Molecularly Imprinted Polymer Nanospheres with Hydrophilic Shells for Efficient Molecular Recognition of Heterocyclic Aromatic Amines in Aqueous Solution.

Heterocyclic aromatic amine molecularly imprinted polymer nanospheres with surface-bound dithioester groups (haa-MIP) were firstly synthesized via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization. Then, a series of core-shell structural heterocyclic aromatic amine molecularly imprinted polymer nanospheres with hydrophilic shells (MIP-HSs) were subsequently prepared by grafting the hydrophilic shells on the surface of haa-MIP via on-particle RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA), and diethylaminoethyl methacrylate (DEAEMA). The haa-MIP nanospheres showed high affinity and specific recognition toward harmine and its structural analogs in organic solution of acetonitrile, but lost the specific binding ability in aqueous solution. However, after the grafting of the hydrophilic shells on the haa-MIP particles, the surface hydrophilicity and water dispersion stability of the polymer particles of MIP-HSs greatly improved. The binding of harmine by MIP-HSs with hydrophilic shells in aqueous solutions is about two times higher than that of NIP-HSs, showing an efficient molecular recognition of heterocyclic aromatic amines in aqueous solution. The effect of hydrophilic shell structure on the molecular recognition property of MIP-HSs was further compared. MIP-PIA with carboxyl groups containing hydrophilic shells showed the highest selective molecular recognition ability to heterocyclic aromatic amines in aqueous solution.

Propolis extract reduces heterocyclic aromatic amine formation in chicken thigh meat.

1. The objective of the present study was to examine the effect of propolis extract on reducing the formation of carcinogenic/mutagenic heterocyclic aromatic amines (HAAs), thereby minimising dietary exposure in human consumers.2. Chicken thigh meat samples were marinated with various concentrations (0%, 0.25%, 0.5% and 1%) of propolis extract, and cooked in a pan at 150°C or 200°C. Proximate composition, pH, lipid oxidation, creatine, creatinine content and twelve HAA levels of samples were analysed.3. Varying levels of IQx (≤35.44 ng/g), MeIQx (≤0.58 ng/g), MeIQ (≤1.60 ng/g), 7,8-DiMeIQx (≤0.83 ng/g), 4,8-DiMeIQx (≤0.75 ng/g), Harman (≤5.54 ng/g), Trp-P-2 (≤1.77 ng/g), PhIP (≤1.61 ng/g) and AαC (≤0.93 ng/g) were quantified in control samples. Total HAA levels ranged between 2.83 and 47.26 ng/g across all samples. Propolis extract decreased the levels of total HAAs by 41.2-89.4% and 49.4-91.4% at 150°C and 200°C, respectively.4. The results demonstrated that propolis extract marination might be an effective strategy to reduce the dietary exposure of HAAs via mitigating their formation in chicken thigh meat.

Formation of Carcinogens in Processed Meat and Its Measurement with the Usage of Artificial Digestion-A Review.

Meat is a rich source of various nutrients. However, it needs processing before consumption, what in turn generates formation of carcinogenic compounds, i.a., polycyclic aromatic hydrocarbons (PAH), nitrosamines (NOCs), and the most mutagenic heterocyclic aromatic amines (HAAs). It was widely found that many factors affect the content of carcinogens in processed meat. However, it has recently been discovered that after digestion free HAAs are released, which are not detectable before enzymatic treatment. It was established that the highest percentage of carcinogens is released in the small intestine and that its amount can be increased up to 6.6-fold. The change in free HAAs content in analyzed samples was dependent on many factors such as meat type, doneness, particle size of meat, and the enzyme concentration used for digestion. In turn, introduction of bacteria naturally occurring in the human digestive tract into the model significantly decreases total amount of HAAs. Contrary, the addition of food ingredients rich in polyphenols, fiber, and water (pepper powder, onions, apples) increases free HAAs' release up to 56.06%. Results suggests that in vitro digestion should be an integral step of sample preparation. Artificial digestion introduced before chromatographic analysis will allow to estimate accurately the content of carcinogens in processed meat.

Constructing xenobiotic maps of metabolism to predict enzymes catalyzing metabolites capable of binding to DNA.

