The metabolism and biotransformation of AFB1: Key enzymes and pathways

In vitro detoxification of aflatoxin B1 by Lactiplantibacillus plantarum isolated from the north of Iran: A pioneering insights into the origin of fermented beverages

The contamination of food and animal feeds with mycotoxions, particularly aflatoxin B1 (AFB1), poses significant risks to human health and causes economic losses. This study investigated bacteria from various fermented milk products to assess their ability to detoxify AFB1. A variety of household fermented kefir milk, kefir-like beverages, and kefir grains were collected from rural areas and subjected to microbiological analysis. Gram-positive bacterial isolates were further identified based on the 16S rRNA gene homology analysis. Seven bacterial isolates that were initially identified as lactic acid bacteria were selected for their potential to detoxify AFB1. Effects of environmental factors, including temperature, time, pH, and cell concentration, as well as bacterial components such as inoculum, fermentation supernatant, and cells, were evaluated on AFB1 detoxification. The most frequent isolates belonged to the new genus Lentilactobacillus and Lactiplantibacillus, of which three strains were identified as L. kefiri, L. diolivorans, and L. plantarum. The selected L. plantarum isolate demonstrated optimal AFB1 detoxification at pH 4, a 4-h exposure time, and a cell concentration of 1.0 × 1016 CFU/mL. Significant differences were observed in toxin removal between fermentation supernatant and cells, while temperature showed no significant effect on toxin detoxification. This study demonstrated the high ability of L. plantarum for AFB1 detoxification, suggesting potential applications for food and feed safety enhancement. Further research is warranted to optimize its effectiveness and explore broader applications.

Aflatoxin B1-induced hepatotoxicity through mitochondrial dysfunction, oxidative stress, and inflammation as central pathological mechanisms: A review of experimental evidence

Aflatoxin B1 (AFB1) is a class of mycotoxin known to contaminate agricultural products, animal feed and animal food products, subsequently causing detrimental effects on human and animal health. AFB1 is the most common and potent aflatoxin found in food and contributes significantly to liver injury as well as the development of hepatocellular carcinoma. Although the liver is a primary target organ for AFB1 toxicity and biotransformation, underlying mechanisms implicated in liver injuries induced by these mycotoxins remain to be fully elucidated for therapeutic purposes. This review aims to dissect the complexities of the pathophysiological and molecular mechanisms implicated in hepatotoxicity induced by AFB1, including mitochondrial dysfunction, oxidative stress and hepatic inflammation. Mechanistically, AFB1 disrupt mitochondrial bioenergetics and membrane potential, promotes mitochondrial cholesterol trafficking and induces mitophagy. Moreover, mitochondrial dysfunction may lead to hepatic oxidative stress as a consequence of uncontrolled production of reactive oxygen species and defects in the antioxidant defense system. Retrieved experimental evidence also showed that AFB1 may lead to hepatic inflammation through gut microbiota dysbiosis, the release of DAMPs and cytokines, and immune cell recruitment. Overall, these mechanisms could be utilized as potential targets to extrapolate treatment for liver injury caused by AFB1.

Degradation of nitrocellulose film under aerobic conditions by a newly isolated Rhodococcus pyridinivorans strain

The explosive and biorefractory nature of nitrocellulose (NC) poses major risks to both humans and the environment. Expanding the range of microorganisms capable of degrading NC is essential, though the most effective known microorganisms, Desulfovibrio genera and Fusarium solani, achieve degradation rates of 5%-25%. Here, a novel strain, Rhodococcus pyridinivorans LZ1 was isolated, demonstrating the ability to degrade NC, with its growth potentially enhanced by the presence of NC. The degradation process was monitored by assessing changes in nitrate, nitrite, and ammonium. Notably, the -OH strength of NC increased over time, whereas the energetic functional groups (-NO2 and O-NO2) diminished. Furthermore, the presence of NC enhanced nitrate esterase activity 1-2-fold, indicating that ammonification was the primary pathway for NC biodegradation. By converting the nitrate ester of NC into hydroxyl, R. pyridinivorans LZ1 mitigates the harmful effects of NC, offering a promising approach for the treatment of NC waste and wastewater.

Impact of Missense Mutations on AFB1 Metabolism in Bovine Cytochrome P4503A Isoforms: A Computational Mutagenesis and Molecular Docking Analysis

Cytochrome P450 3A (CYP3A) enzymes catalyze the metabolism of a wide range of endogenous and exogenous compounds. Genetic variations in the 3 CYP3A isoforms (CYP3A28, CYP3A74, and CYP3A76) may influence their expression and activity, leading to inter-individual differences in xenobiotic metabolism. In domestic cattle, understanding how genetic variations modulate CYP3A activity is crucial for both its therapeutic implications (clinical efficacy and adverse drug effects) and food safety (residues in foodstuff). Here, we updated the variant calling of CYP3As in 300 previously sequenced Piedmontese beef cattle, using the most recent reference genome, which contains an updated, longer sequence for CYP3A28. All but one previously identified missense variants were confirmed and a new variant, R105W in CYP3A28, was discovered. Through computational mutagenesis and molecular docking, we computationally predicted the impact of all identified CYP3A variant enzymes on protein stability and their affinity for aflatoxin B1 (AFB1), a potent carcinogen and food contaminant. For CYP3A28, we also computationally predicted its affinity for the probe substrate nifedipine (NIF). We found that CYP3A28 with R105W variant cannot accommodate NIF nor AFB1 in the binding pocket, thus affecting their metabolism. Our work provides computational foundation and prioritized ranking of CYP3A variants for future experimental validations.

