Amounts Of MeIQx Research Articles

Formation of heterocyclic aromatic amines in grilled pork depending on the pre-thermal treatment method

Electric grilled pork pretreated using four methods was analyzed for heterocyclic aromatic amines: 2-amino-3,8-dimethylimidazo [4,5-f] quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). It was found that pre-thermal treatment of pork led to both a decrease and an increase in the content of heterocyclic aromatic amines in grilled steaks. In contrast to the control sample, the sample pretreated with an oil-based marinade exhibited a 3.2-fold decrease in the amount of MeIQx and 4.82-fold decrease in the amount of PhIP. The sample pretreated with a water-based marinade exhibited a 1.75-fold decrease in the amount of PhIP and a 3.81-fold increase in the amount of MeIQx. The sample pretreated with a dry curing mixture with red hot pepper exhibited a 3.5-fold increase in the amount of MeIQx and a 2.44-fold increase in the amount of PhIP. The sample pretreated with a dry curing mixture with paprika showed a 8.21-fold increase in the amount of MeIQx and a 3.65-fold increase in the amount of PhIP compared to the control sample. The study has shown that pretreatment of meat leads to both an increase and a decrease in the amount of heterocyclic aromatic amines formed during high-temperature thermal treatment depending on the non-meat ingredients used.

Effect of basil use in meatball production on heterocyclic aromatic amine formation.

Herein, the effects of basil usage in meatball production on various quality criteria and heterocyclic aromatic amine (HAA) formation were investigated. The use of basil at every rate caused a significant reduction in TBARS value compared to control group. Cooking caused an increase in pH and TBARS values. IQx, IQ, AαC and MeAαC compounds could not be detected, while various amounts of MeIQx, MeIQ, 7,8-DiMeIQx, 4,8-DiMeIQx and PhIP were determined in the samples. Total HAA contents were determined up to 1.61ngg-1 and increasing of cooking temperature increased total HAA content, except for meatball with 1% basil. The reducing or enhancing effect of the use of basil in meatball production on the formation of HAA varied depending on the usage rate and cooking temperature. It was determined that even if 100g of the meatballs containing 0.5% basil cooked at 250°C whose total amount of HAA content was the highest, is eaten, the intake amount is far below 1μg.

Rapid detection and quantification of dietary mutagens in food using mass spectrometry and ultra performance liquid chromatography

Meat is universally consumed as human diet across the globe. More than 24 different types of food mutagens have been identified till date from cooked meat products. Their study therefore assumes a greater significance from the point of view of the worldwide problem of cancer. Using rapid ultra performance liquid chromatography (UPLC) and MALDI-TOF MS the detection and quantification of two main heterocyclic aromatic amines (HAAs) – MeIQx (2-amino-3,8 dimethylimidazo 4,5-f quinoxaline) and PhIP (2-amino-1-methyl-6 phenylimidazo (4,5-b pyridine) has been achieved in beef, mutton, chicken and fish samples subjected to a range of time duration and temperature. Temperature and duration of heating directly affect the generation and amount of MeIQx and PhIP. MeIQx was generated at 180°C. PhIP was not formed before 240°C except in chicken. MeIQx was found in higher amounts in chicken 128.32±0.452ng/g and in fish 44.06±1.499ng/g while PhIP was found in higher amount in mutton 40.21±0.650ng/g.

An in vitro model system to predict the bioaccessibility of heterocyclic amines from a cooked meat matrix

To understand the impact of variation in digestion parameters on the release of heterocyclic amines naturally formed during cooking, we developed and characterized a model system to assess the effect of amylase, pepsin, and pancreatin on digestion of well-done chicken. The amounts of MeIQx, DiMeIQx, IFP, and PhIP in the liquid portion of the digestate were compared to levels in the undigested meat to determine the percentage released (accessible fraction). Incubating the meat with amylase and pepsin did not change the accessibility of HAs when compared to incubation with water alone. In contrast, increasing amounts of pancreatin increased the accessibility up to 6.4-fold. Comparing the amounts of the HAs in the liquid to the solid fraction showed that there was more MeIQx, DiMeIQx, and IFP in the liquid fraction. In contrast, PhIP was equally divided between the solid and liquid fractions. For all four compounds, increasing the doneness of the meat decreased the amount of the compound accessible from the meat matrix. Our data suggest that bioaccessability of HAs may vary according to the polarity of the individual HAs and also may depend upon the doneness of the meat. These results may have important ramifications for human feeding studies, which assume that the total amount of each HA in the meat matrix is equally bioavailable.

Biomonitoring of heterocyclic aromatic amine metabolites in human urine

Human exposure to heterocyclic aromatic amines such as MeIQx (2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline) may be monitored by measuring the levels of the heterocyclic aromatic amine in urine. In order to investigate the contribution of N-oxidation to the metabolism of MeIQx in vivo, we developed a biomonitoring procedure for the analysis and quantification of the N 2-glucuronide conjugate of 2-hydroxyamino-3,8-dimethylimidazo[4,5- f]quinoxaline in human urine. Subjects ( n=66) in the dietary study ingested a uniform diet of cooked meat containing known amounts of MeIQx, and urine was collected after consumption of the test meal. A method based on solid-phase extraction and immunoaffinity separation was used to isolate N 2-(β-1-glucosiduronyl)-2-hydroxyamino-3,8-dimethylimidazo[4,5- f]quinoxaline and its stable isotope-labeled internal standard from urine. The isolated conjugate was converted to the deaminated product 2-hydroxy-3,8-dimethylimidazo[4,5- f]quinoxaline by treatment with acetic acid under moderate heating. 2-Hydroxy-3,8-dimethylimidazo[4,5- f]quinoxaline and the [ 2H 3]methyl analog were derivatized to form the corresponding 3,5- bis(trifluoromethyl)benzyl ether derivatives and quantified by capillary gas chromatography–negative ion chemical ionization mass spectrometry employing selected ion monitoring procedures. The amounts of N 2-(β-1-glucosiduronyl)-2-hydroxyamino-3,8-dimethylimidazo[4,5- f]quinoxaline recovered in urine collected 0–12 h after the test meal accounted for 2.2–17.1% of the ingested dose, with a median value of 9.5%. The variability in the proportion of the dose excreted among the subjects may be reflective of several factors, including interindividual variation in the enzymic activity of CYP1A2 and/or conjugation reactions of the N-hydroxylamine metabolite with N-glucuronosyltransferase(s).

Incorporation of carbon atoms from glucose into the food mutagens MeIQx and 4,8-DiMeIQx using 14C-labelled glucose in a model system.

Mixtures of creatinine, glucose and threonine with the addition of a small amount, 250 microCi, of [U-14C]glucose, [1-14C]glucose or [6-14C]glucose were heated at 180 degrees C for 30 min in an aqueous model system. The mixtures were purified and analysed using HPLC, scintillation and Ames tests. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were detected as the main radioactive mutagens. The amount of MeIQx and 4,8-DiMeIQx produced from threonine was estimated at 18 and 60 nmol/mmol glucose respectively. Radioactive carbon atoms originating from glucose were also shown to be incorporated into 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx). The specific activity was calculated to be 0.6, 0.3 and 0.1-0.3 mCi/mmol for MeIQx, 4,8-DiMeIQx and IQx respectively for all three labelled forms of glucose. By the incorporation of carbon atoms originating from glucose into the imidazoquinoxaline mutagens it was clearly demonstrated that glucose is a precursor in the formation of these food mutagens.