Aflatoxins in the autopsy brain tissue of children in Nigeria

Aflatoxin B1-induced redox imbalance in the hippocampus and cerebral cortex of male Wistar rats is accompanied by altered cholinergic, indoleaminergic, and purinergic pathways: Abatement by dietary rutin

The neurotoxic impact of dietary exposure to aflatoxin B1 (AFB1) is well documented in experimental studies. Rutin is a phytochemical with prominent anti-inflammatory and antioxidant activities. There is an information gap on the influence of rutin on AFB1-induced neurotoxicity. This study investigated the influence of rutin on neurobehavioral and biochemical abnormalities in male Wistar rats (six weeks old) orally treated with AFB1 (0.75, and 1.5 mg/kg body weight) or co-administered with rutin (50 mg/kg) for 30 uninterrupted days. Results indicate that AFB1-induced depression-like behavior by Tail Suspension Test (TST) and cognitive impairment by Y-maze was abated following rutin co-administration. Abatement of AFB1-induced decreases in acetylcholinesterase (AChE) activity, and increased antioxidant status, by rutin was accompanied by a marked reduction in oxidative stress markers and increased hydrolysis of the purinergic molecules in the cerebral cortex and hippocampus of rats. Additionally, rutin co-treatment abrogated AFB1-mediated elevation of interleukin-6 (IL-6), nitric oxide (NO) levels, and activity of myeloperoxidase (MPO). Correspondingly, rutin co-treatment lowered the activity and immunocontent of immunosuppressive indoleamine 2, 3-dioxygenase (IDO). Further, rutin co-treatment prevented histological injuries in the cerebral cortex and hippocampus. In conclusion, abatement of AFB1-induced neurobehavioral abnormalities by rutin involves the mechanisms of anti-inflammatory, antioxidant, and regulation of cholinergic, purinergic, and indoleaminergic pathways in rats.

Aflatoxin B1 induces infertility, fetal deformities, and potential therapies

Aflatoxin B1 (AFB1) is a subsidiary poisonous metabolite, archetypally spawned by Aspergillus flavus and A. parasiticus, which are often isolated in warm or tropical countries across the world. AFB1 is capable of disrupting the functioning of several reproductive endocrine glands by interrupting the enzymes and their substrates that are liable for the synthesis of various hormones in both males and females. In men, AFB1 is capable of hindering testicular development, testicular degeneration, and reduces reproductive capabilities. In women, a direct antagonistic interaction of AFB1 with steroid hormone receptors influencing gonadal hormone production of estrogen and progesterone was responsible for AFB1-associated infertility. AFB1 is potentially teratogenic and is responsible for the development of malformation in humans and animals. Soft-tissue anomalies such as internal hydrocephalus, microphthalmia, cardiac defects, augmented liver lobes, reproductive changes, immune modifications, behavioral changes and predisposition of animals and humans to neoplasm development are AFB1-associated anomalies. Substances such as esculin, selenium, gynandra extract, vitamins C and E, oltipraz, and CDDO-Im are potential therapies for AFB1. Thus, this review elucidates the pivotal pathogenic roles of AFB1 in infertility, fetal deformities, and potential therapies because AFB1 toxicity is a key problem globally.

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.

Lipidomic profiling study on neurobehavior toxicity in zebrafish treated with aflatoxin B1

Mycotoxin aflatoxin B1 (AFB1) has been proven to cause neurotoxicity, but its potential interference with the normal function of brain tissue is not fully defined. As the indispensable role of lipids in maintaining the normal function of brain tissue, the aim of this study is to clarify the effect of AFB1 short-term (7 days) exposure on brain tissue from the perspective of lipid metabolism. In this study, zebrafish were exposed to two concentrations (5, 20 μg/L). Through quantitative analysis of AFB1, the detection of AFB1 in zebrafish brain tissue was discovered for the first time, combined with the changes in zebrafish neurobehavior, the occurrence of brain injury was deduced. Subsequently, 1734 lipids in zebrafish brain tissue were mapped using ion mobility time-of-flight mass spectrometry (UPLC-QTOF-IMS-MS), which has great advantages in lipid detection. Comparative analysis of the abnormal lipid metabolism in zebrafish brain revealed 114 significantly changed lipids, mainly involving two pathways of sphingolipid metabolism and fatty acid degradation. This study discovered the detection of AFB1 in the brain and revealed a potential link between AFB1-induced behavioral abnormalities and lipid metabolism disorders in brain tissue, providing reliable evidence for elucidating the neurotoxicity of AFB1.

