Simultaneous determination of advanced glycation end products and heterocyclic amines in roast/grilled meat by UPLC-MS/MS

Advanced glycation end products (AGEs) and heterocyclic amines (HAs) are main harmful Maillard reaction products of meat products. Simultaneous quantification of both with high sensitivity, selectivity and accuracy remains a major challenge due to inconsistencies in their pre-treatment and instrumental methods and the different polarity of AGEs and HAs. We developed a method for the simultaneous determination of AGEs and HAs in roast/grilled meat by ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) using dynamic multiple reaction monitoring (D-MRM). The instrument parameters and pre-treatment method were optimized to achieve reasonably good separation and high response for the 11 target analytes within 8 min. From 10 to 200 ng/mL, the limits of detection (LODs) and limits of quantitation (LOQs) ranged from 0.3 to 5.5 μg/L and 0.9 to 6.3 μg/L, respectively, and the correlation coefficient (R2) was >0.99. It was acceptable to recoveries, standard deviations (RSDs), and matrix effects. Six types of roast/grilled meat samples were then tested using the developed method.

Effects of seasoning addition and cooking conditions on the formation of free and protein-bound heterocyclic amines and advanced glycation end products in braised lamb

The accumulation of heterocyclic amines (HAs) and advanced glycation end products (AGEs) in thermally processed meats has been arising safety concerns. The effects of cooking conditions and seasoning addition on the formation of HAs and AGEs in Chinese traditional braised lamb were investigated by UPLC-MS/MS analysis. Soy sauce significantly increased the formation of HAs and AGEs, among which light soy sauce had the greatest promoting effect (69.45-15300.62 %). Conversely, spices inhibited HAs and AGEs formation, the inhibition rate of free HAs and AGEs reached 22.06-34.72 % when using 70 % ethanol extract. Hot blanching treatment and adding soy sauce and spices at a later stage could significantly suppress HAs and AGEs production. Flavonoids, including galangin, hesperidin, narirutin, etc., were identified as key effectors in spices. These findings help to promote awareness of the formation of HAs and AGEs in braised lamb and provide valuable insights for optimizing processing techniques to minimize their production.

Synergistic inhibition against heterocyclic amines in beef patties: Caused by carbonyl-trapping and toxicity-reducing of amino acid combinations

The inhibitory effects of amino acids and their combinations on the formation of heterocyclic amines were investigated in this study. The great potential in the inhibition of HAs was observed in amino acid combinations compared with that of single agents. At a mass ratio of 1:1, a His-Pro combination achieved a maximum inhibitory rate of 80 %, and the total HAs content decreased to 4.70 ± 0.18 ng/g relative to the control (24.49 ± 2.18 ng/g). However, the inhibitory rate of triple combinations showed no obvious increase compared with the binary combinations. Benzaldehyde, phenylacetaldehyde, methylglyoxal, and glyoxal were positively correlated with HAs formation, and His-Pro combination (1:4) led to a significant reduction of benzaldehyde and phenylacetaldehyde at scavenging rates of 79 % and 92 %. Thus, the synergistic inhibition was achieved by simultaneously scavenging these aldehyde intermediates, and other inhibitory target, such as competition with precursors and elimination of final products can serve as supporting factors. These results provide a new perspective for approaches to enhance the suppression of HAs and control the formation of flavor compounds.

Attenuation of heterocyclic amine formation and lipid and protein oxidation in air-fried fish fillets by marination with selected legume seed extracts

The present study aimed to investigate the potential of marination with extracts prepared from five legume seeds on heterocyclic amine (HA) formation in chemical models and air-fried fish fillets. In terms of total HAs, clove seed marinade (CSM) was found with the maximum inhibitory effect (43.98 %), followed by tamarind seed marinade (TSM) (40.26 %), fenugreek seed marinade (FSM) (39.07 %), acacia seed marinade (ASM) (37.99 %), and black bean seed marinade (BSM) (29.95 %). In particular, at higher levels (3 mg/mL, 4 mg/mL), CSM and FSM achieved the greatest mitigating effect against 4,8-DiMeIQx, 7,8-DiMeIQx, and MeIQx. Furthermore, all marinades were effective in lowering thiobarbituric acid-reactive substances (TBARS) and carbonyl and retaining thiol content relative to the control. PCA analysis revealed that higher levels of ASM, BSM, and FSM had better mitigating effect against IQ and MeIQx formation, whereas Pearson correlation shows that TBARS and carbonyl were positively correlated to HAs.

Development of a two-step pretreatment and UPLC-MS/MS-based method for simultaneous determination of acrylamide, 5-hydroxymethylfurfural, advanced glycation end products and heterocyclic amines in thermally processed foods

A two-step pretreatment and UPLC-MS/MS-based method was established to extract and determine 17 thermal processing hazards (TPHs) simultaneously. The first step was to extract acrylamide (AA), 5-hydroxymethylfurfural (HMF) and free heterocyclic amines (HAs). The bound HAs and advanced glycation end products (AGEs) were released by acid hydrolysis in the second step. A fairly good separation was achieved within 7 min. Almost all TPHs showed high correlation coefficients (R2 >0.999) in their respective linear ranges. The accuracy ranged from 98.13 to 100.96%. LODs and LOQs were in the range of 0.01-0.89 µg/L and 0.02-2.96 µg/L, respectively. The method was successfully applied to four representative food products, including high-starch, high-protein, high-fat and high-sugar foods, showing acceptable recoveries, intra-day and inter-day precisions. Moreover, PCA was performed to visualize the association between TPHs and food matrices. The developed method provided technical support for the formation and control researches of TPHs.

Effect of Angelica dahurica, Angelica dahurica polysaccharides, and imperatorin on free and bound heterocyclic amine generation in roasted beef patties and release profiles of bound heterocyclic amines during in vitro digestion

This study explored the suppressive activity of Angelica dahurica (AD), AD polysaccharides, and imperatorin on free and bound heterocyclic amine (HA) formation in roast beef patties and release profiles of bound HAs during in vitro digestion. The suppressive effects and potential mechanisms associated with free radical quenching were explored using UPLC-MS/MS, multivariate statistical analysis, and electron paramagnetic resonance (EPR). AD (0.5%, 1.0%, and 1.5%) and imperatorin (0.005%, 0.010%, and 0.015%) showed a dose-dependent inhibition for both free and bound HAs, with AD polysaccharides showing a slight inhibitory capacity. The maximum inhibition of free and bound HAs was 36.31% (1.5% AD) and 35.68% (0.015% imperatorin). The EPR results demonstrated that alkyl radicals and 1O2 were the pivotal free radicals for HAs. Furthermore, AD and imperatorin dose-dependently decreased the level of these radicals. Intriguingly, after in vitro digestion, only AD polysaccharides significantly inhibited the release of bound HAs, with imperatorin even facilitating the release process. In this study, the capacity of the AD polysaccharide to suppress the release of bound HAs and the ability of AD and imperatorin to inhibit free and bound HAs in beef patties were identified for the first time.

Paprika extract as a natural antioxidant in cold-stored pork patties: Effect on oxidative stability and heterocyclic amines inhibition

In this study, we compared the degree of oxidation of pork patties refrigerated at 7 °C for 0, 7, and 14 days and the content of 10 types of heterocyclic amines (HCAs) after heating. The pork patties used in the study were added with 0.7 mg sodium nitrite (SN) and 5 mg paprika extract (PE), respectively. IQx (2-Amino-3-methyl-imidazo[4,5-f]-quinoxaline), MeIQx (2-Amino-3, 8-dimethyl-imidazo[4,5-f]-quinoxaline), PhIP (2-Amino-1-methyl-6-phenyl-imidazo[4,5-b]-pyridine), and Harman (1-Methyl-9H-pyrido[4,3-b]-indole) contents increased with increasing storage periods of treatment. On the other hand, HCAs production in SN and PE treatments were suppressed over the storage period, with IQ (2-Amino-3-methyl-imidazo[4,5-f]-quinoline) and Aαc (2-Amino-9H-dipyrido[2,3-b]-indole) being suppressed significantly (P < 0.05). The control's pH, cooking loss, lipid, and protein oxidation were higher than SN and PE-treated patties at 14 d (P < 0.05). These differences affect the formation of HCAs. PLS-DA showed a strong correlation between protein oxidation and IQx, Harman, 4,8-DiMelQx (2-Amino-3, 4, 8-trimethyl-imidazo[4,5-f]-quinoxaline), PhIP, and MeIQx, while lipid oxidation correlated with IQx, Harman, and PhIP. Both SN and PE showed HCAs inhibitory activity and exhibited oxidative stability during storage.