Aflatoxin Exposure-Caused Male Reproductive Toxicity: Molecular Mechanisms, Detoxification, and Future Directions

Widespread endocrine disorders and infertility caused by environmental and food pollutants have drawn considerable global attention. Aflatoxins (AFTs), a prominent class of mycotoxins, are recognized as one of the key contributors to environmental and food contamination. Aflatoxin B1 (AFB1) is the most potent and toxic pollutant among them and is known to cause multiple toxic effects, including neuro-, nephro-, hepato-, immune-, and genotoxicity. Recently, concerns have been raised regarding AFB1-induced infertility in both animals and humans. Exposure to AFB1 can disrupt the structure and functionality of reproductive organs, leading to gametogenesis impairment in males, subsequently reducing fertility. The potential molecular mechanisms have been demonstrated to involve oxidative stress, cell cycle arrest, apoptosis, inflammatory responses, and autophagy. Furthermore, several signaling pathways, including nuclear factor erythroid 2-related factor 2; NOD-, LRR-, and pyrin domain-containing protein 3; nuclear factor kappa-B; p53; p21; phosphoinositide 3-kinase/protein kinase B; the mammalian target of rapamycin; adenosine 5'-monophosphate-activated protein kinase; and mitochondrial apoptotic pathways, are implicated in these processes. Various interventions, including the use of small molecules, Chinese herbal extracts, probiotic supplementation, and camel milk, have shown efficacy in ameliorating AFB1-induced male reproductive toxicity, by targeting these signaling pathways. This review provides a comprehensive summary of the harmful impacts of AFB1 exposure on male reproductive organs in mammals, highlighting the potential molecular mechanisms and protective agents.

Chemical contaminants in donkey milk: A review of literature on sources, routes and pathways of contamination, regulatory framework, health risks, and preventive measures

Donkey milk has garnered increasing attention due to its potential health benefits and nutritional properties, positioning it as a valuable alternative to cow's milk for specific consumer groups, such as individuals with allergies, young children, elderly populations, and those with compromised immune systems. However, the presence of chemical contaminants in donkey milk presents a significant concern for food safety and public health. This review aims to provide an assessment of the types and sources of chemical contaminants in donkey milk, including heavy metals, mycotoxins, pesticides, polychlorinated biphenyls, and antimicrobial and antiparasitic veterinary drugs. Through a comprehensive analysis of available literature, we examine the routes and pathways through which these contaminants enter the milk, their prevalence, and the associated health risks. The review also briefly discusses analytical methods for detecting these contaminants and the existing legislative framework that regulates these contaminants, underscoring its critical role in safeguarding public health and promoting safe consumption of donkey milk products. By identifying gaps in existing research and suggesting areas for further study, this review seeks to contribute to the development of more effective strategies for monitoring and mitigating chemical contamination in donkey milk, ultimately safeguarding consumer health and supporting the sustainable production of this niche dairy product.

Widespread distribution of the DyP-carrying bacteria involved in the aflatoxin B1 biotransformation in Proteobacteria and Actinobacteria

Aflatoxin is one of the most notorious mycotoxins, of which aflatoxin B1 (AFB1) is the most harmful and prevalent. Microbes play a crucial role in the environment for the biotransformation of AFB1. In this study, a bacterial consortium, HS-1, capable of degrading and detoxifying AFB1 was obtained. Here, we combined multi-omics and cultivation-based techniques to elucidate AFB1 biotransformation by consortium HS-1. Co-occurrence network analysis revealed that the key taxa responsible for AFB1 biotransformation in consortium HS-1 mainly belonged to the phyla Proteobacteria and Actinobacteria. Moreover, metagenomic analysis showed that diverse microorganisms, mainly belonging to the phyla Proteobacteria and Actinobacteria, carry key functional enzymes involved in the initial step of AFB1 biotransformation. Metatranscriptomic analysis indicated that Paracoccus-related bacteria were the most active in consortium HS-1. A novel bacterium, Paracoccus sp. strain XF-30, isolated from consortium HS-1, contains a novel dye-decolorization peroxidase (DyP) enzyme capable of effectively degrading AFB1. Taxonomic profiling by bioinformatics revealed that DyP, which is involved in the initial biotransformation of AFB1, is widely distributed in metagenomes from various environments, primarily taxonomically affiliated with Proteobacteria and Actinobacteria. The in-depth examination of AFB1 biotransformation in consortium HS-1 will help us to explore these crucial bioresources more sensibly and efficiently.

Identification of cytochrome P450 2C18 and 2C76 in tree shrews: P450 2C18 effectively oxidizes typical human P450 2C9/2C19 chiral substrates warfarin and omeprazole with less stereoselectivity

Cytochromes P450 (P450s or CYPs), especially the CYP2C family, are important drug-metabolizing enzymes that play major roles in drug metabolism. Tree shrews, a non-rodent primate-like species, are used in various fields of biomedical research, notably hepatitis virus infection; however, its drug-metabolizing enzymes have not been fully investigated. In this study, tree shrew CYP2C18, CYP2C76a, CYP2C76b, and CYP2C76c cDNAs were identified and contained open reading frames of 489 or 490 amino acids with high sequence identities (70-78 %) to human CYP2Cs. Tree shrew CYP2C76a, CYP2C76b, and CYP2C76c showed higher sequence identities (79-80 %) to cynomolgus CYP2C76 and were not orthologous to any human CYP2C. Phylogenetic analysis revealed that tree shrew CYP2C18 and CYP2C76s were closely related to rat CYP2Cs and cynomolgus CYP2C76, respectively. Tree shrew CYP2C genes formed a gene cluster similar to human CYP2C genes. All four tree shrew CYP2C mRNAs showed predominant expressions in liver, among the tissue types examined; expression of CYP2C18 mRNA was also detected in small intestine. In liver, CYP2C18 mRNA was the most abundant among the tree shrew CYP2C mRNAs. In metabolic assays using human CYP2C substrates, all tree shrew CYP2Cs showed metabolic activities toward diclofenac, R,S-omeprazole, paclitaxel, and R,S-warfarin, with the activity of CYP2C18 exceeding that of the other CYP2Cs. Moreover, tree shrew CYP2C76 enzymes metabolized progesterone more efficiently than human, cynomolgus, or marmoset CYP2Cs. Therefore, these novel tree shrew CYP2Cs are expressed abundantly in liver, encode functional enzymes that metabolize human CYP2C substrates, and are likely responsible for drug clearances.

