Metabolism of anethole. I. Pathways of metabolism in the rat and mouse.

The metabolic fate of the naturally occurring food flavouring trans-anethole has been investigated in rats and mice. A single 50-mg/kg dose of trans-[methoxy-14C]anethole was given orally to female Wistar albino rats and by ip injection to male CD-1 mice. The major routes of elimination of 14C were the urine and expired air (as 14CO2). Excretion of 14C in the faeces and as volatile compounds in the expired air was very low (total less than 2% of the dose). Urinary metabolites were separated by solvent extraction, TLC and HPLC and were characterized by MS and GC-MS directly and following methylation or trimethylsilylation, the results being compared where possible with authentic standards. Eleven 14C-containing urinary metabolites were identified in the rat and ten in the mouse. These compounds arose from side-chain oxidation, side-chain cleavage and various conjugations. The major urinary metabolites were two isomers of 1-(4'-methoxyphenyl)propane-1,2-diol, 2-hydroxy-1-methylthio-1-(4'-methoxyphenyl)propane and 4-methoxyhippuric acid, the first three all being excreted as glucuronides. In addition to these 14C-labelled metabolites, 4-hydroxypropenylbenzene, the unlabelled product of oxidative O-demethylation of trans-[14C]anethole, was excreted extensively in urine as the glucuronide.

Metabolism of anethole. II. Influence of dose size on the route of metabolism of trans-anethole in the rat and mouse.

The effect of dose size on the metabolism of trans-anethole was investigated in rodents over the dose range 0.05-1500 mg/kg. trans-[methoxy-14C]Anethole was administered to female Wistar rats by gavage and to male CD-1 mice by ip injection. Urine, faeces and 14CO2 in expired air were collected and their 14C content was measured. Urinary metabolites were separated as described by Sangster et al. (Fd Chem. Toxic. 1984, 22, 695) and quantitated by radioHPLC and TLC. The major route of metabolism of trans-anethole in rodents is via oxidative O-demethylation and the importance of this route was found to decrease with increasing dose from 56 and 72% of the dose at 0.05 mg/kg to 32 and 35% of the dose at 1500 mg/kg in rats and mice, respectively. Over this dose range the elimination of 14C-labelled urinary metabolites increased significantly in both species. There was a species-specific regioselectivity in the side-chain oxidation of anethole. The rat favoured the epoxidation route, resulting in the elimination in the urine of two 1-(4'-methoxyphenyl)propane-1,2-diol isomers, elimination of which together rose from 2 to 15% of the dose over the dose range studied. In contrast the mouse favoured omega-oxidation, yielding cinnamyl compounds and 4-methoxybenzoic and 4-methoxyhippuric acids, the elimination of the latter two rising from 10 to 42% of the dose over the dose range studied. The species differences in metabolism, and the significance of the effect of increasing dose on the metabolic route are discussed with reference to the guidance these results could give in the assessment of the risk to man from dietary exposure to trans-anethole and related compounds.

The metabolism of 4-(4-hydroxyphenyl)butan-2-one (raspberry ketone) in rats, guinea-pigs and rabbits.

1. The metabolism of 4-(4-hydroxyphenyl)butan-2-one(raspberry ketone) was studied in rats, guinea-pigs and rabbits. 2. Following intragastric dosage (1 mmol/kg) urinary metabolite excretion was nearly complete within 24 h, amounting to roughly 90% of the dose in all species. 3. The most prominent urinary metabolites were raspberry ketone and its corresponding carbinol, both largely conjugated with glucuronic acid and/or sulphate. The extent of ketone reduction was greatest in rabbits. 4. Oxidative metabolism included ring hydroxylation and side-chain oxidation. The latter pathway led to 1,2- and 2,3-diol derivatives. It is proposed that the latter undergo cleavage to furnish the C6-C3 and C6-C2 derivatives detected.

Absorption, distribution and metabolism of propyl anthranilate.

Analysis of the gut contents of rats killed at intervals after dosage with propyl anthranilate or anthranilic acid suggested that both acid and ester were absorbed rapidly; the chief site of absorption was the stomach. Not more than a trace of the ester was hydrolysed in the stomach but of the dosed ester detected in the small intestine (less than 7%) a considerable proportion, increasing with time after dosing was present as anthranilic acid. Measurement of the level of radioactivity in the blood after administration of 14C-labelled propan-1-ol, propyl anthranilate or anthranilic acid showed that the alcohol was absorbed more rapidly than either the ester or acid. Unchanged propyl anthranilate was readily detected in the blood of rats dosed with the ester and some unhydrolysed ester was excreted in the urine. The level of radioactivity of the organs of rats 2 h and 4 h after administration of the 14C-labelled compounds was measured. Velocity constants for the excretion of 14CO2 by rats dosed with 14C-labelled propyl anthranilate were significantly lower than those found for rats dosed with [14C]propan-1-ol indicating a limiting step in the metabolism of the propyl moiety of the ester which did not occur in the metabolism of propan-1-ol. The urinary metabolites of anthranilic acid excreted by rabbits and rats dosed with the acid were qualitatively the same as those excreted by these species after dosing with propyl anthanilate; some quantitative differences were however, observed.

