Role of glutathione on acrylamide inhibition: Transformation products and mechanism.

Glutathione (GSH) is a potential inhibitor for acrylamide (AA) in heated food. In the present study, the inhibition pathways of GSH on AA were investigated in the asparagine(Asn)/glucose(Glc)/GSH model system. In comparison to the Asn/Glc model system, three unique molecular ions (m/z 470, 379, and 193) were identified in the Asn/Glc/GSH model system. Those molecular ions were confirmed as the Amadori rearrangement products which formed in the reaction between Glc and GSH, as well as the addition reaction products between AA and the sulfhydryl group (-SH) of GSH and cysteine (Cys). The competition between Asn and GSH for Glc in the competitive reactions was assumed to be the major pathway. Additionally, the elimination reaction between AA and GSH or between AA and Cys also played a minor role in the inhibition of AA. The variances of precursors, intermediates, and final products provided quantitative evidence for the above pathways.

Protective Effect of the Intracellular Content from Potential Probiotic Bacteria against Oxidative Damage Induced by Acrylamide in Human Erythrocytes.

The aim of this study was to assess the protective effect of the intracellular content obtained from potential probiotic bacteria against acrylamide-induced oxidative damage in human erythrocytes. First, the antioxidant properties of 12 potential probiotic strains was evaluated. Two commercial probiotic bacteria were included as reference strains, namely, Lactobacillus casei Shirota and Lactobacillus paracasei 431. Data showed that the intracellular content from four strains, i.e., Lactobacillus fermentum J10, Lactobacillus pentosus J24 and J26, and Lactobacillus pentosus J27, showed higher (P < 0.05) antioxidant capacity in most methods used. Thereafter, the intracellular content of such pre-selected strains was able to prevent the disturbance of the antioxidant system of human erythrocytes exposed to acrylamide, thereby reducing cell disruption and eryptosis development (P < 0.05). Additionally, the degree of oxidative stress in erythrocytes exposed to acrylamide was significantly (P < 0.05) reduced to levels similar to the basal conditions when the intracellular content of Lact. fermentum J10, Lact. pentosus J27, and Lact. paracasei 431 were employed. Hence, our findings suggest that the intracellular contents of specific Lactobacillus strains represent a potential source of metabolites with antioxidant properties that may help reduce the oxidative stress induced by acrylamide in human erythrocytes.

Acrylamide applied during pregnancy causes the neurotoxic effect by lowering BDNF levels in the fetal brain.

OBJECTIVES: The aim of this study is to elucidate the possible mechanism of neurotoxic effect of acrylamide (AA) applied during pregnancy on fetal brain development and to show the effect of N-acetylcysteine (NAC) on AA toxicity. MATERIALS AND METHODS: Four groups were formed with 9 pregnant rats each as control (C), acrylamide (AA), N-acetylcysteine (NAC), acrylamide plus N-acetylcysteine (AA plus NAC) groups. Caesarian section was implemented on the 20th day of pregnancy. Malondialdehyde (MDA), reduced glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT) and Brain-derived neurotrophic factor (BDNF) levels were analyzed and histopathologic examinations were performed in brain tissues of the fetuses. RESULTS: Our data indicated that AA caused necrotic death and hemorrhagic damages in fetal brain tissue with decreasing BNDF levels and increasing oxidative stress. N-acetylcysteine prevented the toxic effects of its on fetal brain (p < 0.05). CONCLUSION: Our study indicated that acrylamide has toxic effects in the fetal brain and N-acetylcysteine prevents its toxic effect.

Acrylamide-induced oxidative stress and inflammatory response are alleviated by N-acetylcysteine in PC12 cells: Involvement of the crosstalk between Nrf2 and NF-κB pathways regulated by MAPKs.

Acrylamide (ACR) is a classic neurotoxin in animals and humans. However, the mechanism underlying ACR neurotoxicity remains controversial, and effective prevention and treatment measures against this condition are scarce. This study focused on clarifying the crosstalk between the involved signaling pathways in ACR-induced oxidative stress and inflammatory response and investigating the protective effect of antioxidant N-acetylcysteine (NAC) against ACR in PC12 cells. Results revealed that ACR exposure led to oxidative stress characterized by significant increase in reactive oxygen species (ROS) and malondialdehyde (MDA) levels and glutathione (GSH) consumption. Inflammatory response was observed based on the dose-dependently increased levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6). NAC attenuated ACR-induced enhancement of MDA and ROS levels and TNF-α generation. In addition, ACR activated nuclear transcription factor E2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB) signaling pathways. Knockdown of Nrf2 by siRNA significantly blocked the increased NF-κB p65 protein expression in ACR-treated PC12 cells. Down-regulation of NF-κB by specific inhibitor BAY11-7082 similarly reduced ACR-induced increase in Nrf2 protein expression. NAC treatment increased Nrf2 expression and suppressed NF-κB p65 expression to ameliorate oxidative stress and inflammatory response caused by ACR. Further results showed that mitogen-activated protein kinases (MAPKs) pathway was activated prior to the activation of Nrf2 and NF-κB pathways. Inhibition of MAPKs blocked Nrf2 and NF-κB pathways. Collectively, ACR activated Nrf2 and NF-κB pathways which were regulated by MAPKs. A crosstalk between Nrf2 and NF-κB pathways existed in ACR-induced cell damage. NAC protected against oxidative damage and inflammatory response induced by ACR by activating Nrf2 and inhibiting NF-κB pathways in PC12 cells.