BACKGROUND: The liver plays a major role in the metabolic activation of xenobiotics (drugs, chemicals such as pollutants, pesticides, food additives...). Among environmental contaminants of concern, heterocyclic aromatic amines (HAA) are xenobiotics classified by IARC as possible or probable carcinogens (2A or 2B). There exist little information about the effect of these HAA in humans. While HAA is a family of more than thirty identified chemicals, the metabolic activation and possible DNA adduct formation have been fully characterized in human liver for only a few of them (MeIQx, PhIP, A[Formula: see text]C). RESULTS: We have developed a modeling approach in order to predict all the possible metabolites of a xenobiotic and enzymatic profiles that are linked to the production of metabolites able to bind DNA. Our prediction of metabolites approach relies on the construction of an enriched and annotated map of metabolites from an input metabolite.The pipeline assembles reaction prediction tools (SyGMa), sites of metabolism prediction tools (Way2Drug, SOMP and Fame 3), a tool to estimate the ability of a xenobotics to form DNA adducts (XenoSite Reactivity V1), and a filtering procedure based on Bayesian framework. This prediction pipeline was evaluated using caffeine and then applied to HAA. The method was applied to determine enzymes profiles associated with the maximization of metabolites derived from each HAA which are able to bind to DNA. The classification of HAA according to enzymatic profiles was consistent with their chemical structures. CONCLUSIONS: Overall, a predictive toxicological model based on an in silico systems biology approach opens perspectives to estimate the genotoxicity of various chemical classes of environmental contaminants. Moreover, our approach based on enzymes profile determination opens the possibility of predicting various xenobiotics metabolites susceptible to bind to DNA in both normal and physiopathological situations.

An accurate, rapid, and sensitive method for simultaneous determination of four typical heterocyclic amines in roasted pork patties: Application in the study of inhibitory effects of astaxanthin.

Heterocyclic aromatic amines, as a group of mutagenic and carcinogenic compounds, have gained worldwide concern. In this study, an accurate, rapid, and sensitive confirmation and quantification method of four major heterocyclic aromatic amines in roasted pork was developed based on Q-Orbitrap along with Quick, Easy, Cheap, Effective, Rugged, and Safe extraction. The limit of detections and limit of quantitations were found to be 0.2-1.2 µg/kg and 0.6-3.5 µg/kg, respectively, revealing the high sensitivity of this method. Obtained results showed recoveries ranging from 78.1 to 97.4%, depending on the different heterocyclic aromatic amines and spiked levels. Precision was in the range of 2.6-4.5% for four heterocyclic aromatic amines at different levels. In addition, the developed method had been applied to investigate the inhibitory effects of astaxanthin on the above-mentioned heterocyclic aromatic amines in roasted pork. The amount of astaxanthin with the best inhibitory effects was 7.5 mg (0.0375%), which led to significant reduction in heterocyclic aromatic amines levels over 50%.

Effect of Freeze-Thaw Cycles on the Oxidation of Protein and Fat and Its Relationship with the Formation of Heterocyclic Aromatic Amines and Advanced Glycation End Products in Raw Meat.

The aim of this research was to investigate the effect of the number of freeze-thaw cycles (0, 1, 3, 5, and 7) on porcine longissimus protein and lipid oxidation, as well as changes in heterocyclic aromatic amines (HAAs) and advanced glycation end products (AGEs) and their precursors. We analyzed the relationship among HAAs, AGEs, oxidation, and precursors and found the following results after seven freeze-thaw cycles. The HAAs, Norharman and Harman, were 20.33% and 16.67% higher, respectively. The AGEs, Nε-carboxyethyllysine (CEL) and Nε-carboxymethyllysine (CML), were 11.81% and 14.02% higher, respectively. Glucose, creatine, and creatinine were reduced by 33.92%, 5.93%, and 1.12%, respectively after seven freeze-thaw cycles. Norharman was significantly correlated with thiobarbituric acid reactive substances (TBARS; r2 = 0.910) and glucose (r2 = -0.914). Harman was significantly correlated to TBARS (r2 = 0.951), carbonyl (r2 = 0.990), and glucose (r2 = -0.920). CEL was correlated to TBARS (r2 = 0.992) and carbonyl (r2 = 0.933). These changes suggest that oxidation and the Maillard reaction during freeze-thaw cycles promote HAA and AGE production in raw pork.

