Contribution of coffee aroma constituents to the mutagenicity of coffee

Reactivity of the 2-Methylfuran Phase I Metabolite 3-Acetylacrolein Toward DNA

2-Methylfuran (2-MF) is a well-known industrial chemical and also formed via thermal treatment of food. One main source of 2-MF in the human diet is coffee. 2-MF is known to form 3-acetylacrolein (AcA, 4-oxopent-2-enal) via cytochrome P 450 metabolism and further reacts with amino acids in vivo. Still the reactivity toward other biomolecules is rather scarce. Therefore, AcA was synthesized, and its reaction with 2'-deoxyadenosine (dA), 2'deoxyguanosine (dG), 2'deoxycytosine (dC), and 2'-deoxythymidine (dT) was tested. For this purpose, adduct formation was performed by acid hydrolysis of 2,5-dihydro-2,5-dimethoxy-2-methylfuran (DHDMMF) as well as pure AcA. The structures of these adducts were confirmed by UPLC-ESI+-MS/MS fragmentation patterns and 1H-/13CNMR spectra. Except for dT, which showed no reactivity, all adducts of AcA were characterized, which enabled the development of sensitive quantification methods via (U)HPLC-ESI±-MS/MS. Pure AcA was synthesized by oxidation of 2-MF using dimethyldioxirane (DMDO), and its behavior in aqueous medium was studied. Incubations of AcA and isolated DNA of primary rat hepatocytes (pRH) showed time- and dose-dependent formation of the identified DNA adducts dA-AcA, dG-AcA, or dC-AcA. In contrast, the DNA adducts dA-AcA, dG-AcA, or dC-AcA were not detected on a cellular level when pRH were incubated with 2-MF or AcA. This indicates an efficient detoxification or reaction with biomolecules in the cell, although the induction of other DNA damage, possibly also by other metabolites, cannot be ruled out in principle.

Scientific opinion on the renewal of the authorisation of proFagus Smoke R709 (SF-008) as a smoke flavouring Primary Product

The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of the smoke flavouring Primary Product proFagus Smoke R709 (SF-008), for which a renewal application was submitted in accordance with Article 12(1) of Regulation (EC) No 2065/2003. This opinion refers to the assessment of data submitted on chemical characterisation, dietary exposure and genotoxicity of the Primary Product. ProFagus Smoke R709 is obtained by pyrolysis of beech and oak wood as main source materials. The panel concluded that the compositional data provided on the Primary Product are adequate. At the maximum proposed use levels, dietary exposure estimates calculated with DietEx ranged from 0.8 to 12.2 mg/kg body weight (bw) per day at the mean and from 2.3 to 51.4 mg/kg bw per day at the 95th percentile. The Panel concluded that three components in the Primary Product raise a potential concern for genotoxicity. In addition, a potential concern for genotoxicity was identified for the unidentified part of the mixture. The Primary Product contains furan-2(5H)-one, for which a concern for genotoxicity was identified in vivo upon oral administration. Considering that the exposure estimates for this component are above the TTC of 0.0025 μg/kg bw per day for DNA-reactive mutagens and/or carcinogens, the panel concluded that the Primary Product raises concern with respect to genotoxicity.

Scientific opinion on the renewal of the authorisation of Smoke Concentrate 809045 (SF-003) as a smoke flavouring Primary Product

The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of the smoke flavouring Primary Product Smoke Concentrate 809045 (SF-003), for which a renewal application was submitted in accordance with Article 12(1) of Regulation (EC) No 2065/2003. This opinion refers to the assessment of data submitted on chemical characterisation, dietary exposure and genotoxicity of the Primary Product. Product Smoke Concentrate 809045 is obtained by pyrolysis of beech wood. The Panel concluded that the compositional data provided on the Primary Product are adequate. At the maximum proposed use levels, dietary exposure estimates calculated with DietEx ranged from 0.1 to 1.5 mg/kg body weight (bw) per day at the mean and from 0.2 to 5.2 mg/kg bw per day at the 95th percentile. The Panel concluded that eleven components in the Primary Product raise a potential concern for genotoxicity. In addition, a potential concern for genotoxicity was identified for the unidentified part of the mixture. The Primary Product contains furan-2(5H)-one and benzene-1,2-diol, for which a concern for genotoxicity was identified in vivo upon oral administration. Considering that the exposure estimates for these two components are above the threshold of toxicological concern (TTC) of 0.0025 μg/kg bw per day for DNA-reactive mutagens and/or carcinogens, the Panel concluded that the Primary Product raises concern with respect to genotoxicity.

