Metabolism of drugs. LI. The metabolic fate of alkylaryl ethers in rabbits

Effect of omega-trifluorination on the microsomal metabolism of ethyl and pent-1-yl p-nitrophenyl ether

p-Nitrophenyl pent-1-yl ether was metabolized (65-70%) in the presence of liver microsomes from phenobarbital-treated rats to give the 4-(major), 3-(minor), and 2-hydroxypent-1-yl (minor) derivatives which were characterized by g.l.c.-mass spectrometry; O-dealkylation (reflecting 1-hydroxylation) and 5-hydroxylation did not occur to a significant extent. 5,5,5-Trifluorination of the pent-1-yl group markedly reduced the extent of metabolism (to approximately 10%). p-Nitrophenyl 2,2,2-trifluoroethyl ether was virtually completely resistant to microsomal metabolism under conditions where the ethyl analogue was extensively O-dealkylated.

Metabolites of 1,2-epoxy-3-phenoxy- and 1,2-epoxy-3-(p-nitrophenoxy)propane

1. Rabbits and rats dosed with 1,2-epoxy-3-phenoxypropane excrete 2-hydroxy-3-phenoxypropionic acid and N-acetyl-S-(2-hydroxy-3-phenoxypropyl)-L-cysteine. 2. Rabbits and rats dosed with 1,2-epoxy-3-(p-nitrophenoxy)propane excrete 2-hydroxy-3-(p-nitrophenoxy)propionic acid, N-acetyl-S-[2-hydroxy-3-(p-nitrophenoxy/propyl)propyl]-L-cysteine and p-nitrophenol. 3. The administration of either epoxide to the rat produces a marked fall in hepatic GSH level. 4. The biliary excretion of metabolites of 1,2-epoxy-3-(p-nitrophenoxy)-propane is described.

Metabolism of butyl p-nitrophenyl ether in vitro with rabbit liver preparations

1. The metabolism of butyl p-nitrophenyl ether in vitro has been investigated with rabbit liver preparations. 2. Evidence for three metabolic pathways is presented. These involve initial microsomal hydroxylation at alpha, omega--1 or the omega positions of the butyl chain. 3. (omega--1)-Hydroxybutyl p-nitrophenyl ether was oxidized chiefly by the soluble fraction to the corresponding (omega--1)-oxo derivative which spontaneously decomposed to give p-nitrophenol. 4. omega-Hydroxybutyl p-nitrophenyl ether identified as a metabolite was further oxidized by the soluble fraction to p-nitrophenoxybutyric acid.

The metabolism of phenyl o-(2-N-morpholinoethoxy)-phenyl ether hydrochloride in the rabbit and rat

1. Urinary and faecal excretion of radioactivity in 120 h after oral administration of [U-14-C]phenyl o-(2-N-morpholinoethoxy)phenyl ether hydrochloride (200 mg/kg) were 92 and 3% dose in the rabbit, and 60 and 35% in the rat. 2. Urinary metabolites were produced by aromatic hydroxylation and aryl alkyl ether bond cleavage. Some evidence for formation of dioxomorpholino, oxohydroxymorpholino, and ethanolamino derivatives of the drug was obtained. 3. The aromatic hydroxylation product, p-hydroxyphenyl o-(2-N-morpholinoethoxy)phenyl ether hydrochloride had vasopressor activity comparable with the parent compound, but with shorter duration of action.