The effects of pinealectomy and melatonin treatment in acrylamide-induced nephrotoxicity in rats: Antioxidant and anti-inflammatory mechanisms

OBJECTIVE

Acrylamide (AA) is toxic and forms in food that undergoes high-temperature processing. This study aimed to investigate the effects of AA-induced toxicity on renal tissue in pinealectomized rats and the possible protective effect of exogenous Melatonin (ML) administration.

MATERIALS AND METHODS

Sixty rats were randomized into 6 groups (n = 10): Sham, Sham+AA, Sham+AA+ML, PX, PX+AA, and PX+AA+ML. Sham and pinealectomized rats received AA (25 mg/kg/day orally) and ML (0.5 ml volume at 10 mg/kg/day, intraperitoneal) for 21 days.

RESULTS

The results showed that malondialdehyde (MDA), total oxidant status (TOS), oxidative stress index (OSI), tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) levels of the kidney and urea and creatinine levels of serum in the PX (pinealectomy)+AA group were more increased than in the Sham+AA group. In addition, glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and total antioxidant status (TAS) levels decreased more in the PX+AA group than in the Sham+AA group. Also, we observed more histopathologic damage in the PX+AA group. On the other hand, up-regulation of kidney tissue antioxidants, down-regulation of tissue oxidants, and improvement in kidney function were achieved with ML treatment. Also, histopathological findings such as inflammatory cell infiltration, shrinkage of glomeruli, and dilatation of tubules caused by AA toxicity improved with ML treatment.

CONCLUSION

ML supplementation exhibited adequate nephroprotective effects against the nephrotoxicity of AA on pinealectomized rat kidney tissue function by balancing the oxidant/antioxidant status and suppressing the release of proinflammatory cytokines.

Protective role of vitamin E against acrylamide-induced testicular toxicity from pregnancy to adulthood: insights into oxidative stress and aromatase regulation

Acrylamide (ACR) is a toxic chemical frequently encountered in daily life, posing health risks. This study aimed to elucidate the molecular-level mechanism of ACR's toxic effects on testicles and investigate whether Vitamin E can mitigate these effects. A total of 40 adult pregnant rats were utilized, divided into four groups: Control, ACR, Vitamin E, and ACR + Vitamin E. ACR and Vitamin E were administered to the mother rats during pregnancy and lactation, and to the male offspring until the 8th week post-birth. Serum hormone levels, oxidant-antioxidant parameters, histopathological examination of testicular tissue, and mRNA and protein levels of the testicular and liver aromatase gene were analyzed. Spermiogram analysis was conducted on the collected sperm samples from the male offspring. The results revealed that ACR exposure adversely affected hormone levels, oxidant-antioxidant parameters, histological findings, as well as aromatase gene and protein expressions. However, Vitamin E administration effectively prevented the toxic effects of ACR. These findings demonstrate that ACR application significantly impairs the reproductive performance of male offspring rats by increasing liver aromatase activity.

Probiotic Escherichia coli Nissle 1917 alleviates the neurotoxicity caused by acrylamide in zebrafish

Neurotoxicity is caused by damage to the brain tissue by neurotoxic agents present in the environment and artificial substances produced by human beings. Acrylamide (ACR) is one such chemical substance that causes neurotoxicity, affecting the brain cells. This neurotoxicity causes damage to the sensory and metabolic functions. The current research investigates the favourable effect of probiotic EcN (Escherichia coli Nissle 1917) on ACR-induced neurotoxicity in zebrafish. The protective role of EcN against ACR induced toxicity was assessed based on behaviour, biochemical, and gene expression analysis. Initially, the colonisation period of EcN in the zebrafish gut was determined and EcN was given orally to the zebrafish only once prior to the ACR treatment. Very interestingly, this dosage was able to ameliorate the adverse effects of ACR significantly in the brain cells. Quantification of oxidative stress and neuronal cell death clearly vindicate the efficiency of probiotic EcN in reversing the damages caused by ACR. EcN is being explored largely in recent days for its therapeutic applications. This study strongly supports the view that EcN can be developed as a supplement to the patients diagnosed with neuronal cell toxicity.

Therapeutic role of boron on acrylamide-induced nephrotoxicity, cardiotoxicity, neurotoxicity, and testicular toxicity in rats: Effects on Nrf2/Keap-1 signaling pathway and oxidative stress

BACKGROUND

Acrylamide (ACR) is a heat-related carcinogen used in cooking some foods as well as in other thermal treatments. The present study aims to investigate the possible protective effect of boron (BA) against ACR-induced toxicity of kidney, brain, heart, testis, and bladder tissues in rats.

METHODS

Rats have been divided into 5 equal groups: Control (saline), ACR (38.27 mg/kg), BA (20 mg/kg), BA+ ACR (10 mg/kg + ACR), and BA+ ACR (20 mg/kg BA+ACR). Kidney tissue from rats was collected and the levels of malondialdehyde (MDA), glutathione (GSH), and the activity of superoxide dismutase (SOD) were measured. In addition, the kidneys of these animals, as well as the brain, heart, testes, and bladder tissues were examined for possible histological changes. Total Nrf2 and Keap-1 protein expression in kidney, heart, and testis tissues was examined by immunohistochemistry.

RESULTS

While significant increases in MDA levels were observed in the kidneys of rats receiving ACR alone, significant decreases in antioxidant markers (SOD and GSH) were observed. Besides, kidney, brain, heart, and testicular tissues were analyzed and damage was observed in the groups receiving ACR. However, no significant histologic changes were noted in the bladder tissue. Both dosages of BA in combination with ACR improved the changes in ACR-induced antioxidant tissue parameters. Despite the fact that MDA levels were decreased with these two dosages, histological structural abnormalities were found to be greatly improved.

CONCLUSION

Our results show that BA has a strong protective effect on ACR-induced multi-organ toxicity. The study results show that BA could be a potential element to reduce ACR toxicity to which we are often exposed.

Reconstructing hepatic metabolic profile and glutathione-mediated metabolic fate of acrylamide

The toxicity of acrylamide (AA) has continuously attracted wide concerns as its extensive presence from both environmental and dietary sources. However, its hepatic metabolic transformation and metabolic fate still remain unclear. This study aims to unravel the metabolic profile and glutathione (GSH) mediated metabolic fate of AA in liver of rats under the dose-dependent exposure. We found that exposure to AA dose-dependently alters the binding of AA and GSH and the generation of mercapturic acid adducts, while liver as a target tissue bears the metabolic transformation of AA via regulating GSH synthesis and consumption pathways, in which glutamine synthase (GSS), cytochrome P450 2E1 (CYP2E1), and glutathione S-transferase P1 (GSTP1) play a key role. In response to high- and low-dose exposures to AA, there were significant differences in liver of rats, including the changes in GSH and cysteine (CYS) activities and the conversion ratio of AA to glycidamide (GA), and liver can affect the transformation of AA by regulating the GSH-mediated metabolic pathway. Low-dose exposure to AA activates GSH synthesis pathway in liver and upregulates GSS activity and CYS content with no change in γ-glutamyl transpeptidase 1 (GGT1) activity. High-dose exposure to AA activates the detoxification pathway of GSH and increases GSH consumption by upregulating GSTP1 activity. In addition, molecular docking results showed that most of the metabolic molecules transformed by AA and GA other than themselves can closely bind to GSTP1, GSS, GGT1, N-acetyltransferase 8, and dimethyl sulfide dehydrogenase 1. The binding of AA-GSH and GA-GSH to GSTP1 and CYP2E1 enzymes determine the tendentiousness between toxicity and detoxification of AA, which exerts a prospective avenue for targeting protective role of hepatic enzymes against in vivo toxicity of AA.

Two decades of research in dietary acrylamide: What do we know today

After nearly two decades since acrylamide was first raised as a potential safety issue in foods, significant progress has been made in understanding its formation during cooking, how to reduce levels in the most concerned foods, and the possible cancer risk to humans. Despite the huge wealth of knowledge gathered on this topic over the past years, a few new discoveries in occurrence, mitigation, analysis and risk assessment are worthy to note. This short review highlights the salient novelties pertaining to acrylamide, particularly in the areas of formation & analysis, existing and possible future regulations in the European Union, and finally considerations that may lead to possibly revisiting the toxicity of acrylamide and the main metabolite, glycidamide.