Determination of 14 heterocyclic aromatic amines in meat products using solid-phase extraction and supercritical fluid chromatography coupled to triple quadrupole mass spectrometry.

A novel, simple, and sensitive method has been developed for simultaneous determination of 14 heterocyclic aromatic amines in meat product using solid-phase extraction combined with ultrahigh-performance supercritical fluid chromatography coupled to tandem quadrupole mass spectrometry. The analytes could be separated within 7 min and identified using their retention times and mass. The developed method was validated based on the linearity, limits of quantification, precision, and accuracy. The recovery ranged from 52.3 to 97.5% with an acceptable standard deviation, which is not higher than 6%. The limits of quantitation ranged from 0.03 to 0.17 µg/kg. The selectivity and sensitivity were satisfactory in multiple reaction monitoring mode. The method was applied to commercial meat products, and the results demonstrated that the novel method has potential for the analysis of the targets in food matrices. This is the first work reporting the simultaneous quantification of 14 heterocyclic aromatic amines by means of ultrahigh-performance supercritical fluid chromatography coupled to tandem quadrupole mass spectrometry.

A screen-printed electrode modified with silver nanoparticles and carbon nanofibers in a nafion matrix for ionic liquid-based dispersive liquid-liquid microextraction and voltammetric assay of heterocyclic amine 8-MeIQx in food.

An electrochemical method is described for the determination of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx) which is a heterocyclic aromatic amine formed in cooked food samples. The method uses a screen-printed carbon nanofiber electrode that is modified with silver nanoparticles (AgNPs) in a Nafion matrix. The surface of the modified electrode was characterized by UV-vis spectrometry, dynamic light scattering, scanning electron microscopy and Raman spectroscopy. The average size of the AgNPs is 14 nm. The modified electrode exhibits good properties in terms of reversibility, fast kinetics of electron transfer, and large electroactive area toward the reduction of 8-MeIQx. Differential pulse voltammetry is the most suitable electrochemical technique for quantification of 8-MeIQx, best at a voltage of -0.21 V (versus Ag reference electrode). The first derivative serves as the analytical signal that increases linearly in the 0.015-40 mg L-1 8-MeIQx concentration range, with a 5 µg L-1 detection limit. A dispersive liquid-liquid microextraction procedure assisted via ionic liquid was developed to isolate the analyte from real samples. The whole extraction-preconcentration and voltammetric method allows to determine 30 and 70 µg L-1 in (spiked) bouillon cube, meat broth, beer and wine, with recoveries in the 93.6-110.4% range. Graphical abstractSchematic presentation for the analysis of aromatic amine 8-MeIQx, resultant compound from cooking meat. Extracted sample solution was placed onto modified electrode surface thus obtaining voltammetric analytical signal. So, quantification atrelevant levels can be performed.

Recent advances in heterocyclic aromatic amines: An update on food safety and hazardous control from food processing to dietary intake.

Heterocyclic aromatic amines (HAAs) as probable carcinogenic substances are mainly generated in meat products during thermal processing. Numerous studies have contributed to the analysis, formation, and mitigation of HAAs during food processing. However, few articles have comprehensively reviewed food safety aspects from both food processing and dietary intake regarding the formation, mitigation, metabolism, biomarkers for exposure, hazard control, and risk assessment of HAAs, and related food safety researches. Several factors may influence the generation of HAAs, including processing temperature, processing time, and chemical composition of the meat. Nonetheless, these mutagenic compounds are attenuated to different levels by the addition of natural or synthetic flavorings and antioxidant-rich marinades, as well as pretreatments using technique such as microwave heating. After dietary intake, different types of HAAs are metabolized in humans by several enzymes, including cytochrome P450s, peroxidases, N-acetyltransferases, sulfotransferases, uridine diphosphate-glucuronosyltransferases, and glutathione S-transferases. Their primary metabolites are further conjugated with DNA or ultimately excreted in urine and feces. The 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in hair as well as DNA, hemoglobin, and serum albumin adducts has been considered as biomarkers for exposure assessment. Dietary intake information obtained from questionnaires and the results of epidemiological investigations have shown a positive relationship between the intakes of red meat and processed meat and high risk of cancer incidence. As several cancers have been reported to be associated with HAAs, HAAs should be both effectively reduced during food processing and controlled from dietary intake to facilitate human health.