Effects of volatile organic compounds of smoke from different woods on the heterocyclic amine formation and quality changes in pork patty

This study investigated the effects of smoke derived from cypress (CY), mulberry (MU), metasequoia (ME), pine (PI), and camphor (CA) on the heterocyclic aromatic amines (HAs), flavor, and sensory attributes of smoked pork patty. The results showed that the smoke derived from the five kinds of wood and the flavor of the corresponding smoked meat were classified into three types. Moreover, the smoke of CY and PI, and the smoke of MU and ME can be classified into one category respectively, which significantly improved the flavor of the smoked meat. Both free and protein-bound HAs were detected in smoked meat, while the smoking process significantly increased the HAs content, especially free Norharman (3.26 ng/g in control meat, and 82.24 ng/g in meat smoked with CY). Correlation analysis showed that various volatile organic compounds (VOCs) and HAs were closely associated. Future research should pay attention to the VOCs in smoked meat including vanillin, Close attention should be paid to tridecane and crotonic acid, as well as tetradecane and α-Dehydro-ar-himachalene in smoke, which were consistently correlated with various HAs and may participate in HAs formation. These results may reveal how the smoking process influences the formation of HAs and which factors should be targeted to inhibit HAs in smoked meat products.

Formation of morpholine-acetamide derivatives as potent anti-tumor drug candidates: Pharmacological evaluation and molecular docking studies

Heterocyclic amines and acetamide derivatives are known for their chemotherapeutic potential. Hence, in the present study, morpholine was taken as a principal product and novel morpholine derivatives were designed, formulated, characterized, and screened for the mechanism of inhibition of carbonic anhydrase and their anticancer potential. In addition, in vitro inhibition of hypoxia-inducible factor-1 (HIF-1) protein was also investigated. Results revealed that compounds 1c, 1d, and 1h possessed significant inhibitory activities against carbonic anhydrase with IC50 of 8.80, 11.13, and 8.12 μM, respectively. Interestingly, the carbonic anhydrase inhibitory activity of compound 1h was comparable with that of standard acetazolamide (IC50 7.51 μM). The compounds 1h and 1i significantly inhibited the proliferation of ovarian cancer cell line ID8 with IC50 of 9.40, and 11.2 μM, respectively while the standard cisplatin exhibited an IC50 8.50 μM. In addition, compounds 1c, 1b, 1h and 1i also exhibited significant inhibitory effects on HIF-1α. In conclusion, we report first time the biological potential of morpholine based compounds against ovarian cancer and HIF-1α that may serve as lead molecules for drug discovery.

The effect of the rs1799931 G857A (G286E) polymorphism on N-acetyltransferase 2-mediated carcinogen metabolism and genotoxicity differs with heterocyclic amine exposure

Human N-acetyltransferase 2 (NAT2) is subject to genetic polymorphism in human populations. In addition to the reference NAT2*4 allele, two genetic variant alleles (NAT2*5B and NAT2*7B) are common in Europe and Asia, respectively. NAT2*5B possesses a signature rs1801280 T341C (I114T) single-nucleotide polymorphism (SNP), whereas NAT2*7B possesses a signature rs1799931 G857A (G286E) SNP. NAT2 alleles possessing the T341C (I114T) or G857A (G286E) SNP were recombinant expressed in yeast and tested for capacity to catalyze the O-acetylation of the N-hydroxy metabolites of heterocyclic amines (HCAs). The T341C (I114T) SNP reduced the O-acetylation of N-hydroxy-2-amino-3-methylimidazo [4,5-f] quinoline (N-OH-IQ), N-hydroxy-2-amino-3,8-dimethylimidazo [4,5-f] quinoxaline (N-OH-MeIQx) and N-hydroxy- 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (N-OH-PhIP), whereas the G857A (G286E) SNP reduced the O-acetylation of N-OH-IQ and N-OH-MeIQx but not N-OH-PhIP. The G857A (G286E) SNP significantly (p < 0.05) reduced apparent Km toward N-OH-PhIP but did not significantly (p > 0.05) affect apparent Vmax. Cultures of DNA repair-deficient Chinese hamster ovary (CHO) cells transfected with human CYP1A2 and NAT2*4, NAT2*5B or NAT2*7B alleles were incubated with various concentrations of IQ, MeIQx or PhIP and double-stranded DNA damage and reactive oxygen species (ROS) were measured. Transfection with human CYP1A2 did not significantly (p > 0.05) increase HCA-induced DNA damage and ROS over un-transfected cells. Additional transfection with NAT2*4, NAT2*5B or NAT2*7B allele increased both DNA damage and ROS. The magnitude of the increases was both NAT2 allele- and substrate-dependent showing the same pattern as observed for the O-acetylation of the N-hydroxylated HCAs suggesting that both are mediated via NAT2-catalyzed O-acetylation. The results document the role of NAT2 and its genetic polymorphism on the O-acetylation and genotoxicity of HCAs.

Induction of glucose production by heterocyclic amines is dependent on N-acetyltransferase 2 genetic polymorphism in cryopreserved human hepatocytes

Heterocyclic amines (HCAs) are mutagenic compounds found in cooked meat. Recent epidemiological studies reported significant associations between dietary HCA exposure and insulin resistance and type II diabetes, and we recently reported that HCAs induce insulin resistance and glucose production in human hepatocytes. It is well known that HCAs require hepatic bioactivation by cytochrome P450 1A2 (CYP1A2) and N-acetyltransferase 2 (NAT2). NAT2 expresses a well-defined genetic polymorphism in humans that, depending on the combination of NAT2 alleles, correlates to rapid, intermediate, or slow acetylator phenotype that exhibits differential metabolism of aromatic amines and HCAs. No previous studies have examined the role of NAT2 genetic polymorphism in the context of HCA-mediated induction of glucose production. In the present study, we assessed the effect of three HCAs commonly found in cooked meat (2-amino-3,4-dimethylimidazo[4,5-f]quinoline [MeIQ], 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline [MeIQx], and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine [PhIP]) on glucose production in cryopreserved human hepatocytes with slow, intermediate, or rapid NAT2 acetylator phenotype. HCA treatment did not affect glucose production in slow NAT2 acetylator hepatocytes, while a slight increase in glucose production was observed in intermediate NAT2 acetylators treated with MeIQ or MeIQx. However, significant increases in glucose production were observed in rapid NAT2 acetylators following each HCA. The current findings suggest that individuals who are rapid NAT2 acetylators may be at a greater risk of developing hyperglycemia and insulin resistance following dietary exposure to HCAs.

Heterocyclic amines reduce insulin-induced AKT phosphorylation and induce gluconeogenic gene expression in human hepatocytes

Heterocyclic amines (HCAs) are well-known for their mutagenic properties. One of the major routes of human exposure is through consumption of cooked meat, as certain cooking methods favor formation of HCAs. Recent epidemiological studies reported significant associations between dietary HCA exposure and insulin resistance and type II diabetes. However, no previous studies have examined if HCAs, independent of meat consumption, contributes to pathogenesis of insulin resistance or metabolic disease. In the present study, we have assessed the effect of three HCAs commonly found in cooked meat (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline [MeIQ], 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline [MeIQx], and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine [PhIP]) on insulin signaling and glucose production. HepG2 or cryopreserved human hepatocytes were treated with 0-50 μM of MeIQ, MeIQx, or PhIP for 3 days. Treatment of HepG2 cells and hepatocytes with MeIQ and MeIQx resulted in a significant reduction in insulin-induced AKT phosphorylation, suggesting that HCA exposure decreases hepatic insulin signaling. HCA treatment also led to significant increases in expression of gluconeogenic genes, G6PC and PCK1, in both HepG2 and cryopreserved human hepatocytes. Additionally, the level of phosphorylated FOXO1, a transcriptional regulator of gluconeogenesis, was significantly reduced by HCA treatment in hepatocytes. Importantly, HCA treatment of human hepatocytes led to increases in extracellular glucose level in the presence of gluconeogenic substrates, suggesting that HCAs induce hepatic glucose production. The current findings suggest that HCAs induce insulin resistance and promote hepatic glucose production in human hepatocytes. This implicates that exposure to HCAs may lead to the development of type II diabetes or metabolic syndrome.