Allicin Alleviates Mitochondrial Dysfunction in Acrylamide-Induced Rat Kidney Involving the Regulation of SIRT1

Acrylamide (AA), commonly formed in carbohydrate-rich thermally processed foods, exerts harmful effects on the kidney. Allicin, from crushed garlic cloves, exhibits strong biological activities. In the current study, the protection mechanisms of allicin against AA-caused nephrotoxicity were comprehensively examined using an in vivo rat model based on previous research that allicin plays a key role in improving renal function. The results showed that allicin attenuated histological changes of the kidney and ameliorated renal function. Damaged mitochondrial structures, upregulated voltage-dependent anion channel 1 expression, and decreased membrane potential and adenosine 5'-triphosphate levels were observed after AA treatment. Surprisingly, allicin notably reversed the adverse effects. Further, allicin effectively restored mitochondrial function via modulating mitochondrial biogenesis and dynamics, which might be associated with the upregulated expression of sirtuin 1 (SIRT1). Meanwhile, allicin dramatically activated the SIRT1 activity and subsequently inhibited p53 acetylation, prevented the translocation of cytochrome c to the cytoplasm, and reduced the caspase expression, thus further inhibiting mitochondrial apoptosis caused by AA. In summary, the relieving effect of allicin on AA-caused nephrotoxicity lies in its inhibition of mitochondrial dysfunction and mitochondrial apoptosis.

Prepubertal oral exposure to relevant doses of acrylamide impairs the testicular antioxidant system in adulthood, increasing protein carbonylation and lipid peroxidation

The increased prevalence of human infertility due to male reproductive disorders has been linked to extensive exposure to chemical endocrine disruptors. Acrylamide (AA) is a compound formed spontaneously during the thermal processing of some foods that are mainly consumed by children and adolescents. We previously found that prepubertal exposure to AA causes reduced sperm production and functionality. Oxidative stress is recognized as the main cause of reduced sperm quality and quantity. In this sense, our objective was to evaluate the expression and activity of genes related to enzymatic antioxidant defense, nonprotein thiols, lipid peroxidation (LPO), protein carbonylation (PC) and DNA damage in the testes of rats exposed to acrylamide (2.5 or 5 mg/kg) from weaning to adult life by gavage. For the AA2.5 and AA5 groups, there were no alterations in the transcript expression of genes related to enzymatic antioxidant defense. The enzymatic activities and metabolic parameters were also not affected in the AA2.5 group. For the AA5 group, the enzymatic activities of G6PDH and GPX were reduced, SOD was increased, and protein carbonylation (PC) was increased. Data were also evaluated by Integrate Biomarker Response (IBRv2), a method to analyze and summarize the effects on biomarkers between doses. The IBRv2 index was calculated as 8.9 and 18.71 for AA2.5 and AA5, respectively. The following biomarkers were affected by AA2.5: decreased enzymatic activities of G6PDH, SOD, and GPX, increased GST and GSH, increased LPO and PC, and decreased DNA damage. For AA5, decreased enzymatic activities of G6PDH, GST, CAT and GPX, increased SOD and GSH, increased PC, and decreased LPO and DNA damage were observed. In conclusion, AA exposure during the prepubertal period causes imbalances in the testicular enzymatic antioxidant defense, contributing to the altered spermatic scenario in the testes of these rats.

Characterization of L-asparaginase from Streptomyces koyangensis SK4 with acrylamide-minimizing potential in potato chips

Microbial L-asparaginase is well known for its application in food industries to reduce acrylamide content in fried starchy food. L-asparaginase produced by Arctic actinomycetes Streptomyces koyangensis SK4 was purified and studied for biochemical characterization. The L-asparaginase was purified with a yield of 15.49% and final specific activity of 179.77 IU/mg of protein. The enzyme exhibited a molecular weight of 43 kDa. The optimum pH and temperature for maximum activity of the purified enzyme were 8.5 °C and 40 °C, respectively. The enzyme expressed maximum activity at an incubation period of 30 min and a substrate concentration of 0.06 M. The enzyme has a low Km value of 0.041 M and excellent substrate specificity toward L-asparagine. The enzyme activity was inhibited by metal ions Ba2+ and Hg2+, while Mn2+ and Mg2+ enhanced the activity. The study evaluated the acrylamide reduction potential of L-asparaginase from Streptomyces koyangensis SK4 in potato chips. The blanching plus L-asparaginase treatment of potato slices resulted in a 50% reduction in acrylamide content. The study illustrated an effective acrylamide reduction strategy in potato chips using L-asparaginase from a psychrophilic actinomycete. Besides the acrylamide reduction potential, L-asparaginase from Streptomyces koyangensis SK4 also did not exhibit any glutaminase or urease activity which is an outstanding feature of L-asparaginase to be used as a chemotherapeutic agent.

Chronotoxicity of Acrylamide in Mice Fed a High-Fat Diet: The Involvement of Liver CYP2E1 Upregulation and Gut Leakage

Acrylamide (ACR) is produced under high-temperature cooking of carbohydrate-rich foods via the Maillard reaction. It has been reported that ACR has hepatic toxicity and can induce liver circadian disorder. A high fat diet (HFD) could dysregulate liver detoxification. The current study showed that administration of ACR (100 mg/kg) reduced the survival rate in HFD-fed mice, which was more pronounced when treated during the night phase than during the day phase. Furthermore, ACR (25 mg/kg) treatment could cause chronotoxicity in mice fed a high-fat diet, manifested as more severe mitochondrial damage of liver during the night phase than during the day phase. Interestingly, HFD induced a higher CYP2E1 expressions for those treated during the night phase, leading to more severe DNA damage. Meanwhile, the expression of gut tight junction proteins also significantly decreases at night phase, leading to the leakage of LPSs and exacerbating the inflammatory response at night phase. These results indicated that a HFD could induce the chronotoxicity of ACR in mice liver, which may be associated with increases in CYP2E1 expression in the liver and gut leak during the night phase.

Exposure to acrylamide induces zygotic genome activation defects of mouse embryos

Acrylamide (ACR) is an important chemical raw material for wastewater treatment, paper industry and textile industry, which is widely exposed from occupational, environmental and dietary situation. ACR has neurotoxicity, genotoxicity, potential carcinogenicity and reproductive toxicity. Recent study indicates that ACR affected oocyte maturation quality. In the present study, we reported the effects of ACR exposure on zygotic genome activation (ZGA) in embryos and its related mechanism. Our results showed that ACR treatment caused 2-cell arrest in mouse embryos, indicating the failure of ZGA, which was confirmed by decreased global transcription levels and aberrant expression of ZGA-related and maternal factors. We found that histone modifications such as H3K9me3, H3K27me3 and H3K27ac levels were altered, and this might be due to the occurrence of DNA damage, showing with positive γ-H2A.X signal. Moreover, mitochondrial dysfunction and high levels of ROS were detected in ACR treated embryos, indicating that ACR induced oxidative stress, and this might further cause abnormal distribution of endoplasmic reticulum, Golgi apparatus and lysosomes. In conclusion, our results indicated that ACR exposure disrupted ZGA by inducing mitochondria-based oxidative stress, which further caused DNA damage, aberrant histone modifications and organelles in mouse embryos.

Neurotoxicity of acrylamide in adult zebrafish following short-term and long-term exposure: evaluation of behavior alterations, oxidative stress markers, expression of antioxidant genes, and histological examination of the brain and eyes

In the present work, 224 adult female zebrafish (56 fish in each group) were randomly divided into four groups (two control groups and two toxicity groups) as per duration of exposure (7 and 21 days). All fish of the two toxicity groups were exposed to 0.610 mM acrylamide (ACR) concentration for 7 and 21 days. The effects of ACR exposure on behavior, oxidative stress biomarkers, molecular expression of antioxidant genes (sod, cat, and nrf2), and histopathological examination of the brain and eye were examined. Our result shows that ACR exposure for 7 days produced an anxiety-like behavior in zebrafish. Short-term exposure of ACR resulted in alterations of oxidative stress markers (SOD and CAT activity, and the level of GSH and MDA) in the brain and eye of zebrafish. However, the antioxidant defense system of adult female zebrafish could be able to counteract the free radicals generated in long-term ACR exposure as indicated by non-significant difference in oxidative insult following short-term and long-term exposure. ACR exposure downregulated the mRNA expression of the sod, cat, and nrf2 (nuclear factor erythroid 2-related factor 2) genes in the brain and eye without significant difference between the two toxicity groups. Mild histological changes in the dorsal telencephalic area, tectum opticum, medulla, and hypothalamus area of the brain of zebrafish have been observed following short-term and long-term ACR exposure. In the eye, marked histological changes in the retinal pigmented epithelium layer (RPE), structural changes of the photoreceptor layer (PRL) with disorganized layer of rods and cones, and reduction of the relative thickness of the RPE, PRL, outer nuclear layer (ONL), and inner nuclear layer (INL) have been noted following ACR exposure for 21 days as compared to 7 days. ACR produced neurobehavioral aberrations and oxidative stress within 7 days of exposure, while various histological changes in the brain and eyes have been observed following long-term exposure (21 days) to ACR.

A DFT Study of the Reaction of Acrylamide with L-Cysteine and L-Glutathione

Thermal processing of certain foods implies the formation of acrylamide, which has been proven to provoke adverse effects on human health. Thus, several strategies to mitigate it have been developed. One of them could be the application of organosulfur compounds obtained from natural sources to react with the acrylamide, forming non-toxic adducts. A DFT study of the acrylamide reaction with the organosulfur model compounds L-cysteine and L-glutathione by Michael addition and a free radical pathway complemented by a kinetic study of these model molecules has been applied. The kinetic evaluation results demonstrate that the L-glutathione reaction exhibited a higher rate constant than the other studied compound.