Aflatoxin B1 Exacerbates Genomic Instability and Apoptosis in the BTBR Autism Mouse Model via Dysregulating DNA Repair Pathway

The pathophysiology of autism is influenced by a combination of environmental and genetic factors. Furthermore, individuals with autism appear to be at a higher risk of developing cancer. However, this is not fully understood. Aflatoxin B1 (AFB1) is a potent food pollutant carcinogen. The effects of AFB1 on genomic instability in autism have not yet been investigated. Hence, we have aimed to investigate whether repeated exposure to AFB1 causes alterations in genomic stability, a hallmark of cancer and apoptosis in the BTBR autism mouse model. The data revealed increased micronuclei generation, oxidative DNA strand breaks, and apoptosis in BTBR animals exposed to AFB1 when compared to unexposed animals. Lipid peroxidation in BTBR mice increased with a reduction in glutathione following AFB1 exposure, demonstrating an exacerbated redox imbalance. Furthermore, the expressions of some of DNA damage/repair- and apoptosis-related genes were also significantly dysregulated. Increases in the redox disturbance and dysregulation in the DNA damage/repair pathway are thus important determinants of susceptibility to AFB1-exacerbated genomic instability and apoptosis in BTBR mice. This investigation shows that AFB1-related genomic instability can accelerate the risk of cancer development. Moreover, approaches that ameliorate the redox balance and DNA damage/repair dysregulation may mitigate AFB1-caused genomic instability.

Aflatoxin B1 Increases Soluble Epoxide Hydrolase in the Brain and Induces Neuroinflammation and Dopaminergic Neurotoxicity

Parkinson's disease (PD) is an increasingly common neurodegenerative movement disorder with contributing factors that are still largely unexplored and currently no effective intervention strategy. Epidemiological and pre-clinical studies support the close association between environmental toxicant exposure and PD incidence. Aflatoxin B1 (AFB1), a hazardous mycotoxin commonly present in food and environment, is alarmingly high in many areas of the world. Previous evidence suggests that chronic exposure to AFB1 leads to neurological disorders as well as cancer. However, whether and how aflatoxin B1 contributes to the pathogenesis of PD is poorly understood. Here, oral exposure to AFB1 is shown to induce neuroinflammation, trigger the α-synuclein pathology, and cause dopaminergic neurotoxicity. This was accompanied by the increased expression and enzymatic activity of soluble epoxide hydrolase (sEH) in the mouse brain. Importantly, genetic deletion or pharmacological inhibition of sEH alleviated the AFB1-induced neuroinflammation by reducing microglia activation and suppressing pro-inflammatory factors in the brain. Furthermore, blocking the action of sEH attenuated dopaminergic neuron dysfunction caused by AFB1 in vivo and in vitro. Together, our findings suggest a contributing role of AFB1 to PD etiology and highlight sEH as a potential pharmacological target for alleviating PD-related neuronal disorders caused by AFB1 exposure.

Chronic Aflatoxin Exposure and Cognitive and Language Development in Young Children of Bangladesh: A Longitudinal Study

Aflatoxin can cross the blood-brain barrier, damage brain tissues, and have the potential to harm the development of the human brain. Although dietary aflatoxin exposure is common in children, there is a paucity of data on aflatoxin exposure and child developmental outcomes. The child's cognitive, motor, and language functions were assessed using the Bayley Scales of Infant and Toddler Development-III or BSID-III at the same time points. Association between exposure to aflatoxin and subtests of BSID-III were examined using mixed-effect linear regression. Aflatoxin assays were performed on 194, 167, and 163 children at 15, 24, and 36 months of age, and chronic aflatoxin exposure was detected in 20.6%, 16.8%, and 60.7% of children, respectively. Multi-variable analyses showed that aflatoxin exposure was independently related to the children's cognitive score (β: -0.69; 95% CI: -1.36, -0.02), receptive language score (β: -0.90; 95% CI: -1.62, -0.17), and expressive language score (β: -1.01; 95% CI: -1.96, -0.05). We did not observe any association between exposure to aflatoxin and the motor function of children. Chronic exposure to aflatoxin exposure was linked to reduced cognitive, expressive, and receptive language scores of the study children. Further research is needed in a different setting to confirm this novel finding.