Bioactivation of the tobacco carcinogens 4-aminobiphenyl (4-ABP) and 2-amino-9H-pyrido[2,3-b]indole (AαC) in human bladder RT4 cells.

Occupational and tobacco exposure to aromatic amines (AAs) including 4-aminobiphenyl (4-ABP) and 2-naphthylamine (2-NA) are associated with bladder cancer (BC) risk. Several epidemiological studies have also reported a possible role for structurally related heterocyclic aromatic amines (HAAs) formed in tobacco smoke or cooked meats with BC risk. We had screened for DNA adducts of 4-ABP, 2-NA, and several prominent HAAs formed in tobacco smoke or grilled meats including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-9H-pyrido[2,3-b]indole (AαC) in the bladder DNA of BC patients, using liquid chromatography/mass spectrometry. We detected DNA adducts of 4-ABP, but not adducts of the other carcinogens. In this study, we have examined the capacity of RT4 cells, an epithelial human bladder cell line, to bioactivate AAs and HAAs to DNA damaging agents, which may contribute to BC. 4-ABP and AαC formed DNA adducts, but DNA adducts of 2-NA, PhIP, and MeIQx were not detected. 4-ABP DNA adducts were formed at tenfold higher levels than AαC adducts. Pretreatment of RT4 cells with α-naphthoflavone (1-10 µM), a specific cytochrome P450 1 (CYP1) inhibitor, decreased AαC adduct formation by 50% but did not affect the level of 4-ABP adducts. However, cell pretreatment with 8-methoxypsoralen (0.1-1 µM), a potent inhibitor of CYP2A, resulted in a 90% decrease of 4-ABP DNA adducts levels. These data signify that CYP2A and CYP1A isoforms expressed in the target urothelium bioactivate 4-ABP and AαC, respectively, and may be a critical feature of aromatic amine-induced urinary bladder carcinogenesis. The bioactivation of other tobacco and environmental AAs by bladder CYPs and their ensuing bladder DNA damage warrants further study.

Human exposure to biologically active heterocyclic aromatic amines arising from thermal processing of protein rich food

Frequent consumption of thermally processed meat was classified by the International Agency for Research on Cancer to directly carcinogenic agents for humans. During the heat treatment of high protein food, mutagenic and carcinogenic, as well as neurotoxic heterocyclic aromatic amines are formed. Epidemiological studies confirm that exposure to some of these compounds may increase the risk of cancer in humans, especially the colon cancer. Most heterocyclic amines contain fried and grilled meat products, and the lowest content of these compounds can be found in boiled and slightly baked dishes. The use of spices and vegetable additives with antioxidant properties allows to obtain dishes with reduced content of these xenobiotics. An effective way to reduce human exposure to cancerogenic amines may be simultaneous consumption, together with meat dishes, products containing fiber which can adsorb molecules of heterocyclic amines in the gastrointestinal tract, as well as enrichment of the diet in the crucifers plants, as isothiocyanates released from them can inhibit the metabolic activation processes of heterocyclic amines. Raising the public awareness of the formation of mutagenic and carcinogenic compounds, including heterocyclic aromatic amines, during the intensive heat treatment of high protein food, as well as the dissemination of knowledge on the conditions regarding the preparation of dishes with reduced content of such compounds could become one of the components of cancer prevention programs in Poland.

Application of micro-solid-phase extraction for the on-site extraction of heterocyclic aromatic amines in seawater.

