Effects of heat-induced food contaminant furan on reproductive system of male rats from weaning through postpuberty

The impact of furan exposure on steroidogenesis in Leydig cells: cellular and molecular observations

BACKGROUND

Furan is an organic compound that occurs as a result of heat treatment during the processing and cooking of many food products. Furthermore, the environment contains furan in tobacco smoke and vehicle exhaust gases, and it serves as an intermediate molecule in the synthesis of various pharmaceutical and chemical agents, pesticides, and stabilizers. Studies on the male reproductive system have not been able to elucidate the pathway through which furan exerts its negative effects.

METHODS AND RESULTS

In this study, the TM3 Leydig cell line was exposed to various furan concentrations (0.03, 0.3, and 3 mM) for 24 h. In order to assess the cytotoxic effects of furan on Leydig cells, we examined cell viability, cell proliferation, and lactate dehydrogenase enzyme levels. To investigate the detrimental effects of furan on testosterone biosynthesis, quantitative analyses were conducted on cAMP and testosterone levels, as well as the expression levels of key genes and transcription factors implicated in the steroidogenic pathway. The results indicate that furan inhibited the viability and proliferation of Leydig cells and enhanced the activity of lactate dehydrogenase. Leydig cells administered to furan exhibited notable reductions in cAMP and testosterone levels. Additionally, while the expression levels of steroidogenic genes were downregulated, significant changes were detected in the expression levels of the transcription factors responsible for the regulation of these genes.

CONCLUSIONS

Consequently, our findings suggest that furan exerts inhibitory effects on steroidogenesis in Leydig cells through multiple mechanisms, ultimately leading to infertility by inducing dysfunction in Leydig cells.

Targeted quantification and untargeted exploration of furan and derivatives in infant food by headspace extraction-gas chromatography-Q Exactive Orbitrap mass spectrometry

The aim of the present study was to assess the performance and complementarity of methods capable of both quantifying furan, 2-Methylfuran (2-MF) and 3-Methylfuran (3-MF) in infant foods, but also to comprehensively explore other furan derivatives. It is more particularly a question of validating and comparing the couplings of the two headspace extraction methods most used for the analysis of furan compounds - Headspace Solid Phase Microextraction (HS-SPME) and Static HeadSpace (SHS) - with gas chromatography hyphenated to a high-resolution mass detector (Q Exactive-Orbitrap MS) which allows both targeted quantification and suspect screening. Firstly, the accuracy profile approach was implemented to assess, validate and compare HS-SPME- and SHS-GC-Q Exactive-Orbitrap MS for the quantification of furan in two model infant foods, apple puree and first infant formula. SHS-GC-Q Exactive-Orbitrap MS, showed better accuracy (uncertainty < 17.2 % vs 22.5 % for HS-SPME GC-Q Exactive-Orbitrap MS) and better sensitivity (LOQ < 2.8 vs LOQ < 4.0 µg/kg) over a broader validation range (2-100 µg/kg vs 5-100 µg/kg in apple puree). Secondly, SHS-GC-Q Exactive-Orbitrap MS was assessed and validated by accuracy profile for the quantification of 2-MF and 3-MF, with performance close to those for furan except for 3-MF in apple puree. Thirdly, SHS-GC-Q Exactive-Orbitrap MS was used to quantify the levels of these compounds in 20 commercial samples (n = 3) belonging to the four main categories of infant food (infant formulae, fruit purees, infant cereals, vegetable/fish baby meals). Furan was quantified in 75 % of the samples, with maximum levels in the vegetable/fish-based infant foods (up to 127 µg/kg) while 2-MF and 3-MF were quantified in 45 % and 15 % of products respectively, with maximum levels of 14.1 µg/kg in follow-on formula 3rd age and 9.2 µg/kg in apple puree. Finally, SHS- and HS-SPME-GC-Q Exactive-Orbitrap MS data of the 20 infant products were processed in suspect screening mode using Compound DiscovererTM software. Coupling with HS-SPME, it made it possible to identify 13 additional furan derivatives, i.e. 5 more than with SHS. The relevance and safety status of the compounds identified are discussed.