Exposure assessment and risk characterization of aflatoxins intake through consumption of maize (Zea mays) in different age populations in the Volta Region of Ghana

Aflatoxin contamination in foods is a vital health challenge for low and middle-income countries in subtropical regions. Maize (Zea mays L.), a staple food most widely grown in Africa including Ghana, and extensively consumed as much as three times per day, is a source of aflatoxin contamination owing to its susceptibility to fungal infection. Aflatoxin levels were checked against international (European Commission, EC) and local (Ghana Standards Authority, GSA) standards, and health risks associated with maize sampled from the Volta Region (Hohoe, Ho, Battor Dugame, and Keta) of Ghana were determined. Total aflatoxins (totalAFs) and the constituent aflatoxins (AFB1, AFB2, AFG1, and AFG2) were measured with High-Performance Liquid Chromatography (HPLC) with a Fluorescence Detector (FLD). Intake and Risk assessments were also conducted using deterministic models prescribed by the Joint FAO/WHO Expert Committee on Additives (JECFA). The degree of occurrence of aflatoxins was observed to be in decreasing order of AFG2 < AFG1 < AFB2 < AFB1 and were within the ranges of 0.78 ± 0.04 $$-$$ - 234.73 ± 3.8 µg/kg, 0.47 ± 0.03 $$-$$ - 21.6 ± 0.33 µg/kg, 1.01 ± 0.05 $$-$$ - 13.75 ± 1.2 µg/kg and 0.66 ± 0.06 $$-$$ - 5.51 ± 0.26 µg/kg respectively. Out of the 100 samples analyzed for total aflatoxins (totalAFs), 68 (68%) exceeded the limits of EC and were of range 4.98 ± 0.6 $$-$$ - 445.01 ± 8.9 µg/kg whereas 58 (58%) and ranged between 12.12 ± 1.4 $$-$$ - 445.01 ± 8.9 µg/kg exceeded GSA limits. Intake and risk assessments of total aflatoxins (totalAFs) for infants, toddlers, children, adolescents, and adults in the Volta Region were; 0.037–1.14 µg/kg bw/day, 0.35–10.81, and 1.47 -45.14 cases/10,000 person/yr respectively for Estimated Daily Intake (EDI), Margin of Exposure (MOE), and Cancer Risks. It was inferred that the consumption of maize posed potential adverse health effects on all age categories studied because all calculated MOE values were less than 10,000.

Aflatoxin M1 exposure in a fermented millet-based milk beverage 'brukina' and its cancer risk characterization in Greater Accra, Ghana

Brukina is a millet based fermented milk product which is consumed as a beverage in Ghana. It is however prone to aflatoxin M1 (AFM1) contamination, which is a serious health challenge for low and middle-income countries in subtropical regions. This study aimed at evaluating AFM1 levels and cancer risks associated with brukina (n = 150) sampled from different locations of the Greater Accra Region of Ghana. AFM1 were measured with High-Performance Liquid Chromatography (HPLC) connected to a Fluorescence Detector (FLD).Cancer risk assessments were also conducted using models prescribed by the Joint FAO/WHO Expert Committee on Additives (JECFA). Out of the 150 samples analyzed for AFM1, 80/150 (53%) tested positive between the range 0.00 ± 0.001-3.14 ± 0.77 µg/kg. Cancer risk assessments of AFM1 produced outcomes which ranged between 0.64 and 1.88 ng/kg bw/day, 0.31-9.40, 0.0323, and 1.94 × 10-3-0.06 for cases/100,000 person/yr for Estimated Daily Intake (EDI), Hazard Index (H.I), Average Potency, and Cancer Risks respectively for all age categories investigated. It was concluded that the consumption of brukina posed adverse health effects on the majority of the age categories in the different locations of Greater Accra Region since the calculated H.Is were greater than one (> 1). Therefore, contamination of brukina with AFM1 should be considered a high priority in public health and Ghana's cancer risk management actions.