An efficient on-site extraction technique to determine carcinogenic heterocyclic aromatic amines in seawater has been reported. A micro-solid-phase extraction device placed inside a portable battery-operated pump was used for the on-site extraction of seawater samples. Before on-site applications, parameters that influence the extraction efficiency (extraction time, type of sorbent materials, suitable desorption solvent, desorption time, and sample volume) were investigated and optimized in the laboratory. The developed method was then used for the on-site sampling of heterocyclic aromatic amines determination in seawater samples close to distillation plant. Once the on-site extraction completed, the small extraction device with the analytes was brought back to the laboratory for analysis using high-performance liquid chromatography with fluorescence detection. Based on the optimized conditions, the calibration curves were linear over the concentration range of 0.05-20 µg/L with correlation coefficients up to 0.996. The limits of detection were 0.004-0.026 µg/L, and the reproducibility values were between 1.3 and 7.5%. To evaluate the extraction efficiency, a comparison was made with conventional solid-phase extraction and it was applied to various fortified real seawater samples. The average relative recoveries obtained from the spiked seawater samples varied in the range 79.9-95.2%.

Unraveling the inhibitory effect of dihydromyricetin on heterocyclic aromatic amines formation.

BACKGROUND: Heterocyclic aromatic amines (HAAs) are mutagens and rodent carcinogens. Flavonoids have attracted considerable attention for development into effective inhibitors against the formation of genotoxic HAAs in thermally processed foods. RESULTS: The inhibitory effect of dihydromyricetin (DMY) on the formation of key HAAs, including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx), and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), was significant. In chemical models, DMY (0.05 mmol, 0.1 mmol, and 0.2 mmol) significantly decreased the amount of PhIP formed (43.0%, 54.7%, and 75.7% respectively). A significant inhibitory effect on the formation of MeIQx and 4,8-DiMeIQx was also observed. Moreover, DMY (0.05%, 0.1%, and 0.2%) reduced the generation of PhIP (by 48.0%, 59.0%, and 80.1% respectively) and that of MeIQx (by 45.8%, 62.0%, and 76.7% respectively) in fried beef patties. CONCLUSION: The results indicate that DMY could be converted into myricetin during thermal processing, and both DMY and myricetin could trap phenylacetaldehyde, a major Strecker aldehyde of phenylalanine, in a similar manner to thus inhibit the generation of PhIP. This study provides valuable information for the development of effective strategies to minimize HAA content in thermally processed foods and also sheds light on the mechanism that accounts for the inhibitory effect. © 2017 Society of Chemical Industry.

Inhibition effects of flavonoids on 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline and 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline formation and alkoxy radical scavenging capabilities of flavonoids in a model system.

BACKGROUND: Heterocyclic aromatic amines (HAAs) have been considered as carcinogenic and mutagenic chemicals generated during thermal processing of protein-rich foods that can be inhibited by some flavonoids. Free radical scavenging is a major characteristic of flavonoids. RESULTS: The half-maximal inhibitory concentration (IC50 ) values of nine flavonoids were determined by evaluating their capacity to inhibit 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx) formation in a model system. The results of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) test validated that MeIQx and 7,8-DiMeIQx formed via a free radical pathway. Electron spin resonance (ESR) spectroscopic analysis with spin trapping (α-(4-pyridyl N-oxide)-N-tert-butylnitrone (POBN) spin adduct, aN = 15.2 G and aH = 2.7 G) revealed that an alkoxy radical was the generated intermediate. The scavenging capacities of the nine flavonoids on alkoxy radicals were then evaluated based on the ESR spectra of the POBN spin adducts. CONCLUSION: The weak correlation between the alkoxy radical scavenging capacities and IC50 of the flavonoids suggested that their inhibitory activity against MeIQx and 7,8-DiMeIQx formation operates by a more complex mechanism than simply scavenging alkoxy radicals. © 2017 Society of Chemical Industry.

Screening of molecular cell targets for carcinogenic heterocyclic aromatic amines by using CALUX® reporter gene assays.