Analytical methods, risk assessment, and mitigation strategies for furan in processed foods in various countries

This article provides an overview of analytical methods for measuring furan levels in food. Given the potential carcinogenicity of furans in humans, several studies have focused on assessing furan levels in various food products. In this review, we specifically examine furan levels in foods that are central to regional culinary traditions and summarize the results of country-specific risk assessments. Consequently, we have identified foods that contribute significantly to dietary furan exposure in each region. Coffee and baby foods, regardless of region, emerged as the primary sources of furan intake among adults and infants, respectively. Several previous studies have been conducted to develop various mitigation strategies aimed at reducing exposure to furan through food intake. Therefore, in this paper, we categorize effective mitigation strategies into two main groups: alterations to processing conditions and the addition or removal of food additives and ingredients.

A Comprehensive Bibliometric Study in the Context of Chemical Hazards in Coffee

The research aimed to carefully review the chemical hazards linked to the coffee production chain to analyse the risks and opportunities for consumers and the environment, as well as identify potential knowledge gaps. The Scopus database was consulted from 1949 to April 2024 to conduct a bibliometric analysis. As a result, 680 articles were analysed. Results indicated a significant increase in research activity since 2015. China, Brazil, and the USA were the leading countries in scientific production and collaborations. The most prolific journals in this field were Chemosphere, Science of the Total Environment, Food Chemistry, Journal of Agricultural and Food Chemistry, and Journal of Environmental Management, all of which are in the first quartile. The word analysis revealed two main themes: the first focuses on the chemical hazards of coffee and their impact on health, while the second explores the waste generated during coffee production and its potential for reuse. The topics covered in the research include the composition of coffee, associated chemical hazards, possible health risks, and ways to reuse waste for environmental protection. Future research should concentrate on optimising techniques and processes to ensure quality, safety, and sustainability.

Oral exposure to polystyrene nanoplastics altered the hypothalamic-pituitary-testicular axis role in hormonal regulation, inducing reproductive toxicity in albino rats

BACKGROUND

Nanoplastics can be considered a novel contaminant for the environment because of their extensive applications in modern society, which represents a possible threat to humans. Nevertheless, the negative effect of polystyrene nanoplastics (PS-NPs) on male reproduction, fertility, and progeny outcomes is not well known. Thus, the aim of the present work was to calculate the median lethal dose (LD50) and investigate the consequences of exposure to PS-NPs (25 nm) on male reproductive toxicity.

METHODS

This investigation first determined the LD50 of PS-NPs in male Wistar rats, and then in a formal study, 24 rats were distributed into three groups (n = 8): the control group; the low-dose group (3 mg/kg bw); and the high-dose group (10 mg/kg bw) of PS-NPs administered orally for 60 days. On the 50th day of administration, the fertility test was conducted.

RESULTS

The LD50 was determined to be 2500 mg/kg. PS-NP administration induced significant alternations, mainly indicating mortality in the high-dose group, a significant elevation in body weight gain, declined sperm quality parameters, altered reproductive hormonal levels, thyroid endocrine disruption, an alternation of the normal histo-architecture and the histo-morphometric analysis of the testes, and impaired male fertility.

CONCLUSION

Altogether, the current findings provide novel perspectives on PS-NP general toxicity with specific reference to male reproductive toxicity.

Mitigating effect of pomegranate peel extract against the furan induced testicular injury by apoptosis, steroidogenic enzymes and oxidative stress

Furan is generated in a wide array of heat-treated foods through thermal degradation, leading to severe impairments in the male reproductive system. The main objective of this study was to investigate the potential of pomegranate peel extract (PGPE) in mitigating testicular dysfunctions induced by furan. Male rats were categorized into four groups: control/untreated, PGPE, furan, and PGPE + furan group. The study results revealed that furan-treated rats exhibited significantly elevated aminotransferase and phosphatase activity, and also generated increased oxidative stress, and reduced antioxidative stress protein activity. Additionally, protein content levels (ALT, AST, ALP, and ACP) and activities of steroidogenic Leydig cell hydroxysteroid dehydrogenase (3β-HSD and 17β-HSD) enzymes were significantly decreased. Significant variations in testicular parameters, apoptotic genes (Bcl-2, P53, and Caspase3), inflammatory and anti-inflammatory cytokines (IL1β, IL10), male sex hormones follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and sperm quality were also observed. Furthermore, testicular histological abnormalities were confirmed by biochemical and molecular modifications. Notably, PGPE pre-treated furan-intoxicated animals exhibited significant improvements in most of the assessed parameters compared to furan-treated groups. In conclusion, PGPE presents essential preventive measures and a novel pharmacological potential therapy against furan-induced testicular injury.