The role of mycotoxins in neurodegenerative diseases: current state of the art and future perspectives of research

Mycotoxins are fungal metabolites that can cause various diseases in humans and animals. The adverse health effects of mycotoxins such as liver failure, immune deficiency, and cancer are well-described. However, growing evidence suggests an additional link between these fungal metabolites and neurodegenerative diseases. Despite the wealth of these initial reports, reliable conclusions are still constrained by limited access to human patients and availability of suitable cell or animal model systems. This review summarizes knowledge on mycotoxins associated with neurodegenerative diseases and the assumed underlying pathophysiological mechanisms. The limitations of the common in vivo and in vitro experiments to identify the role of mycotoxins in neurotoxicity and thereby in neurodegenerative diseases are elucidated and possible future perspectives to further evolve this research field are presented.

Neuroprotective role of gallic acid in aflatoxin B1 -induced behavioral abnormalities in rats

The neurotoxic impact of dietary exposure to aflatoxin B₁ (AFB₁ ) is documented in experimental and epidemiological studies. Gallic acid (GA) is a triphenolic phytochemical with potent anticancer, anti-inflammatory, and antioxidant activities. There is a knowledge gap on the influence of GA on AFB₁ -induced neurotoxicity. This study probed the influence of GA on neurobehavioral and biochemical abnormalities in rats orally treated with AFB₁ per se (75 µg/kg body weight) or administered together with GA (20 and 40 mg/kg) for 28 uninterrupted days. Behavioral endpoints obtained with video-tracking software demonstrated significant (p < .05) abatement of AFB₁ -induced anxiogenic-like behaviors (increased freezing, urination, and fecal bolus discharge), motor and locomotor inadequacies, namely increased negative geotaxis and diminished grip strength, absolute turn angle, total time mobile, body rotation, maximum speed, and total distance traveled by GA. The improvement of exploratory behavior in animals that received both AFB₁ and GA was confirmed by track plots and heat maps appraisal. Abatement of AFB₁ -induced decreases in acetylcholinesterase activity, antioxidant status and glutathione level by GA was accompanied by a marked reduction in oxidative stress markers in the cerebellum and cerebrum of rats. Additionally, GA treatment abrogated AFB₁ -mediated decrease in interleukin-10 and elevation of inflammatory indices, namely tumor necrosis factor-α, myeloperoxidase activity, interleukin-1β, and nitric oxide. Further, GA treatment curtailed caspase-3 activation and histological injuries in the cerebral and cerebellar tissues. In conclusion, abatement of AFB₁ -induced neurobehavioral abnormalities by GA involves anti-inflammatory, antioxidant, and antiapoptotic mechanisms in rats.

Environmental toxins and Alzheimer's disease progression

Alzheimer's disease (AD) is the most common form of dementia, which causes progressive memory loss and cognitive decline. Effective strategies to treat or prevent remains one of the most challenging undertakings in the medical field. AD is a complex and multifactorial disease that involves several risk factors. Aging and genetic factors both play important roles in the onset of the AD, however; certain environmental factors have been reported to increase the risk of AD. Chronic exposure to toxins has been seen as an environmental factor that may increase the risk of developing a neurodegenerative disease such as AD. Exposure to metals and biotoxins produced by bacteria, molds, and viruses may contribute to the cognitive decline and pathophysiology associated with AD. Toxins may contribute to the pathology of the disease through various mechanisms such as deposition of amyloid-beta (Aβ) plaques and tangles in the brain, induction of apoptosis, inflammation, or oxidative damage. Here, we will review how toxins affect brain physiology with a focus on mechanisms by which toxins may contribute to the development and progression of AD. A better understanding of these mechanisms may help contribute towards the development of an effective strategy to slow the progression of AD.

