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

Yoxall, Victoria; Parker, David; Kentish, Peter; Ioannides, Costas

doi:10.1007/s00204-004-0562-3

Cited by 8 publications

(6 citation statements)

References 33 publications

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“…is believed to be the ultimate carcinogen (Kleman and Ö vervik, 1995). In accordance with the studies of McArdle et al (1999) and Yoxall et al (2004), it has been demonstrated that exposure to doash tea, for either 1 day or 1 month, suppressed the excretion of both direct and indirect acting mutagens in the urine of rats treated with a single dose of IQ; this effect appears to be related to a rise in the expression of CYP1A2 in the liver.…”

Section: Discussionsupporting

confidence: 77%

“…Both heterocyclic amines are oxidized by microsomal cytochrome P450 enzymes to the corresponding hydroxylamine, which is conjugated with acetate or sulfate, to generate the acetoxy or sulphatoxy esters that break down spontaneously to release the nitrenium ion, which is believed to be the ultimate carcinogen (Kleman and Övervik, 1995). In accordance with the studies of McArdle et al (1999) and Yoxall et al (2004), it has been demonstrated that exposure to doash tea, for either 1 day or 1 month, suppressed the excretion of both direct and indirect acting mutagens in the urine of rats treated with a single dose of IQ; this effect appears to be related to a rise in the expression of CYP1A2 in the liver.…”

Section: Methodssupporting

confidence: 77%

“…Embola et al (2001) reported that green tea had a potential effect to detoxify IQ when administered to rats for 6 weeks, so as to favor detoxification pathways, investigating the tea-mediated changes in urinary mutagens. Moreover, it was demonstrated that black tea suppresses the excretion of mutagens in the urine of rats, when administered even for a single day, prior to a single dose of IQ (Yoxall et al, 2004). This effect was linked to enhancement of hepatic CYP1A2 activity, which is responsible for the metabolism of IQ (Turesky, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Impact of aqueous doash extract on urinary mutagenicity in rats exposed to heterocyclic amines

et al. 2011

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Doash (Origanum majorana) is an herbaceous plant found commonly in Saudi Arabia. It is used as a food flavor and a folk remedy to treat a number of diseases. The 2-amino-3-methylimidazo[4,5-f] quinoline (IQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) are the most abundant of the heterocyclic amine carcinogens present in cooked food. In the present study, the potential of doash tea to influence carcinogen metabolism was investigated indirectly using heterocyclic amines as model mutagens, IQ and PhIP. Results obtained showed that doash tea had no influence on body weight in both the studies. Rats were treated with different doses of IQ (1, 3, 5 and 10 mg/kg) or PhIP (1, 5, 10 and 20 mg/kg). The selected dosage was 5 mg/kg for both heterocyclic amines. Results obtained revealed that rats treated with doash tea and given a single dose of the heterocyclic amines, whether for 1 day (short-term) or for 1 month (long term), showed a statistically significant decrease in their excretion of indirect mutagens (IQ or PhIP). Following treatment of the rats with a single oral dose of IQ or PhIP, the highest mutagenic activity determined in the presence of an activation system was excreted in the urine after 24 h, with much lower levels of mutagencity being excreted during subsequent elimination from the body. No mutagenicity was observed in the absence of an activation system that is direct-acting mutagenicity using (IQ and PhIP). Statistical analysis revealed that, in comparison with the control group, the aqueous doash extract significantly reduced the mutagenic response after 24 h. It was concluded that doash extract significantly decreased the excretion of mutagens in comparison with the control group (water only).

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Section: Discussionsupporting

confidence: 77%

Section: Methodssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Impact of aqueous doash extract on urinary mutagenicity in rats exposed to heterocyclic amines

et al. 2011

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“…On the other hand, up-regulation of CYP1a2 may be beneficial by increasing the detoxification and elimination of harmful compounds, as has been shown for black tea which up-regulated hepatic CYP1a2 expression and activity leading to increased urinary excretion of mutagens (Yoxall et al, 2004). Thus the real result of the up-regulation of the Phase I enzyme activities depends on the nature of the substrates and the catalyzing capacity of the Phase II enzymes involved in the subsequent reactions.…”

Section: Discussionmentioning

confidence: 99%

“…The remarkable increases of Phase I enzyme activities induced by BEX and obesity–diabetes may be useful if they correspond to greater detoxification of pro-carcinogens (Stedman et al, 2004; Yoxall et al, 2004), although they may also facilitate transformation of therapeutic drugs and BEX itself, thereby decreasing biological efficacy. Furthermore, increases of UGT and GST activities in the obese–diabetic mice contrast with lowered activity of SULT enzymes.…”