Associations of Hemoglobin Adducts of Acrylamide and Glycidamide with Prevalent Metabolic Syndrome in a Nationwide Population-Based Study

Environmental and dietary exposures to acrylamide (AA) have been linked with various metabolic-related outcomes, but the results are mixed. However, the association between long-term exposure to AA and the prevalence of metabolic syndrome (MetS) remains unknown. In this study, we aimed to assess the relationship between hemoglobin adducts of AA, biomarkers of internal exposure to AA, and MetS prevalence among a U.S. nationwide population. MetS patients were defined by meeting three or more of the following five characteristics: elevated blood pressure, high fasting glucose, abdominal obesity, hypertriglyceridemia, and lower high-density lipoprotein cholesterol (HDL-C). Multivariate-adjusted logistic regression models and restricted cubic spline models were used to analyze the associations between AA hemoglobin biomarkers and MetS prevalence. A total of 1552 MetS cases were documented. After adjustment for the potential confounders, the odds ratios (95% confidence intervals) of MetS prevalence in the highest quartile of AA hemoglobin biomarkers were 0.60 (0.40-0.89), 1.26 (0.84-1.89), 0.93 (0.71-1.21), and 1.61 (1.18-2.20) for HbAA, HbGA, the sum of HbAA and HbGA (HbAA + HbGA), and the ratio of HbGA to HbAA (HbGA/HbAA), compared with the lowest quartile, respectively. HbAA was significantly and inversely associated with blood pressure, fasting glucose, abdominal obesity, hypertriglyceridemia, and low HDL-C, while the HbGA/HbAA ratio was also positively associated with abdominal obesity, hypertriglyceridemia, and low HDL-C. The restricted cubic spline models revealed a positive relationship between the HbGA/HbAA ratio and the prevalence of MetS, while the HbAA level was inversely associated with MetS prevalence. Our current findings provided epidemiological evidence that HbAA and the HbGA/HbAA ratio were significantly associated with MetS prevalence among general U.S. adults. Further studies should be conducted to examine the association between internal exposure to AA and MetS prevalence.

Risk assessment of the exposure of Spanish children to acrylamide using human biomonitoring

Acrylamide (AA) is an organic contaminant that naturally forms in starchy foods during high-temperature cooking under low-moisture conditions. It is mainly produced from the sugars and amino acids present in food by the Maillard reaction. When humans are exposed to AA, AA is eliminated in the urine as mercapturic acid conjugates, primarily including N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA), N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA3), and N-acetyl-3-[(3-amino-3-oxopropyl)sulfinyl]-L-alanine (AAMA-Sul), which are used as exposure biomarkers of AA in human biomonitoring studies. Although the carcinogenic effects of AA on humans have not been demonstrated yet, some studies have shown that AA may negatively affect children's health. The main objective of this study was to evaluate the exposure of Spanish children (n = 612) to AA. For this purpose, the levels of AAMA, AAMA-Sul, and GAMA3 in first-morning urine samples were analyzed by "dilute and shoot" and liquid chromatography coupled to tandem mass spectrometry. The three metabolites were detected in all the children involved in this study in the following order (geometric mean (GM)): AAMA (79 ng ml^-1) > AAMA-Sul (28 ng ml^-1) > GAMA3 (18 ng ml^-1). Statistical analysis suggested that the intake of fried potato products and biscuits could be associated with higher levels of AA metabolites in urine. Estimated daily intakes of AA in the children under study were in the range of 1.2-1.5 μg AA·kg-body weight^-1·day^-1 (GM). Risk assessment calculations indicate that the health risk of AA exposure cannot be overlooked and the exposure of Spanish children to AA should be closely monitored.

Total cholesterol: a potential mediator of the association between exposure to acrylamide and hypertension risk in adolescent females

Acrylamide (AA) exposure is associated with a range of adverse health effects. However, whether AA exposure is related to hypertension in adolescents remains unclear. The associations of blood hemoglobin biomarkers of AA (HbAA) and its metabolite glycidamide (HbGA) with hypertension risk, diastolic blood pressure (DBP), and systolic blood pressure (SBP) were evaluated by multivariate logistic regression and linear regression. We identified a potential positive association between blood HbGA and hypertension risk in adolescent females (OR 1.81, 95% CI 1.00-3.30; P for trend = 0.022); however, there was no correlation in the non-linear model (P = 0.831). In the sex-stratified linear models, blood HbGA level had a strong positive association with SBP in adolescent females (beta 0.84, 95% CI 0.13-1.55, P = 0.020). Mechanistically, a one-unit increase in blood HbGA (ln transformed) was associated with a 2.83 mg/dL increase in total cholesterol (TC) among females in the fully adjusted model. Mediation analysis showed that TC mediated 24.15% of the association between blood HbGA level and the prevalence of hypertension in females. The present results provide epidemiological evidence that exposure to AA, mainly its metabolite glycidamide, is positively associated with the prevalence of hypertension or increased SBP in adolescent females.

Determination of N7-glycidamide guanine adducts in human blood DNA following exposure to dietary acrylamide using liquid chromatography/tandem mass spectrometry

RATIONALE

Acrylamide is classified as a probable human carcinogen that is metabolised to glycidamide, which can covalently bind to DNA. The aim of this study was to investigate the formation of N7-glycidamide guanine (N7-GA-Gua) adducts in human blood DNA following exposure to acrylamide present in carbohydrate-rich foods as part of the normal human diet.

METHODS

Lymphocyte DNA was extracted from blood samples obtained from healthy human volunteers. Following thermal depurination of the DNA samples, N7-GA-Gua adducts were quantified using a validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) method incorporating a stable isotope labelled internal standard. Estimated dietary acrylamide intake was recorded by completion of food frequency questionnaires for the 24 hours prior to volunteer blood donation.

RESULTS

An LC/MS/MS method was validated with a limit of detection of 0.25 fmol and a lower limit of quantitation of 0.50 fmol on column. N7-GA-Gua adducts were detected in human blood DNA with the levels ranging between 0.3 to 6.3 adducts per 10⁸ nucleotides. The acrylamide intake was calculated from the food frequency questionnaires ranging between 20.0 and 78.6 μg.

CONCLUSIONS

Identification and quantification of N7-GA-Gua adducts in the blood DNA of healthy volunteers suggests that dietary acrylamide exposure may lead to the formation of DNA adducts. This important finding warrants further investigation to ascertain a correlation between environmental/dietary acrylamide exposure and levels of DNA adducts.

Suppression of the tonoplast sugar transporter StTST3.2 improves quality of potato chips

Which sugar transporter regulates sugar accumulation in tubers is largely unknown. Accumulation of reducing sugar (RS) in potato (Solanum tuberosum L.) tubers negatively affects the quality of tubers undergoing the frying process. However, little is known about the genes involved in regulating RS content in tubers at harvest. Here, we have identified two tonoplast sugar transporter (TST) 3-type isoforms (StTST3.1 and StTST3.2) in potato. Quantitative real-time PCR results indicate that StTST3.1 and StTST3.2 possess distinct expression patterns in various potato tissues. StTST3.2 was found to be the expressed TST3-type isoform in tubers. Further subcellular localization analysis revealed that StTST3.2 was targeted to the tonoplast. Silencing of StTST3.2 in potato by stable transformation resulted in significantly lower RS content in tubers at harvest or after room temperature storage, suggesting StTST3.2 plays an important role in RS accumulation in tubers. Accordingly, compared with the unsilenced control, potato chips processed from StTST3.2-silenced tubers exhibited lighter color and dramatically decreased acrylamide production at harvest or after room temperature storage. In addition, we demonstrated that silencing of StTST3.2 has no significant effect on potato growth and development. Thus, suppression of StTST3.2 could be another effective approach for improving processing quality and decreasing acrylamide content in potato tubers.