Aflatoxins in organs and biological samples from children affected by kwashiorkor, marasmus and marasmic-kwashiorkor: A scoping review

Originally, the kwashiorkor is a pathology justified by the low consumption of proteins and high carbohydrates in weaned children. However, today, it can appear due to multifactorial causes, one of the hypotheses being the presence of aflatoxins in foods consumed by the child population and detected in biological fluids. The objective of this work is to scoping review the presence of aflatoxins in kwashiorkor, marasmus and marasmic-kwashiorkor from organs and biological samples in children. Results reflected that the presence of aflatoxins in kwashiorkor is greater compared to marasmic-kwashiorkor and marasmus in the organs and biological samples analyzed. The relationship of this mycotoxin with the pathology shows that it can affect both genders, even up to 12 years, in addition they are detected in eight biological samples and organs, except in the spleen, and in ten African countries and in the Philippines. The appearance of this pathology has been associated in children when after weaning they consume foods with low protein content and rich in carbohydrates, but coincidentally coincides with foods where the growth of aflatoxigenic fungi is more prevalent, and even the presence of other fungi that can generate other mycotoxins, such as ochratoxin A and fumonisin B1.

Mitigation of aflatoxin B1- and sodium arsenite-induced cytotoxicities in HUC-PC urinary bladder cells by curcumin and Khaya senegalensis

Background Concomitant exposure to environmental/occupational toxicants such as aflatoxin B1 (AFB1) and arsenic in some regions of the world has been well reported. Therefore, this calls for the assessment of the efficacy of agents such as phytochemicals, which are already known for their ethno-medicinal uses in prophylaxis/remediation. We investigated the possible cytotoxic bio-interactions between AFB1 and sodium arsenite (SA) in urinary bladder cells. We also assessed the cytoprotective effects of curcumin and the ethanol stem bark extract of Khaya senegalensis (K2S). Methods The cells were exposed to graded levels of AFB1, SA, curcumin, and K2S for 24, 48, and 72 h. Subsequently, using optimum toxic concentrations of AFB1 and SA, respectively, the influence of non-toxic levels of curcumin and/or K2S was tested on exposure of the cells to AFB1 and/or SA. Hoechst 33342/propidium iodide staining technique was used to determine the end-points due to cytotoxicity with changes in adenosine triphosphate (ATP) levels determined using Promega's CellTiter-Glo luminescent assay. Results Co-treatment of the cells with AFB1 and SA resulted in synergy in cytotoxic effects. Cytotoxicity was reduced by 3.5- and 2.9-fold by pre-treatment of the cells with curcumin and K2S before treatment with AFB1, while post-treatment resulted in 1.1- and 2.6-fold reduction, respectively. Pre-exposure of the cells with curcumin and K2S before treatment with SA ameliorated cytotoxicity by 3.8- and 3.0-fold, but post-treatment caused a 1.2- and 1.3-fold reduction, respectively. Conclusions Pre-treatment of the cells with either curcumin or K2S exhibited cytoprotective effects by ameliorating AFB1- and SA-induced cytotoxicity with inferred tendencies to prevent carcinogenesis.

Histological and ultrastructural study of AflatoxinB1 induced neurotoxicity in Sciatic nerve of adult male Albino rats

Aflatoxins are mycotoxins produced by Aspergillus spp. which is a common contaminant of food items such as corn, spices, rice, nuts, and flour. Aflatoxin contamination of foods is a worldwide problem. Chronic aflatoxin exposure is found to be associated with Sciatic nerve damage. In vivo study was carried out to evaluate the toxic effect of aflatoxin B₁ (AFB₁) on the Sciatic nerve. Twenty-one adult male rats were included and divided equally into 3 groups (7 rats each): Group I (control group), group II (olive oil group) and group III: (AflatoxinB1 group). The rats received AFB₁ (250 μg/kg B.W./day) orally by gastric tube 5 days/week for 4 weeks. Sciatic nerve specimens were prepared, and semi-thin sections were stained with Toluidine blue, examined by light microscope and photographed. Ultrathin sections (50-80 nm) from selected areas of the trimmed blocks were made, examined and photographed by transmission electron microscopy (JEOL-JSM-1011) in King Saud University Electron Microscopy Unit. The findings indicate that the administration of AFB₁ to rats' results in degeneration in the sciatic nerve in the form of Wallerian degeneration in the myelin sheath. Macrophages appear to engulf the degenerated myelin and neutrophils.