Aflatoxin M1 levels in urine and breast milk of lactating mothers in Kuala Lumpur, Malaysia

Aflatoxins are carcinogens that can contaminate food and affect various body organs especially liver and kidney. When consumed, aflatoxin B1 (AFB1) is partially metabolised into aflatoxin M1 (AFM1), which is excreted in the urine. Breast milk may also contain AFM1 due to maternal dietary intake from contaminated food. This cross-sectional study aimed to determine the levels of AFM1 in both urine and breast milk among breastfeeding mothers (n = 256). The mother's demographic information was collected during recruitment. Mothers were then scheduled for an appointment to provide a morning urine sample along with five to ten mL samples of breast milk. AFM1 levels in both samples were analysed using an enzyme-linked immunosorbent assay (ELISA). Spearman's rho and Chi-square were used to determine the associations between mean levels of AFM1 in urine and breast milk. Findings show 68.0% of urine samples were contaminated with AFM1 (mean levels = 0.08 ± 0.04 ng/mL), while 14.8% of breast milk samples had AFM1 (mean levels = 5.94 ± 1.81 ng/kg). Urine AFM1 levels were not significantly associated with AFM1 levels in breast milk (p > 0.05). This study can act as a baseline for future research examining long-term aflatoxin exposure among both mothers and infants.

New insights into aflatoxin B1 mechanistic toxicology in cattle liver: an integrated approach using molecular docking and biological evaluation in CYP1A1 and CYP3A74 knockout BFH12 cell lines

Aflatoxin B1 (AFB1) is a pro-carcinogenic compound bioactivated in the liver by cytochromes P450 (CYPs). In mammals, CYP1A and CYP3A are responsible for AFB1 metabolism, with the formation of the genotoxic carcinogens AFB1-8,9-epoxide and AFM1, and the detoxified metabolite AFQ1. Due to climate change, AFB1 cereals contamination arose in Europe. Thus, cattle, as other farm animals fed with grains (pig, sheep and broiler), are more likely exposed to AFB1 via feed with consequent release of AFM1 in milk, posing a great concern to human health. However, knowledge about bovine CYPs involved in AFB1 metabolism is still scanty. Therefore, CYP1A1- and CYP3A74-mediated molecular mechanisms of AFB1 hepatotoxicity were here dissected. Molecular docking of AFB1 into CYP1A1 model suggested AFB1 8,9-endo- and 8,9-exo-epoxide, and AFM1 formation, while docking of AFB1 into CYP3A74 pointed to AFB1 8,9-exo-epoxide and AFQ1 synthesis. To biologically confirm these predictions, CYP1A1 and CYP3A74 knockout (KO) BFH12 cell lines were exposed to AFB1. LC-MS/MS investigations showed the abolished production of AFM1 in CYP1A1 KO cells and the strong increase of parent AFB1 in CYP3A74 KO cells; the latter result, coupled to a decreased cytotoxicity, suggested the major role of CYP3A74 in AFB1 8,9-exo-epoxide formation. Finally, RNA-sequencing analysis indirectly proved lower AFB1-induced cytotoxic effects in engineered cells versus naïve ones. Overall, this study broadens the knowledge on AFB1 metabolism and hepatotoxicity in cattle, and it provides the weight of evidence that CYP1A1 and CYP3A74 inhibition might be exploited to reduce AFM1 and AFBO synthesis, AFB1 toxicity, and AFM1 milk excretion.

Anti-Aflatoxigenic Burkholderia contaminans BC11-1 Exhibits Mycotoxin Detoxification, Phosphate Solubilization, and Cytokinin Production

The productivity and quality of agricultural crops worldwide are adversely affected by disease outbreaks and inadequate nutrient availability. Of particular concern is the potential increase in mycotoxin prevalence due to crop diseases, which poses a threat to food security. Microorganisms with multiple functions have been favored in sustainable agriculture to address such challenges. Aspergillus flavus is a prevalent aflatoxin B1 (AFB1)-producing fungus in China. Therefore, we wanted to obtain an anti-aflatoxigenic bacterium with potent mycotoxin detoxification ability and other beneficial properties. In the present study, we have isolated an anti-aflatoxigenic strain, BC11-1, of Burkholderia contaminans, from a forest rhizosphere soil sample obtained in Luzhou, Sichuan Province, China. We found that it possesses several beneficial properties, as follows: (1) a broad spectrum of antifungal activity but compatibility with Trichoderma species, which are themselves used as biocontrol agents, making it possible to use in a biocontrol mixture or individually with other biocontrol agents in an integrated management approach; (2) an exhibited mycotoxin detoxification capacity with a degradation ratio of 90% for aflatoxin B1 and 78% for zearalenone, suggesting its potential for remedial application; and (3) a high ability to solubilize phosphorus and produce cytokinin production, highlighting its potential as a biofertilizer. Overall, the diverse properties of BC11-1 render it a beneficial bacterium with excellent potential for use in plant disease protection and mycotoxin prevention and as a biofertilizer. Lastly, a pan-genomic analysis suggests that BC11-1 may possess other undiscovered biological properties, prompting further exploration of the properties of this unique strain of B. contaminans. These findings highlight the potential of using the anti-aflatoxigenic strain BC11-1 to enhance disease protection and improve soil fertility, thus contributing to food security. Given its multiple beneficial properties, BC11-1 represents a valuable microbial resource as a biocontrol agent and biofertilizer.