Eruca sativa seed extract modulates oxidative stress and apoptosis and up-regulates the expression of Bcl-2 and Bax genes in acrylamide-induced testicular dysfunction in rats

Acrylamide (ACR) has been previously associated with male sexual dysfunction and infertility. Eruca sativa (L.) (arugula or rocket) have been widely used in traditional remedies in Mediterranean region and western Asia and was known for its strong aphrodisiac effect since Roman times. The current study was designed to investigate LC/MS analysis of total ethanol extract Eruca sativa (L.) and the efficiency and mechanism of action of Eruca sativa seed extract (ESS) in reducing hypogonadism induced by acrylamide in male rats. Male Wistar rats were divided into 6 groups (n = 7): control group, Eruca sativa seed extract (ESS) at doses of 100 and 200 mg\kg, acrylamide (ACR), ACR + ESS 100 mg/kg, and ACR + ESS 200 mg/kg. The animals received ACR at a dose of 10 mg/kg b.wt for 60 days. Sperm indices, testicular oxidative stress, testosterone hormone, and testicular histopathology and immunohistochemistry of PCNA and caspase-3 were investigated. Moreover, the expression level of testicular B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) genes was evaluated. In respect to the LC/MS of total ethanol extract Eruca sativa (L.) seed revealed tentative identification of 39 compounds, which belongs to different classes as sulphur-containing compounds, flavonoids, phenolic acid, and fatty acids. Administration of ESS extract (100, 200 mg/kg) improved semen quality, diminished lipid peroxidation, enhanced testicular antioxidant enzyme, restored serum testosterone level, and reduced testicular degeneration and Leydig cell death in the rats intoxicated with ACR. However, the effects of ESS at the dose of 200 mg/kg were similar to that of control group. Furthermore, ESS treatment significantly induced anti-apoptotic effect indicated by elevation of both Bcl-2 and Bax expressions. Nutriceutics of ESS extract protects testis against ACR-induced testicular toxicity via normalizing testicular steroidogenesis, keeping Leydig cells, and improving oxidative stress status.

Evaluation of acrylamide-removing properties of bacterial consortia under simulated gastrointestinal conditions

BACKGROUND

Previous studies have demonstrated the acrylamide-removing properties of probiotic monocultures; however, potential advantages of consortia over monocultures in reducing the dietary exposure to acrylamide have not been proven. Hence this work aims to assess the acrylamide (AA)-binding properties of bacterial consortia, consisting of either probiotic strains and / or representative bacteria of duodenal microbiota, exposed to simulated gastrointestinal conditions (SGC). The AA binding capacity of ten probiotic strains (PS) and six duodenal strains (NDS) was evaluated under different conditions; then, three different consortia (PS, NDS, and PS + NDS) were assessed under SGC.

RESULTS

Among individual PS, Bacillus coagulans GBI-30, Lactobacillus fermentum J23, L. pentosus J37 and J24, and L. casei Shirota, exhibited the highest AA-binding capacity (80-87%), while Bifidobacterium catenulatun ATCC27676, Streptococcus salivarius subsp. thermophilus ATCC19258, and S. gallolyticus ATCC9809 were the best (ca. 68%) NDS monocultures. Probiotic strain consortia showed higher (P < 0.05) AA binding capacity (> 90%) than monoculture bacteria. Conversely, individual NDS cultures displayed higher (P < 0.05) binding capacity than NDS consortia (60%). A significant reduction (P < 0.05) in AA removal capacity was observed when consortia were exposed to SGC, PS consortia being the most effective (> 60% removal).

CONCLUSION

These results suggest that consortia of specific PS could play an important role in reducing the intestinal availability of acrylamide. © 2021 Society of Chemical Industry.

Associations of acrylamide with non-alcoholic fatty liver disease in American adults: a nationwide cross-sectional study

BACKGROUND

Acrylamide (AA) is a toxicant to humans, but the association between AA exposure and the risk of non-alcoholic fatty liver disease (NAFLD) remains unclear. In this study, our objective is to examine the cross-sectional association between AA exposure and the risk of NAFLD in American adults.

METHODS

A total of 3234 individuals who took part in the National Health and Nutrition Examination Survey (NHANES) 2003-2006 and 2013-2016 were enrolled in the study. NAFLD was diagnosed by the U.S. Fatty Liver Index. Multivariable logistic regression models were applied to estimate the association between AA and NAFLD in the whole group and the non-smoking group.

RESULTS

We discovered that in the whole group, serum hemoglobin adducts of AA (HbAA) were negatively associated with the prevalence of NAFLD after adjustment for various covariables (P for trend < 0.001). Compared with individuals in the lowest HbAA quartiles, the odds ratios (ORs) with 95% confidence intervals (CIs) in the highest HbAA quartiles were 0.61 (0.46-0.81) and 0.57 (0.36-0.88) in the whole group and the non-smoking group, respectively. In contrast, HbGA/HbAA showed a significantly positive correlation with the prevalence of NAFLD in both groups (P for trend < 0.001). In addition, HbGA was not significantly associated with NAFLD in the whole group or the non-smoking group.

CONCLUSIONS

HbAA is negatively associated with NAFLD whereas HbGA/HbAA is positively associated with NAFLD in adults in the U.S. Further studies are needed to clarify these relationships.

Potential protective effects of Spirulina platensis on liver, kidney, and brain acrylamide toxicity in rats

Acrylamide (AA) is a hazardous chemical that is widely used in industrial practices. Spirulina platensis (SP) is a blue green alga that is rich in bioactive compounds with many medicinal benefits. The aim of the present study was to evaluate the ameliorative effect of SP against AA toxicity in rats. Animals were divided into six groups: Group (1) was normal rats, groups (2) and (3) received SP at 500 and 1000 mg/kg BW orally respectively for 21 days, group (4) was administered 20 mg/kg BW AA daily for 14 days, while groups (5) and (6) were given orally SP at the same doses of groups (2) and (3), then AA at similar dose of group (4). Rats that received AA alone displayed markedly increased serum levels of liver enzymes (ALT, AST, and ALP), kidney function parameters (urea and creatinine), DNA damage marker (8-OHdG), and proinflammatory cytokines (IL-1β, IL-6, and TNF-α), compared to control rats. Furthermore, tissue analysis revealed marked increases in hepatic, renal, and brain MDA and NO, as well as marked reductions in the antioxidant biomarkers (GSH, GSH-Px, SOD, and CAT) in acrylamide-intoxicated rats. Spirulina ameliorated the alterations in serum biochemical parameters and reduced MDA and NO, as well as improved antioxidant biomarkers in AA-intoxicated rats in a dose-dependent manner. Our results show that SP has a powerful protective effect on serum biochemistry and liver, kidney, and brain antioxidant machinery in AA-intoxicated rats.

Cord blood acrylamide levels and birth size, and interactions with genetic variants in acrylamide-metabolising genes

BACKGROUND

Up to now, 3 epidemiological studies have shown clear inverse associations between prenatal acrylamide exposure and birth size. In addition to studying the association between acrylamide and birth size, we investigated the interaction between acrylamide and polymorphisms in acrylamide-metabolising genes, with the aim of probing the causality of the inverse relationship between acrylamide and fetal growth.

METHODS

We investigated the association between prenatal acrylamide exposure (acrylamide and glycidamide hemoglobin adduct levels (AA-Hb and GA-Hb) in cord blood) and birth weight, length and head circumference in 443 newborns of the ENVIRONAGE (ENVIRonmental influence ON AGEing in early life) birth cohort. In addition, we studied interaction with single nucleotide polymorphisms (SNPs) in CYP2E1, EPHX1 and GSTP1, using multiple linear regression analysis.

RESULTS

Among all neonates, the body weight, length and head circumference of neonates in the highest quartile was - 101 g (95% CI: - 208, 7; p for trend = 0.12), - 0.13 cm (95% CI: - 0.62, 0.36; p for trend = 0.69) and - 0.41 cm (- 0.80, - 0.01; p for trend = 0.06) lower, respectively, compared to neonates in the lowest quartile of AA-Hb in cord blood, For GA-Hb, the corresponding effect estimates were - 222 g (95% CI: - 337, - 108; p for trend = 0.001), - 0.85 (95% CI: - 1.38, - 0.33; p for trend = 0.02) and - 0.55 (95% CI: - 0.98, - 0.11; p for trend = 0.01), respectively. The associations for GA-Hb were similar or stronger in newborns of non-smoking mothers. There was no statistically significant interaction between acrylamide exposure and the studied genetic variations but there was a trend of stronger inverse associations with birth weight and head circumference among newborns with homozygous wildtypes alleles for the CYP2E1 SNPS and with variant alleles for a GSTP1 SNP (rs1138272).

CONCLUSIONS

Prenatal dietary acrylamide exposure, specifically in the form of its metabolite glycidamide, was inversely associated with birth weight, length and head circumference. The interaction pattern with SNPs in CYP2E1, although not statistically significant, is an indication for the causality of this association. Other studies are needed to corroborate this finding.