Heterocyclic aromatic amines (HCAs) are compounds formed when meat or fish are cooked at high temperatures for a long time or over an open fire. To determine which pathways of toxicity are activated by HCAs, nine out of the ten HCAs known to be carcinogenic in rodents (2-amino-9H-pyrido[2,3-b]indole (AαC), 2-aminodipyrido[1,2-a:3',2-d]imidazole (Glu-P-2), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2)) were tested in the estrogen receptor α (ERα), androgen receptor (AR), glucocorticoid receptor (GR), peroxisome proliferator-activated receptor γ2 (PPARγ2), polycyclic aromatic hydrocarbons (PAH), Nrf2, and p53 CALUX® reporter gene assays. Trp-P-1 was the only HCA that led to a positive response in the ERα, PPARγ2, and Nrf2 CALUX® assays. In the PAH CALUX® assay, Trp-P-2, MeAαC, and AαC induced luciferase activity to a greater extent than MeIQ and PhIP. In the p53 CALUX® assay without a coupled metabolic activation, only Trp-P-1 and Trp-P-2 enhanced luciferase expression; when a metabolic activation step was coupled to the p53 CALUX® assay, Trp-P-1, Glu-P-2, MeIQ, MeIQx, and PhIP induced a positive response. No HCA was positive in the AR and GR CALUX® assays. Taken together, the results obtained show that the battery of CALUX® assays performed in the present study can successfully be used to screen for molecular cell targets of carcinogenic compounds such as HCAs.

Preparation of arginine-modified reduced graphene oxide composite filled in an on-line solid-phase extraction disk and its application in the analysis of heterocyclic aromatic amines.

An arginine-modified reduced graphene oxide composite was prepared in an on-line solid-phase extraction disk and coupled to high-performance liquid chromatography for the re-enrichment of heterocyclic aromatic amines. The synthetic composite presented an excellent adsorption capability because of the ultrahigh active surface area of graphene and the abundant alkaline groups of arginine. The adsorption capacity of it was 52.7 mg 2-amino-3-methyl-imidazo[4,5-f]-quinoline per gram, nearly twice that of threonine-modified reduced graphene oxide composite, glutamic acid modified reduced graphene oxide composite, and reduced graphene oxide. This on-line method was successfully applied to the detection of a series of heterocyclic aromatic amines in beef jerky. After clean-up and re-enrichment of the on-line solid-phase extraction disk, the chromatographic background of the sample was low and the shape of chromatographic peaks was sharp. The method detection limit was in the range of 0.30-0.49 ng/g, and the recovery was in the range of 82.0-111.5%.

Role of human sulfotransferase 1A1 and N-acetyltransferase 2 in the metabolic activation of 16 heterocyclic amines and related heterocyclics to genotoxicants in recombinant V79 cells.

Heterocyclic aromatic amines (HAAs) are primarily produced during the heating of meat or fish. HAAs are mutagenic and carcinogenic, and their toxicity in model systems depend on metabolic activation. This activation is mediated by cytochrome P450 (CYP) enzymes, in particular CYP1A2. Some studies have indicated a role of human sulfotransferase (SULT) 1A1 and N-acetyltransferase (NAT) 2 in the terminal activation of HAAs. In this study, we conducted a metabolism/genotoxicity relationship analysis for 16 HAAs and related heterocyclics. We used the γH2AX genotoxicity assay in V79 cells (deficient in CYP, SULT and NAT) and V79-derived cell lines genetically engineered to express human CYP1A2 alone or in combination with human SULT1A1 or NAT2. Our data demonstrated genotoxic properties for 13 out of the 16 compounds tested. A clear relationship between metabolic bioactivation and genotoxicity allowed to distinguish four groups: (1) Trp-P-1 genotoxicity was linked to CYP1A2 bioactivation only-with negligible effects of phase II enzymes; (2) Glu-P-2, Glu-P-1, Trp-P-2, APNH, MeAαC and AαC were bioactivated by CYP1A2 in combination with either phase II enzyme tested (NAT2 or SULT1A1); (3) IQ, 4-MeIQ, IQx, 8-MeIQx, and 4,8-DiMeIQx required CYP1A2 in combination with NAT2 to be genotoxic, whereas SULT1A1 did not enhance their genotoxicity; (4) PhIP became genotoxic after CYP1A2 and SULT1A1 bioactivation-NAT2 had not effect. Our results corroborate some previous data regarding the genotoxic potency of seven HAAs and established the genotoxicity mechanism for five others HAAs. This study also permits to compare efficiently the genotoxic potential of these 13 HAAs.

Formation of heterocyclic amines in Chinese marinated meat: effects of animal species and ingredients (rock candy, soy sauce and rice wine).