A combination of additives can synergically decrease acrylamide content in gingerbread without compromising sensory quality.

BACKGROUND: The present study tested whether replacement of the leavening agent ammonium carbonate by sodium hydrogen carbonate in combination with calcium cation and acidifying agent will synergically decrease acrylamide (AA) content in gingerbread. RESULTS: The type of leavening agent and the presence of Ca2+ and citric acid accounted for 33.6%, 13.2% and 53.2% of the explained variability of the AA content, respectively (P < 0.01). The AA content in gingerbread produced with (NH4 )2 CO3 alone was 186.5 µg kg-1 . Irrespective of other tested additives, NaHCO3 decreased (P < 0.05) AA content to 42% compared to (NH4 )2 CO3 . Combination of NaHCO3 + CaCl2 + citric acid in dough reduced (P < 0.05) AA content below the limit of detection (25 µg kg-1 ). The AA content in gingerbread (y; µg kg-1 ) decreased with an increasing number of additives used (x) according to the equation y = 158.8 - 47.94x (r2 = 0.42; P < 0.0001). A comprehensive sensory analysis did not indicate any significant deterioration (P > 0.05) in the organoleptic quality of gingerbread produced using calcium cation and citric acid. CONCLUSION: The present study demonstrates that the combination of additives NaHCO3 /Ca2+ /citric acid synergically decreases AA content in gingerbread without compromising the sensory quality. © 2016 Society of Chemical Industry.

The kinetics of the inhibition of acrylamide by glycine in potato model systems.

BACKGROUND: Acrylamide (AA) is a potential carcinogen which widely exists in heat-processed foods. The addition of glycine (Gly) has been shown to reduce the formation of AA. The objective of this work was to investigate the kinetics of the inhibition of AA by Gly in both asparagine (Asn)/glucose (Glc) and Asn/Glc/Gly potato model systems during heating at 160 °C, 180 °C, and 200 °C. RESULTS: The simplified two consecutive first-order kinetic model fitted well to the changes of AA in both systems. No significant difference in rate constant (kF) and apparent activation energy (EaF) was observed for AA formation between the two systems (P > 0.05). Whereas EaE and only kE at 200 °C for AA elimination in the Asn/Glc/Gly system was significantly higher than Asn/Glc system (P < 0.05). The elimination reaction between Gly and AA was confirmed by the identification of their major reaction product 2-((3-amino-3-oxopropyl)amino)acetic acid in the Asn/Glc/(15) N-Gly system. CONCLUSION: The reduction of AA by Gly is predominantly attributed to the elimination reaction between Gly and AA.

Acrylamide: inhibition of formation in processed food and mitigation of toxicity in cells, animals, and humans.

Potentially toxic acrylamide is largely derived from the heat-inducing reactions between the amino group of the amino acid asparagine and carbonyl groups of glucose and fructose in plant-derived foods including cereals, coffees, almonds, olives, potatoes, and sweet potatoes. This review surveys and consolidates the following dietary aspects of acrylamide: distribution in food, exposure and consumption by diverse populations, reduction of the content in different food categories, and mitigation of adverse in vivo effects. Methods to reduce acrylamide levels include selecting commercial food with a low acrylamide content, selecting cereal and potato varieties with low levels of asparagine and reducing sugars, selecting processing conditions that minimize acrylamide formation, adding food-compatible compounds and plant extracts to food formulations before processing that inhibit acrylamide formation during processing of cereal products, coffees, teas, olives, almonds, and potato products, and reducing multiorgan toxicity (antifertility, carcinogenicity, neurotoxicity, teratogenicity). The herein described observations and recommendations are of scientific interest for food chemistry, pharmacology, and toxicology, but also have the potential to benefit nutrition, food safety, and human health.

Potential protective effect of L-cysteine against the toxicity of acrylamide and furan in exposed Xenopus laevis embryos: an interaction study.