The impact of temperature-controlled smoldering smoking on polycyclic aromatic hydrocarbons and heterocyclic amines contents in Frankfurter-type sausages

The impact of temperature-controlled smoldering smoking conditions on the accumulations of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HAs) in Frankfurter-type sausages was investigated. Depending on the temperature, smoking can be divided into two phases: an unstable pyrolysis stage (≈ 200 s) and a stable pyrolysis stage (>200 s), which had different effects on hazardous substances contents. The unstable pyrolysis stage, which contributed 66.9 ∼ 89.6% of PAH accumulations by comparing with sausages smoked for 15 min, has significant impact on high PAH residues. By contrast, the contents of HAs showed steady increase trends with smoking time. Few types of free-HAs with low concentrations (3.05 ∼ 22.9 ng/g DW), but more types of bound-HAs with much higher levels (10.8 ∼ 396 ng/g DW) were found. In addition, the formation of some HAs followed the first-order reaction model. However, the detailed formation mechanisms of PAHs and HAs under temperature-controlled smoldering smoking conditions remain to be studied.

Quantification of hetero-cyclic amines from different categories of braised beef by optimized UPLC-TQ-XS/ESI method

This research work has developed and optimized a sensitive analytical method for separation and quantification of heterocyclic amines (HCAs) mainly including PhIP, Harman, Norharman, IQ, MeIQ, AαC, MeAαC and Trp-P-2 by optimizing UPLC-TQ-XS using electrospray ionization source (ESI+) on ACQUITY UPLC® BEH C18 column in <7 min, from braised beef sample matrix. Meanwhile, modified HCAs extraction by modifying QuEChERS (quick, easy, cheap, efficient, rugged and safe) technique and revisited with solid phase extraction (SPE) for HCAs purification, instead using traditional QuEChERS salts. Moreover, optimized pH conditions of HCA extracts before purification, for better extraction recoveries. Furthermore, this method was validated in terms of method validation parameters. Lastly, simulation of real braised beef model provided the minimum formation of HCAs by optimizing cooking parameters and precursors in a cooking system. Therefore, this method could be applied simultaneously on braised beef matrix either marketed or home cooked for HCAs analysis.

Interaction between Chinese quince fruit proanthocyanidins and bovine serum albumin: Antioxidant activity, thermal stability and heterocyclic amine inhibition

Heterocyclic amines (HCAs) are carcinogenic and mutagenic substances produced in fried meat. Adding natural antioxidants (e.g., proanthocyanidins (PAs)) is a common method to reduce HCAs; however, the interaction between the PAs and protein can affect the inhibitory efficacy of PAs on the formation of HCAs. In this study, two PAs (F1 and F2) with different degrees of polymerization (DP) were extracted from Chinese quince fruits. These were combined with bovine serum albumin (BSA). The thermal stability, antioxidant capacity and HCAs inhibition of all four (F1, F2, F1-BSA, F2-BSA) were compared. The results showed that F1 and F2 interact with BSA to form complexes. Circular dichroism spectra indicate that complexes had fewer α-helices and more β-sheets, β-turns and random coils than BSA. Molecular docking studies indicated that hydrogen bonds and hydrophobic interactions are the forces holding the complexes together. The thermal stabilities of F1 and, particularly, F2 were stronger than those of F1-BSA and F2-BSA. Interestingly, F1-BSA and F2-BSA showed increased antioxidant activity with increasing temperature. F1-BSA's and F2-BSA's HCAs inhibition was stronger than F1 and F2, reaching 72.06 % and 76.3 %, respectively, for norharman. This suggests that PAs can be used as natural antioxidants for reducing the HCAs in fried foods.

Study on the reduction of heterocyclic amines by marinated natural materials in pork belly

This study was conducted to determine the effect of natural ingredient seasoning on the reduction of heterocyclic amine (HCA) production that may occur when pork belly is cooked at a very high temperature for a long time. Pork belly seasoned with natural ingredients, such as natural spices, blackcurrant, and gochujang, was cooked using the most common cooking methods, such as boiling, pan fry, and barbecue. HCAs in pork belly were extracted through solid-phase extraction and analyzed via high-performance liquid chromatography. For short-term toxicity, a mouse model was used to analyze weight, feed intake, organ weight, and length; hematology and serology analysis were also performed. Results revealed that HCAs formed only when heating was performed at a very high temperature for a long time, not under general cooking conditions. Although the toxicity levels were not dangerous, the method showing the relatively highest toxicity among various cooking methods was barbecue, and the natural material with the highest toxicity reduction effect was blackcurrant. Furthermore, seasoning pork belly with natural materials containing a large amount of antioxidants, such as vitamin C, can reduce the production of toxic substances, such as HCAs, even if pork belly is heated to high temperatures.

and kaempferol on heterocyclic amines and advanced glycation end products in roasted beef patties and related mechanistic analysis by density functional theory

The capacity of Kaempferia galanga L. (KG) and kaempferol to mitigate the formation of free and bound heterocyclic amines (HAs) and advanced glycation end products (AGEs) in roast beef patties was explored. Electron paramagnetic resonance (EPR) and density functional theory (DFT) were used to reveal the possible mechanisms involved in quenching the free radicals. KG (0.5%, 1.0%, 1.5%) and kaempferol (0.005%, 0.010%, 0.015%) reduced HAs and AGEs in a dose-dependent manner. Alkyl free radical, HOO·, and ¹O₂ were critical to the formation of HAs, and ¹O₂ was pivotal to AGEs. They were quenched by KG and kaempferol in a dose-dependent manner. DFT indicated that the 3-OH group of kaempferol was most pivotal and quenched the HOO· mainly via H-atom transfer. The active carbonyl intermediates phenylacetaldehyde, glyoxal, and methylglyoxal can also be reduced by KG and kaempferol in a dose-dependent manner, which may be result from the quenching of free radicals.

Simultaneous kinetics formation of heterocyclic amines and polycyclic aromatic hydrocarbons in phenylalanine model system

A combination of chemical model system with kinetics study was used to investigate the simultaneous formation of heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Heating a mixture of phenylalanine, creatinine, and glucose at a commonly practiced household cooking time and temperature successfully differentiated the rate formation (k) of HCAs and PAHs. The good fit suggested that the simultaneous formation was an endothermic bimolecular reaction, and followed the first-order model. The rate formation (k) of HCAs and PAHs significantly increased with increasing heating time and temperature. Only 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) showed degradation rate (k) at higher heating temperatures of 210 °C and 240 °C respectively. Increasing phenylalanine concentration increased the possibility of higher HCAs and PAHs formation. The activation energy (Ea) showed that heating phenylalanine mixture resulted in higher rate of formation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and benzo[b]fluoranthen (BbF).

Effect of Different Roasting Conditions and Coreopsis Extract on Heterocyclic Amine Formation in Roast Lamb Products

ABSTRACT

Heterocyclic amines (HCAs), which are known carcinogens in thermally processed foods, were investigated in roast lamb patties under various time and temperature conditions. HCAs in lamb products roasted at some temperatures increased with roasting time. An exponential model with a time factor fit well for the production of HCAs. The mean pH and cooking loss at various temperatures were also determined. The mean pH decreased as the temperature increased. Coreopsis extract was added to lamb patties roasted at 230°C for 15 min per side. The amount of coreopsis extract added had a significant effect on HCA development. A weak positive relationship was observed between the antioxidant activity of the lamb patty with the coreopsis extract and the inhibitory effect of coreopsis extract on various HCAs, with a correlation coefficient of 0.14 to 0.44 (P > 0.05). Coreopsis extract containing flavonoids can be a beneficial additive for production of barbecue meat.