Comparative genomic analysis of Fischer F344 rat livers exposed for 90 days to 3-methylfuran or its parental compound furan

Furan is a naturally forming compound found in heat-processed foods such as coffee, canned meats, and jarred baby food. It is concurrently found with analogues including 2-methylfuran (2-MF) and 3-methylfuran (3-MF), and toxicity studies demonstrate all are potent liver toxins. Toxicity studies found 3-MF is more toxic than either furan, or 2-MF. The present analysis assesses the transcriptional response in liver samples taken from male Fischer (F344) rats exposed to furan or 3-MF from 0 to 2.0 and 0-1.0 mg/kg bw/day, respectively, for 90 days. Transcriptional analyses found decreased liver function and fatty acid metabolism are common responses to both furan and 3-MF exposure. Furan liver injury promotes a ductular reaction through Hippo and TGFB signalling, which combined with increased immune response results in ameliorating perturbed bile acid homeostasis in treated rats. Failure to activate these pathways in 3-MF exposed rats and decreased p53 activity leads to cholestasis, and increased toxicity. Finally, BMD analysis indicate many of the most sensitive pathways affected by furan and 3-MF exposure relate to metabolism - malate dehydrogenase and glucose metabolism with BMDLs of 0.03 and 0.01 mg/kg bw/day for furan and 3-MF exposure, respectively, which agrees with BMDLs previously reported for apical and microarray data.

Furan promotes cytotoxic effects through DNA damage and cell apoptosis in Leydig cells

Furan is an organic chemical that can cause adverse effects on human health and is formed as a result of the thermal decomposition of many food components during cooking, storage, and processing techniques. Studies have shown that exposure to furan causes nephrotoxicity, hepatotoxicity, immunotoxicity, and reproductive toxicity. According to our current knowledge of the literature, the genotoxic mode of action of furan is highly controversial. The genotoxic effects of furan on the male reproductive system, however, have not been studied. In this study, the TM3 Leydig cell line was treated with 750, 1500, and 3000 μM concentrations of furan for 24 h. Following the completion of the exposure period, the cytotoxicity of furan in TM3 Leydig cells was assessed using a cell viability assay and a spectrophotometric measurement of lactate dehydrogenase (LDH) enzyme levels. The double fluorescence staining method was used to demonstrate furan-induced apoptosis, and DNA damage was shown using the micronucleus, comet, and chromosomal aberration assays. The result indicated that furan administration of Leydig cells resulted in an increase in structural chromosomal aberration, comet, and micronucleus formation, reduced cell viability, increased LDH activity, and a higher incidence of apoptotic cells. These findings revealed that furan induces DNA damage in TM3 Leydig cells, causing genotoxicity and DNA damage-induced cytotoxicity.

Assessment of the oxidative damage and apoptotic pathway related to furan cytotoxicity in cultured mouse Leydig cells

Research on heat-induced food contamination is being given more attention as a result of the health risks that have been publicly revealed in recent years. Furan is known as a colorless, combustible, heterocyclic aromatic organic molecule and is formed when food products are processed and stored. It has been established that furan, which is inevitably ingested, has a deleterious impact on human health and causes toxicity. Furan is known to have adverse effects on the immune system, neurological system, skin, liver, kidney, and fat tissue. Infertility caused by furan is a result of its damaging effects on several tissues and organs as well as the reproductive system. Although studies on the adverse effects of furan on the male reproductive system have been performed, there is no study revealing apoptosis in Leydig cells at the gene level. In this study, TM3 mouse Leydig cells were exposed to 250- and 2,500-μM concentrations of furan for 24 h. The findings demonstrated that furan decreased cell viability and antioxidant enzyme activity while increasing lipid peroxidation, reactive oxygen species, and apoptotic cell rates. Furan also increased the expression of the important apoptotic genes Casp3 and Trp53 while decreasing the expression of another pro-apoptotic gene, Bcl2, and antioxidant genes Sod1, Gpx1, and Cat. In conclusion, these results imply that furan may cause loss of cell function in mouse Leydig cells responsible for testosterone biosynthesis by impairing the efficiency of the antioxidant system, possibly by inducing cytotoxicity, oxidative stress, and apoptosis.