Impact of agro-forestry systems on the aroma generation of coffee beans

A long experiment has been established since 2000 at CATIE (Tropical Agricultural Research and Higher Education Center), Turrialba, Costa Rica. Twenty agro-forestry systems with different shade types and managements (organic and non-organic) consisting of an incomplete randomized block-design with shade tree as main effect and subplots represented by management were set up. The effects of different managements and shade types on the aroma and color generation of roasted coffee beans were investigated. The total protein content was significantly higher (P < 0.05) under the intensive conventional (IC) (168 g/Kg) and intensive organic (IO) (167 g/Kg) managements than under the moderate conventional (MC) (153 g/Kg in IC vs. MC group, 157 g/Kg in MC vs. IO group). Comparing with the moderate conventional (MC) management, the intensive organic (IO) management had a stronger ability to generate more flavor and color. The total protein content was significantly higher (P < 0.05) under the full sun system (172 g/Kg) than under the shaded (159 g/Kg) and Erythrina system (155 g/Kg), under the service system (165 g/Kg) than under the timber system (146 g/Kg), under the legume timber system (170 g/Kg) than under the non-legume timber system (152 g/Kg). The full sun system had a greater flavor generation and color after roasting. Comparing with the timber system, the service system produced roasted beans with the more flavor and color. Comparing with the non-legume shade tree, the legume shade tree improved the performance of flavor and color in the roasted coffee beans.

Model Predictions of Occupational Exposures to Diacetyl and 2,3-Pentanedione Emitted From Roasted Whole Bean and Ground Coffee: Influence of Roast Level and Physical Form on Specific Emission Rates

Roasted coffee emits hazardous volatile organic compounds including diacetyl and 2,3-pentanedione. Workers in non-flavored coffee roasting and packaging facilities might inhale diacetyl and 2,3-pentanedione from roasted coffee above occupational exposure limits depending on their work activities and proximity to the source of emissions. Objectives of this laboratory study were to: (1) investigate factors affecting specific emission rates (SERs) of diacetyl and 2,3-pentanedione from freshly roasted coffee, (2) explore the effect of time on SERs of coffee stored in sealed bags for 10-days, and (3) predict exposures to workers in hypothetical workplace scenarios. Two roast levels (light and dark) and three physical forms (whole bean, coarse ground, and fine ground) were investigated. Particle size for whole bean and ground coffee were analyzed using geometric mean of Feret diameter. Emitted chemicals were collected on thermal desorption tubes and quantified using mass spectrometry analysis. SERs developed here coupled with information from previous field surveys provided model input to estimate worker exposures during various activities using a probabilistic, near-field/far-field model. For freshly roasted coffee, mean SER of diacetyl and 2,3-pentantedione increased with decreasing particle size of the physical form (whole bean &lt; coarse ground &lt; fine ground) but was not consistent with roast levels. SERs from freshly roasted coffee increased with roast level for diacetyl but did not change for 2,3-pentanedione. Mean SERs were greatest for diacetyl at 3.60 mg kg−1 h−1 for dark, fine ground and for 2,3-pentanedione at 3.88 mg kg−1 h−1 for light, fine ground. For storage, SERs of whole bean remained constant while SERs of dark roast ground coffee decreased and light roast ground coffee increased. Modeling demonstrated that near-field exposures depend on proximity to the source, duration of exposure, and air velocities in the near-field further supporting previously reported chemical air measurements in coffee roasting and packaging facilities. Control of source emissions using local exhaust ventilation especially around grinding activities as well as modification of work practices could be used to reduce exposures in this workforce.

Detection of a Hemoglobin Adduct of the Food Contaminant Furfuryl Alcohol in Humans: Levels of N-((Furan-2-yl)methyl)-valine in Two Epidemiological Studies

SCOPE

Furfuryl alcohol is a heat-induced food contaminant, classified as possibly carcinogenic to humans. The proximal carcinogen 2-sulfoxymethylfuran leads to adduct formation in DNA and proteins (e.g., N-((furan-2-yl)methyl)-Val (FFA-Val) in hemoglobin).

METHODS AND RESULTS

This study analyzed human erythrocyte samples from two studies for the presence of FFA-Val: the Risks and Benefits of a Vegan Diet study (RBVD; 72 adults) and the ENVIRonmental influence ON early AGEing birth cohort study (ENVIRONAGE; 100 mother-newborn pairs). In the RBVD study, FFA-Val levels are lower in vegans compared to omnivores (median 13.0 vs 15.8 pmol g^-1 hemoglobin, p = 0.008), and lower in non-smokers compared to smokers (median 14.1 vs 17.0 pmol g^-1 hemoglobin, p = 0.003). In the birth cohort, FFA-Val levels are distinctly higher in maternal compared to newborn samples (median 15.2 vs 2.2 pmol g^-1 hemoglobin, p < 0.001).