In vitro mutagenicity of selected environmental carcinogens and their metabolites in MutaMouse FE1 lung epithelial cells

Chemicals in commerce or under development must be assessed for genotoxicity; assessment is generally conducted using validated assays (e.g. Tk mouse lymphoma assay) as part of a regulatory process. Currently, the MutaMouse FE1 cell mutagenicity assay is undergoing validation for eventual use as a standard in vitro mammalian mutagenicity assay. FE1 cells have been shown to be metabolically competent with respect to some cytochrome P450 (CYP) isozymes; for instance, they can convert the human carcinogen benzo[a]pyrene into its proximate mutagenic metabolite. However, some contradictory results have been noted for other genotoxic carcinogens that require two-step metabolic activation (e.g. 2-acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoxaline). Here, we examined three known or suspected human carcinogens, namely acrylamide, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 4-aminobiphenyl (4-ABP), together with their proximate metabolites (i.e. glycidamide, N-OH-PhIP and N-OH-4-ABP), to aid in the validation of the FE1 cell mutagenicity assay. Assessments of the parent compounds were conducted both in the presence and absence of an exogenous metabolic activation mixture S9; assessments of the metabolites were in the absence of S9. The most potent compound was N-OH-PhIP -S9, which elicited a mutant frequency (MF) level 5.3-fold over background at 5 µM. There was a 4.3-fold increase for PhIP +S9 at 5 µM, a 1.7-fold increase for glycidamide -S9 at 3.5 mM and a 1.5-fold increase for acrylamide +S9 at 4 mM. Acrylamide -S9 elicited a marginal 1.4-fold MF increase at 8 mM. Treatment with PhIP -S9, 4-ABP ±S9 and N-OH-4-ABP -S9 failed to elicit significant increases in lacZ MF with any of the treatment conditions tested. Gene expression of key CYP isozymes was quantified by RT-qPCR. Cyp1a1, 1a2 and 1b1 are required to metabolise PhIP and 4-ABP. Results showed that treatment with both compounds induced expression of Cyp1a1 and Cyp1b1 but not Cyp1a2. Cyp2e1, which catalyses the bioactivation of acrylamide to glycidamide, was not induced after acrylamide treatment. Overall, our results confirm that the FE1 cell mutagenicity assay has the potential for use alongside other, more traditional in vitro mutagenicity assays.

Are AAMA and GAMA Levels in Urine after Childbirth a Suitable Marker to Assess Exposure to Acrylamide from Passive Smoking during Pregnancy?-A Pilot Study

Introduction: Acrylamide (AA) is a “probably carcinogenic to humans” monomer that can form in heated starchy food and in tobacco smoke. N-Acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA) and N-Acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA), acrylamide metabolites in urine, are recognized as good markers of exposure to acrylamide. Aim: The aim of the study is a preliminary assessment whether the levels of AAMA and GAMA in urine after childbirth are good markers of acrylamide exposure due to passive smoking during pregnancy. Material and method: The study group consisted 67 non-smokers and 10 passive-smoker women during pregnancy. AAMA and GAMA levels in urine samples were determined using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Results: The median AAMA levels in urine of non-smoking and passively smoking women were 30.7 μg/g creatinine and 25.2 μg/g creatinine, respectively. Much lower values were determined for GAMA: 11.4 μg/g creatinine and 10.3 μg/g creatinine, respectively. There is no significant difference between AAMA and GAMA content in urine samples between both groups of women as well as in the anthropometric parameters of newborns between those two groups of mothers. Conclusion: Our pilot study did not confirm that postpartum AAMA and GAMA concentrations in urine are good markers of exposure to acrylamide from passive smoking during pregnancy. It is probably due to the different ways of acrylamide absorption from tobacco smoke by active and passive smokers. Exposure of pregnant women to acrylamide from passive smoking requires further research.

Rapid Simultaneous Determination of Cascade Metabolites of Acrylamide in Urine for Toxicokinetics Profiles and Short-Term Dietary Internal Exposure

The current study developed an ultrahigh-performance liquid chromatography tandem mass spectrometry method to simultaneously analyze cascade metabolites of acrylamide in urine of rats and humans, including acrylamide, glycidamide, N-acetyl-S-(2-carbamoylethyl)-l-cysteine (AAMA), N-acetyl-S-(2-carbamoylethyl)-l-cysteine-sulfoxide, N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-l-cysteine, and N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-l-cysteine. A tandem solid-phase extraction procedure was novelly used to purify all metabolites at once from human urine. The rapid analysis showed high sensitivity with LOD and LOQ ranges of 0.1-0.8 and 0.4-5.8 ng/mL, respectively, and achieved acceptable within-laboratory reproducibility (RSD < 12.0%) and spiking recovery (92.2%-117.3%) within 8 min per sample. Approximately 70.7 and 63.0% of ingested acrylamide were recovered during the toxicokinetics analysis from urine of male and female rats, respectively. For nonsmoking participants, the urinary levels of acrylamide and glycidamide were higher in men than women, whereas the urinary concentration of AAMA showed the opposite behavior. The current analysis provides methodological support of cascade metabolites of acrylamide for the dietary short-term internal exposure assessment of acrylamide.

No association between dietary acrylamide and renal cell carcinoma: an updated meta-analysis

BACKGROUND

The relationship between dietary acrylamide intake and renal cell carcinoma risk is inconclusive. In consideration of the recent findings, we conducted an updated meta-analysis to assess the association between acrylamide intake and renal cell carcinoma risk.

RESULTS

PubMed, EMBASE, and Cochrane databases have been used to identify epidemiological studies on dietary acrylamide intake and renal cell carcinoma risk. This meta-analysis study included eight studies, 2843 cases, and 309 920 controls/participants. We performed meta-analyses to calculate the summary relative risk (RR) for the highest versus lowest intake of dietary acrylamide. No meaningful association was found for renal cell carcinoma; RR was 1.12 (95% confidence interval (CI): 0.97-1.28). Among participants who never smoked, no association was found between dietary acrylamide and renal cell carcinoma; the RR for highest versus lowest intake of dietary acrylamide was 1.11 (95% CI: 0.93-1.32).

CONCLUSION

This meta-analysis study indicates that dietary acrylamide is not related to the risk of renal cell carcinoma. © 2020 Society of Chemical Industry.

Sensorineural hearing loss and volatile organic compound metabolites in urine

PURPOSE

Oxidative stress in the auditory system contributes to acquired sensorineural hearing loss. Systemic oxidative stress, which may predict auditory oxidative stress, can be assessed by measuring volatile organic compound metabolite concentrations in urine. The purpose of this retrospective study was to determine if hearing decreased in those with higher concentrations of urinary volatile organic compound metabolites.

MATERIALS AND METHODS

Audiometric, demographic, and metabolite concentration data were downloaded from the 2011-2012 cycle of the U.S. National Health and Nutritional Examination Survey. Participants were first grouped by reported noise exposure. For each metabolite, an analysis of covariance was used to look for differences in age-adjusted hearing loss among urinary volatile organic compound metabolite concentration groups. Participants were grouped into quartiles based on concentration for each metabolite separately because many individuals were at the lower limit of concentration detection for several metabolites, leading to a non-normal distribution.

RESULTS

Age-adjusted high-frequency pure-tone thresholds were significantly (FDR < 0.05) increased by about 3 to 4 dB in high concentration quartile groups for five metabolites. All five metabolites were glutathione-dependent mercapturic acids. The parent compounds of these metabolites included acrylonitrile, 1,3 butadiene, styrene, acrylamide, and N,N-dimethylformamide. Significant associations were only found in those with no reported noise exposure.

CONCLUSIONS

Urinary metabolites may help to explain susceptibility to oxidative stress-induced hearing loss.

Ecotoxicological biomarkers as investigating tools to evaluate the impact of acrylamide on Theba pisana snails

Acrylamide (ACR) is a widespread industrial chemical with recognized adverse effects not only to humans but to other organisms in the environment as well. In the present study, the ecotoxicological effects of dietary exposure to sublethal concentration (1/20 LC₅₀) of ACR on the land snail, Theba pisana after 2 weeks of exposure and 1-week recovery with respect to oxidative stress parameters; lipid peroxidation (LPO), reduced glutathione (GSH), catalase (CAT), and glutathione-S-transferase (GST), cytogenetic parameter; deoxyribonucleic acid (DNA) content, as well as immunological parameters; cell death, phagocytosis, lysosomal membrane stability (LMS), lectins, superoxide anion (O₂^-) generation, phenoloxidase (PO), peroxidase (POD), and hemocyanin (Hc) were examined. The results showed that ACR significantly increased LPO level and the activity of CAT and GST, cell death, and Hc level, whereas a significant decline in DNA and GSH contents, phagocytic activity, LMS, lectins, O₂^- generation, POD, and PO activities compared to the controls after 2-week exposure was observed. After 1-week recovery, most of the tested parameters in exposed snails were permanent and not reversible to the control levels. This study suggests that the tested multiple parameters of T. pisana species may be used as biomarkers of ACR exposure. Besides, T. pisana snails could be used as a good sentinel organism for ACR exposure in pollution monitoring studies.

Modelling Contaminant Formation during Thermal Processing of Sea Buckthorn Purée

Background: The impact of thermal treatment on acrylamide (ACR) and hydroxymethylfurfural (HMF) formation was investigated for thermally treated sea buckthorn purée. Methods: An optimized procedure for minimizing ACR and HMF formation in thermally treated sea buckthorn purée was described. The precursors of ACR and HMF and their impact in heating of sea buckthorn purée to obtain jam-like products were also evaluated. Results: The contaminant content formed in samples was analyzed on thirteen running variants using a temperature range of 59.3-200.7 °C, and for heating durations between 5.9 and 34.1 min. The calculated equations of contaminant formation in sea buckthorn purée have established that the minimum content is formed at the lowest exposure time, between 10 and 20 min, for both ACR and HMF. The lowest ACR content was attained at 5.9-min exposure time and 130 °C temperature (0.3 µg/kg). For HMF the results revealed a lower quantity at 59.3 °C for 20-min exposure time (1.4 mg/kg). Conclusions: the found model is useful for the prediction of the best temperature/time conditions of the thermal treatment to obtain the lowest contaminates levels in the final product.

