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Biomedical subjects

J V Crayford

Publications and source records attributed to J V Crayford.

6 recordsLinked to original sources
PubMed1984

The metabolic fate of the herbicide nitralin in the rat.

14C-Nitralin (4-methylsulphonyl-2,6-dinitro-N,N-dipropyl-[14C]aniline) was dosed orally to rats (50 mg/kg). The radioactivity was quantitatively recovered (99.8%) between 0 and 72 h after dosing. Most of this was distributed equally between the urine and the faeces; about 1.5% was found in the carcass, skin and intestines. Structural analysis of the urinary metabolites showed that the metabolism proceeded via a complex multistep series of biotransformations involving nitro-group reduction, side-chain oxidation and removal and the subsequent formation of a variety of heterocyclic ring structures. A major metabolite was 7-amino-2-ethyl-5-methylsulphonyl-1-propylbenzimidazole; however, this accounted for only three-four per cent of the ingested radioactivity and was one of about five metabolites produced in this yield. Seven other metabolites were identified, none of which was derived from single-step biotransformation of nitralin. The latter, simpler, metabolites were detected on the incubation of nitralin with rat-liver enzymes of the type used in microbial mutagenicity testing. Two pathways (nitro-reduction and N-dealkylation) were observed under aerobic conditions but the former greatly predominated under anaerobic conditions.

Aniline Compounds↗
PubMed1980

Xenobiotic triglyceride formation.

1. When 3-phenoxy[14C]benzoic acid was dosed orally (0.76 mg/kg) to rats, 1--3% of the administered radioactivity was found in the skin four days after dosing. Approximately 90% of this residue was unchanged 3-phenoxybenzoate, 10% was a neutral compound. 2. The residue in the skins of rats dosed with 193 mg of 3-phenoxybenzoic acid over 7 days (c. 100 mg/kg per day) contained 40% 3-phenoxybenzoate and 60% neutral metabolites. 3. The components were separated and purified by gel permeation, absorption and t.l.c. and analysed by mass spectrometry. 4. 2- and 3-(3-Phenoxybenzoyl)dipalmitins were major components of the neutral metabolite.

Animals↗
PubMed1980

The metabolism of 3-phenoxybenzoic acid and its glucoside conjugate in rats.

1. 3-Phenoxy[14C]benzoic acid administered orally to rats (0.76 to > 100 mg/kg) is extensively metabolized and rapidly eliminated mostly via the urine. 2. The major metabolic pathway involves 4'-hydroxylation followed by conjugation of the resulting phenol with sulphate. Only minor amounts of amino acid and glucuronic acid conjugation were observed. 3. 3-Phenoxy[14C]benzoyl glucoside, derived from the metabolism of the acid by corn leaves, was also rapidly absorbed by rats and eliminated as a mixture of metabolites very similar to that derived from 3-phenoxybenzoic acid. It was concluded that the glucoside conjugate was rapidly hydrolysed to the free acid in vivo.

Animals↗
PubMed1978

An example of the oxidative de-esterification of an isopropyl ester. Its role in the metabolism of the herbicide flampropisopropyl.

1. Two mammalian metabolites of the herbicidal ester, flamprop-isopropyl (BARNON), have been characterized as products of omega-hydroxylation of the isopropoxycarbonyl grouping (-CO2 CHMe 2). 2. Hydroxylation at the methine group of this moiety, to afford an unstable lactol (-CO2C(OH)Me2) and thence the corresponding carboxylic acid also appears to occur. On the basis of experiments with rat liver microsomes, this pathway to the acid may be as important as the esterase-catalysed route. 3. Biomimetic oxidation studies with peroxytrifluoroacetic acid of a simple model of the herbicide (isopropyl acetate) have provided confirmation of the feasibility of the novel biotransformation.

Anilides↗
PubMed1977

The fate of the herbicide flamprop-isopropyl (barnon) in rats and dogs.

1. [14C]Flamprop-isoppropyl (BARNON) administered orally to rats and dogs is excreted mostly via the faeces (90-5% and 76-3% in male and female rats respectively and 53% in dogs). Elimination was rapid from both species, and greater than 96% of the dose of 14C was excreted by rats 0-48 h after dosing. Distribution of 14C between urine and faeces was different in male and female rats, but the same for dogs of either sex. 2. The predominant metabolic pathway in both species was loss of the isopropyl group; the resulting carboxylic acid was excreted free and as the ester glucuronide. 3. Aromatic hydroxylation occurred at the para- and meta-positions of the N-benzoyl ring; the presence of a 3,4-dihydroxybenzoyl metabolite (but no dihydrodiol) suggests that arene oxide formation is involved. However, direct hydroxylation at position 3 cannot be precluded. Aromatic hydroxylation occurred with the following facility (0-48 h); male rat, 18%; female rat, 13%; dog (either sex), 2%. 4. Hydroxylation occurred readily in the isopropyl side chain yielding mostly a propan-1,2-diol ester in the dog. In the rat, this metabolite was mostly oxidized to yield a 2-lactyl ester.

Administration, Oral↗