Effectiveness of Hydrated Sodium Calcium Aluminosilicates and Discarded Date Pits as Dietary Adsorbents for Aflatoxin B1 in Enhancing Broiler Chicken Productive Performance, Hepatic Function, and Intestinal Health

The research aimed to evaluate how effective hydrated sodium calcium aluminosilicates (HSCASs) and discarded date pits (DDPs) are as dietary adsorbents for aflatoxin B1 (AFB1) in enhancing the performance and health of broiler chickens aged 16 to 30 days. A total of 240 Ross 308 straight-run broilers were randomly allocated into four dietary groups, each with 10 replicates: a control diet, a control diet with 1000 ppb AFB1, an AFB1-contaminated diet with 0.5% HSCAS, and an AFB1-contaminated diet with 4% DDP. Incorporating HSCASs or DDPs into the AFB1-contaminated diet resulted in significant improvements across various parameters, involving increased body weight, improved feed conversion ratio, higher dressing percentage, decreased relative weights of kidney and spleen, elevated serum levels of total protein, globulin, and glucose, reduced serum alanine aminotransferase activity, and heightened hepatic protein concentration and glutathione peroxidase activity, along with diminished hepatic malondialdehyde content and glutamic oxaloacetic transaminase activity. Moreover, both supplements led to increased ileal villus height and surface area, enhanced apparent nitrogen-corrected metabolizable energy digestibility, and decreased AFB1 residues in the liver and kidney. Moreover, the dietary inclusion of DDPs significantly decreased relative liver weight, raised serum albumin concentration, lowered serum alkaline phosphatase activity, enhanced hepatic total antioxidant capacity level, and augmented ileal villus width. Conversely, the dietary addition of HSCASs significantly heightened apparent crude protein digestibility. In conclusion, the inclusion of HSCASs and DDPs in AFB1-contaminated diets can mitigate the toxic effects of AFB1 on broiler chickens, with DDPs exhibiting additional advantages in optimizing liver function and gut morphology.

A sandwich-type photoelectrochemical biosensor based on Ru(bpy)32+ sensitized In2S3 for aflatoxin B1 detection

Aflatoxin B1 (AFB1), classified as a class I carcinogen, is a widespread mycotoxin that poses a serious threat to public health and economic development, and the food safety problems caused by AFB1 have aroused worldwide concern. The development of accurate and sensitive methods for the detection of AFB1 is significant for food safety monitoring. In this work, a sandwich-type photoelectrochemical (PEC) biosensor for AFB1 detection was constructed on the basis of an aptamer-antibody structure. A good photocurrent response was obtained due to the sensitization of In2S3 by Ru(bpy)32+. In addition, this sandwich-type sensor constructed by modification with the antibody, target detector, and aptamer layer by layer attenuated the migration hindering effect of photogenerated carriers caused by the double antibody structure. The aptamer and antibody synergistically recognized and captured the target analyte, resulting in more reliable PEC response signals. CdSe@CdS QDs-Apt were modified as a signal-off probe onto the sensor platform to quantitatively detect AFB1 with a "signal-off" response, which enhanced the sensitivity of the sensor. The PEC biosensor showed a linear response range from 10-12 to 10-6 g mL-1 with a detection limit of 0.023 pg mL-1, providing a feasible approach for the quantitative detection of AFB1 in food samples.

Detoxification of Aflatoxin B1 by Phytochemicals in Agriculture and Food Science

Aflatoxin B1 (AFB1), the most toxic and harmful mycotoxin, has a high likelihood of occurring in animal feed and human food, which seriously affects agriculture and food safety and endangers animal and human health. Recently, natural plant products have attracted widespread attention due to their low toxicity, high biocompatibility, and simple composition, indicating significant potential for resisting AFB1. The mechanisms by which these phytochemicals resist toxins mainly involve antioxidative, anti-inflammatory, and antiapoptotic pathways. Moreover, these substances also inhibit the genotoxicity of AFB1 by directly influencing its metabolism in vivo, which contributes to its elimination. Here, we review various phytochemicals that resist AFB1 and their anti-AFB1 mechanisms in different animals, as well as the common characteristics of phytochemicals with anti-AFB1 function. Additionally, the shortcomings of current research and future research directions will be discussed. Overall, this comprehensive summary contributes to the better application of phytochemicals in agriculture and food safety.

Omics analysis revealed the intestinal toxicity induced by aflatoxin B1 and aflatoxin M1

Aflatoxin B1 (AFB1), a common mycotoxin, can occur in agricultural products. As a metabolite of AFB1, aflatoxin M1 (AFM1) mainly exist in dairy products. These two mycotoxins threaten human health, although it is unclear how they affect the function of the intestinal barrier. In this study, mice were exposed to AFB1 (0.3 mg/kg body b.w.) and AFM1(3.0 mg/kg b.w.) either individually or in combination for 28 days to explore the main differentially expressed proteins (DEPs) and the associated enriched pathways. These findings were preliminarily verified by the transcriptomic and proteomic analyses in differentiated Caco-2 cells. The results revealed that AFB1 and AFM1 exposure in mice disrupted the function of the intestinal barrier, and the combined toxicity was greater than that of each toxin alone. Further proteomic analysis in mice demonstrated that the mechanisms underlying these differences could be explained as follows: (i) lipid metabolism was enriched by AFB1-induced DEPs. (ii) protein export pathway was stimulated by AFM1-induced DEPs. (iii) cell metabolic ability was inhibited (as evidenced by changes in UDP-GT1, UDP-GT2, and Gatm6), apoptosis was induced (MAP4K3), and epithelial cell integrity was disrupted (Claudin7 and IQGAP2), resulting in more extensive intestinal damage after combined treatment. In conclusion, the hazardous impact of co-exposure to AFB1 and AFM1 from proteomic perspectives was demonstrated in the present study.