HIGHLIGHTS

Effects of the non-covalent interactions between polyphenols and proteins on the formations of the heterocyclic amines in dry heated soybean protein isolate

Soybean proteins are the main component of plant-based meat alternatives in the Chinese market. The effects of non-covalent interactions between polyphenols and proteins on the protein structures, the rest physicochemical properties, and formations of heterocyclic amines (HAs) were examined using a polyphenols-containing soybean protein isolate (SPI) complex as a model to dry heating at 170℃ for 10 min. The results showed that tetrahydro-curcumin had extensive inhibitory effects on the HA formation. In addition, tea polyphenols, grapeseed procyanidins, and dihydromyricetin were also found to have inhibitory effects only on some HAs. Correlation analysis showed that polyphenols altered the secondary structure and steric structure of the protein by interacting with the protein, which affects the HA formation. The results provided theoretical references and a basis for the formation mechanisms of HAs in polyphenol-inhibiting protein foods.

The inhibitory effects of yellow mustard (Brassica juncea) and its characteristic pungent ingredient allyl isothiocyanate (AITC) on PhIP formation: Focused on the inhibitory pathways of AITC

The effects of yellow mustard (Brassica juncea) and its characteristic component allyl isothiocyanate (AITC) on the formation of 2-amino-y1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) in roast beef patties and PhIP-producing model systems were investigated. The probable inhibitory pathways of AITC on PhIP formation were also investigated in the model systems. The results revealed that yellow mustard and AITC can reduce PhIP in roast beef patties up to 41.7% and 60.2%, respectively. The rate of inhibition of PhIP also reached 64.8% in the PhIP-producing model systems. Furthermore, AITC could react with creatinine and phenylalanine in the model system (reducing each by 15.0%%-23.7% and 31.4%-55.8%, respectively). AITC showed the great scavenging ability of free radical scavenging (up to 64.2%). AITC also reacted with the intermediate phenylacetaldehyde (16.9%-30.8%) and the final product PhIP (7.0%-24.6%). It is speculated that AITC can inhibit PhIP through competitive inhibition of precursors, blocking intermediate, free radical scavenging, and direct elimination of PhIP.

Dissecting grilled red and white meat flavor: Its characteristics, production mechanisms, influencing factors and chemical hazards

Meat flavor is composed of a complex mixture of volatile compounds developed as a result of heat driven multi-directional reactions. Typical reactions include Maillard reaction, lipid oxidation, as well as nitrogenous compounds degradation. Such complex flavor is characterized by a rich variety of volatile species, and to strongly influence consumer's preference. The objective of this review is to holistically dissect the flavor characteristic for cooked meat products with special emphasis on grilling and the factors that affect their production to ensure best quality and or safety levels. The review also highlights different analytical techniques used for the detection of flavor compounds in grilled meat. This comprehensive literature research critically analyze grilled flavor derived from heat mediated reactions, with a special emphasis on key flavors or hazard chemicals and their production mechanism. The various influencing factors i.e., grilling temperature, meat, food components, animal ante-mortem factors and food additives are summarized.

Mitigation of heterocyclic amines by phenolic compounds in allspice and perilla frutescens seed extract: The correlation between antioxidant capacities and mitigating activities

The effect of different levels of allspice and perilla frutescens seed extract (ASE and PSE) on the formation of heterocyclic amines (HCAs) in pan-fried chicken meat patties and the bioactive components found in ASE and PSE that contribute to the mitigation of HCAs were investigated in this study. DPPH radical scavenging activity was evaluated and the results indicated that APSE (ASE + PSE) showed the highest capacity to scavenge free radicals, and the most effective inhibition of HCAs formation. Furthermore, Single and mixed phenolic compounds exhibited a positive effect in scavenging free radicals and mitigating HCAs. The radical scavenging activity and HCAs inhibition effect of single phenolic compounds were highly correlated, whereas mixed phenolic compounds exhibited poor correlation. PCA analysis indicated that phenolic compounds had the maximum inhibitory effect on IQ, followed by Norharman and harman and the minimal effect on PhIP and 7,8-DiMeIQx.

Heterocyclic amines in cooked meat products, shortcomings during evaluation, factors influencing formation, risk assessment and mitigation strategies

At this point in time, the evidence of a link between well-done meat intake and the incidence of cancer is stronger than it was 20 years ago. Several cohort and case-control studies have confirmed this evidence, and have shown a higher odd ratio and increased exposure to heterocyclic amines (HCAs) among those who frequently consume red meat. However, in most epidemiological studies, dietary assessment, combined with analytical data, is used to estimate the intake of HCAs, which has many inconsistencies. In addition, there is a lack of findings indicating a substantial correlation between various factors, like types of raw meat, types of meat products, and cooking methods that directly or indirectly influence the occurrence of cancer. Although numerous mitigation strategies have been developed to reduce HCAs levels in meat, there is still a high prevalence of carcinogenesis caused by HCAs in humans. The aim of this review is to summarise conflicting reports, address shortcomings and identify emerging trends of cutting-edge research related to HCAs.

Heterocyclic Amine Formation and Mitigation in Processed Meat and Meat Products: A Mini-Review

ABSTRACT

This review provides an assessment of heterocyclic amine (HCA) formation and mitigation in processed meat and meat products. HCAs are formed when amino acids react with creatine during thermal processing of meat and meat products. The formation of HCAs depends on various factors, including the temperature, cooking time, fat contents, and presence of HCA precursors such as water, lipids, and marinades. Additional factors that could affect HCA formation are pH, meat type, and ingredients added during cooking such as antioxidants, amino acids, ions, fat, and sugars, which promote production of HCAs. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, 2-amino-3-methylimidazo-[4,5-f]quinoline, and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline are HCAs of importance because of their link to cancer in humans. More than 25 HCAs have been identified in processed foods. Of these, nine HCAs are possible human carcinogens (group 2B) and one is a probable human carcinogen (group 2A). To mitigate HCA generation during heat processing, various techniques have been used, including recipe variations, adjustments of thermal processing conditions, addition of flavorings, pretreatments such as microwave heating, and addition of naturally occurring and artificial antioxidants.

HIGHLIGHTS

Synthesis of a new series of pyrazolo[1,5-a]pyrimidines as CDK2 inhibitors and anti-leukemia

Based on the structural study of previously known CDK2 inhibitors, a new series of pyrazolo[1,5-a]pyrimidine derivatives was designed and synthesized. The target compounds were biologically assessed as potent CDK2 inhibitors and promising anti-leukemia hits. The 7-(4-Bromo-phenyl)-3-(3-chloro/2-chloro-phenylazo)-pyrazolo[1,5-a]pyrimidin-2-ylamines 5 h and 5i revealed the best CDK2 inhibitory activity with comparable potency (IC₅₀ = 22 and 24 nM, respectively) to that of dinaciclib (IC₅₀ = 18 nM). Additionally, both analogues showed potent activities against CDK1, CDK5 and CDK9 at nanomolar concentrations (IC₅₀ = 28-80 nM). The anti-leukemia screening of the target compounds showed strong to moderate cytotoxicity against the used leukemia cell lines (MOLT-4 and HL-60). Compound 5 h inhibited MOLT-4 and HL-60 by 1.4 and 2.3 folds (IC₅₀ = 0.93 and 0.80 µM), respectively, compared to dinaciclib (IC₅₀ = 1.30 and 1.84 µM). Furthermore, compound 5i was comparable to dinaciclib against MOLT-4 and exhibited twice its activity against HL-60. Besides, the cytotoxicity of the promising analogues on normal human blood cells indicated the safety of 5h and 5i as compared to the reference dinaciclib. The pharmacokinetic properties of 5h and 5i were predicted using ADME calculations revealing good oral bioavailability and high GI absorption. The molecular docking simulations indicated, as expected, that the dinaciclib analogues can well-accommodate the CDK2 binding site, forming a variety of interactions.