A comprehensive review of furan in foods: From dietary exposures and in vivo metabolism to mitigation measures

Furan is a thermal food processing contaminant that is ubiquitous in various food products such as coffee, canned and jarred foods, and cereals. A comprehensive summary of research progress on furan is presented in this review, including discussion of (i) formation pathways, (ii) occurrence and dietary exposures, (iii) analytical techniques, (iv) toxicities, (v) metabolism and metabolites, (vi) risk assessment, (vii) potential biomarkers, and (viii) mitigation measures. Dietary exposure to furan varies among different countries and age groups. Furan acts through various toxicological pathways mediated by its primary metabolite, cis-2-butene-1,4-dial (BDA). BDA can readily react with glutathione, amino acids, biogenic amines, or nucleotides to form corresponding metabolites, some of which have been proposed as potential biomarkers of exposure to furan. Present risk assessment of furan mainly employed the margin of exposure approach. Given the widespread occurrence of furan in foods and its harmful health effects, mitigating furan levels in foods or exploring potential dietary supplements to protect against furan toxicity is necessary for the benefit of food safety and public health.

Mechanistic insight into the protective effects of fisetin against arsenic-induced reproductive toxicity in male rats

Arsenic is one of the most hazardous environmental contaminants, which adversely affects the dynamics of male reproductive system. Fisetin (FIS) is a bioactive flavonoid, which is known to exert strong antioxidative effects. Therefore, the current research was planned to evaluate the alleviative efficacy of FIS against arsenic-induced reproductive damages. Forty-eight male albino rats were divided into 4 groups (n = 12), which were treated as follows: (1) Control, (2) Arsenic-intoxicated group (8 mg kg-1), (3) Arsenic + FIS-treated group (8 mg kg-1 + 10 mg kg-1), and (4) FIS-treated group (10 mgkg-1). After 56 days of treatment, the biochemical, lipidemic, steroidogenic, hormonal, spermatological, apoptotic and histoarchitectural profiles of rats were analyzed. Arsenic intoxication reduced the enzymatic activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GSR), in addition to glutathione (GSH) level. Conversely, the levels of thiobarbituric acid reactive substance (TBARS) and reactive oxygen species (ROS) were increased. Moreover, it escalated the level of low-density lipoprotein (LDL), triglycerides and total cholesterol, while declining the level of high-density lipoprotein (HDL). Furthermore, steroidogenic enzymes expressions, 3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD, steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (CYP11A1) and 17α-hydroxylase/17, 20-lyase (CYP17A1), were found to be reduced, which brought down the level of testosterone. Besides, the levels of gonadotropins (LH and FSH) were decreased. Additionally, a decline in sperm mitochondrial membrane potential (MMP), motility, epididymal sperm count and hypo-osmotic swelling (HOS) coil-tailed sperms was observed, whereas the dead sperms and structural damages (head, midpiece and tail) of sperms were escalated. Moreover, arsenic exposure up-regulated the mRNA expressions of apoptotic markers, namely Bax and caspase-3, whereas lowered the expression of anti-apoptotic marker, Bcl-2. In addition, it induced histoarchitectural changes in testes of rats. However, FIS treatment resulted in remarkable improvements in testicular and sperm parameters. Therefore, it was inferred that FIS could serve as a therapeutic candidate against arsenic-generated male reproductive toxicity attributing to its anti-oxidant, anti-lipoperoxidative, anti-apoptotic, and androgenic efficacy.

Rhamnetin alleviates polystyrene microplastics-induced testicular damage by restoring biochemical, steroidogenic, hormonal, apoptotic, inflammatory, spermatogenic and histological profile in male albino rats