CONCLUSIONS

FFA-Val, hitherto detected only in blood samples of mice, is quantifiable in all human samples, indicating a general exposure to furfuryl alcohol. The low adduct levels in blood samples from newborn children suggested that the placenta is a barrier to furfuryl alcohol. Dietary habits and tobacco smoking are two main influencing factors on the formation of FFA-Val, which may be of use as a biomarker of exposure to furfuryl alcohol.

Scientific Opinion on Flavouring Group Evaluation 67, Revision 3 (FGE.67Rev3): consideration of 23 furan-substituted compounds evaluated by JECFA at the 55th, 65th, 69th and 86th meetings

The Panel on Food Additives and Flavourings (FAF) was requested to consider the JECFA evaluations of 25 flavouring substances assigned to the Flavouring Group Evaluation 67 (FGE.67Rev3), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Eleven substances have already been considered in FGE.67 and its revisions (FGE.67Rev1 and FGE.67Rev2). During the current assessment, two substances were no longer supported by industry, therefore 12 candidate substances are evaluated in FGE.67Rev3. New genotoxicity and toxicity data are available for 2-pentylfuran [FL-no: 13.059] and 2-acetylfuran [FL-no: 13.054], which are representative substances of subgroup IV [FL-no: 13.069, 13.106, 13.148] and VI-B [FL-no: 13.045, 13.070, 13.083, 13.101, 13.105, 13.138, 13.163], respectively. Based on these data, the Panel concluded that the concern for genotoxicity is ruled out for both [FL-no: 13.054] and [FL-no: 13.059] and consequently for the substances that they represent. Since the candidate substances cannot be anticipated to be metabolised to innocuous products only, they were evaluated along the B-side of the Procedure. The Panel derived a NOAEL of 22.6 mg/kg bw per day and a BMDL of 8.51 mg/kg bw per day, for 2-acetylfuran and 2-pentylfuran, respectively. For all 12 substances sufficient margins of safety were calculated when based on the MSDI approach. Adequate specifications for the materials of commerce are available for all 23 flavouring substances. The Panel agrees with JECFA conclusions, for all 23 substances, 'No safety concern at estimated levels of intake as flavouring substances' based on the MSDI approach. For 18 substances [FL-no: 13.021, 13.022, 13.023, 13.024, 13.031, 13.045, 13.047, 13.054, 13.059, 13.074, 13.083, 13.101, 13.105, 13.106, 13.138, 13.148, 13.163 and 13.190], the mTAMDI intake estimates are above the threshold of toxicological concern (TTC) for their structural classes and more reliable data on uses and use levels are required to finalise their evaluation.

Scientific Opinion on Flavouring Group Evaluation 13 Revision 3 (FGE.13Rev3): furfuryl and furan derivatives with and without additional side-chain substituents and heteroatoms from chemical group 14

The Panel on Food additives and Flavourings of the EFSA was requested to update Flavouring Group Evaluation 13 using the Procedure as outlined in Commission Regulation (EC) No 1565/2000, to include an evaluation of the flavouring substances 2-ethyl-5-methylfuran [FL-no: 13.125] and 2-octylfuran [FL-no: 13.162]. FGE.13 revision 3 (FGE.13Rev3) deals with 26 flavourings substances of which 24 have been already evaluated to be of no safety concern. For [FL-no: 13.125] and [FL-no: 13.162], a concern for genotoxicity was raised in FGE.13Rev1. This concern could be ruled out based on new genotoxicity data on supporting substances in FGE.67Rev3. Subsequently, [FL-no: 13.125 and 13.162] were evaluated, through a stepwise approach that integrates intake from current uses, toxicological threshold of concern (TTC), and available data on metabolism and toxicity, along the B-side of the Procedure, making use of a BMDL of 8.51 mg/kg body weight (bw) per day. The Panel derived this BMDL from an oral subchronic toxicity study with the supporting substance 2-pentylfuran [FL-no: 13.059]. Using this BMDL, for [FL-no: 13.125 and 13.162], adequate margins of safety were calculated based on the MSDI approach. The Panel concluded that the 26 candidate substances in FGE.13Rev3 do not give rise to safety concerns at their levels of dietary intake, when estimated on the basis of the MSDI approach. Adequate specifications for the materials of commerce have been provided for all 26 substances. Data on uses and use levels are needed for [FL-no: 13.130]. For 21 flavouring substances [FL-no: 13.011, 13.102, 13.108, 13.113, 13.114, 13.122, 13.125, 13.127, 13.129, 13.132, 13.133, 13.135, 13.136, 13.139, 13.141, 13.143, 13.146, 13.149, 13.162, 13.178 and 13.185], the mTAMDI intake estimates are above the TTC for their structural class and more reliable data on uses and use levels are required to finalise their evaluation.