Exploring the Impact of Efavirenz on Aflatoxin B1 Metabolism: Insights from a Physiologically Based Pharmacokinetic Model and a Human Liver Microsome Study

Physiologically based pharmacokinetic (PBPK) models were utilized to investigate potential interactions between aflatoxin B1 (AFB1) and efavirenz (EFV), a non-nucleoside reverse transcriptase inhibitor drug and inducer of several CYP enzymes, including CYP3A4. PBPK simulations were conducted in a North European Caucasian and Black South African population, considering different dosing scenarios. The simulations predicted the impact of EFV on AFB1 metabolism via CYP3A4 and CYP1A2. In vitro experiments using human liver microsomes (HLM) were performed to verify the PBPK predictions for both single- and multiple-dose exposures to EFV. Results showed no significant difference in the formation of AFB1 metabolites when combined with EFV (0.15 µM) compared to AFB1 alone. However, exposure to 5 µM of EFV, mimicking chronic exposure, resulted in increased CYP3A4 activity, affecting metabolite formation. While co-incubation with EFV reduced the formation of certain AFB1 metabolites, other outcomes varied and could not be fully attributed to CYP3A4 induction. Overall, this study provides evidence that EFV, and potentially other CYP1A2/CYP3A4 perpetrators, can impact AFB1 metabolism, leading to altered exposure to toxic metabolites. The results emphasize the importance of considering drug interactions when assessing the risks associated with mycotoxin exposure in individuals undergoing HIV therapy in a European and African context.

Modulatory potential of Bacopa monnieri against aflatoxin B1 induced biochemical, molecular and histological alterations in rats

Oxidative injury is concerned with the pathogenesis of several liver injuries, including those from acute liver failure to cirrhosis. This study was designed to explore the antioxidant activity of Bacopa monnieri (BM) on Aflatoxin B1 (AFB1) induced oxidative damage in Wistar albino rats. Aflatoxin B1 treatment (200 μg/kg/day, p.o.) for 28 days induced oxidative injury by a significant alteration in serum liver function test marker enzymes (AST, ALT, ALP, LDH, albumin and bilirubin), inflammatory cytokines (IL-6, IL-10 and TNF-α), thiobarbituric acid reactive substances (TBARS) along with reduction of antioxidant enzymes (GSH, SOD, CAT), GSH cycle enzymes and drug-metabolizing enzymes (AH and AND). Treatment of rats with B. monnieri (20, 30 and 40 mg/kg for 5 days, p.o.) after 28 days of AFB1 intoxication significantly restored these parameters near control in a dose-dependent way. Histopathological examination disclosed extensive hepatic injuries, characterized by cellular necrosis, infiltration, congestion and sinusoidal dilatation in the AFB1-treated group. Treatment with B. monnieri significantly reduced these toxic effects resulting from AFB1. B. monnieriper se group (40 mg/kg) did not show any significant change and proved safe. The cytotoxic activity of B. monnieri was also evaluated on HepG2 cells and showed a good percentage of cytotoxic activity. This finding suggests that B. monnieri protects the liver against oxidative damage caused by AFB1, which aids in the evaluation of the traditional usage of this medicinal plant.

Therapeutic detoxification of quercetin for aflatoxin B1-related toxicity: Roles of oxidative stress, inflammation, and metabolic enzymes

Aflatoxins (AFTs), a type of mycotoxin mainly produced by Aspergillus parasiticus and Aspergillus flavus, could be detected in food, feed, Chinese herbal medicine, grain crops and poses a great threat to public health security. Among them, aflatoxin B1 (AFB1) is the most toxic one. Exposure to AFB1 poses various health risks to both humans and animals, including the development of chronic inflammatory diseases, cardiovascular diseases, neurodegenerative diseases, and cancer. The molecular mechanisms underlying these risks are intricate and dependent on specific contexts. This review primarily focuses on summarizing the protective effects of quercetin, a natural phenolic compound, in mitigating the toxic effects induced by AFB1 in both in vitro experiments and animal models. Additionally, the review explores the molecular mechanisms that underlie these protective effects. Quercetin has been demonstrated to not only have the direct inhibitory action on the production of AFTs from Aspergillus, both also possess potent ameliorative effects against AFB1-induced cytotoxicity, hepatotoxicity, and neurotoxicity. These effects are attributed to the inhibition of oxidative stress, mitochondrial dysfunction, mitochondrial apoptotic pathway, and inflammatory response. It could also directly target several metabolic enzymes (i.e., CYP3As and GSTA1) to reduce the production of toxic metabolites of AFB1 within cells, then reduce AFB1-induced cytotoxicity. In conclusion, this review highlights quercetin is a promising detoxification agent for AFB1. By advancing our understanding of the protective mechanisms offered by quercetin, we aim to contribute to the development of effective detoxification agents against AFB1, ultimately promoting better health outcomes.

Chicken CYP1A5 is able to hydroxylate aflatoxin B1 to aflatoxin M1

Aflatoxin B1 (AFB1), a naturally-occurring mycotoxin, can cause severe toxicological and carcinogenic effects in livestock and humans. Given that the chicken is one of the most important food-producing animals, knowledge regarding AFB1 metabolism and enzymes responsible for AFB1 transformation in the chicken has important implications for chicken production and food safety. Previously, we have successfully expressed chicken CYP1A5 and CYP3A37 monooxygenases in E. coli, and reconstituted them into a functional CYP system consisting of CYP1A5 or CYP3A37, CPR and cytochrome b5. In this study, we aimed to investigate the roles of CYP1A5 and CYP3A37 in the bioconversion of AFB1 to AFM1. Our results showed that chicken CYP1A5 was able to hydroxylate AFB1 to AFM1. The formation of AFM1 followed the typical Michaelis-Menten kinetics. The kinetics parameters of Vmax and Km were determined as 0.83 ± 0.039 nmol/min/nmol P450 and 26.9 ± 4.52 μM respectively. Docking simulations further revealed that AFB1 adopts a "side-on" conformation in chicken CYP1A5, facilitating the hydroxylation of the C9a atom and the production of AFM1. On the other hand, AFB1 assumes a "face-on" conformation in chicken CYP3A37, leading to the displacement of the C9a atom from the heme iron and explaining the lack of AFM1 hydroxylation activity. The results demonstrate that chicken CYP1A5 possesses efficient hydroxylase activity towards AFB1 to form AFM1.