Mutagenicity of carcinogenic heterocyclic amines in Salmonella typhimurium YG strains and transgenic rodents including gpt delta

Chemical carcinogens to humans have been usually identified by epidemiological studies on the relationships between occupational or environmental exposure to the agents and specific cancer induction. In contrast, carcinogenic heterocyclic amines were identified under the principle that mutagens in bacterial in the Ames test are possible human carcinogens. In the 1970s to 1990s, more than 10 heterocyclic amines were isolated from pyrolysates of amino acids, proteins, meat or fish as mutagens in the Ames test, and they were demonstrated as carcinogens in rodents. In the 1980s and 1990s, we have developed derivatives of the Ames tester strains that overexpressed acetyltransferase of Salmonella typhimurium. These strains such as Salmonella typhimurium YG1024 exhibited a high sensitivity to the mutagenicity of the carcinogenic heterocyclic amines. Because of the high sensitivity, YG1024 and other YG strains were used for various purposes, e.g., identification of novel heterocyclic amines, mechanisms of metabolic activation, comparison of mutagenic potencies of various heterocyclic amines, and the co-mutagenic effects. In the 1990s and 2000s, we developed transgenic mice and rats for the detection of mutagenicity of chemicals in vivo. The transgenics were generated by the introduction of reporter genes for mutations into fertilized eggs of mice and rats. We named the transgenics as gpt delta because the gpt gene of Escherichia coli was used for detection of point mutations such as base substitutions and frameshifts and the red/gam genes of λ phage were employed to detect deletion mutations. The transgenic rodents gpt delta and other transgenics with lacI or lacZ as reporter genes have been utilized for characterization of mutagenicity of heterocyclic amines in vivo. In this review, we summarized the in vitro mutagenicity of heterocyclic amines in Salmonella typhimurium YG strains and the in vivo mutagenicity in transgenic rodents. We discussed the relationships between in vitro and in vivo mutagenicity of the heterocyclic amines and their relations to the carcinogenicity.

Main mechanisms for carcinogenic heterocyclic amine reduction in cooked meat by natural materials

Carcinogens such as heterocyclic amine (HCA), produced during meat cooking, pose a risk of digestive and reproductive cancers in humans. Nevertheless, the exact mechanisms for HCA formation in meat and the control of HCA formation are not known. In this review, we provide an overview of the main cause of HCA formation in cooked meat, fundamental data on natural materials to inhibit HCA carcinogenicity, and methods to analyze HCA in cooked meat. Related past studies has shown that natural substances contain various components that act as antioxidants, and these antioxidants can prevent HCA and mutagenic factors. Free radicals and DNA adducts produced by HCA metabolism have carcinogenic properties. Antioxidants have been found to inhibit oxidative stress caused by free radicals and DNA adducts. Therefore, we can be hypothesized that various natural materials can inhibit HCA carcinogens and mutagens.

Simultaneous determination of the PhIP-proline adduct and related precursors by UPLC-MS/MS for confirmation of direct elimination of PhIP by proline

The effect and elimination pathway of proline on reducing PhIP and the effect of processing temperature, duration, and proline addition on the PhIP-proline adduct and its precursors were investigated. The results have demonstrated that PhIP and proline could condense to produce the adduct by direct heating, which could also be detected in the PhIP-producing model system and in beef patties with proline. The analytical method was optimized and has a good limit of detection (0.006-73 ng/mL), limit of quantification (0.021-245 ng/mL), recovery rate (about 80%-120%), and precision (below 15%). A high dose of proline (5.0%, w/w) promoted the formation of the adduct and reduction of PhIP; long heating duration and high temperature were not conducive to the formation of the adduct in beef patties. With increased addition of proline, creatine and creatinine decreased in a dose-dependent manner; phenylalanine and glucose did not show the same trend.

The role of heterocyclic aromatic amines in colorectal cancer: the evidence from epidemiologic studies

Since Dr. Sugimura’s discovery of heterocyclic aromatic amines (HAA) in broiled fish, many epidemiological studies have been conducted to investigate their role in human cancers, often focusing on colorectal cancer. The difficulty in measuring HAA exposure from meat and fish intake in these studies has resulted in inconsistent findings. Because studying individuals who may be particularly susceptible to the carcinogenic effects of HAA might facilitate the demonstration of a link with cancer, multiple studies have focused on individuals with the high activity phenotype for CYP1A2 and/or NAT2, the two main metabolic enzymes involved in the bioactivation of HAA. These investigations have also yielded inconsistent results. Two recent large pooled analyses of colorectal cancer studies have helped clarify the overall evidence. One was conducted in whites and reported no interaction of red meat intake and NAT2 genotype on risk in Whites. The other was conducted in Japanese and African Americans, two populations with high rates of the disease and a prevalence of the at-risk rapid NAT2 phenotype 10- and 2-fold greater than in whites, respectively. In those groups, a significant interaction was found, with the association of red meat with colorectal cancer being strongest among individuals with the rapid NAT2 phenotype, intermediate among those with the intermediate phenotype and not significant among those with the slow NAT2 phenotype. Recent research on biomarkers has focused on PhIP hair content, as a marker of exposure to HAA, and on DNA adducts using new sensitive quantitative methods, as markers of early biological effects. These advances, when brought to bear, may contribute greatly to the further elucidation of the carcinogenicity of HAA in humans.

Effects of ten vegetable oils on heterocyclic amine profiles in roasted beef patties using UPLC-MS/MS combined with principal component analysis

Soybean oil (SBO), rapeseed oil (RSO), peanut oil (PO), corn oil (CO), olive oil (OO), sunflower oil (SFO), rice germ oil (RGO), walnut oil (WO), torreya seed oil (TSO), and grapeseed oil (GSO) were used to investigate the formation of heterocyclic amines (HAs) in roasted beef patties. Seven HAs, including 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinolone (MeIQ), 2-amino-3-methyl-3H-imidazo[4,5-f]quinoxaline (IQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 1-methyl-9H-pyrido[3,4-b]indole (harman), and 9H-pyrido[3,4-b]indole (norharman) were detected in control patties and patties with vegetable oils. GSO, SFO, and WO greatly reduced the content of PhIP and MeIQ. 1.25%TSO and 3.75% RGO showed higher inhibition effects on the more strongly mutagenic compounds (PhIP, MeIQ, IQx, 4,8-DiMeIQx, MeIQx). SBO, PO, and RSO promoted imidazoquin(ox)aline (MeIQ, MeIQx, 4,8-DiMeIQx, and IQx) and β-carboline (harman and norharman); 1.25% SBO had the most significant promoting effect on total HA. This could be useful for the reduction of HA by selecting oils during cooking.

Memories of a friend and colleague - Takashi Sugimura

Takashi Sugimura, M.D., Honorary President of the National Cancer Center in Tokyo, and former President of The Japan Academy, is regarded by many as a pre-eminent contributor to the field of environmental genotoxicology. His pioneering spirit led to many key discoveries over a long and distinguished scientific career, including the first preclinical models for gastric cancer, identification of novel mutagens from cooked food, and the development of fundamental concepts in environmental chemical carcinogenesis. With his passing on September 6, 2020, many will reflect on the loss of an astute and engaging "Scientific Giant," who with warmth and good humor maintained lasting friendships both at home and abroad, beyond his many important scientific contributions.

Accumulation of heterocyclic amines across low-temperature sausage processing stages as revealed by UPLC-MS/MS

The accumulation of heterocyclic amines (HAs) in low-temperature sausages in each processing stage was investigated using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). The maximum total levels for free HAs, protein-bound HAs, and all HAs were respectively 1.91 ng/g, 162.91 ng/g and 164.82 ng/g. Harman, norharman, Glu-P-1, and PhIP accumulated from raw sausages and reached maximum of 50.88 ng/g, 84.59 ng/g, 9.60 ng/g, and 4.69 ng/g after steaming. The highest level of IQ[4,5-b] was 0.36 ng/g found in raw sausages. AαC, MeAαC, DMIP, and 1,5,6-TMIP were all produced after drying and reached maximum after steaming: 3.25 ng/g, 6.52 ng/g, 0.15 ng/g, and 2.78 ng/g. Additionally, Phe-P-1 reached a maximum of only 0.02 ng/g after drying. MeIQ was generated only after steaming, reaching a maximum of 2.11 ng/g. These results may provide some basis for the inhibition of HAs in meat products through target processing stages.