Identification of flavouring substances of genotoxic concern present in e-cigarette refills

E-cigarettes have become very popular, a trend that has been stimulated by the wide variety of available e-liquid flavours. Considering the large number of e-liquid flavours (>7000), there is an urgent need to establish a screening strategy to prioritize the flavouring substances of highest concern for human health. In the present study, a prioritization strategy combining analytical screening, in silico tools and literature data was developed to identify potentially genotoxic e-liquid flavourings. Based on the analysis of 129 e-liquids collected on the Belgian market, 60 flavourings with positive in silico predictions for genotoxicity were identified. By using literature data, genotoxicity was excluded for 33 of them whereas for 5, i.e. estragole, safrole, 2-furylmethylketon, 2,5-dimethyl-4-hydroxyl-3(2H)-furanone and transhexanal, there was a clear concern for in vivo genotoxicity. A selection of 4 out of the remaining 22 flavourings was tested in two in vitro genotoxicity assays. Three out of the four tested flavourings induced gene mutations and chromosome damage in vitro, whereas equivocal results were obtained for the fourth compound. Thus, although there is a legislative framework which excludes the use of CMR compounds in e-liquids, flavourings of genotoxic concern are present and might pose a health risk for e-cigarette users.

Long-term intake of the reactive metabolite methylglyoxal is not toxic in mice

Reactive carbonyls, including methylglyoxal (MG), are considered toxic compounds in foodstuffs because they irreversibly modify proteins and produce advanced glycation end products (AGEs). Therefore, we studied the long-term effect of increased MG intake in mature adult mice. Six-month-old C57BL/6N mice received MG by drinking water (2.5 mg/ml; i.e., 200-300 mg/kg BW/d) until death. This treatment caused an immediate strong increase in urine MG and a delayed moderate increase in plasma MG. At 24 months of age, mice administered MG showed no changes in the blood and tissue activity of glyoxalase-1 (Glo1), an intracellular MG-detoxifying enzyme; no signs of renal insufficiency and diabetes, including unchanged AGE modifications of plasma and vessel proteins; reduced tumour incidence; and slightly increased survival. Mice simultaneously deficient in the receptor for AGEs (RAGE) and overexpressing Glo1 exhibited higher basal plasma MG levels and did generally not respond to long-term MG intake. In vitro experiments supported the minor relevance of Glo1 in the detoxification of circulating MG but the important role of plasma albumin as an MG scavenger. In conclusion, the detoxification of dietary MG through renal excretion and further mechanisms largely prevents the toxicity of MG and possibly other food-derived reactive carbonyls in mature adults.

Extending (Q)SARs to incorporate proprietary knowledge for regulatory purposes: is aromatic N-oxide a structural alert for predicting DNA-reactive mutagenicity?

(Quantitative) structure-activity relationship or (Q)SAR predictions of DNA-reactive mutagenicity are important to support both the design of new chemicals and the assessment of impurities, degradants, metabolites, extractables and leachables, as well as existing chemicals. Aromatic N-oxides represent a class of compounds that are often considered alerting for mutagenicity yet the scientific rationale of this structural alert is not clear and has been questioned. Because aromatic N-oxide-containing compounds may be encountered as impurities, degradants and metabolites, it is important to accurately predict mutagenicity of this chemical class. This article analysed a series of publicly available aromatic N-oxide data in search of supporting information. The article also used a previously developed structure-activity relationship (SAR) fingerprint methodology where a series of aromatic N-oxide substructures was generated and matched against public and proprietary databases, including pharmaceutical data. An assessment of the number of mutagenic and non-mutagenic compounds matching each substructure across all sources was used to understand whether the general class or any specific subclasses appear to lead to mutagenicity. This analysis resulted in a downgrade of the general aromatic N-oxide alert. However, it was determined there were enough public and proprietary data to assign the quindioxin and related chemicals as well as benzo[c][1,2,5]oxadiazole 1-oxide subclasses as alerts. The overall results of this analysis were incorporated into Leadscope's expert-rule-based model to enhance its predictive accuracy.

