also investigated to evaluate its reactivity as a free sulfhydryl in addition reactions.

Degree

Ph.D.

Subject Area

Analytical chemistry

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