Magnetic cross-linked enzyme aggregates of acrylamidase from Cupriavidus oxalaticus ICTDB921 for biodegradation of acrylamide from industrial waste water

Acrylamidase from Cupriavidus oxalaticus ICTDB921 was immobilized on magnetic nanoparticles (MNPs) for degradation of acrylamide (a group 2A carcinogen and an environmental contaminant) from industrial waste water. Acrylamidase-MNPs were prepared (maximum recovery ∼94%) at optimized process parameters viz. 1.5:1 (v/v) of acetone: crude acrylamidase/5 mM of glutaraldehyde/90 min/1.5:1 of enzyme: MNP ratio. MNPs and acrylamidase-MNPs were characterized by particle size analysis, FTIR, XRD, SEM and vibrating sample magnetometer. Acrylamidase-MNPs showed a shift in optimum pH (8-8.5) and temperature (60-65 °C) with higher pH/thermal stability vis-à-vis free enzyme. A significant increase in kinetic constants, thermal inactivation constants and thermodynamic parameters were noted for acrylamidase-MNPs. A complete degradation of acrylamide ∼2100 mg/L was achieved in industrial waste water under optimized conditions for batch process and the kinetics was best represented by Haldane model. Acrylamidase-MNPs retained >80% of its initial activity after 4 cycles for both pure acrylamide and industrial waste water.

Biodegradation of acrylamide by a novel isolate, Cupriavidus oxalaticus ICTDB921: Identification and characterization of the acrylamidase produced

Acrylamide is neurotoxic, genotoxic, teratogenic and carcinogenic. Its widespread use in various industrial processes leads to environmental contamination. Acrylamidase produced by certain bacteria degrade acrylamide to acrylic acid and ammonia. The present study details the isolation and identification of soil bacterium which could degrade acrylamide. Among the 18 acrylamide-degrading isolates tested, isolate ICTDB921 demonstrated superior acrylamide degradation which was confirmed by HPLC, FTIR and GC-MS. The partial 16S rRNA sequencing confirmed the isolate to be Cupriavidus oxalaticus ICTDB921, which showed highest growth at 60 mM acrylamide, neutral pH and 30 °C. The kinetic model predictions were consistent with experimental results. The acrylamidase from this isolate showed potency at pH (6-8) and temperatures (30-60 °C), with reasonable pH (6-8) and thermal stability (upto 60 °C). The enzyme was stable against most metal ions and amino acids, and also degraded other aliphatic amides, demonstrating its potential in remediation of acrylamide from the environment and food systems.

Associations of hemoglobin biomarker levels of acrylamide and all-cause and cardiovascular disease mortality among U.S. adults: National Health and Nutrition Examination Survey 2003-2006

BACKGROUND

The potential hazards of acrylamide (AA) have been proposed due to its lifelong exposure. However, the association between AA exposure and mortality remains unclear.

OBJECTIVES

We evaluated the prospective association of AA hemoglobin adducts (HbAA and HbGA) with all-cause and cardiovascular disease (CVD) mortality in U.S. population from National Health and Nutrition Examination Survey (NHANES) 2003-2006.

METHODS

We followed 5504 participants who were ≥25 years of age for an average of 6.7 years at the baseline examination with annual linkage to the NHANES statistics database. Using AA hemoglobin biomarkers [HbAA, HbGA, sum of HbAA and HbGA (HbAA + HbGA), and ratio of HbGA to HbAA (HbGA/HbAA)], we determined mortality from all-causes and CVD through Cox proportional hazard regression analysis with multivariable adjustments both in non-smoker group and smoker group. In addition, subgroup analyses and sensitivity analyses were further conducted.

RESULTS

After adjusting for sociodemographic, life behavioral and cardiovascular risk factors in non-smoker group, HbAA was positively associated with all-cause mortality (p for trend = 0.0197) and non-CVD mortality (p for trend = 0.0124). HbGA and HbGA/HbAA were inversely associated with all-cause mortality (p for trend = 0.0117 and 0.0098, respectively) and CVD mortality (p for trend=0.0009 and 0.0036, respectively). The multivariable adjusted hazard ratios (HRs) [95% confidence intervals (CIs)] of the upper three quartiles were 0.472 (95% CI: 0.283-0.786), 0.517 (95% CI: 0.299-0.894) and 0.470 (95% CI: 0.288-0.766) between HbGA/HbAA and all-cause mortality comparing with the lowest quartile, respectively. No significant associations were found between HbAA + HbGA and mortality in non-smoker group, and between all AA hemoglobin biomarkers and mortality in smoker group.

CONCLUSIONS

Hemoglobin biomarker levels of AA were strongly associated with mortality in general U.S. non-smoker adults. These findings proposed a continuous public health concern in relation to environmental and dietary exposure to AA.

Relationships between acrylamide and glycidamide hemoglobin adduct levels and allergy-related outcomes in general US population, NHANES 2005-2006

BACKGROUND

Acrylamide-induced immunotoxicity and allergic dermatitis have been reported in animal experiments and clinical reports, respectively. However, epidemiological evidence from the general population is limited.

OBJECTIVES

The purpose of the present study was to estimate the associations between acrylamide exposure and allergy-related outcomes in the general US population.

METHODS

A total of 6982 subjects were selected from the National Health and Nutrition Examination Survey 2005-2006 (NHANES). Internal exposure was measured by the hemoglobin adducts of acrylamide (HbAA) and its metabolite glycidamide (HbGA). Allergy-related outcomes including asthma, hay fever, allergy, itchy rash, sneeze, wheeze and eczema were obtained by self-administered questionnaires. Allergic sensitization was assessed by the total immunoglobulin E (IgE) levels. The associations of HbAA and HbGA quartiles with allergy-related outcomes were calculated using logistic regression models with multivariable adjustments. Analyses were additionally stratified according to age, gender and serum cotinine levels.

RESULTS

When setting quartile 1 of HbAA as reference, the odds ratios (ORs) [95% confidence intervals (CIs)] of quartile 2 to 4 for eczema were 1.18 (0.79-1.76), 1.14 (0.73-1.78) and 1.58 (1.14-2.18), respectively (p_trend = 0.002). Individuals at the highest quartile of HbGA had significantly elevated likelihoods of itchy rash (OR = 1.37, 95% CI = 1.02-1.83, p_trend = 0.032) and eczema (OR = 1.45, 95% CI = 1.06-1.97, p_trend = 0.044). The stratification analyses indicated various results in different subgroups.

CONCLUSIONS

This study indicated significant associations between HbAA and HbGA levels and the likelihoods of allergy-related outcomes in the general US population, depending on age, gender and smoke exposure status. These findings suggested potential public health concerns for the widespread exposure to acrylamide.

Inhibitory effects of Japanese horseradish (Wasabia japonica) on the formation and genotoxicity of a potent carcinogen, acrylamide

BACKGROUND

The formation of acrylamide (AA) in cooked foods has raised human health concerns. AA is metabolized by cytochrome P450 2E1 (CYP2E1) to glycidamide (GA), which forms DNA adducts. This study examined the inhibitory effects of wasabi (Japanese horseradish, Wasabia japonica) roots and leaves as well as their active component, allyl isothiocyanate (AIT), on the formation and genotoxicity of AA.

RESULTS

AA formation (51.8 ± 4.2 µg kg^-1 ) was inhibited with ≥2 mg mL^-1 of AIT. Wasabi roots also inhibited AA formation (∼90% reduction), but wasabi leaves were not effective at 2 mg mL^-1 . Wasabi roots and leaves decreased the number of cells with micronuclei by approximately 33 and 24% respectively compared with the AA treatment group. Moreover, wasabi roots and leaves (100 mg kg^-1 body weight (BW) day^-1 for each) decreased AA (100 mg kg^-1 BW day^-1 )-induced DNA damage. The AA-induced CYP2E1 activity was decreased by 39 and 26% with wasabi roots and leaves respectively. Further, the activity of glutathione S-transferase, which catalyzes the detoxification of AA via glutathione conjugation, increased by 54 and 33% with wasabi roots and leaves respectively.

CONCLUSION

These results indicate that wasabi roots and leaves are effective ingredients for inhibiting the formation and genotoxicity of AA. © 2016 Society of Chemical Industry.

Effect of added nitrogen fertilizer on pyrazines of roasted chicory

BACKGROUND

Coffee substitutes made of roasted chicory are affected by the formation of acrylamide whose main precursor is asparagine. One strategy for limiting the formation of acrylamide is to reduce free asparagine in the chicory roots by lessening the supply of nitrogen in the field. However, decreasing nitrogen fertilizer could affect the formation of the volatile compounds and, consequently, the sensory characteristics of the roasted chicory. The present study aimed to investigate the impact of the nitrogen supply in five commercial varieties on their aroma profile.