Genotoxicity of three biofuel candidates compared to reference fuels

Global demand for alternative energy sources increases due to concerns regarding energy security and greenhouse gas emissions. However, little is known regarding the impacts of biofuels to the environment and human health even though the identification of such impacts is important to avoid biofuels leading to undesired effects. In this study mutagenicity and genotoxicity of the three biofuel candidates ethyl levulinate (EL), 2-methyltetrahydrofuran (2-MTHF) and 2-methylfuran (2-MF) were investigated in comparison to two petroleum-derived fuels and a biodiesel. None of the samples induced mutagenicity in the Ames fluctuation test. However, the Micronucleus assay revealed significant effects in Chinese hamster (Cricetulus griseus) V79 cells caused by the potential biofuels. 2-MF revealed the highest toxic potential with significant induction of micronuclei below 20.0 mg/L. EL and 2-MTHF induced micronuclei only at very high concentrations (>1000.0 mg/L). In regard to the genotoxic potential of 2-MF, its usage as biofuel should be critically discussed.

Scientific opinion on flavouring group evaluation 77, revision 3 (FGE.77Rev3): consideration of pyridine, pyrrole and quinoline derivatives evaluated by JECFA (63rd meeting) structurally related to pyridine, pyrrole, indole and quinoline derivatives evaluated by EFSA in FGE.24Rev2

The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the EFSA was requested to consider evaluations of flavouring substances assessed since 2000 by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and to decide whether further evaluation is necessary, as laid down in Commission Regulation (EC) No 1565/2000. The present consideration concerns a group of 22 pyridine, pyrrole and quinoline derivatives evaluated by JECFA (63rd meeting). The revision of this consideration is made since additional genotoxicity data have become available for 6-methylquinoline [FL-no: 14.042]. The genotoxicity data available rule out the concern with respect to genotoxicity and accordingly the substance is evaluated through the Procedure. For all 22 substances [FL-no: 13.134, 14.001, 14.004, 14.007, 14.030, 14.038, 14.039, 14.041, 14.042, 14.045, 14.046, 14.047, 14.058, 14.059, 14.060, 14.061, 14.065, 14.066, 14.068, 14.071, 14.072 and 14.164] considered in this Flavouring Group Evaluation (FGE), the Panel agrees with the JECFA conclusion, 'No safety concern at estimated levels of intake as flavouring substances' based on the Maximised Survey-derived Daily Intake (MSDI) approach. Besides the safety assessment of these flavouring substances, the specifications for the materials of commerce have also been evaluated, and the information is considered adequate for all the substances. For the following substances [FL-no: 13.134, 14.001, 14.030, 14.041, 14.042, 14.058, 14.072], the Industry has submitted use levels for normal and maximum use. For the remaining 15 substances, use levels are needed to calculate the modified Theoretical Added Maximum Daily Intakes (mTAMDIs) in order to identify those flavouring substances that need more refined exposure assessment and to finalise the evaluation.

Scientific Opinion on Flavouring Group Evaluation 74, Revision 4 (FGE.74Rev4): Consideration of aliphatic sulphides and thiols evaluated by JECFA (53rd and 61st meeting) structurally related to aliphatic and alicyclic mono-, di-, tri- and polysulphides with or without additional oxygenated functional groups from chemical group 20 evaluated by EFSA in FGE.08Rev5

The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to consider evaluations of flavouring substances assessed since 2000 by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), and to decide whether further evaluation is necessary, as laid down in Commission Regulation (EC) No 1565/2000. The present revision of this FGE is on the assessment of recently submitted toxicity data on methyl propyl trisulfide [FL‐no: 12.020], being the representative for a group of seven additional flavouring substances: diallyl trisulfide [FL‐no: 12.009], dimethyl trisulfide [FL‐no: 12.013], dipropyl trisulfide [FL‐no: 12.023], methyl allyl trisulfide [FL‐no: 12.045], diallyl polysulfides [FL‐no: 12.074], methyl ethyl trisulfide [FL‐no: 12.155] and diisopropyl trisulphide [FL‐no: 12.280]. Specifications have been provided for all substances. The Panel decided that the 90‐day study submitted for [FL‐no: 12.020] can be considered only once it is clearly demonstrated that the material tested is representative of the material of commerce and that potential reaction products of the components are not of safety concern. Therefore, no conclusion on the safety of the eight flavouring substances [FL‐no: 12.009, 12.013, 12.020, 12.023, 12.045, 12.074, 12.155 and 12.280] can be reached. For 2‐methyl‐4‐oxopentane‐2‐thiol [FL‐no: 12.169] and 2‐mercapto‐2‐methylpentan‐1‐ol [FL‐no: 12.241], additional subchronic toxicity data are required. The remaining nine substances [FL‐no: 12.088, 12.179, 12.198, 12.212, 12.238, 12.239, 12.255, 12.257 and 12.291] in this FGE are not considered of safety concern under the intended conditions of use.