Effect of Acrylamide and Mycotoxins in SH-SY5Y Cells: A Review

Thermal processes induce the formation of undesired toxic components, such as acrylamide (AA), which has been shown to induce brain toxicity in humans and classified as Group 2A by the International Agency of Research in Cancer (IARC), as well as some mycotoxins. AA and mycotoxins' toxicity is studied in several in vitro models, including the neuroblastoma cell line model SH-SY5Y cells. Both AA and mycotoxins occur together in the same food matrix cereal base (bread, pasta, potatoes, coffee roasting, etc.). Therefore, the goal of this review is to deepen the knowledge about the neurological effects that AA and mycotoxins can induce on the in vitro model SH-SY5Y and its mechanism of action (MoA) focusing on the experimental assays reported in publications of the last 10 years. The analysis of the latest publications shows that most of them are focused on cytotoxicity, apoptosis, and alteration in protein expression, while others are interested in oxidative stress, axonopathy, and the disruption of neurite outgrowth. While both AA and mycotoxins have been studied in SH-SY5Y cells separately, the mixture of them is starting to draw the interest of the scientific community. This highlights a new and interesting field to explore due to the findings reported in several publications that can be compared and the implications in human health that both could cause. In relation to the assays used, the most employed were the MTT, axonopathy, and qPCR assays. The concentration dose range studied was 0.1-10 mM for AA and 2 fM to 200 µM depending on the toxicity and time of exposure for mycotoxins. A healthy and varied diet allows the incorporation of a large family of bioactive compounds that can mitigate the toxic effects associated with contaminants present in food. Although this has been reported in some publications for mycotoxins, there is still a big gap for AA which evidences that more investigations are needed to better explore the risks for human health when exposed to AA and mycotoxins.

Key Role of Porcine Cytochrome P450 2A19 in the Bioactivation of Aflatoxin B1 in the Liver

The metabolic transformation of aflatoxin B1 (AFB1) in pigs remains understudied, presenting a gap in our toxicological understanding compared with extensive human-based research. Here, we found that the main products of AFB1 in porcine liver microsomes (PLMs) were AFB1-8,9-epoxide (AFBO), the generation of which correlated strongly with the protein levels and activities of cytochrome P450 (CYP)3A and CYP2A. In addition, we found that porcine CYP2A19 can transform AFB1 into AFBO, and its metabolic activity was stronger than the other CYPs we have reported, including CYP1A2, CYP3A29, and CYP3A46. Furthermore, we stably transfected all identified CYPs in HepLi cells and found that CYP2A19 stable transfected HepLi cells showed more sensitivity in AFB1-induced DNA adducts, DNA damage, and γH2AX formation than the other three stable cell lines. Moreover, the CYP2A19 N297A mutant that lost catalytic activity toward AFB1 totally eliminated AFB1-induced AFB1-DNA adducts and γH2AX formations in CYP2A19 stable transfected HepLi cells. These results indicate that CYP2A19 mainly mediated AFB1-induced cytotoxicity through metabolizing AFB1 into a highly reactive AFBO, promoting DNA adduct formation and DNA damage, and lastly leading to cell death. This study advances the current understanding of AFB1 bioactivation in pigs and provides a promising target to reduce porcine aflatoxicosis.

Optimizing the degradation of aflatoxin B1 in corn by Trametes versicolor and improving the nutritional composition of corn

BACKGROUND

Corn, being an important grain, is prone to contamination by aflatoxin B1 (AFB1 ), and AFB1 -contaminated corn severely endangers the health of humans and livestock. Trametes versicolor, a fungus that can grow in corn, possesses the ability to directly degrade AFB1 through its laccase. This study aimed to optimize the fermentation conditions for T. versicolor to degrade AFB1 in corn and investigate the effect of T. versicolor fermentation on the nutritional composition of corn. AFB1 -contaminated corn was used as the culture substrate for T. versicolor. A combination of single-factor experiments and response surface methodology was employed to identify the optimal conditions of AFB1 degradation.

RESULTS

The optimal conditions of AFB1 degradation were as follows: 9 days of fermentation, a fermentation temperature of 26.7 °C, a moisture content of 70.5% and an inoculation amount of 4.9 mL (containing 51.99 mg of T. versicolor mycelia). With the optimal conditions, the degradation rate of AFB1 in corn could reach 93.01%, and the dry basis content of protein and dietary fiber in the fermented corn was significantly increased. More importantly, the lysine content in the fermented corn was also significantly increased.

CONCLUSION

This is the first report that direct fermentation of AFB1 -contaminated corn by T. versicolor not only efficiently degrades AFB1 but also improves the nutritional composition of corn. These findings suggest that the fermentation of corn by T. versicolor is a promising, environmentally friendly and efficient approach to degrade AFB1 and improve the nutritional value of corn. © 2023 Society of Chemical Industry.

An Insight into Different Experimental Models used for Hepatoprotective Studies: A Review

Numerous factors, including exposure to harmful substances, drinking too much alcohol, contracting certain hepatitis serotypes, and using specific medicines, contribute to the development of liver illnesses. Lipid peroxidation and other forms of oxidative stress are the main mechanisms by which hepatotoxic substances harm liver cells. Pathological changes in the liver include a rise in the levels of blood serum, a decrease in antioxidant enzymes, as well as the formation of free radical radicals. It is necessary to find pharmaceutical alternatives to treat liver diseases to increase their efficacy and decrease their toxicity. For the development of new therapeutic medications, a greater knowledge of primary mechanisms is required. In order to mimic human liver diseases, animal models are developed. Animal models have been used for several decades to study the pathogenesis of liver disorders and related toxicities. For many years, animal models have been utilized to investigate the pathophysiology of liver illness and associated toxicity. The animal models are created to imitate human hepatic disorders. This review enlisted numerous hepatic damage in vitro and in vivo models using various toxicants, their probable biochemical pathways and numerous metabolic pathways via oxidative stressors, different serum biomarkers enzymes are discussed, which will help to identify the most accurate and suitable model to test any plant preparations to check and evaluate their hepatoprotective properties.