Short-term toxicity of allyl alcohol in rats.

Groups of 15 male and 15 female rats were give 0 (control), 50, 100, 200 or 800 ppm allyl alcohol in the drinking water for 15 weeks. There were no effects attributable to allyl alcohol in the results of the haematological examinations or analyses of serum. There was a dose-related reduction in the fluid intake at all treatment levels in both sexes, while growth and food consumption were reduced in both sexes given 800 ppm and in males give 200 ppm. Males given 100 ppm or above and females given 200 or 800 ppm produced less urine than the controls in a period without water or following a water load. The only changes in organ weight that could be attributed to treatment were increased values for the relative weights of liver, spleen and kidney. All 3 organs were affected in both sexes given 800 ppm and the kidneys were also affected in both sexes given 200 ppm and in females given 100 ppm. No effects attributable to allyl alcohol treatment were seen at autopsy or in the histopathological examination. The no-untoward-effect level established in this study was 50 ppm of the drinking water, a level equivalent to an intake in rats of between 4.8 and 6.2 mg allyl alcohol/kg/day.

Determination of some L-3,4-dihydroxyphenylalanine and dopamine metabolites in urine by means of mass fragmentography.

We describe a mass-fragmentographic method for determination in urine of the following metabolites of L-3,4-dihydroxyphenylalanine and dopamine: vanillactic acid, 3,4-dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylethanol, and 3,4-dihydroxyphenylethanol. Deuterated analogs were used as internal standards. The method is fast, reproducible, sensitive, and selective, and does not require the use of time-consuming clean-up procedures. Normal excretion values in terms of creatinine, expressed as a function of age, as well as values obtained for patients with neurogenic tumors, a patient during therapy with L-3,4-dihydroxyphenylalanine, and a patient receiving dopamine are presented and discussed.

Gas chromatographic determination of urinary vanilglycolic acid, vanilglycol, vanilacetic acid and vanillactic acid-chemical parameters for the diagnosis of neurogenic tumours and the evaluation of their treatment.

A gas chromatographic method is described for the determination of urinary vanilglycolic acid, vanilglycol, vanilacetic acid and vanillactic acid as their trimethylsilyl derivatives. These metabolites are chemical parameters for the dignosis of neurogenic tumours. Their determination is especially recommended in order to evaluate the effect of the therapy. Results in normals and controls are given. Data in a number of selected patients with neuroblastoma, ganglioneuroma and phaeochromocytoma are presented and discussed.

The metabolism of vanillin and isovanillin in the rat.

1. The metabolism of vanillin, isovanillin and the corresponding alcohols and acids in rats was investigated using t.l.c., g.l.c. and combined g.l.c.-mass spectrometry. 2. Oral dosage (100 mg/kg) of the aldehyde resulted in urinary excretion of most metabolites within 24 h, mainly as glucuronide and/or sulphate conjugates although the acids formed were also excreted free and as their glycine conjugates. In 48 h 94% of the dose of vanillin was accounted for as follows (%) : vanillin (7), vanillyl alcohol (19), vanillic acid (47), vanilloylglycine (10), catechol (8), 4-methylcatechol (2), guaiacol (0-5) and 4-methylguaiacol (0-6). Similarly, 89% of the dose of isovanillin was accounted for as follows: isovanillin (19), isovanillyl alcohol (10), isovanillic acid (22), vanillic acid (11), isovanilloylglycine (19), catechol(7) and 4-methylcatechol (1). Protocatechuic acid was also formed from both aldehydes. 3. By means of (a) investigation of biliary metabolites, (b) prevention of biliary excretion, (c) suppression of intestinal bacteria with neomycin sulphate and (d) inhibition of intestinal beta-glucuronidase with saccharo-1,4-lactone, it was found that glucuronides of the aldehydes and their respective alcohol and acid derivatives are excreted in the bile and that the conjugates are metabolized by the intestinal bacteria to toluene derivatives and decarboxylated products.