Risks for public health related to the presence of furan and methylfurans in food

The European Commission asked EFSA for a scientific evaluation on the risk to human health of the presence of furan and methylfurans (2-methylfuran, 3-methylfuran and 2,5-dimethylfuran) in food. They are formed in foods during thermal processing and can co-occur. Furans are produced from several precursors such as ascorbic acid, amino acids, carbohydrates, unsaturated fatty acids and carotenoids, and are found in a variety of foods including coffee and canned and jarred foods. Regarding furan occurrence, 17,056 analytical results were used in the evaluation. No occurrence data were received on methylfurans. The highest exposures to furan were estimated for infants, mainly from ready-to-eat meals. Grains and grain-based products contribute most for toddlers, other children and adolescents. In adults, elderly and very elderly, coffee is the main contributor to dietary exposure. Furan is absorbed from the gastrointestinal tract and is found in highest amounts in the liver. It has a short half-life and is metabolised by cytochrome P450 2E1 (CYP2E1) to the reactive metabolite, cis-but-2-ene-1,4-dialdehyde (BDA). BDA can bind covalently to amino acids, proteins and DNA. Furan is hepatotoxic in rats and mice with cholangiofibrosis in rats and hepatocellular adenomas/carcinomas in mice being the most prominent effects. There is limited evidence of chromosomal damage in vivo and a lack of understanding of the underlying mechanism. Clear evidence for indirect mechanisms involved in carcinogenesis include oxidative stress, gene expression alterations, epigenetic changes, inflammation and increased cell proliferation. The CONTAM Panel used a margin of exposure (MOE) approach for the risk characterisation using as a reference point a benchmark dose lower confidence limit for a benchmark response of 10% of 0.064 mg/kg body weight (bw) per day for the incidence of cholangiofibrosis in the rat. The calculated MOEs indicate a health concern. This conclusion was supported by the calculated MOEs for the neoplastic effects.

Ethanol and 4-methylpyrazole increase DNA adduct formation of furfuryl alcohol in FVB/N wild-type mice and in mice expressing human sulfotransferases 1A1/1A2

Furfuryl alcohol (FFA) is a carcinogenic food contaminant, which is formed by acid- and heat-catalyzed degradation of fructose and glucose. The activation by sulfotransferases (SULTs) yields a DNA reactive and mutagenic sulfate ester. The most prominent DNA adduct, N(2)-((furan-2-yl)methyl)-2'-deoxyguanosine (N(2)-MF-dG), was detected in FFA-treated mice and also in human tissue samples. The dominant pathway of FFA detoxification is the oxidation via alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs). The activity of these enzymes may be greatly altered in the presence of inhibitors or competitive substrates. Here, we investigated the impact of ethanol and the ADH inhibitor 4-methylpyrazole (4MP) on the DNA adduct formation by FFA in wild-type and in humanized mice that were transgenic for human SULT1A1/1A2 and deficient in the mouse (m) Sult1a1 and Sult1d1 genes (h1A1/1A2/1a1(-)/1d1(-)). The administration of FFA alone led to hepatic adduct levels of 4.5 N(2)-MF-dG/10(8) nucleosides and 33.6 N(2)-MF-dG/10(8) nucleosides in male and female wild-type mice, respectively, and of 19.6 N(2)-MF-dG/10(8) nucleosides and 95.4 N(2)-MF-dG/10(8) nucleosides in male and female h1A1/1A2/1a1(-)/1d1(-) mice. The coadministration of 1.6g ethanol/kg body weight increased N(2)-MF-dG levels by 2.3-fold in male and by 1.7-fold in female wild-type mice and by 2.5-fold in male and by 1.5-fold in female h1A1/1A2/1a1(-)/1d1(-) mice. The coadministration of 100mg 4MP/kg body weight had a similar effect on the adduct levels. These findings indicate that modulators of the oxidative metabolism, e.g. the drug 4MP or consumption of alcoholic beverages, may increase the genotoxic effects of FFA also in humans.