The current research was performed to evaluate the ameliorative effects of Rhamnetin (RHM) on polystyrene microplastics (PS-MPs)-instigated testicular dysfunction in male albino rats. 48 albino rats were distributed in four groups, i.e., control, PS-MPs treated, PS-MPs + RHM co-treated and RHM only supplemented group. PS-MPs exposure considerably reduced anti-oxidant enzymes i.e., catalase (CAT), glutathione peroxidase (GSR), superoxide dismutase (SOD) and glutathione reductase (GPx) activities. Whereas, reactive oxygen species (ROS) level along with malondialdehyde (MDA) was considerably escalated in PS-MPs treated rats as well as a potential decline was observed in sperm progressive motility. Additionally, a substantial upsurge was noticed in the count of dead sperms, deformity in the tail, mid-piece and head of sperms in PS-MPs treated rats. PS-MPs exposure also decreased steroidogenic enzymes, 17β-hydroxysteroid dehydrogenase (17β-HSD), steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase (3β-HSD) expressions. Moreover, the levels of inflammatory indices i.e., Interleukin-6 (IL-6), Nuclear factor kappa-B (NF-κB), Interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2) activity were also increased in PS-MPs administrated group. Besides it increased the expression of apoptotic markers (Bax and caspase-3) expression. Whereas, anti-apoptotic marker i.e., Bcl-2 expression was reduced. Moreover, luteinizing hormone (LH), follicle-stimulating hormone (FSH) as well as plasma testosterone levels were also decreased. PS-MPs exposure also led to a substantial histopathological damage in testicular tissues. However, RHM supplementation potentially reduced the damaging effects of PS-MPs in the reproductive tissues of male albino rats. Thus, the current study revealed, RHM possesses potential to prevent PS-MPs-induced testicular damage due to its anti-oxidant anti-apoptotic, anti-inflammatory as well as androgenic properties.

Accidental lead in contaminated pipe-borne water and dietary furan intake perturbs rats' hepatorenal function altering oxidative, inflammatory, and apoptotic balance

Inadvertent exposure to furan and Pb is associated with hepatorenal abnormalities in humans and animals. It is perceived that these two chemical species may work in synergy to orchestrate liver and kidney damage. Against this background, we investigated the combined effect of furan and incremental lead (Pb) exposure on hepatorenal dysfunction. Wistar rats (n = 30; 150 g) were treated for 28 days accordingly: Control; FUR (8 mg/kg), PbAc (100 µg/L), FUR + PbAc₁ (8 mg/kg FUR + 1 µg/L PbAc); FUR + PbAc₁ (8 mg/kg FUR + 10 µg/L PbAc), and FUR + PbAc₁ (8 mg/kg FUR + 100 µg/L PbAc). Biomarkers of hepatorenal function, oxidative stress, inflammation, DNA damage, and apoptosis were examined. Furan and incrementally Pb exposure increased the levels of hepatorenal biomarkers and oxidative and pro-inflammatory mediators, including lipid peroxidation, reactive oxygen and nitrogen species, and interleukin-1 beta. Increased DNA damage, caspases- 9 and -3, and atypical histoarchitecture of the hepatorenal tissues exemplified furan and Pb treatment-related perturbations. Furthermore, the levels of antioxidants and IL-10 were also suppressed. Furan and Pb dose-dependently exacerbated hepatorenal derangements by altering the redox and inflammatory rheostats, worsened DNA damage, and related apoptotic onset that may potentiate hepatorenal disorders in humans and animals. The findings validate the synergistic effect of furan and Pb in the pathophysiology of kidney and liver disorders.

Dose-Dependent Effect of Polystyrene Microplastics on the Testicular Tissues of the Male Sprague Dawley Rats

Due to the continuous increase in polystyrene microplastics (PS MPs) incorporation in the environment, growing number of adverse effects on living organisms and ecosystem have become a global concern. Therefore, current study was planned to elucidate the impacts of 5 different concentrations control, 2, 20, 200, and 2000 μgL-1 of PS MPs on testicular tissues of rats. PS MPs significantly reduced the activities of antioxidant enzymes (catalase, superoxide dismutase and peroxidase) as well as total protein contents, while elevated the level of lipid peroxidation and reactive oxygen species. Moreover, expressions of steroidogenic enzymes (3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein) as well as the levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) in plasma, intra-testicular testosterone and plasma testosterone were reduced and a significant (P < 0.05) reduction was noticed in the sperm count, motility and viability. Furthermore, PS MPs significantly up-regulated the expressions of Bax and caspase-3, while down-regulated the Bcl-2 expression. The histomorphological assessment revealed significant damages in the testicles as well as decrease in the number of germ cells (spermatogenic, spermatocytes and spermatids). Collectively, PS MPs generated oxidative stress (OS) and caused potential damage to the testicles of rats in a dose-dependent manner.

