Pharmacokinetics, tissue distribution and excretion study of dictamnine, a major bioactive component from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae).

Dictamnine is an herbal ingredient isolated from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae). The present study was aimed at the development of an ultra-high performance liquid chromatography-tandem mass spectrometry method to quantify the concentration of dictamnine in rat plasma and tissues for the in vivo pharmacokinetics, tissue distribution and excretion study. Biological samples were processed with protein precipitation. Skimmianine was chosen as internal standard. The chromatographic separation was carried out on a Thermo Syncronis C18 column (2.1mm×50mm, 1.7µm) with an isocratic mobile phase consisting of methanol and 0.1% formic acid water (75:25, v/v). The detection was accomplished by using positive ion electrospray ionization in multiple reaction monitoring (MRM) mode. The MS/MS ion transitions were monitored at m/z 200.0→129.0 for dictamnine and 260.3→227.1 for IS, respectively. An excellent linearity was observed over the concentration range from 0.5 to 250ng/mL. The lower limit of quantification (LLOQ) was 0.5ng/mL for dictamnine. The developed method was rapid, accurate, and highly sensitive and selective. It was successfully applied to the in vivo pharmacokinetics, tissue distribution and excretion study of dictamnine in rats after oral or intravenous administration of dictamnine.

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

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).

A liquid chromatography-quadrupole time-of-flight (LC-QTOF)-based metabolomic approach reveals new metabolic effects of catechin in rats fed high-fat diets.

Unbalanced diets generate oxidative stress commonly associated with the development of diabetes, atherosclerosis, obesity and cancer. Dietary flavonoids have antioxidant properties and may limit this stress and reduce the risk of these diseases. We used a metabolomic approach to study the influence of catechin, a common flavonoid naturally occurring in various fruits, wine or chocolate, on the metabolic changes induced by hyperlipidemic diets. Male Wistar rats ( n = 8/group) were fed during 6 weeks normolipidemic (5% w/w) or hyperlipidemic (15 and 25%) diets with or without catechin supplementation (0.2% w/w). Urines were collected at days 17 and 38 and analyzed by reverse-phase liquid chromatography-mass spectrometry (LC-QTOF). Hyperlipidic diets led to a significant increase of oxidative stress in liver and aorta, upon which catechin had no effect. Multivariate analyses (PCA and PLS-DA) of the urine fingerprints allowed discrimination of the different diets. Variables were then classified according to their dependence on lipid and catechin intake (ANOVA). Nine variables were identified as catechin metabolites of tissular or microbial origin. Around 1000 variables were significantly affected by the lipid content of the diet, and 76 were fully reversed by catechin supplementation. Four variables showing an increase in urinary excretion in rats fed the high-fat diets were identified as deoxycytidine, nicotinic acid, dihydroxyquinoline and pipecolinic acid. After catechin supplementation, the excretion of nicotinic acid was fully restored to the level found in the rats fed the low-fat diet. The physiological significance of these metabolic changes is discussed.

Urinary excretion of N-OH-2-amino-3-methylimidazo[4,5-f]quinoline-N-glucuronide in F344 rats is enhanced by green tea.

The effects of green tea on the metabolism of the food carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) with emphasis on the formation of the detoxified glucuronides was studied. Two groups of 20 adult male and female Fischer 344 rats consumed 2% green tea or water for 6 weeks before being administered a single dose of 40 mg/kg body weight of [2-14C]IQ by oral gavage. Major metabolites in 24 h urine samples were separated by high-performance liquid chromatography (HPLC), including N-OH-IQ-N-glucuronide, 5-OH-IQ glucuronide and sulfate, IQ sulfamate and IQ itself. The structures of the main metabolites were established by mobility on the HPLC and by mass spectrometry. Sulfate esters and sulfamate were hydrolyzed by 0.1 N HCl for 15 min at 100 degrees C, yielding 5-OH-IQ and high levels of IQ. HPLC of the resulting product showed the N-OH-IQ-N-glucuronide and the 5-OH-IQ glucuronide, as well as IQ. The male and female rats drinking tea displayed a significantly higher (P < 0.05) excretion of the two major glucuronides. We conclude that intake of green tea increases the excretion of N-OH-IQ-N-glucuronide, a detoxified metabolite of the proximate carcinogen N-OH-IQ.

Green tea and the metabolism of 2-amino-3-methylimidazo.

The effects of green tea intake on the metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in the rat was studied. IQ belongs to a new class of mutagens and carcinogens, heterocyclic arylamines, formed during cooking through browning meats and fish, thus, in the food chain of most non-vegetarians. Ten adult male and female Fischer 344 rats were placed on a 2% solution of green tea and 10 control rats were on water for 6 weeks. Then, animals were administered a single dose of 40 mg/kg body weight of [2-14C]IQ by oral gavage. Twenty-four hour urine samples were collected and metabolites were separated by HPLC and quantitated by scintillation counting. Two minor and three major metabolites were isolated, including, small quantities of IQ itself. The rats on tea showed significant differences (P < 0.05) in the recovery of the three major metabolites, namely, IQ-sulfamate, IQ-5-O-sulfate, and IQ-5-O-glucuronide, respectively. Green tea, therefore, influences the manner in which the food carcinogen IQ is metabolized and excreted in urine. Formation of glucuronides, increased by green tea, represent a key means of detoxification of the heterocyclic amine, IQ.

Studies on the mechanism of cancer protection by wheat bran: effects on the absorption, metabolism and excretion of the food carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ).

We examined ways in which dietary supplements of wheat bran may protect against colon cancer. The effects of supplementing the diet of female Wistar rats with 10% wheat bran on the disposition and metabolism of the dietary carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) labelled with (14)C was determined. Our data show that the wheat bran had a major effect on both the distribution and metabolism of IQ. At a low dose of IQ (1 mg/kg), we unexpectedly found that up to 2 h after gavage there were higher concentrations of radioactivity in the plasma of rats fed wheat bran compared with the controls, but there were lower concentrations of radioactivity after 2 h. At a high dose of IQ (50 mg/kg), there were always lower concentrations of radioactivity in the plasma of rats fed wheat bran compared with the control rats. One of the most marked effects of wheat bran was apparently to significantly retard the metabolism of IQ in the plasma when this was fed at either dose. There were also differences between the rats fed wheat bran and the control in the concentrations and types of IQ metabolites in the urine.