Consumption of tea modulates the urinary excretion of mutagens in rats treated with IQ. Role of caffeine

McArdle, Nicholas J.; Clifford, Michael N.; Ioannides, Costas

doi:10.1016/s1383-5718(99)00047-9

Cited by 26 publications

(11 citation statements)

References 34 publications

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“…We have previously reported that a 4-week treatment with tea, both green and black, suppressed the urinary excretion of direct-and indirect-acting mutagens in rats administered a single oral dose of IQ (McArdle et al 1999). We hypothesised that IQ metabolism was modulated by exposure to tea, and the work of Embola and his colleagues (Embola et al 2001a(Embola et al , 2001b, at least in the case of green tea, showed that following 6 weeks' exposure green tea enhanced the metabolism of IQ through pathways, such as 5-hydroxylation, that generate inactive products.…”

Section: Discussionmentioning

confidence: 98%

“…For the determination of the excretion of indirectacting mutagens, urine was diluted (1:4) with water, and 15 ll aliquots were used in the Ames test. It is relevant to emphasise that in these studies urine was not concentrated; at the levels used in the Ames test, it has been established that rat urine influences neither the spontaneous reversion rate nor the mutagenic activity induced by chemicals (McArdle et al 1999). Urine samples were not treated with deconjugating enzymes since, in our previous studies (McArdle et al 1999), such treatment did not impact on the mutagenic response.…”

Section: Methodsmentioning

confidence: 99%

“…The principal objective of the present study was to extend our previous studies (McArdle et al 1999) and evaluate whether even short-term intake of black tea can modulate urinary excretion of mutagens after IQ administration and to establish whether such an effect is related to changes in the hepatic xenobiotic-metabolising enzyme systems active in the metabolism of this carcinogenic heterocyclic amine.…”

Section: Introductionmentioning

confidence: 91%

“…We have previously demonstrated that when rats were provided with either green or black tea as their sole drinking fluid for 4 weeks and then were exposed to a single oral dose of IQ (2-amino-3-methylimidazo-[4,5-f]quinoline), urinary excretion of mutagens, monitored using the Ames test in the presence and absence of an activation system, decreased (McArdle et al 1999). No such effect was observed when decaffeinated tea was employed, but was restored when decaffeinated tea was supplemented with the normal amount of caffeine, indicating that the xanthine is largely responsible for this effect, and may be associated with the documented upregulation of the cytochrome P450 enzyme CYP1A2 by caffeine, so modulating the metabolic pathways of the carcinogen (Ayalogu et al 1995;Bu-Abbas et al 1999a;Chen et al 1996).…”

Section: Introductionmentioning

confidence: 99%

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Short-term black tea intake modulates the excretion of urinary mutagens in rats treated with 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ): role of CYP1A2 upregulation

et al. 2004

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Rats were exposed to black tea (2.5% w/v) as their sole drinking liquid for either 1 day or 1 month, while controls were maintained on water. After this treatment period, all animals received a single oral dose IQ (2-amino-3-methylimidazo-[4,5-f]quinoline), and urine was collected for 48 h. Mutagenic activity of the urine was determined in the Ames test in the presence and absence of an activation system. The excretion of direct-acting mutagens was markedly reduced following tea intake, and was more pronounced after the 1-day treatment. Similarly, both tea treatments suppressed the excretion of indirect-acting mutagens. Furthermore, both tea treatments induced hepatic CYP1A2 activity and expression, but cytosolic glutathione S-transferase activity was only modestly induced in the group of animals receiving tea for 1 day, and only when DCNB (1,2-dichloro-4-nitrobenzene) was used as substrate; glucuronosyl activity was elevated modestly only in the animals receiving the tea for a month. It is concluded that even short-term exposure to black tea is capable of influencing the metabolic fate of IQ, and this is most likely related to the upregulation of CYP1A2.

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Section: Discussionmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Short-term black tea intake modulates the excretion of urinary mutagens in rats treated with 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ): role of CYP1A2 upregulation

et al. 2004

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“…Through these various mechanisms, tea has demonstrated excellent chemoprotective properties in animal models of skin, lung, esophageal, and gastrointestinal cancers (6)(7)(8)(9). Included among these investigations of the inhibitory properties of tea are several reports that focused on protection against the mutagenic and carcinogenic effects of heterocyclic amines (9)(10)(11)(12).…”

Section: Introductionmentioning

confidence: 99%

Inhibition by White Tea of 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]Pyridine-Induced Colonic Aberrant Crypts in the F344 Rat

Santana-Rios¹,

Orner²,

Xu³

et al. 2001

Nutrition and Cancer

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There is growing interest in the potential health benefits of tea, including the anticarcinogenic properties. We report here that white tea, the least processed form of tea, is a potent inhibitor of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP)-induced colonic aberrant crypts in the rat. Male Fischer 344 rats were treated for 8 wk with white tea (2% wt/vol) or drinking water alone, and on alternating days in experimental Weeks 3 and 4 the animals were given PhIP (150 mg/kg body wt po) or vehicle alone. At the end of the study there were 5.65 ± 0.81 and 1.31 ± 0.27 (SD) aberrant crypt foci per colon in groups given PhIP and PhIP + white tea, respectively (n = 12, P < 0.05). No changes were detected in N-acetyltransferase or arylsulfotransferase activities compared with controls, but there was marked induction of ethoxyresorufin O-deethylase, methoxyresorufin Odemethylase, and UDP-glucuronosyltransferase after treatment with white tea. Western blot revealed corresponding increases in cytochrome P-450 1A1 and 1A2 proteins. Enzyme assays and Western blot also revealed induction of glutathione S-transferase by white tea. There was less parent compound and 4′-hydroxy-PhIP but more PhIP-4′-O-glucuronide and PhIP-4′-O-sulfate in the urine from rats given PhIP + white tea than in urine from animals given carcinogen + drinking water. The results indicate that white tea inhibits PhIP-induced aberrant crypt foci by altering the expression of carcinogen-metabolizing enzymes, such that there is increased ring hydroxylation at the 4′ position coupled with enhanced phase 2 conjugation.

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Tea and Its Constituents

Lambert

Yang

Gelderblom

et al. 2009

Chemoprevention of Cancer and DNA Damage by Dietary Factors

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Consumption of tea modulates the urinary excretion of mutagens in rats treated with IQ. Role of caffeine

Cited by 26 publications

References 34 publications

Short-term black tea intake modulates the excretion of urinary mutagens in rats treated with 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ): role of CYP1A2 upregulation

Short-term black tea intake modulates the excretion of urinary mutagens in rats treated with 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ): role of CYP1A2 upregulation

Inhibition by White Tea of 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]Pyridine-Induced Colonic Aberrant Crypts in the F344 Rat

Tea and Its Constituents

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