Metabolism of drugs. LVII. Isolation, characterization and identification of p-nitrophenoxy acetic acid, a metabolite of butyl p-nitrophenyl ether in rats, mice and guinea pigs

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.

Some metabolites of 1-bromobutane in the rabbit and the rat

1. Rabbits and rats dosed with 1-bromobutane excrete in urine, in addition to butylmercapturic acid, (2-hydroxybutyl)mercapturic acid, (3-hydroxybutyl)mercapturic acid and 3-(butylthio)lactic acid. 2. Although both species excrete both the hydroxybutylmercapturic acids, only traces of the 2-isomer are excreted by the rabbit. The 3-isomer has been isolated from rabbit urine as the dicyclohexylammonium salt. 3. 3-(Butylthio)lactic acid is formed more readily in the rabbit; only traces are excreted by the rat. 4. Traces of the sulphoxide of butylmercapturic acid have been found in rat urine but not in rabbit urine. 5. In the rabbit about 14% and in the rat about 22% of the dose of 1-bromobutane is excreted in the form of the hydroxymercapturic acids. 6. Slices of rat liver incubated with S-butylcysteine or butylmercapturic acid form both (2-hydroxybutyl)mercapturic acid and (3-hydroxybutyl)mercapturic acid, but only the 3-hydroxy acid is formed by slices of rabbit liver. 7. S-Butylglutathione, S-butylcysteinylglycine and S-butylcysteine are excreted in bile by rats dosed with 1-bromobutane. 8. Rabbits and rats dosed with 1,2-epoxybutane excrete (2-hydroxybutyl)mercapturic acid to the extent of about 4% and 11% of the dose respectively. 9. The following have been synthesized: N-acetyl-S-(2-hydroxybutyl)-l-cysteine [(2-hydroxybutyl)mercapturic acid] and N-acetyl-S-(3-hydroxybutyl)-l-cysteine [(3-hydroxybutyl)mercapturic acid] isolated as dicyclohexylammonium salts, N-toluene-p-sulphonyl-S-(2-hydroxybutyl)-l-cysteine, S-butylglutathione and N-acetyl-S-butylcysteinyl-glycine ethyl ester.