Dietary mycotoxins exposure and child growth, immune system, morbidity, and mortality: a systematic literature review

The aim of this study was to systematically review associations between dietary mycotoxins exposure and child growth and morbidity of children aged 5 years or younger. Peer-reviewed literature was searched in MEDLINE, EMBASE, COCHRANE, CINAHL, Web of Science, and PsycINFO. Experimental and observational studies were considered. The exposures were dietary mycotoxins during pregnancy, lactation and childhood, and mycotoxins concentrations in the diet, breast milk, urine, and blood. From a total of 4869 references, 86 full-text papers were extracted of which 50 were included in this review. The methodological quality and risk of bias were evaluated and quality of the collective evidence was assessed using GRADE. Uncertainty remains whether mycotoxins exposure affects child growth, immunity and mortality and the overall quality of the evidence is very low. Overall however, we cannot rule out a possible association between dietary mycotoxins, in particular, AF and FUM and child malnutrition. Our analyses were limited by the reporting quality, difference in findings, heterogeneity of outcomes, mycotoxins detection methods, and the observational nature of most studies. Robust study designs with adequate sample size, use of validated biomarkers of exposure and assessment of co-occurrence of mycotoxins and their synergistic effects are required to provide the further evidence regarding a potential effect of dietary mycotoxins exposure on child growth and immunity.

Chronic neurodegeneration by aflatoxin B1 depends on alterations of brain enzyme activity and immunoexpression of astrocyte in male rats

Aflatoxin B1 poses the greatest risk among the mycotoxins to target-organisms particularly human, however, no studies addressed the neurotoxicity of chronic exposure of aflatoxin. The oral dose level 1/600th of LD50 for 30, 60, and 90 days was used for three aflatoxin groups, respective to negative and vehicle control groups. Activity levels of brain antioxidants viz: superoxide dismutase, catalase, glutathione, and glutathione peroxidase significantly decreased in the three experimental durations in time-dependent trend, in contrast, lipid peroxidation showed a significant increase compared to controls. Significantly, chronic-dependent increase trend was noticed in the AF60 and AF90 group for acid phosphatase (16.1%, 35.2%), alkaline phosphatase (32.1%, 50.8%), aspartate aminotransferase (38.7%, 120.0%) and lactate dehydrogenase (30.6%, 42.1%) activities, respectively. However, a significant 23.7% decrease in the brain creatine kinase activity following 90 days of AFB1administration. Chronic administration of aflatoxin also causes alterations in activities of protein carbonyl with a maximum increase (twofold) after 90 days. Further, histopathological and immunohistochemical results confirmed time-related vasodilation, necrosis and astrocytes gliosis by high glial fibrillary acidic protein immunostaining in response to AFB1. These findings infer that long-term exposure to AFB1 results in several pathophysiological circumstances in a duration-dependent manner concerning neurodegeneration especially Alzheimer's disease.

Maternal aflatoxin exposure during pregnancy and adverse birth outcomes in Uganda

Aflatoxins are toxic metabolites of Aspergillus moulds and are widespread in the food supply, particularly in low- and middle-income countries. Both in utero and infant exposure to aflatoxin B1 (AFB1 ) have been linked to poor child growth and development. The objective of this prospective cohort study was to investigate the association between maternal aflatoxin exposure during pregnancy and adverse birth outcomes, primarily lower birth weight, in a sample of 220 mother-infant pairs in Mukono district, Uganda. Maternal aflatoxin exposure was assessed by measuring the serum concentration of AFB1 -lysine (AFB-Lys) adduct at 17.8 ± 3.5 (mean ± SD)-week gestation using high-performance liquid chromatography. Anthropometry and birth outcome characteristics were obtained within 48 hr of delivery. Associations between maternal aflatoxin exposure and birth outcomes were assessed using multivariable linear regression models adjusted for confounding factors. Median maternal AFB-Lys level was 5.83 pg/mg albumin (range: 0.71-95.60 pg/mg albumin, interquartile range: 3.53-9.62 pg/mg albumin). In adjusted linear regression models, elevations in maternal AFB-Lys levels were significantly associated with lower weight (adj-β: 0.07; 95% CI: -0.13, -0.003; p = 0.040), lower weight-for-age z-score (adj-β: -0.16; 95% CI: -0.30, -0.01; p = 0.037), smaller head circumference (adj-β: -0.26; 95% CI: -0.49, -0.02; p = 0.035), and lower head circumference-for-age z-score (adj-β: -0.23; 95% CI: -0.43, -0.03; p = 0.023) in infants at birth. Overall, our data suggest an association between maternal aflatoxin exposure during pregnancy and adverse birth outcomes, particularly lower birth weight and smaller head circumference, but further research is warranted.