Influence of dietary patterns on contaminants bioaccessibility and intestinal transport by in vitro assays

Food contaminants are usually studied as isolated molecules, not considering the overall meal components. Notwithstanding, contaminants are not ingested individually, therefore their risks should be assessed in the context of the overall diet. In the present study the influence of three well known dietary patterns, Western (W), Mediterranean (M) and vegetarian (V), on the bioaccessibility and intestinal transport of polycyclic aromatic hydrocarbons (PAHs) (benzo[a]pyrene (BaP) and benzo[b]fluoranthene (BbF)), heterocyclic aromatic amines (HAAs) (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-Amino-9H-pyrido[2,3-b]indole (AAC)) and mycotoxins (MY) (aflatoxin B2 (AB2) and ochratoxin A (OTA)) was evaluated. Whole meals representative of W, M and V patterns were spiked with 100 µg kg^-1 of each contaminant and subjected to the Infogest in vitro digestion method. Intestinal transport was performed using Caco-2 cells in apical/basolateral inserts. Contaminants were quantified by QuEChERS/HPLC/Fluorescence analysis. The dietary pattern itself influenced significantly the bioaccessibility of some contaminants, since higher bioaccessibility of HAAs (PhIP and AAC) was observed for V diet, while higher bioaccessibility of PAHs (BBF and BAP) and the MY (OTA) was observed for W diet. Concerning intestinal transport, the effect of the diet matrices was less noticed. Notwithstanding, AAC transport increased with W diet, while AB2s transport increased with the V diet. Regarding PAHs the three patterns either blocked (BbF) or reduced (BaP) the transport. Besides the well known nutritional, protective or deleterious effects of the different dietary patterns, the increased bioaccessibility or intestinal transport of some food contaminants, can have an additional influence on the global health impact.

and selected flavonoid ingredients on heterocyclic amines in roast beef patties and Density Function Theory calculation of binding between heterocyclic amines intermediates and flavonoids

The inhibitory effects of Portulaca oleracea L. (PO) and its flavonoid ingredients on the formation of heterocyclic amines (HAs) in roast beef patties were investigated. Ten HAs were found in control patties, and the total content was 212.73 ± 7.13 ng/g. With the addition of PO (1%, 5%, and 10%, w/w), HAs decreased by 62.39%, 68.03%, and 73.75%, respectively. The main flavonoid ingredients (rutin, hesperidin, and flavanone) also present a similar inhibitory effect. The Density Function Theory (DFT) methods were adopted to investigate the inhibitory mechanism. These ingredients bonded with the intermediate to block the formation of norharman. Both experimental and calculated data of the ingredients were analyzed on their HAs inhibitory capacity. Our results provide a novel and valuable strategy to reduce HAs via a low additive level of medicinal and edible plants. And the correlation between experimental and calculated data could be applied to predict the inhibitory ability of inhibitors.

Validation of analytical methods for heterocyclic amines in seven food matrices using high-performance liquid chromatography-tandem mass spectrometry

Heterocyclic amines (HCAs) are potent mutagens generated by the high temperatures of the cooking process. The purpose of this study was to develop and validate analytical methods for HCAs determination using high-performance liquid chromatography-tandem mass spectrometry in seven food matrices: corn oil, milk, 20% ethanol, pork, flat fish, sea mustard (Undaria pinnatifida), and radish. Six isotopically labelled internal standards were used for quantitation, and Chem Elut and Oasis hydrphilic-liphophilic balance cartridges were applied for sample preparation to remove interferences. Calibration curves showed good linearity (R² > 0.99) in all matrices. The ranges of the method detection limit and method quantitation limit were 0.009-2.35 ng g^-1 and 0.025-7.13 ng g^-1, respectively. The recoveries ranged from 67.5% to 119.6%. The coefficients of variation ranged from 0.3% to 15.1% for intra-day and ranged from 0.8% to 19.1% for inter-day. The methods were applied to 24 total diet study samples for HCAs quantitation. These results indicate that the established methods are reliable for determining HCAs in various foods.

Rapid determination of heterocyclic amines in ruminant meats using accelerated solvent extraction and ultra-high performance liquid chromatograph-mass spectrometry

Cooking techniques such as grilling confer several benefits to meat during food preparation including improved palatability, digestibility, preservation, and safety, as well as enhancing the sensory characteristics and net nutritional gain. However, grilling can lead to the formation of harmful compounds such heterocyclic amines (HCAs). HCAs are potent carcinogenic and mutagenic nitrogen containing compounds produced during certain cooking conditions of protein rich foods. Dietary intake of HCAs is associated with increased risk factors for cancers in humans. As such, there is overwhelming interest in identifying improved methods for rapid and accurate determination of heterocyclic amines in food matrices that is sensitive and avoids exhaustive sample preparation steps. Herein, we describe an approach that involves first extracting HCAs by pressurized accelerated solvent extractor using methanol as solvent, followed by addition of internal standard and quantification of HCAs by ultra-high performance liquid chromatography-high resolution accurate mass spectrometric detection (UHPLC-HRAMS). This method is fast, accurate, reproducible and does not require exhaustive sample pre-treatments prior to UHPLC-HRAMS analysis compared to existing/traditional methods for HCA analysis. •The method is automated, fast and uses tunable pressurized liquid extractor to selectively extract HCAs•Method does not require exhaustive cleanup and preconcentration steps prior to UHPLC/HRAMS analysis of HCAs•Validation showed method to be accurate, precise, and useful for routine multi-sample HCA analyses.

Mechanistic formation of hazardous molecular heterocyclic amines from high temperature pyrolysis of model biomass materials: cellulose and tyrosine

Background

Research inventories on the co-pyrolysis of major biomass components such as cellulose with amino acid materials is scarce in literature despite the fact that such studies are critical in understanding toxic product relations from high temperature cooking, combustion of bio-fuels, cigarette smoking and forest fires. This paper explores, quantitatively, the yields of heterocyclic nitrogenated molecular reaction products of grave mutagenetic concern from the co-pyrolysis of model biomass materials; tyrosine and cellulose. Research has established that heterocyclic amines such as isocyanates are mutagens as well precursors for asthma, and other respiratory disorders.

Methods

An equimassic mixture of tyrosine and cellulose (50 ± 2 mg) by weight were pyrolyzed in a tubular quartz reactor in flowing nitrogen at 1 atm. Besides, varying combinations of tyrosine and cellulose in the ratios 3:1 and 1:3 were also explored for comparison. The reaction time was set at 2 s so as to simulate combustions events in nature. The pyrolysate was collected over 5 mL dichloromethane and characterized using a gas chromatograph coupled to a mass spectrometer detector.

Results

Evidently, it was noted that 1-methylindazole was released in high yields at 300 °C, constituting ~ 300 µg in the entire pyrolysis temperature range (200–700 °C). Nonetheless, isoindazole gave the highest yield ~ 730 µg while 1-naphthyl isocyanate gave a total yield of ~ 336 µg in the same temperature range. Remarkably, the change in char yield between 300 and 450 °C for the pyrolysis of 25% tyrosine in 75% cellulose was found to be ~ 48% whereas the change in char yield for the pyrolysis of 75% tyrosine in 25% cellulose was 49%.

Conclusion

The char and tar yields considered important residues of biomass burning have been reported in this study and found to be consistent with other research output in literature. The striking similarities of % yield of char across all temperatures for various combinations was the most significant observation in this investigation—char yield was independent of the mixing ratio during pyrolysis. From a mechanistic standpoint, it was noted that tyrosine inhibited cellulose based nitrogenated products. Thus N-products dominated the O-products.

Carcinogenic risk associated with popular Korean dishes: An approach of combined risk assessments using Oral Slope Factor and BMDL10 values

Cooking-related carcinogens are formed during the heating or processing of foods. To date, numerous studies analyzing carcinogens present in cooking ingredients or formed through different cooking methods have been conducted. However, combined risk assessment is important for practical reasons. The purpose of this study was to conduct a combined risk assessment of five cooking-related genotoxic carcinogens encompassing 25 chemicals: heterocyclic amines, acrylamide, furan, polycyclic aromatic hydrocarbons, and nitrosamines. Oral Slope Factor (OSF) and benchmark dose lower-bound confidence limit 10% (BMDL₁₀) of the compounds were obtained from public databases, and the values for the compounds that did not have published reference values were approximated using related toxicity values. The high-risk contributing food items and cooking methods for each carcinogen were selected for the study based on the Korean Total Diet Study (TDS) and Korea National Health and Nutrition Examination Survey (KNHANES). Exposure to the carcinogens from selected dishes per serving was estimated based on concentrations determined in TDS and consumption data gathered from 24-h recalls in the 2014 to 2016 KNHANES. The combined cancer risks were obtained by summing the risks of individual compounds in a dish, which were calculated by multiplying the OSF values by the concentrations of carcinogens per serving. The combined risks were used to compare the risk of different dishes, not to calculate the lifetime risk from the individual dishes. The risks of the dishes prepared with potatoes were found to be high, whereas namul (vegetable dish) had the lowest risk. Soup or stew dishes exhibited relatively high risks. Estimated combined risks based on BMDL₁₀ showed similar trends, except for fried potatoes and roasted or fried meat dishes. Combined risks of cooking-related carcinogens may vary based on the major contributors of individual carcinogens. The results of this study could provide an insightful guideline for selecting menus for consumers.