Study of occupational exposure to brick kiln emissions on heavy metal burden, biochemical profile, cortisol level and reproductive health risks among female workers at Rawat, Pakistan

The present study was planned to understand the heavy metal burden and its possible actions in blood of occupational females working at brick kilns at Rawat, Pakistan. A total of 232 women were included in the study, of which 114 presented control subjects. Apart from collection of demographic data, fertility indicators and body mass index (BMI), blood was collected from subjects that was later used for the determination of heavy metal concentrations using atomic absorption spectroscopy and haematological profile. Blood was centrifuged and plasma was obtained and stored at - 20° to study biochemical variables (sodium dismutase, peroxidase, reactive oxygen species, thiobarbituric acid reactive species, protein estimation), lipid profile and cortisol concentrations among the two groups. Analysis of heavy metal in blood showed elevated levels of cadmium (3.09 ± 0.01 μg/dl), chromium (4.20 ± 0.02 μg/dl) and nickel (5.59 ± 0.03 μg/dl) in worker's group as compared with control. Increased platelet count; decreased antioxidant enzyme and increased oxidants level; increased total cholesterol, low-density lipoprotein (LDL) and triglyceride (TG); decreased total protein and high-density lipoprotein (HDL); and increased cortisol levels were evident among workers as compared with the control group. The study concluded that occupational workers experience increased heavy metals burden in blood and, therefore, pose a risk to human health by causing reduction in antioxidant enzymes concentration and increase in stress conditions.

Effects of endocrine disruptor furan on reproductive physiology of Sprague Dawley rats: An F1 Extended One-Generation Reproductive Toxicity Study (EOGRTS)

The present study investigated the reproductive toxicity of furan in an Extended One-Generation Reproductive Toxicity Study in rats. Sprague Dawley F0 weaning rats (30 per sex per group) were exposed to furan orally at 0, 1, 2.5, 5, and 10 mg kg^-1 for 10 weeks (males) and 2 weeks (females) and then mated. Results of F0 indicated that in the furan-treated groups (5 mg kg^-1 and 10 mg kg^-1), body weight (bw) gain decreased during prebreed and gestational period while increased during lactation periods. F0 animals prebreeding exposure resulted in head tilt and foot splay at 10 mg kg^-1. Number of live pups at birth were decreased (p < 0.001) at 10 mg kg^-1. At postnatal day (PND) 70, a significant (p = 0.03) decrease in testosterone levels of male rats and estrogen levels of female rats (p = 0.05) was observed in 10 mg kg^-1 furan-treated group in F1 generation. Luteinizing hormone, follicle-stimulating hormone, and progesterone levels were also reduced, but their reduction was not statistically significant in all groups. In higher dose furan group (10 mg kg^-1), testicular and ovarian weights were reduced in F1 generation at PND 70, with decreased daily sperm production (p = 0.01) and disturbed estrous cyclicity (p < 0.01). Some histopathological changes were also observed in testis and ovaries in groups whose parents were previously exposed to 10 mg kg^-1 bw of furan group. Based on the above results, it is suggested that exposure to food-based contaminant furan induced remarkable changes in the F0 (parental stage) and F1 (offspring, pubertal, and adult stage) generations of Sprague Dawley rats.

Toxicological effects of furan on the reproductive system of male rats: An "in vitro" and "in vivo"-based endocrinological and spermatogonial study

Furan is a colorless toxic chemical produced in various food items during heat processing and in chemical industries. Both in vitro and in vivo studies have reported that it induces oxidative stress and endocrine disruption; however, limited data are available regarding the effects of furan on the reproduction of mammals. In the present study, an in vitro experiment was designed to investigate the direct effects of furan exposure on oxidative stress and testosterone concentration in rat testicular tissue. Furan not only generated high oxidative stress but also decreased antioxidant enzyme activity in the testicular tissue. On the basis of in vitro study results, an in vivo sub-chronic exposure study was performed. Male rats were orally exposed to different concentrations of furan (0, 5, 10, 20, and 40 mg kg^-1). An increase (P < 0.05) of reactive oxygen species (ROS) and of the lipid profile (cholesterol, triglycerides, and LDL) in higher dose treatment groups of furan was observed, while total protein content and antioxidant enzyme activity were considerably decreased after furan exposure. Also, plasma and intratesticular testosterone concentrations were reduced in high-dose treatment groups. Sperm parameters such as sperm viability, sperm count, and sperm motility showed a decrease (P < 0.05) in a dose-dependent manner. Histopathological findings revealed significant alterations in testis and epididymis tissues. These results confirm that furan can induce toxic effects on the reproductive system of male rats.