Cellular and molecular mechanisms of aflatoxin B1-mediated neurotoxicity: The therapeutic role of natural bioactive compounds

Aflatoxin B1 (AFB1), a dietary toxin from the mold Aspergillus species, is well acknowledged to elicit extra-hepatic toxicity in both animals and humans. The neurotoxicity of AFB1 has become a global public health concern. Contemporary research on how AFB1 enters the brain to elicit neuronal dysregulation leading to noxious neurological outcomes has increased greatly in recent years. The current review discusses several neurotoxic outcomes and susceptible targets of AFB1 toxicity at cellular, molecular and genetic levels. Specifically, neurotoxicity studies involving the use of brain homogenates, neuroblastoma cell line IMR-32, human brain microvascular endothelial cells, microglial cells, and astrocytes, as well as mammalian and non-mammalian models to unravel the mechanisms associated with AFB1 exposure are highlighted. Further, some naturally occurring bioactive compounds with compelling therapeutic effects on AFB1-induced neurotoxicity are reviewed. In conclusion, available data from literature highlight AFB1 as a neurotoxin and its possible pathological contribution to neurological disorders. Further mechanistic studies aimed at discovering and developing effective therapeutics for AFB1 neurotoxicity is warranted.

Discovering the Protective Effects of Quercetin on Aflatoxin B1-Induced Toxicity in Bovine Foetal Hepatocyte-Derived Cells (BFH12)

Aflatoxin B1 (AFB1) induces lipid peroxidation and mortality in bovine foetal hepatocyte-derived cells (BFH12), with underlying transcriptional perturbations associated mainly with cancer, cellular damage, inflammation, bioactivation, and detoxification pathways. In this cell line, curcumin and resveratrol have proven to be effective in mitigating AFB1-induced toxicity. In this paper, we preliminarily assessed the potential anti-AFB1 activity of a natural polyphenol, quercetin (QUE), in BFH12 cells. To this end, we primarily measured QUE cytotoxicity using a WST-1 reagent. Then, we pre-treated the cells with QUE and exposed them to AFB1. The protective role of QUE was evaluated by measuring cytotoxicity, transcriptional changes (RNA-sequencing), lipid peroxidation (malondialdehyde production), and targeted post-transcriptional modifications (NQO1 and CYP3A enzymatic activity). The results demonstrated that QUE, like curcumin and resveratrol, reduced AFB1-induced cytotoxicity and lipid peroxidation and caused larger transcriptional variations than AFB1 alone. Most of the differentially expressed genes were involved in lipid homeostasis, inflammatory and immune processes, and carcinogenesis. As for enzymatic activities, QUE significantly reverted CYP3A variations induced by AFB1, but not those of NQO1. This study provides new knowledge about key molecular mechanisms involved in QUE-mediated protection against AFB1 toxicity and encourages in vivo studies to assess QUE's bioavailability and beneficial effects on aflatoxicosis.

Detoxification of aflatoxin B1 by Bacillus aryabhattai through conversion of double bond in terminal furan

AIMS

This study aimed to screen a bacterial strain with high detoxifying capability for aflatoxin B1 (AFB1), verify its biotransformation efficiency, and detoxification process.

METHODS AND RESULTS

A total of 350 samples collected from different environmental niche were screened using coumarin as the sole carbon source. High Performance Liquid Chromatography (HPLC) was used to detect residues of AFB1, and 16S rRNA sequencing was performed on the isolated strain with the highest AFB1 removal ratio for identification. The detoxified products of this strain were tested for toxicity in Escherichia coli as well as LO2, Caco-2, and HaCaT human cell lines. HPLC-MS was applied to further confirm the AFB1 removal and detoxification process.

CONCLUSIONS

We identified a strain from plant leaf designated as DT with high AFB1-detoxifying ability that is highly homologous to Bacillus aryabhattai. The optimum detoxification conditions of this strain were 37°C and pH 8.0, resulting in 82.92% removal ratio of 2 μg mL-1 AFB1 in 72 h. The detoxified products were nontoxic for E. coli and significantly less toxic for the LO2, Caco-2, and HaCaT human cell lines. HPLC-MS analysis also confirmed the significant drop of the AFB1 characteristic peak. Two possible metabolic products, C19H15O8 (m/z 371) and C19H19O8 (m/z 375), were observed by mass spectrometry. Potential biotransformation pathway was based on the cleavage of double bond in the terminal furan of AFB1. These generated components had different chemical structures with AFB1, manifesting that the attenuation of AFB1 toxicity would be attributed to the destruction of lactone structure of AFB1 during the conversion process.

Incidence of aflatoxin M1 in cows' milk in Pakistan, effects on milk quality and evaluation of therapeutic management in dairy animals

The present study was aimed at measuring the concentration of aflatoxin M1 (AFM1) in the milk of Holstein Friesian cows, its effect on the milk quality and seasonal trends, as well as to investigate the efficacy of a commercial clay-based toxin binder. For this purpose, milk samples from dairy cows (n = 72) were collected and assayed for AFM1 before employing a clay-based toxin binder. The milk samples (n = 72) were collected from selected animals, revealing that 69.4% of the milk samples had AFM1 levels above the United States permissible limit (0.5 μg/kg). The incidence of AFM1 in milk during the winter and summer was 82.5% and 53.1%, respectively. Owing to the presence of AFM1, the level of milk fat, solids-not-fat, and protein were found to be low. Subsequently, the affected animals were divided into two groups, i.e., AFM1 positive control (n = 10) and the experimental group (n = 40). The experimental group of animals were fed the clay-based toxin binder at 25 g/animal/day. A progressive decrease of 19.8% in the AFM1 levels was observed on day 4 and on day 7 (53.6%) in the treatment group. Furthermore, the fat, solids-non-fat and protein increased significantly in the milk. In conclusion, a high level of AFM1 contamination occurs in the milk in Pakistan, affecting the quality of the milk production. Clay-based toxin binders may be used to ensure the milk quality and to protect the animal and consumer health.