Bioactivation of food genotoxicants 5-hydroxymethylfurfural and furfuryl alcohol by sulfotransferases from human, mouse and rat: a comparative study

5-Hydroxymethylfurfural (HMF) and furfuryl alcohol (FFA) are moderately potent rodent carcinogens that are present in thermally processed foodstuffs. The carcinogenic effects were hypothesized to originate from sulfotransferase (SULT)-mediated bioactivation yielding DNA-reactive and mutagenic sulfate esters, a confirmed metabolic pathway of HMF and FFA in mice. It is known that orthologous SULT forms substantially differ in substrate specificity and tissue distribution. This could influence HMF- and FFA-induced carcinogenic effects. Here, we studied HMF and FFA sulfoconjugation by 30 individual SULT forms of humans, mice and rats. The catalytic efficiencies (k_cat/K_M) of HMF sulfoconjugation of human SULT1A1 (13.7 s⁻¹ M⁻¹), mouse Sult1a1 (15.8 s⁻¹ M⁻¹) and 1d1 (4.8 s⁻¹ M⁻¹) and rat Sult1a1 (5.3 s⁻¹ M⁻¹) were considerably higher than those of all other SULT forms investigated (≤0.73 s⁻¹ M⁻¹). FFA sulfoconjugation was monitored using adenosine as a nucleophilic scavenger for the reactive 2-sulfoxymethylfuran (t_1/2 = 20 s at 37 °C). The resulting adduct N⁶-((furan-2-yl)methyl)-adenosine (N⁶-MF-A) was quantified by isotope-dilution UPLC-MS/MS. The rates of N⁶-MF-A formation showed that hSULT1A1 and its orthologues in mice and rats were also the most important contributors to FFA sulfoconjugation in each of the species. Taken together, the catalytic capacity of hSULT1A1 is comparable to that of mSult1a1 in mice, the species in which carcinogenic effects of HMF and FFA were detected. This is of primary concern due to the expression of hSULT1A1 in many different tissues.

The effect of knockout of sulfotransferases 1a1 and 1d1 and of transgenic human sulfotransferases 1A1/1A2 on the formation of DNA adducts from furfuryl alcohol in mouse models

Furfuryl alcohol is a rodent carcinogen present in numerous foodstuffs. Sulfotransferases (SULTs) convert furfuryl alcohol into the DNA reactive and mutagenic 2-sulfoxymethylfuran. Sensitive techniques for the isotope-dilution ultra performance liquid chromatography-tandem mass spectrometry quantification of resulting DNA adducts, e.g. N (2)-((furan-2-yl)methyl)-2'-deoxyguanosine (N (2)-MF-dG), were developed. To better understand the contribution of specific SULT forms to the genotoxicity of furfuryl alcohol in vivo, we studied the tissue distribution of N (2)-MF-dG in different mouse models. Earlier mutagenicity studies with Salmonella typhimurium strains expressing different human and murine SULT forms indicated that human SULT1A1 and murine Sult1a1 and 1d1 catalyze furfuryl alcohol sulfo conjugation most effectively. Here, we used three mouse lines to study the bioactivation of furfuryl alcohol by murine SULTs, FVB/N wild-type (wt) mice and two genetically modified models lacking either murine Sult1a1 or Sult1d1. The animals received a single dose of furfuryl alcohol, and the levels of the DNA adducts were determined in liver, kidney, lung, colon and small intestine. The effect of Sult1d1 gene disruption on the genotoxicity of furfuryl alcohol was moderate and limited to kidney and small intestine. In contrast, the absence of functional Sult1a1 had a massive influence on the adduct levels, which were lowered by 33-73% in all tissues of the female Sult1a1 null mice compared with the wt animals. The detection of high N (2)-MF-dG levels in a humanized mouse line expressing hSULT1A1/1A2 instead of endogeneous Sult1a1 and Sult1d1 supports the hypothesis that furfuryl alcohol is converted to the mutagenic 2-sulfoxymethylfuran also in humans.

Novel experimental model of non-infectious pharyngitis in rats

INTRODUCTION

Currently, there is a paucity of scientific literature and reports related to screening models for non-infectious type of pharyngitis. In this context, we made a sincere attempt to establish a novel animal model for screening drugs against non-infectious pharyngitis in rats. We have considered the use of pyridine, croton oil and their combination for inducing non-infectious pharyngitis in rats.

METHODS

Various concentrations of pyridine were applied topically to the pharyngeal region of rats and the extent of inflammation was assessed by Evans Blue (EB) dye exudation test, evaluating the serum levels of proinflammatory cytokines and histopathology. Dexamethasone and diclofenac were used as reference standards.