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

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

Protective role of garlic oil against oxidative damage induced by furan exposure from weaning through adulthood in adult rat testis

Furan is produced in a wide variety of heat-treated foods via thermal degradation. Furan contamination is found to be relatively high in processed baby foods, cereal products, fruits juices, and canned vegetables. Several studies have demonstrated that furan is a potent hepatotoxin and hepatocarcinogen in rodents. However, few studies have investigated the toxic effects of furan in the testis. In addition, the exact mechanism(s) by which furan exerts toxicity in the testis has not been fully elucidated. In this study, we investigated the potential of furan exposure from weaning through adulthood to induce oxidative stress in adult rat testis, as well as the potential of garlic oil (GO) to ameliorate the induced toxicity. Our results reveal that furan administration significantly reduced serum testosterone levels and increased the levels of malondialdehyde (MDA); furthermore, furan administration decreased significantly the enzymatic activity of testicular antioxidants, including glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) and induced histopathological alterations in the testis. GO co-administration ameliorated the reduction in testosterone levels and dramatically attenuated the furan-induced oxidative and histopathological changes. In addition, Go significantly down-regulated the increased caspase-3 and cytochrome P450 2E1 (CYP2E1) expression in the furan-treated testis. To the best of our knowledge, this study is the first to demonstrate the furan-induced oxidative changes in the adult rat testis and the protective role of GO to ameliorate these changes through its antioxidant effects and its ability to inhibit CYP2E1 production.

Toxicity of food contaminant furan on liver and kidney of growing male rats

Furan is a chemical used in some industrial products and occurs naturally in heat-treated foods. We aimed to investigate the effects of orally administered furan on liver and kidney in growing Wistar male rats for 90 days. In this respect, biochemical, morphological, histopathological, and histomorphometrical examinations were performed. Three- to 4-week aged rats were divided into five groups of eight animals each; control, oil control; 2, 4, 8 mg/kg/day furan treatment groups. At the end of the experiment, antioxidant enzyme activities and serum AST, ALT, HDL, Urea, etc. levels were analyzed. Malondialdehyde (MDA) levels, superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were also measured in liver homogenates. Also, liver and kidney were examined morphologically and histopathologically under light microscopy. According to the results of biochemical analysis, ALT, ALP, and LDL levels in treatment groups were significantly different compared with control groups. While LDL levels in treatment groups increased significantly, ALT and ALP levels decreased significantly. No significant changes were observed in liver MDA levels, superoxide dismutase and catalase activities in treatment groups. While IL-6 levels did not change in treatment groups, furan caused dose-dependent increases in liver TNF-α level of rats. In treatment groups, absolute and relative liver weights changed significantly, however, no significant changes were observed in kidney and relative kidney weights. Hyperemic blood vessels in the liver and congestion, edema, fibrosis, and tubular damage in the kidney of rats treated with furan were observed histopathologically. According to histomorphometric examinations, glomeruli diameters and glomerular volume decreased in the kidneys of rats in treatment groups.

Does furan affect the thymus in growing male rats?

Furan has been identified in foods such as heat-treated foods, including coffee, canned meat, hazelnuts, and infant foods and formulas. Children may be exposed to furan via either consumption of these foods or their derivatives. We evaluated the effects of furan on the thymus of weaning male rats in the present study. Five separate groups containing male rats were used: control, oil control, and three furan-treated groups. Furan was given orally to rats in the treatment groups at doses of 2, 4, and 8 mg/kg/day for 90 days. At the end of the experiment, thymus of the rats were examined morphologically, histopathologically, and immunohistochemically. We observed that absolute and relative weights of thymus were decreased significantly in rats treated with 4- and 8-mg/kg/day doses of furan. In histopathological examination, enlargement of interstitial connective tissue between the thymic lobules, lymphocyte depletion, and hemorrhage were observed. We detected an increase in apoptotic cell counts in thymus of the treatment groups. In addition, we found significant differences in the distribution of fibronectin and transforming growth factor-beta in the thymus of the treatment groups. In conclusion, we suggest that furan has affected the thymus in growing male rats.