RESULTS

The addition of 120 kg ha-1 of nitrogen fertilizer in the field resulted in a greater amount of pyrazines in the roasted chicory. Triangle tests were performed to determine the effect of the nitrogen level on the sensory quality of the five varieties. The results revealed that the chicory aroma was modified in two out of five varieties.

CONCLUSION

The results of the present study suggest that a strategy aiming to limit the amount of acrylamide could affect the sensory quality of some varieties of chicory. Further acceptance tests need to be conducted to assess the effect (whether favourable or otherwise) on the sensory quality of the coffee substitutes. © 2016 Society of Chemical Industry.

Acrylamide and glycidamide hemoglobin adduct levels and endometrial cancer risk: A nested case-control study in nonsmoking postmenopausal women from the EPIC cohort

Acrylamide, classified in 1994 by IARC as "probably carcinogenic to humans," was discovered in 2002 in some heat-treated, carbohydrate-rich foods. Four prospective studies have evaluated the association between dietary acrylamide intake and endometrial cancer (EC) risk with inconsistent results. The purpose of this nested case-control study, based on the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, was to evaluate, for the first time, the association between hemoglobin adducts of acrylamide (HbAA) and glycidamide (HbGA) and the risk of developing EC in non-smoking postmenopausal women. Hemoglobin adducts were measured in red blood cells by HPLC/MS/MS. Four exposure variables were evaluated: HbAA, HbGA, their sum (HbAA+HbGA), and their ratio (HbGA/HbAA). The association between hemoglobin adducts and EC was evaluated using unconditional multivariable logistic regression models, and included 383 EC cases (171 were type-I EC), and 385 controls. Exposure variables were analyzed in quintiles based on control distributions. None of the biomarker variables had an effect on overall EC (HRHbAA;Q5vsQ1 : 0.84, 95%CI: 0.49-1.48; HRHbGA;Q5vsQ1 : 0.94, 95%CI: 0.54-1.63) or type-I EC risk. Additionally, none of the subgroups investigated (BMI < 25 vs. ≥25 kg m(-2) , alcohol drinkers vs. never drinkers, oral contraceptive users vs. non-users) demonstrated effect measure modification. Hemoglobin adducts of acrylamide or glycidamide were not associated with EC or type-I EC risk in 768 nonsmoking postmenopausal women from the EPIC cohort.

Biodegradation of the cross-linked copolymer of acrylamide and potassium acrylate by soil bacteria

Chemical cross-linking and the high molecular weight of superabsorbent copolymers (SAPs) are the two main causes of their resistance to biodegradation. However, SAP particles are colonized by microorganisms. For the purposes of this study, the dry technical copolymer of acrylamide and potassium acrylate containing 5.28 % of unpolymerized monomers was wrapped in a geotextile and incubated in unsterile Haplic Luvisol soil as a water absorbing geocomposite. The highest number of soil bacteria that colonized the hydrated SAP and utilized it as the sole carbon and energy source was found after the first month of incubation in soil. It was equal to 7.21-7.49 log10 cfu g(-1) of water absorbed by the SAP and decreased by 1.35-1.61 log10 units within the next 8 months. During this time, the initial SAP water holding capacity of 1665.8 g has decreased by 24.40 %. Moreover, the 5 g of SAP dry mass has declined by 31.70 %. Two bacteria, Rhizobium radiobacter 28SG and Bacillus aryabhattai 31SG isolated from the watered SAP were found to be able to biodegrade this SAP in pure cultures. They destroyed 25.07 and 41.85 mg of 300 mg of the technical SAP during the 60-day growth in mineral Burk's salt medium, and biodegradation activity was equal to 2.95 and 6.72 μg of SAP μg(-1) of protein, respectively. B. aryabhattai 31SG and R. radiobacter 28SG were also able to degrade 9.99 and 29.70 mg of 82 mg of the ultra-pure SAP in synthetic root exudate medium during the 30-day growth, respectively.

Silencing of vacuolar invertase and asparagine synthetase genes and its impact on acrylamide formation of fried potato products

Acrylamide is produced in a wide variety of carbohydrate-rich foods during high-temperature cooking. Dietary acrylamide is a suspected human carcinogen, and health concerns related to dietary acrylamide have been raised worldwide. French fries and potato chips contribute a significant proportion to the average daily intake of acrylamide, especially in developed countries. One way to mitigate health concerns related to acrylamide is to develop potato cultivars that have reduced contents of the acrylamide precursors asparagine, glucose and fructose in tubers. We generated a large number of silencing lines of potato cultivar Russet Burbank by targeting the vacuolar invertase gene VInv and the asparagine synthetase genes StAS1 and StAS2 with a single RNA interference construct. The transcription levels of these three genes were correlated with reducing sugar (glucose and fructose) and asparagine content in tubers. Fried potato products from the best VInv/StAS1/StAS2-triple silencing lines contained only one-fifteenth of the acrylamide content of the controls. Interestingly, the extent of acrylamide reduction of the best triple silencing lines was similar to that of the best VInv-single silencing lines developed previously from the same potato cultivar Russet Burbank. These results show that an acrylamide mitigation strategy focused on developing potato cultivars with low reducing sugars is likely to be an effective and sufficient approach for minimizing the acrylamide-forming potential of French fry processing potatoes.

Acrylamide and Glycidamide Hemoglobin Adducts and Epithelial Ovarian Cancer: A Nested Case-Control Study in Nonsmoking Postmenopausal Women from the EPIC Cohort

BACKGROUND

Acrylamide was classified as "probably carcinogenic to humans (group 2A)" by the International Agency for Research on Cancer. Epithelial ovarian cancer (EOC) is the fourth cause of cancer mortality in women. Five epidemiological studies have evaluated the association between EOC risk and dietary acrylamide intake assessed using food frequency questionnaires, and one nested case-control study evaluated hemoglobin adducts of acrylamide (HbAA) and its metabolite glycidamide (HbGA) and EOC risk; the results of these studies were inconsistent.

METHODS

A nested case-control study in nonsmoking postmenopausal women (334 cases, 417 controls) was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Unconditional logistic regression models were used to estimate ORs and 95% confidence intervals (CI) for the association between HbAA, HbGA, HbAA+HbGA, and HbGA/HbAA and EOC and invasive serous EOC risk.

RESULTS

No overall associations were observed between biomarkers of acrylamide exposure analyzed in quintiles and EOC risk; however, positive associations were observed between some middle quintiles of HbGA and HbAA+HbGA. Elevated but nonstatistically significant ORs for serous EOC were observed for HbGA and HbAA+HbGA (ORQ5vsQ1, 1.91; 95% CI, 0.96-3.81 and ORQ5vsQ1, 1.90; 95% CI, 0.94-3.83, respectively); however, no linear dose-response trends were observed.

CONCLUSION

This EPIC nested case-control study failed to observe a clear association between biomarkers of acrylamide exposure and the risk of EOC or invasive serous EOC.

IMPACT

It is unlikely that dietary acrylamide exposure increases ovarian cancer risk; however, additional studies with larger sample size should be performed to exclude any possible association with EOC risk.

Effect of residual monomer from polyacrylamide on head lettuce grown in peat substrate

The paper investigates the migration of the acrylamide monomer (AMD) to lettuce chosen as a test plant growing in an organic medium (peat substrate). Polyacrylamide (PAM)-based flocculant added to the growing medium contained no more than 1000 mg kg(-1) of AMD. Plants were grown with varied doses of PAM preparation (0.5-3.0 mg dm(-3) of peat substrate) to compare the results with the control sample. The determination of AMD content, chlorophyll content, weight of the lettuce head, and also analysis of macro- and micro-elements in lyophilised test material was made under the same analytical conditions. The results showed that lettuce plants absorb AMD to the leaves from the peat substrate. The AMD uptake has a negative impact on the growth of lettuce. It reduces the average fresh weight of heads and destabilises the mineral composition of the plant. Therefore, concern related to the transfer risk of the residual AMD from sludge used for organic fertilisation of edible plants still remains a crucial question from a food and consumer safety point of view. To ensure consumer safety, the fate of the AMD following the application of PAM to cropland should be carefully monitored in the whole food chain.

