ABSTRACT
Two main metabolic pathways are available for alcohols: oxidation and direct conjugation. The oxidation of alcohols is carried out by enzymes designated oxidoreductases. In contrast to many oxidative reactions which are catalyzed by NADPH-dependent monooxygenases located in the endoplasmatic reticulum, alcohol oxidation is to a large extent carried out by soluble liver enzymes. The best known of these is liver alcohol dehydrogenase which has been studied mainly in connection with its role in ethanol metabolism, however it is also responsible for the oxidation of many xenobiotic alcohols of various types. The general reaction shown by primary alcohols is:
It is noteworthy that this reaction is reversible, allowing both aldehydes and ketones to be reduced. Since the reaction is pH-dependent, in vitro systems show a shift in the equilibrium to the carbinol form as the pH is lowered to neutrality. However, the formation of the aldehydes is usually favored in vivo because these products can be further oxidized to acids.