The embryo toxicities of two food-processing-induced toxic compounds, acrylamide and furan, with and without added L-cysteine were examined individually and in mixtures using the frog embryo teratogenesis assay-Xenopus (FETAX). The following measures of developmental toxicity were used: (a) 96 h LC50, the median concentration causing 50% embryo lethality; (b) 96 h EC50, the median concentration causing 50% malformations of the surviving embryos; and (c) teratogenic index (96 h LC50/96 h EC50), an estimate of teratogenic risk. Calculations of toxic units (TU) were used to assess possible antagonism, synergism, or response addition of several mixtures. The evaluated compounds demonstrated counterintuitive effects. Furan had lower than expected toxicity in Xenopus embryos and, unlike acrylamide, does not seem to be teratogenic. However, the short duration of the tests may not show the full effects of furan if it is truly primarily genotoxic and carcinogenic. L-Cysteine showed unexpected properties in the delay of hatching of the embryos. The results from the interaction studies between combination of two or three components (acrylamide plus L-cysteine; furan plus L-cysteine; acrylamide plus furan; acrylamide plus furan and L-cysteine) show that furan and acrylamide seem to have less than response addition at 1:1 toxic unit ratio in lethality. Acrylamide and L-cysteine show severe antagonism even at low 19 acrylamide/1 L-cysteine TU ratios. Data from the mixture of acrylamide, furan, and L-cysteine show a slight antagonism, less than would have been expected from binary mixture exposures. Bioalkylation mechanisms and their prevention are discussed. There is a need to study the toxicological properties of mixtures of acrylamide and furan concurrently formed in heat-processed food.

Chrysin reduced acrylamide-induced neurotoxicity in both in vitro and in vivo assessments.

BACKGROUND: Acrylamide (ACR) is a well-known industrial toxic chemical that produces neurotoxicity, which is characterized by progressive central and peripheral neuronal degeneration. Chrysin is a natural, biologically active flavonoid compound, which is commonly found in many plants. The antioxidant and neuroprotective properties of chrysin have been demonstrated. METHODS: In this study, the possible effect of chrysin on ACR-induced toxicity was evaluated in both in vitro and in vivo experiments. PC12 cells were used as a suitable in vitro model. Cells were exposed to chrysin (0.5-5 µM) for 12 and 24 h, and then ACR in IC50 concentration was added to the cells. Finally, cell viability was determined using (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium assay. For in vivo assay, Wistar rats were treated with ACR (50 mg/kg i.p. for 11 days) alone or in combination with chrysin (12.5, 25, and 50 mg/kg). At the end of treatment, behavioral index was evaluated. RESULTS: ACR decreased cell viability and pre-treatment with chrysin (0.5-5 µM) significantly decreased ACR-induced cytotoxicity in the time- and dose-dependent manner. In Wistar rats, exposure to ACR significantly induced severe gait abnormalities, but treatment with chrysin (50 mg/kg) reduced ACR-induced neurotoxicity in animals. CONCLUSION: In the current study, chrysin exhibited neuroprotective effect on PC12 cells as an in vitro model and also on Wistar rats.

Ameliorating effect of fish oil on acrylamide induced oxidative stress and neuronal apoptosis in cerebral cortex.

Acrylamide (ACR) is a known industrial toxic chemical that produce neurotoxicity characterized by progressive neuronal degeneration. This study was designed to investigate the protective effect of fish oil on ACR-induced neuronal damage in Wistar rats. ACR enhances the production of reactive oxygen species and potentially affects brain. ACR administered rats showed increased levels of lipid peroxidative product, protein carbonyl content, hydroxyl radical and hydroperoxide which were significantly modulated by the supplementation of fish oil. The activities of enzymic antioxidants and levels of reduced glutathione were markedly lowered in ACR-induced rats; fish oil treatment augmented these antioxidant levels in cortex. Free radicals generated during ACR administration reduced the activities of membrane adenosine triphosphatases and acetylcholine esterase. Fish oil enhanced the activities of these enzymes near normal level. Histological observation represented the protective role of fish oil in ACR-induced neuronal damage. Fish oil reduced the ACR-induced apoptosis through the modulation in expressions of B-cell lymphoma 2 (Bcl2)-associated X protein and Bcl2-associated death promoter. Further, fish oil increases the expression of heat shock protein 27 (Hsp27) in ACR-induced rats. This study provides evidence for the neuroprotective effect of fish oil on ACR-induced neurotoxicity by reducing oxidative stress and apoptosis with modulation in the expression of Hsp27.

Protective effect of hydroxytyrosol against acrylamide-induced cytotoxicity and DNA damage in HepG2 cells.