Transient absorption spectroscopic studies on 4-nitroquinoline N-oxide: From femtoseconds to microseconds timescale

The singlet excited state of 4-nitroquinoline N-oxide (¹NQNO*) has been characterized by different spectroscopic techniques, combining transient absorption with steady state and time-resolved emission spectroscopy. The energy of ¹NQNO* has been established as 255 kJ/mol from the fluorescence spectrum, whereas its lifetime has been found to be 10 ps in the femto-laser flash photolysis (LFP) experiments, where a characteristic S₁S_n absorption band with maximum centered at 425 nm is observed. In a first stage, the triplet excited state of NQNO (³NQNO*) has also been characterized by emission spectroscopy in solid matrix, at low temperature. Thus, from the steady-state phosphorescence spectrum the triplet energy has been estimated as 183 kJ/mol, whereas the setup with time resolution has allowed us to determine the phosphorescence lifetime as 3 ms. Formation of ³NQNO* by intersystem crossing in solution at room temperature, has been monitored by femto-LFP, which shows the appearance of a band with maximum at 560 nm (T₁-T_n). It increases with the decreasing intensity of its precursor 425 nm (S₁S_n) band, giving rise to an isosbestic point at 500 nm. The characterization of ³NQNO* has been completed by nano-LFP, using xanthone as photosensitizer and oxygen as well as β-carotene as quenchers. In addition, quenching of ³NQNO* by electron donors (DABCO) is also observed in aprotic solvents, leading to the radical anion of NQNO (^-NQNO). If there is a proton source in the medium (Et₃N as electron donor or MeCN:H₂O/4:1 as solvent system) protonation of the radical anion results in formation of the neutral radical of NQNO (NQNOH). In general, all processes are slower in protic solvents because of the solvation sphere. Overall, this information provides a deeper insight into the formation and behavior of excited states and radical ionic species derived from the title molecule NQNO.

High red and processed meat consumption is associated with non-alcoholic fatty liver disease and insulin resistance

BACKGROUND & AIMS

High red and processed meat consumption is related to type 2 diabetes. In addition, cooking meat at high temperatures for a long duration forms heterocyclic amines (HCAs), which are related to oxidative stress. However, the association between meat consumption and non-alcoholic fatty liver disease (NAFLD) is yet to be thoroughly tested. Therefore, we aimed to test the association of meat type and cooking method with NAFLD and insulin resistance (IR).

METHODS

This was a cross-sectional study in individuals who were 40-70 years old and underwent screening colonoscopy between 2013 and 2015 in a single center in Israel. NAFLD and IR were evaluated by ultrasonography and homeostasis model assessment. Meat type and cooking method were measured by a food frequency questionnaire (FFQ) and a detailed meat questionnaire. Unhealthy cooking methods were considered as frying and grilling to a level of well done and very well done. Dietary HCA intake was calculated.

RESULTS

A total of 789 individuals had a valid FFQ and 357 had a valid meat questionnaire. High consumption of total meat (portions/day above the median) (odds ratio [OR] 1.49; 95% CI 1.05-2.13; p = 0.028; OR 1.63; 1.12-2.37; p = 0.011), red and/or processed meat (OR1.47; 95% CI 1.04-2.09; p = 0.031; OR1.55; 1.07-2.23; p = 0.020) was independently associated with higher odds of NAFLD and IR, respectively, when adjusted for: body mass index, physical activity, smoking, alcohol, energy, saturated fat and cholesterol intake. High intake of meat cooked using unhealthy methods (OR1.92; 95% CI 1.12-3.30; p = 0.018) and HCAs (OR2.22; 95% CI 1.28-3.86; p = 0.005) were independently associated with higher odds of IR.

CONCLUSION

High consumption of red and/or processed meat is associated with both NAFLD and IR. High HCA intake is associated with IR. If confirmed in prospective studies, limiting the consumption of unhealthy meat types and improving preparation methods may be considered as part of NAFLD lifestyle treatment.

LAY SUMMARY

High red and processed meat consumption is related to several diseases. In addition, cooking meat at high temperatures for a long duration forms heterocyclic amines, which have harmful health effects. Non-alcoholic fatty liver disease is a significant public health burden and its formation is strongly related to insulin resistance. In this study, both were found to be more frequent in people who consume relatively high quantities of red and processed meat. In addition, a high intake of heterocyclic amines was associated with insulin resistance.

Alterations in the nigrostriatal dopamine system after acute systemic PhIP exposure

Heterocyclic amines (HCAs) are primarily formed during cooking of meat at high temperature. HCAs have been extensively studied as mutagens and possible carcinogens. Emerging data suggest that HCAs are neurotoxic and may be relevant to Parkinson's disease (PD) etiology. However, the majority of HCAs have not been evaluated for in vivo neurotoxicity. Here, we investigated acute in vivo neurotoxicity of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). PhIP is the most prevalent genotoxin in many types of meats. Adult, male Sprague-Dawley rats were subjected to acute, systemic PhIP at doses and time-points that have been extensively utilized in cancer studies (100 and 200 mg/kg for 8, 24 h) and evaluated for changes in dopaminergic, serotoninergic, GABAergic, and glutamatergic neurotransmission. PhIP exposure resulted in decreased striatal dopamine metabolite levels and dopamine turnover in the absence of changes to vesicular monoamine transporter 2 levels; other neurotransmitter systems were unaffected. Quantification of intracellular nitrotyrosine revealed higher levels of oxidative damage in dopaminergic neurons in the substantia nigra after PhIP exposure, while other neuronal populations were less sensitive. These changes occurred in the absence of an overt lesion to the nigrostriatal dopamine system. Collectively, our study suggests that acute PhIP treatment in vivo targets the nigrostriatal dopaminergic system and that PhIP should be further examined in chronic, low-dose studies for PD relevance.

Dissecting the mechanisms and molecules underlying the potential carcinogenicity of red and processed meat in colorectal cancer (CRC): an overview on the current state of knowledge

Meat is a crucial nutrient for human health since it represents a giant supply of proteins, minerals, and vitamins. On the opposite hand, the intake of red and processed meat is taken into account dangerous due to its potential of carcinogenesis and cancer risk improvement, particularly for colorectal cancer (CRC), although it has been reported that also the contaminations of beef infected by oncogenic bovine viruses could increase colorectal cancer's risk. Regarding the mechanisms underlying the potential carcinogenicity of red and processed meat, different hypotheses have been proposed. A suggested mechanism describes the potential role of the heterocyclic amines (HACs) and polycyclic aromatic hydrocarbons (PHAs) in carcinogenesis induced by DNA mutation. Another hypothesis states that heme, through the lipid peroxidation process and therefore the formation of N-nitroso compounds (NOCs), produces cytotoxic and genotoxic aldehydes, resulting in carcinogenesis. Furthermore, a recent proposed hypothesis, is based on the combined actions between the N-Glycolylneuraminic acid (Neu5Gc) and genotoxic compounds. The purpose of this narrative review is to shed a light on the mechanisms underlying the potential carcinogenicity of red and processed meat, by summarizing the data reported in literature on this topic.

Lactoperoxidase, an Antimicrobial Milk Protein, as a Potential Activator of Carcinogenic Heterocyclic Amines in Breast Cancer

BACKGROUND

Lactoperoxidase (LPO) is an antimicrobial protein secreted from mammary, salivary and other mucosal glands. It is an important member of heme peroxidase enzymes and the primary peroxidase enzyme present in breast tissues. In addition to the antimicrobial properties, LPO has been shown to be associated with breast cancer etiology. Heterocyclic amines, an important class of environmental and dietary carcinogens, have been increasingly associated with breast cancer etiology. Heterocyclic amines undergo activation in breast tissue as a result of oxidation by LPO. The current study includes three important heterocyclic amines, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methy-6-phenylimidazo[4,5-b]-pyridine (PhIP), that have carcinogenic activity.