Aflatoxin B1 Degradation by Ery4 Laccase: From In Vitro to Contaminated Corn

Aflatoxins (AFs) are toxic secondary metabolites produced by Aspergillus spp. and are found in food and feed as contaminants worldwide. Due to climate change, AFs occurrence is expected to increase also in western Europe. Therefore, to ensure food and feed safety, it is mandatory to develop green technologies for AFs reduction in contaminated matrices. With this regard, enzymatic degradation is an effective and environmentally friendly approach under mild operational conditions and with minor impact on the food and feed matrix. In this work, Ery4 laccase, acetosyringone, ascorbic acid, and dehydroascorbic acid were investigated in vitro, then applied in artificially contaminated corn for AFB₁ reduction. AFB₁ (0.1 µg/mL) was completely removed in vitro and reduced by 26% in corn. Several degradation products were detected in vitro by UHPLC-HRMS and likely corresponded to AFQ₁, epi-AFQ₁, AFB₁-diol, or AFB₁dialehyde, AFB_2a, and AFM₁. Protein content was not altered by the enzymatic treatment, while slightly higher levels of lipid peroxidation and H₂O₂ were detected. Although further studies are needed to improve AFB₁ reduction and reduce the impact of this treatment in corn, the results of this study are promising and suggest that Ery4 laccase can be effectively applied for the reduction in AFB₁ in corn.

Cloning and expression of the catalase gene (KatA) from Pseudomonas aeruginosa and the degradation of AFB1 by recombinant catalase

BACKGROUND

Aflatoxin B₁ (AFB₁ ) poses a severe threat to human and animal health. Countries worldwide have invested considerable manpower and material resources in degrading aflatoxins. Enzyme degradation is the most efficient and environmentally friendly approach for modifying aflatoxin into less toxic molecules. Catalase is commonly used as a detoxification agent to decrease the contamination levels of aflatoxins in animal feeds. This study aimed to obtain recombinant catalase via gene engineering and determined whether a recombinant catalase could degrade AFB₁ .

RESULTS

The catalase gene (KatA) from Pseudomonas aeruginosa was cloned and expressed in Escherichia coli, and the expression conditions of this recombinant catalase were optimized. The recombinant catalase was isolated and purified using Ni-chelating affinity chromatography, and its ability to degrade AFB₁ was evaluated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the expressed of catalase was approximately 55.6 kDa, which was subsequently purified using Ni-chelating affinity chromatography. The degradation rate of AFB₁ by recombinant catalase in the presence of syringaldehyde was 38.79%.

CONCLUSION

The degradation of AFB₁ by a recombinant catalase has been reported for the first time. This study provides a new paradigm for the use of recombinant catalases in degrading AFB₁ in food and feed. © 2022 Society of Chemical Industry.

Aflatoxin B1 Toxicity and Protective Effects of Curcumin: Molecular Mechanisms and Clinical Implications

One of the most significant classes of mycotoxins, aflatoxins (AFTs), can cause a variety of detrimental outcomes, including cancer, hepatitis, aberrant mutations, and reproductive issues. Among the 21 identified AFTs, aflatoxin B1 (AFB1) is the most harmful to humans and animals. The mechanisms of AFB1-induced toxicity are connected to the generation of excess reactive oxygen species (ROS), upregulation of CYP450 activities, oxidative stress, lipid peroxidation, apoptosis, mitochondrial dysfunction, autophagy, necrosis, and inflammatory response. Several signaling pathways, including p53, PI3K/Akt/mTOR, Nrf2/ARE, NF-κB, NLRP3, MAPKs, and Wnt/β-catenin have been shown to contribute to AFB1-mediated toxic effects in mammalian cells. Curcumin, a natural product with multiple therapeutic activities (e.g., anti-inflammatory, antioxidant, anticancer, and immunoregulation activities), could revise AFB1-induced harmful effects by targeting these pathways. Therefore, the potential therapeutic use of curcumin against AFB1-related side effects and the underlying molecular mechanisms are summarized. This review, in our opinion, advances significant knowledge, sparks larger discussions, and drives additional improvements in the hazardous examination of AFTs and detoxifying the application of curcumin.

Does Bentonite Cause Cytotoxic and Whole-Transcriptomic Adverse Effects in Enterocytes When Used to Reduce Aflatoxin B1 Exposure?

Aflatoxin B1 (AFB1) is a major food safety concern, threatening the health of humans and animals. Bentonite (BEN) is an aluminosilicate clay used as a feed additive to reduce AFB1 presence in contaminated feedstuff. So far, few studies have characterized BEN toxicity and efficacy in vitro. In this study, cytotoxicity (WST-1 test), the effects on cell permeability (trans-epithelial electrical resistance and lucifer yellow dye incorporation), and transcriptional changes (RNA-seq) caused by BEN, AFB1 and their combination (AFB1 + BEN) were investigated in Caco-2 cells. Up to 0.1 mg/mL, BEN did not affect cell viability and permeability, but it reduced AFB1 cytotoxicity; however, at higher concentrations, BEN was cytotoxic. As to RNA-seq, 0.1 mg/mL BEN did not show effects on cell transcriptome, confirming that the interaction between BEN and AFB1 occurs in the medium. Data from AFB1 and AFB1 + BEN suggested AFB1 provoked most of the transcriptional changes, whereas BEN was preventive. The most interesting AFB1-targeted pathways for which BEN was effective were cell integrity, xenobiotic metabolism and transporters, basal metabolism, inflammation and immune response, p53 biological network, apoptosis and carcinogenesis. To our knowledge, this is the first study assessing the in vitro toxicity and whole-transcriptomic effects of BEN, alone or in the presence of AFB1.