Evidence for p-hydroxylation of N-ethyl-N-methylaniline.

1. N,N-Dialkyl- and N-alkyl-4-aminophenols derived from N-ethyl-N-methylaniline have been isolated from incubation mixtures of rabbit hepatic microsomes fortified with an NADPH-generating system. 2. This is the first report of metabolic ring (4-C) hydroxylation in vitro of an N,N-dialkylaniline. 3. N-Ethyl-N-methyl-4-aminophenol was the major ring-hydroxylation product, whilst N-ethyl-4-aminophenol and N-methyl-4-aminophenol were formed in approx. equal amounts at about 15% of the tertiary compound. 4. An apparent Vmax of 1.8 nmol/mg protein per min and Km of 1.7 x 10(-4)M were determined for N-ethyl-N-methyl-4-aminophenol formation using an optimized incubation time of 10 min.