BACKGROUND: Heterocyclic aromatic amines (HAAs) are one type of neo-formed contaminants in protein-rich foods during heat processing. Recently, accumulative studies have focused on the formation of HAs in Western foods. However, there is little knowledge about the occurrence of HAAs in traditional Chinese foods. The objective of this study was to determinate the contents of main HAs in traditional marinated meat products by UPLC-MS/MS, and to investigate the effects of animal species and the ingredients (soy sauce, rock candy, and rice wine) on the formation of HAAs in marinated meats. RESULTS: Five HAs - 2-amino-3-methylimidazo[4,5-f]-quinolone (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4-dimethylimidazo[4,5-f]quinoxaline (MeIQ), 9H-pyrido[3,4-b]indole (Norharman) and l-methyl-9H-pyrido[3,4-b]indole (Harman) - were detected in 12 marinated meats, but 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was only found in three chicken marinates. The animal species and ingredients (soy sauce, rock candy and rice wine) have significant influence on the formation of HAAs in meat marinates. Beef had the highest content of total HAAs compared with pork, mutton and chicken. Meanwhile, soy sauce contributed to the formation of HAAs more greatly than rock candy, soy sauce, and rice wine. CONCLUSION: Choice of raw materials and optimisation of ingredients recipe should be become a critical point to control the HAAs formation in marinated meats. © 2017 Society of Chemical Industry.

Association between NAT2, CYP1A1, and CYP1A2 genotypes, heterocyclic aromatic amines, and prostate cancer risk: a case control study in Japan.

BACKGROUND: Heterocyclic aromatic amines (HAAs) may confer prostate cancer risk; however, the evidence is inconclusive and the activity of HAA-metabolizing enzymes is modulated by gene variants. The purpose of our study was to determine whether there was evidence of an association between HAA intake, polymorphisms in NAT2, CYP1A1, and CYP1A2 and prostate cancer risk in Japanese men. METHODS: Secondary data analysis of an observational case control study was performed. Among 750 patients with prostate cancer and 870 healthy controls, 351 cases and 351 age-matched controls were enrolled for analysis. HAA intake was estimated using a food frequency questionnaire and genotypes were scored by TaqMan real-time PCR assay. Logistic regression analysis was conducted according to affected/control status. RESULTS: We found that high HAA intake was significantly associated with an increased risk of prostate cancer (odds ratio (OR), 1.90; 95% confidence interval (95% CI), 1.40-2.59). The increased risk of prostate cancer was observed among individuals with the NAT2 slow acetylator phenotype (OR, 1.65; 95% CI, 1.04-2.61), CYP1A1 GA + GG genotype (OR, 1.27; 95% CI, 1.02-1.59), and CYP1A2 CA + AA genotype (OR, 1.43; 95% CI, 1.03-2.00). In addition, CYP1A1 GA + GG genotypes were associated with increased cancer risk in low (OR, 2.05; 95% CI, 1.19-3.63), moderate (OR, 1.72; 95% CI, 1.07-2.76), and high (OR, 2.86; 95% CI, 1.83-4.47) HAA intake groups. CONCLUSIONS: Our results suggest that high HAA intake is a risk factor of prostate cancer, and genotypes related to HAA metabolic enzymes can modulate the degree of the risk.

Mechanisms Linking Colorectal Cancer to the Consumption of (Processed) Red Meat: A Review.

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the world. The vast majority of CRC cases have been linked to environmental causes rather than to heritable genetic changes. Over the last decades, epidemiological evidence linking the consumption of red and, more convincingly, of processed red meat to CRC has accumulated. In parallel, hypotheses on carcinogenic mechanisms underlying an association between CRC and the intake of red and processed red meat have been proposed and investigated in biological studies. The hypotheses that have received most attention until now include (1) the presence of polycyclic aromatic hydrocarbons and heterocyclic aromatic amines, two groups of compounds recognized as carcinogenic, (2) the enhancing effect of (nitrosyl)heme on the formation of carcinogenic N-nitroso compounds and lipid peroxidation. However, none of these hypotheses completely explains the link between red and processed red meat intake and the CRC risk. Consequently, scientists have proposed additional mechanisms or refined their hypotheses. This review first briefly summarizes the development of CRC followed by an in-depth overview and critical discussion of the different potential carcinogenic mechanisms underlying the increased CRC risk associated with the consumption of red and processed red meat.