The chemoprotective effect of hydroxytyrosol (HT) against acrylamide (AA)-induced cytotoxicity and DNA damage was investigated in a human hepatoma cell line, HepG2. The cytotoxicity was estimated by methyl thiazol tetrazolium bromide (MTT) assay. The comet assay was used to monitor DNA damage. The intracellular reactive oxygen species (ROS) formation and the level of oxidative DNA damage were estimated by using 2,7-dichlorofluorescein diacetate (DCFH-DA) as a fluorescent probe and by using immunocytochemistry analysis of 8-hydroxydeoxyguanosine (8-OHdG). Intracellular glutathione (GSH) level was estimated by fluorometric methods. The results showed that HT significantly reduced the cytotoxicity, DNA damage, intracellular ROS formation and 8-OHdG level caused by AA in a concentration-dependent manner. It was also found that HT concentration-dependently attenuated GSH depletion in HepG2 cells treated with 10mM AA. These findings suggest that HT has a strong protective ability against the cytotoxicity and DNA damage caused by AA.

Evaluating the potential for enzymatic acrylamide mitigation in a range of food products using an asparaginase from Aspergillus oryzae.

Asparaginase, an enzyme that hydrolyzes asparagine to aspartic acid, presents a potentially very effective means for reducing acrylamide formation in foods via removal of the precursor, asparagine, from the primary ingredients. An extracellular asparaginase amenable to industrial production was cloned and expressed in Aspergillus oryzae . This asparaginase was tested in a range of food products, including semisweet biscuits, ginger biscuits, crisp bread, French fries, and sliced potato chips. In dough-based applications, addition of asparaginase resulted in reduction of acrylamide content in the final products of 34-92%. Enzyme dose, dough resting time, and water content were identified as critical parameters. Treating French fries and sliced potato chips was more challenging as the solid nature of these whole-cut products limits enzyme-substrate contact. However, by treating potato pieces with asparaginase after blanching, the acrylamide levels in French fries could be lowered by 60-85% and that in potato chips by up to 60%.

Inhibition of acrylamide toxicity in mice by three dietary constituents.

The inhibitory effects of three dietary constituents, tea polyphenols, resveratrol, and diallyl trisulfide, on acrylamide-biomacromolecule (liver DNA, protamine, and hemoglobin) adduct formation at human exposure level were studied by accelerator mass spectrometry. The results demonstrated that the three dietary constituents all significantly inhibited the formation of acrylamide adducts with liver DNA, whereas tea polyphenols and diallyl trisulfide reduced protamine and hemoglobin adducts, respectively. Further biochemical studies showed that acrylamide could significantly inactivate creatine kinase and glutathione S-transferase and deplete glutathione. When the inhibitors were cotreated with acrylamide, all of them could effectively recover the activities of creatine kinase. In addition, tea polyphenols and diallyl trisulfide could increase glutathione S-transferase activity remarkably. On the basis of these results, mechanisms of the effects are discussed. This study might provide a beneficial guide to people's diet for the purpose of reducing the harmful effect of acrylamide.

Mitigation strategies to reduce acrylamide formation in fried potato products.

Potato products contain high amounts of acrylamide, which sometimes exceeds the concentration of 1 mg/L. However, many strategies for acrylamide reduction in potato products are possible. In this work, the different approaches for reducing acrylamide formation have been reviewed, keeping in mind that in the application of strategies for acrylamide formation, the main criteria to be maintained are the overall organoleptic and nutritional qualities of the final product.

Chemoprevention of acrylamide toxicity by antioxidative agents in rats--effective suppression of testicular toxicity by phenylethyl isothiocyanate.

The efficacies of N-acetylcysteine (NAC), phenylethyl isothiocyanate (PEITC), and 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ) at preventing the neurotoxicity and testicular toxicity of acrylamide (ACR) were investigated in rats. To this end, Sprague-Dawley males were given 0.02% ACR in drinking water, with or without 1% NAC, 0.5% PEITC or 0.1% HTHQ in the diet for four weeks. A group of untreated controls was also included in the study. All ACR-treated animals exhibited progressive neurotoxicity as judged by gait scores, and among the chemicals co-administered, only HTHQ caused any suppression by the end of the experiment, and this was slight. The severity of the neurotoxicity, as judged by axonal degeneration in the spinal gracile fasciculus and sciatic nerve (distal portion) and aberrant dot-like synaptophysin immunoreactivity, reflecting nerve terminal degeneration in the cerebellar molecular layer, was not clearly reduced by co-administration of HTHQ, NAC or PEITC either. ACR-induced sciatic nerve axon atrophy was marginally and non-significantly reduced by HTHQ. In contrast, in terms of ACR-induced testicular toxicity, exfoliation of spermatids into seminiferous lumen was clearly reduced by co-administered PEITC and was marginally reduced by co-administered HTHQ. These antioxidative agents may therefore reduce/prevent ACR-induced toxicity, at least in the testes.