Acrylamide-induced carcinogenicity in mouse lung involves mutagenicity: cII gene mutations in the lung of big blue mice exposed to acrylamide and glycidamide for up to 4 weeks

Potential health risks for humans from exposure to acrylamide (AA) and its epoxide metabolite glycidamide (GA) have garnered much attention lately because substantial amounts of AA are present in a variety of fried and baked starchy foods. AA is tumorigenic in rodents, and a large number of in vitro and in vivo studies indicate that AA is genotoxic. A recent cancer bioassay on AA demonstrated that the lung was one of the target organs for tumor induction in mice; however, the mutagenicity of AA in this tissue is unclear. Therefore, to investigate whether or not gene mutation is involved in the etiology of AA- or GA-induced mouse lung carcinogenicity, we screened for cII mutant frequency (MF) in lungs from male and female Big Blue (BB) mice administered 0, 1.4, and 7.0 mM AA or GA in drinking water for up to 4 weeks (19-111 mg/kg bw/days). Both doses of AA and GA produced significant increases in cII MFs, with the high doses producing responses 2.7-5.6-fold higher than the corresponding controls (P ≤ 0.05; control MFs = 17.2 ± 2.2 and 15.8 ± 3.5 × 10(-6) in males and females, respectively). Molecular analysis of the mutants from high doses indicated that AA and GA produced similar mutation spectra and that these spectra were significantly different from the spectra in control mice (P ≤ 0.01). The predominant types of mutations in the lung cII gene from AA- and GA-treated mice were A:T → T:A, and G:C → C:G transversions, and -1/+1 frameshifts at a homopolymeric run of Gs. The MFs and types of mutations induced by AA and GA in the lung are consistent with AA exerting its genotoxicity via metabolism to GA. These results suggest that AA is a mutagenic carcinogen in mouse lungs and therefore further studies on its potential health risk to humans are warranted. Environ. Mol. Mutagen. 56:446-456, 2015. © 2015 Wiley Periodicals, Inc.

Microbial aerobic and anaerobic degradation of acrylamide in sludge and water under environmental conditions--case study in a sand and gravel quarry

Polyacrylamides (PAMs) are used in sand and gravel quarries as water purification flocculants for recycling process water in a recycling loop system where the flocculants remove fine particles in the form of sludge. The PAM-based flocculants, however, contain residual amounts of acrylamide (AMD) that did not react during the polymerization process. This acrylamide is released into the environment when the sludge is discharged into a settling basin. Here, we explore the microbial diversity and the potential for AMD biodegradation in water and sludge samples collected in a quarry site submitted to low AMD concentrations. The microbial diversity, analyzed by culture-dependent methods and the denaturing gradient gel electrophoresis approach, reveals the presence of Proteobacteria, Cyanobacteria, and Actinobacteria, among which some species are known to have an AMD biodegradation activity. Results also show that the two main parts of the water recycling loop-the washing process and the settling basin-display significantly different bacterial profiles. The exposure time with residual AMD could, thus, be one of the parameters that lead to a selection of specific bacterial species. AMD degradation experiments with 0.5 g L(-1) AMD showed a high potential for biodegradation in all parts of the washing process, except the make-up water. The AMD biodegradation potential in samples collected from the washing process and settling basin was also analyzed taking into account on-site conditions: low (12 °C) and high (25 °C) temperatures reflecting the winter and summer seasons, and AMD concentrations of 50 μg L(-1). Batch tests showed rapid (as little as 18 h) AMD biodegradation under aerobic and anaerobic conditions at both the winter and summer temperatures, although there was a greater lag time before activity started with the AMD biodegradation at 12 °C. This study, thus, demonstrates that bacteria present in sludge and water samples exert an in situ and rapid biodegradation of AMD at low concentration, whatever the season, and in both the aerobic and anaerobic parts of the water recycling system.

Multiple reuses of Rhodococcus ruber TH3 free cells to produce acrylamide in a membrane dispersion microreactor

In this work, multiple reuses of Rhodococcus ruber TH3 free cells for the hydration of acrylonitrile to produce acrylamide in a membrane dispersion microreactor were carried out. Through using a centrifuge, the reactions reached 39.9, 39.5, 38.6 and 38.0wt% of the final acrylamide product concentration respectively within 35min in a four cycle reuse of free cells. In contrast, using a stirring tank, free cells could only be used once with the same addition speed of acrylonitrile with a microreactor. Through observing the dissolution behavior of acrylonitrile microdroplets in a free cell solution using a coaxial microfluidic device and microscope, it was found that the acrylonitrile microdroplets with a diameter of 75μm were rarely observed within a length of 2cm channel within 10s, which illustrated that the microreactor can intensify the reaction rate to reduce the inhibition of acrylonitrile and acrylamide.

Characterization of fatty acid binding and transfer from Δ98Δ, a functional all-β abridged form of IFABP

Intestinal fatty acid binding protein (IFABP) is an intracellular lipid binding protein whose specific functions within the cell are still uncertain. An abbreviated version of IFABP encompassing residues 29-126, dubbed Δ98Δ is a stable product of limited proteolysis with clostripain of holo-IFABP. Cumulative evidence shows that Δ98Δ adopts a stable, monomeric and functional fold, with compact core and loose periphery. In agreement with previous results, this abridged variant indicates that the helical domain is-not necessary to preserve the general topology of IFABP's β-barrel and that the helix-turn-helix motif is a fundamental element of the portal region involved in ligand binding and protein-membrane interactions. Results presented here suggest that Δ98Δ binds fatty acids with affinities lower than IFABP but higher than those shown by previous helix-less variants, shows a 'diffusional' fatty acid transfer mechanism and it interacts with artificial membranes. This work highlights the importance of the β-barrel of IFABP for its specific functions.

Hydration of acrylonitrile to produce acrylamide using biocatalyst in a membrane dispersion microreactor

In this work, a membrane dispersion microreactor was utilized for the hydration of acrylonitrile to produce acrylamide. Through observation using a microscopy, it was found that the acrylonitrile was dispersed into the continuous phase (the aqueous phase contains nitrile hydratase (NHase)) as droplets with a diameter ranged from 25 to 35 μm, hence the mass transfer specific surface area was significantly increased, and the concentration of acrylamide reached 52.5 wt% within 50 min. By contrast, in stirred tanks, the concentration of acrylamide only got 39.5 wt% within 245 min. Moreover, only a few amounts of acrylonitrile were accumulated in this microreactor system. Through optimizing the flow rate, the concentration of acrylamide reached 45.8 wt% within 35 min, the short reaction time greatly weakened the inhibition of acrylonitrile and acrylamide on the enzyme activity, which is suitable for prolonging the life of free cell.

Change in Content of Sugars and Free Amino Acids in Potato Tubers under Short-Term Storage at Low Temperature and the Effect on Acrylamide Level after Frying

Changes in the sugar and amino acid contents of potato tubers during short-term storage and the effect on the acrylamide level in chips after frying were investigated. The acrylamide content in chips began to increase after 3 days of storage at 2 degrees C in response to the increase of glucose and fructose contents in the tubers. There was strong correlation between the reducing sugar content and acrylamide level, R(2)=0.873 for fructose and R(2)=0.836 for glucose. The sucrose content had less correlation with the acrylamide content because of its decrease after 4 weeks of storage at 2 degrees C, while the reducing sugar in potato tubers and the acrylamide in chips continued to increase. The contents of the four amino acids, i.e., asparatic acid, asparagine, glutamic acid and glutamine, showed no significant correlation with the acrylamide level. These results suggest that the content of reducing sugars in potato tubers determined the degree of acrylamide formation in chips. The chip color, as evaluated by L* (lightness), was correlated well with the acrylamide content.

Mouse spermatocytes express CYP2E1 and respond to acrylamide exposure

Metabolism of xenobiotics by cytochrome P450s (encoded by the CYP genes) often leads to bio-activation, producing reactive metabolites that interfere with cellular processes and cause DNA damage. In the testes, DNA damage induced by xenobiotics has been associated with impaired spermatogenesis and adverse effects on reproductive health. We previously reported that chronic exposure to the reproductive toxicant, acrylamide, produced high levels of DNA damage in spermatocytes of Swiss mice. CYP2E1 metabolises acrylamide to glycidamide, which, unlike acrylamide, readily forms adducts with DNA. Thus, to investigate the mechanisms of acrylamide toxicity in mouse male germ cells, we examined the expression of the CYP, CYP2E1, which metabolises acrylamide. Using Q-PCR and immunohistochemistry, we establish that CYP2E1 is expressed in germ cells, in particular in spermatocytes. Additionally, CYP2E1 gene expression was upregulated in these cells following in vitro acrylamide exposure (1 µM, 18 h). Spermatocytes were isolated and treated with 1 µM acrylamide or 0.5 µM glycidamide for 18 hours and the presence of DNA-adducts was investigated using the comet assay, modified to detect DNA-adducts. Both compounds produced significant levels of DNA damage in spermatocytes, with a greater response observed following glycidamide exposure. A modified comet assay indicated that direct adduction of DNA by glycidamide was a major source of DNA damage. Oxidative stress played a small role in eliciting this damage, as a relatively modest effect was found in a comet assay modified to detect oxidative adducts following glycidamide exposure, and glutathione levels remained unchanged following treatment with either compound. Our results indicate that the male germ line has the capacity to respond to xenobiotic exposure by inducing detoxifying enzymes, and the DNA damage elicited by acrylamide in male germ cells is likely due to the formation of glycidamide adducts.