MATERIALS AND METHODS

The structural binding characterization of IQ, MeIQx and PhIP with LPO was done using in silico approaches. Their binding pattern and interactions with LPO amino acid residues were analyzed.

RESULTS

The three compounds bound in the distal heme cavity of LPO without replacing the important water molecule required for oxidation of substrate compounds. PhIP displayed lesser binding affinity for LPO in comparison to IQ and MeIQx. The binding mode of heterocyclic amines in distal heme cavity of LPO resembled to that of substrate binding pattern.

CONCLUSION

The three heterocyclic amines are suggested to act as LPO substrate. The undisturbed water molecule present in distal heme cavity of the LPO is expected to facilitate the oxidation and activation of the three heterocyclic amines. These activated compounds may potentially bind with DNA in breast tissues forming DNA adducts and may subsequently lead to breast cancer initiation.

Mitigation strategies of acrylamide, furans, heterocyclic amines and browning during the Maillard reaction in foods

The Maillard reaction (MR) occurs widely during food manufacture and storage, through controlled or uncontrolled pathways. Its consequences are ambiguous depending on the nature and processing of the food products. The MR is often used by food manufacturer to develop appealing aromas, colour or texture in food products (cereal based food, coffee, meat…). However, despite some positive aspects, the MR could decrease the nutritional value of food, generate potentially harmful compounds (e.g. acrylamide, furans, heterocyclic amines) or modify aroma or colour although it is not desired (milk, fruit juice). This paper presents a review of the different solutions available to control or moderate the MR in various food products from preventive to removal methods. A brief reminder of the role and influence of the MR on food quality and safety is also provided.

Impact of DNA repair on the dose-response of colorectal cancer formation induced by dietary carcinogens

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers, which is causally linked to dietary habits, notably the intake of processed and red meat. Processed and red meat contain dietary carcinogens, including heterocyclic aromatic amines (HCAs) and N-nitroso compounds (NOC). NOC are agents that induce various N-methylated DNA adducts and O⁶-methylguanine (O⁶-MeG), which are removed by base excision repair (BER) and O⁶-methylguanine-DNA methyltransferase (MGMT), respectively. HCAs such as the highly mutagenic 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) cause bulky DNA adducts, which are removed from DNA by nucleotide excision repair (NER). Both O⁶-MeG and HCA-induced DNA adducts are linked to the occurrence of KRAS and APC mutations in colorectal tumors of rodents and humans, thereby driving CRC initiation and progression. In this review, we focus on DNA repair pathways removing DNA lesions induced by NOC and HCA and assess their role in protecting against mutagenicity and carcinogenicity in the large intestine. We further discuss the impact of DNA repair on the dose-response relationship in colorectal carcinogenesis in view of recent studies, demonstrating the existence of 'no effect' point of departures (PoDs), i.e. thresholds for genotoxicity and carcinogenicity. The available data support the threshold concept for NOC with DNA repair being causally involved.

Cancer in Japan: Prevalence, prevention and the role of heterocyclic amines in human carcinogenesis

In this article, three topics are being studied in order to understand the present state of cancer in Japan. First, the statistics on cancer mortality indicates that the mortality from cancer in young individuals has been decreasing during the last 50 years, although the total mortality from cancer has been steadily and steeply increasing. Second, epidemiological analyses of cancer causes in Japan indicated that 50 % of cancer cases are preventable, and that prevention of infection and refraining from tobacco smoking will reduce cancer mortality by about 40 %. Third, mutagenic/carcinogenic heterocyclic amines present in cooked meat/fish have been suggested to be carcinogenic in humans in many epidemiological studies carried out in Japan and other countries.

Acid-labile protein-adducted heterocyclic aromatic amines in human blood are not viable biomarkers of dietary exposure: A systematic study

Heterocyclic aromatic amines (HCA) are carcinogenic mutagens formed during cooking of protein-rich foods. HCA residues adducted to blood proteins have been postulated as biomarkers of HCA exposure. However, the viability of quantifying HCAs following hydrolytic release from adducts in vivo and correlation with dietary intake are unproven. To definitively assess the potential of labile HCA-protein adducts as biomarkers, a highly sensitive UPLC-MS/MS method was validated for four major HCAs: 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) and 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx). Limits of detection were 1-5 pg/ml plasma and recoveries 91-115%. Efficacy of hydrolysis was demonstrated by HCA-protein adducts synthesised in vitro. Plasma and 7-day food diaries were collected from 122 fasting adults consuming their habitual diets. Estimated HCA intakes ranged from 0 to 2.5 mg/day. An extensive range of hydrolysis conditions was examined for release of adducted HCAs in plasma. HCA was detected in only one sample (PhIP, 9.7 pg/ml), demonstrating conclusively for the first time that acid-labile HCA adducts do not reflect dietary HCA intake and are present at such low concentrations that they are not feasible biomarkers of exposure. Identification of biomarkers remains important. The search should concentrate on stabilised HCA-peptide markers and use of untargeted proteomic and metabolomic approaches.

Determination of Heterocyclic Amines and Acrylamide in Agricultural Products with Liquid Chromatography-Tandem Mass Spectrometry

Heterocyclic amines (HCAs) and acrylamide are unintended hazardous substances generated by heating or processing of foods and are known as carcinogenic and mutagenic agents by the animal experiments. A simple method was established for a rapid and accurate determination of 12 types of HCAs (IQ, MeIQ, Glu-P-1, Glu-P-2, MeIQx, Trp-P-1, Trp-P-2, PhIP, AαC, MeAαC, Harman and Norharman) and acrylamide in three food matrices (non-fat liquid, non-fat solid and fat solid) by isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). In every sample, a mixture of internal standards including IQ-d3, MeIQx-d3, PhIP-d3, Trp-P-2-(13)C2-(15)N and MeAαC-d3 was spiked for quantification of HCAs and (13)C3-acrylamide was also spiked for the analysis of acrylamide. HCAs and acrylamide in sample were extracted with acetonitrile and water, respectively, and then two solid-phase extraction cartridges, ChemElut: HLB for HCAs and Accucat: HLB for acrylamide, were used for efficiently removing interferences such as pigment, lipid, polar, nonpolar and ionic compounds. Established method was validated in terms of recovery, accuracy, precision, limit of detection, limit of quantitation, and linearity. This method showed good precision (RSD < 20%), accuracy (71.8~119.1%) and recovery (66.0~118.9%). The detection limits were < 3.1 ng/g for all analytes. The correlation coefficients for all the HCAs and acrylamide were > 0.995, showing excellent linearity. These methods for the detection of HCAs and acrylamide by LC-MS/MS were applied to real samples and were successfully used for quantitative monitoring in the total diet study and this can be applied to risk assessment in various food matrices.

Curcumin inhibits PhIP induced cytotoxicity in breast epithelial cells through multiple molecular targets

Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), found in cooked meat, is a known food carcinogen that causes several types of cancer, including breast cancer, as PhIP metabolites produce DNA adduct and DNA strand breaks. Curcumin, obtained from the rhizome of Curcuma longa, has potent anticancer activity. To date, no study has examined the interaction of PhIP with curcumin in breast epithelial cells. The present study demonstrates the mechanisms by which curcumin inhibits PhIP-induced cytotoxicity in normal breast epithelial cells (MCF-10A). Curcumin significantly inhibited PhIP-induced DNA adduct formation and DNA double stand breaks with a concomitant decrease in reactive oxygen species (ROS) production. The expression of Nrf2, FOXO targets; DNA repair genes BRCA-1, H2AFX and PARP-1; and tumor suppressor P16 was studied to evaluate the influence on these core signaling pathways. PhIP induced the expression of various antioxidant and DNA repair genes. However, co-treatment with curcumin inhibited this expression. PhIP suppressed the expression of the tumor suppressor P16 gene, whereas curcumin co-treatment increased its expression. Caspase-3 and -9 were slightly suppressed by curcumin with a consequent inhibition of cell death. These results suggest that curcumin appears to be an effective anti-PhIP food additive likely acting through multiple molecular targets.