RESULTS

Upon pyridine application (2.5%, 5%, 10%, 20%, 40% and 80% in saline), dose-dependent increase in EB dye extravasation was observed (increased vascular permeability). In addition, the levels of TNF-α (P<0.01) and IL-6 (P<0.01) were significantly increased compared to control. Furthermore, the histopathology of pharyngeal tissue showed hypertrophy of submucosal glands, severe inflammation of the pharynx characterised by presence of mononuclear cells, neutrophils along with haemorrhages and congestion; however, normal control animals showed normal cytoarchitecture of pharynx. Indeed, dexamethasone (0.25, 0.5 and 1 mg/kg, i.v.) and diclofenac (1, 2.5 and 5 mg/kg, i.v.) showed dose-dependent protection against pyridine-induced pharyngitis. Further, the possible mechanism of pyridine-induced pharyngitis is thought to be primarily mediated through phospholipase A2 and cyclooxygenase (COX) pathway.

CONCLUSION

These findings suggest that pyridine-induced pharyngitis is a simple and versatile novel animal model for screening the drugs against non-infectious pharyngitis in rats.

On-line process monitoring of coffee roasting by resonant laser ionisation time-of-flight mass spectrometry: bridging the gap from industrial batch roasting to flavour formation inside an individual coffee bean

Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOFMS) enables the fast and sensitive on-line monitoring of volatile organic compounds (VOC) formed during coffee roasting. On the one hand, REMPI-TOFMS was applied to monitor roasting gases of an industrial roaster (1500 kg/h capacity), with the aim of determining the roast degree in real-time from the transient chemical signature of VOCs. On the other hand, a previously developed μ-probe sampling device was used to analyse roasting gases from individual coffee beans. The aim was to explore fundamental processes at the individual bean level and link these to phenomena at the batch level. The pioneering single-bean experiments were conducted in two configurations: (1) VOCs formed inside a bean were sampled in situ, i.e. via a drilled μ-hole, from the interior, using a μ-probe (inside). (2) VOCs were sampled on-line in close vicinity of a single coffee bean's surface (outside). The focus was on VOCs originating from hydrolysis and pyrolytic degradation of chlorogenic acids, like feruloyl quinic acid and caffeoyl quinic acid. The single bean experiments revealed interesting phenomena. First, differences in time-intensity profiles between inside versus outside (time shift of maximum) were observed and tentatively linked to the permeability of the bean's cell walls material. Second, sharp bursts of some VOCs were observed, while others did exhibit smooth release curves. It is believed that these reflect a direct observation of bean popping during roasting. Finally, discrimination between Coffea arabica and Coffea canephora was demonstrated based on high-mass volatile markers, exclusively present in spectra of Coffea arabica.

Automatic knowledge extraction from chemical structures: the case of mutagenicity prediction

This work proposes a new structure-activity relationship (SAR) approach to mine molecular fragments that act as structural alerts for biological activity. The entire process is designed to fit with human reasoning, not only to make the predictions more reliable but also to permit clear control by the user in order to meet customized requirements. This approach has been tested on the mutagenicity endpoint, showing marked prediction skills and, more interestingly, bringing to the surface much of the knowledge already collected in the literature as well as new evidence.

Genome-wide association analysis of coffee drinking suggests association with CYP1A1/CYP1A2 and NRCAM

Coffee consumption is a model for addictive behavior. We performed a meta-analysis of genome-wide association studies (GWASs) on coffee intake from 8 Caucasian cohorts (N=18 176) and sought replication of our top findings in a further 7929 individuals. We also performed a gene expression analysis treating different cell lines with caffeine. Genome-wide significant association was observed for two single-nucleotide polymorphisms (SNPs) in the 15q24 region. The two SNPs rs2470893 and rs2472297 (P-values=1.6 × 10(-11) and 2.7 × 10(-11)), which were also in strong linkage disequilibrium (r(2)=0.7) with each other, lie in the 23-kb long commonly shared 5' flanking region between CYP1A1 and CYP1A2 genes. CYP1A1 was found to be downregulated in lymphoblastoid cell lines treated with caffeine. CYP1A1 is known to metabolize polycyclic aromatic hydrocarbons, which are important constituents of coffee, whereas CYP1A2 is involved in the primary metabolism of caffeine. Significant evidence of association was also detected at rs382140 (P-value=3.9 × 10(-09)) near NRCAM-a gene implicated in vulnerability to addiction, and at another independent hit rs6495122 (P-value=7.1 × 10(-09))-an SNP associated with blood pressure-in the 15q24 region near the gene ULK3, in the meta-analysis of discovery and replication cohorts. Our results from GWASs and expression analysis also strongly implicate CAB39L in coffee drinking. Pathway analysis of differentially expressed genes revealed significantly enriched ubiquitin proteasome (P-value=2.2 × 10(-05)) and Parkinson's disease pathways (P-value=3.6 × 10(-05)).