Section: Discussionmentioning

confidence: 99%

The effect of bamboo extract on hepatic biotransforming enzymes – Findings from an obese–diabetic mouse model

Koide

Collier

Berry

et al. 2011

Journal of Ethnopharmacology

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Aim of the study Bamboo leaves are used as a component in traditional Chinese medicine for the anti-inflammatory function. Our previous studies have demonstrated that an ethanol/water extract from Phyllostachys edulis ameliorated obesity-associated chronic systemic inflammation in mice, and therefore relieving the symptoms of type 2 diabetes. The aim of this project was to further investigate the effects of this bamboo extract on hepatic biotransformation enzymes in both lean and obese mice, as an initial step in the toxicological evaluation of using this traditional medicine in obese/diabetic population. Materials and methods Male C57BL/6J mice were randomized to 4 groups and fed standard (10% kcal from fat) diet with or without bamboo extract supplementation at a dose of 10 gram per kilogram diet (n = 10 and n = 9, respectively), or high fat (45% kcal from fat) diet with or without bamboo extract (n = 8 and N = 7, respectively). The dietary treatment lasted for 6 months. Subsequently, the activities and expression of the major Phase I and II hepatic biotransformation enzymes were assessed in subcellular fractions from murine livers. Results Three groups of mice, lean bamboo extract-supplemented, obese/diabetic, and bamboo extract-supplemented obese/diabetic, showed greater activities of cytochromes P450 1a2 and 3a11 compared to control but no changes in the expression level of these proteins. For Phase II enzymes, bamboo extract supplementation in lean mice caused decreased glutathione-S-transferase activity (−12%) and greater uridine diphosphate glucuronosyltransferase activity (+46%), but had no effect on sulfotransferase activity. Conversely, the obese/diabetic condition itself increased glutathione-S-transferase and uridine diphosphate glucuronosyltransferase activities, but decreased total sulfotransferase activity and sulfotransferase 2a1 expression. Conclusions Bamboo extract and obesity/diabetes show significant independent effects on hepatic bio-transformation as well as interaction effects in mice. These changes may alter the clearance of endo-and xenobiotics, including bamboo extract itself, hence this effect should be carefully considered in the medicinal application of bamboo extract as it has potential to alter its own metabolism and that of other medications concurrently administered to obese diabetic patients.

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Inhibitory Effects of Heterocyclic Amine-Induced DNA Adduct Formation in Mouse Liver and Lungs by Beer

Arimoto‐Kobayashi

Takata

Nakandakari

et al. 2004

J. Agric. Food Chem.

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An evaluation of the in vivo antigenotoxic potential of beer components on heterocyclic amines including 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 3-amino-1-methyl-5H-pyrido[4.3-b]indole (Trp-P-2) was determined with particular focus on the target organs of tumorigenesis, and the protective mechanisms involved were investigated. Beer-solution, consisting of a freeze-dried and dissolved sample, given as drinking water, reduced the formation of MeIQx-DNA adducts in mouse liver and lungs. Beer-solution added in the diet as a mimic of food additives also significantly reduced the amount of DNA adducts present in the liver, lung, and kidney DNA of mice fed with MeIQx compared to control mice fed with MeIQx in the absence of beer-solution. The amount of adducts present in the liver of mice with single or continuous administration of Trp-P-2 was significantly reduced when beer-solution was given as part of the diet compared to control mice given Trp-P-2 without beer-solution. Protective effects were observed both with lager- and stout-type samples. In an effort to investigate the mechanisms responsible for the observed protective effects, the effects of beer-solution on metabolizing enzymes for heterocyclic amines were examined. Beer-solutions inhibited the metabolic activation of Trp-P-2 to Trp-P-2(NHOH), as demonstrated by HPLC analysis. Considering the overall suppression of the genotoxicity of MeIQx and Trp-P-2 by beer, we have shown that beer components can inhibit the metabolic activation of heterocyclic amines and subsequently suppress the observed genotoxicity. The results of this study show that beer components are protective against the genotoxic effects of heterocyclic amines on target organs associated with tumorigenesis in vivo.

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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

Cited by 8 publications

References 33 publications

Impact of aqueous doash extract on urinary mutagenicity in rats exposed to heterocyclic amines

Impact of aqueous doash extract on urinary mutagenicity in rats exposed to heterocyclic amines

The effect of bamboo extract on hepatic biotransforming enzymes – Findings from an obese–diabetic mouse model

Inhibitory Effects of Heterocyclic Amine-Induced DNA Adduct Formation in Mouse Liver and Lungs by Beer

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