Presence of unreported carcinogens, Aflatoxins and their hydroxylated metabolites, in industrialized Oaxaca cheese from Mexico City

Aflatoxins (AFs) are toxic secondary metabolites of the fungi Aspergillus flavus, A. parasiticus and A. nomius. The fungi produce these AFs in cereals, oilseeds and spices. AFs have damaging effects on all organisms, including humans, and their symptoms can be classified as acute (vomiting, hemorrhage and death) or chronic (immunodepression, Reye syndrome, Kwashiorkor, teratogenesis, hepatitis, cirrhosis, and various cancers). Basic AFs (AFB₁, AFB₂, AFG₁, and AFG₂) are metabolized in the liver or by microbes that produce hydroxylated metabolites (AFM₁, AFM₂, and AFP₁) and aflatoxicol (AFL), soluble in water and easy to dispose. Thus, AFs can be excreted in fluids, such as milk. AFs are not destroyed in the process of making cheese. The purpose of this study was to identify and quantify the AFs present in 30 samples of industrialized Oaxaca-type cheese sold in Mexico City. The average concentrations of AFs detected in the 30 samples of industrialized cheese were as follows: AFB₁ (0.1 μg kg^-1) in 20% (6/30); a trace amount of AFB₂ (0.01 < LOD) in only 3% (1/30); AFG₁ (0.14 μg kg^-1) in 10% (3/30); AFG₂ (0.6 μg kg^-1) in 30% (9/30); AFM₁ (1.7 μg kg^-1) in 57% (17/30); AFP₁ (0.03% μg kg^-1) in 3% (1/30); and AFL (13.1 μg kg^-1) in 97% (29/30). AFB₁ and AFL were the most abundant aflatoxins in Oaxaca-type cheese. However, eight aflatoxins were present, contributing an average of 15.7 μg kg^-1 AFs distributed among the 30 samples. The risk assessment analysis showed that there was no substantial risk for cancer due to AFs in industrialized Oaxaca cheese from Mexico City.

Aflatoxin B1 inhibits the type 1 interferon response pathway via STAT1 suggesting another mechanism of hepatocellular carcinoma

BACKGROUND

Aflatoxin B1 (AFB1) contamination of food is very high in most sub-Saharan African countries. AFB1 is known to cause hepatocellular carcinoma (HCC) by inducing mutation in the tumour suppressor gene TP53. The number of new HCC cases is high in West Africa with an accompanying high mortality. The type I interferon (IFN) pathway of the innate immune system limits viral infections and exerts its anti-cancer property by up-regulating tumour suppressor activities and pro-apoptotic pathways. Indeed, IFN-α is reported to show significant protective effects against hepatic fibrogenesis and carcinogenesis. However, the mechanism behind AFB1 deregulation of the type I interferon (IFN) signalling pathway, with consequent HCC is largely unknown. This current study seeks to test the hypothesis that AFB1 inhibits the type I IFN response by directly interfering with key signalling proteins and thus increase the risk of HCC in humans.

METHODS

We evaluated the effects of AFB1 on the type I IFN signalling pathway using IFN stimulated response element (ISRE)-based luciferase reporter gene assay. In addition, the effects of AFB1 on the transcript levels of JAK1, STAT1 and OAS3 were assessed by real-time quantitative polymerase chain reaction (RT-qPCR) and confirmed by immunoblot assay.

RESULTS

Our results indicated that AFB1 inhibited the type I IFN signalling pathway in human hepatoma cell line HepG2 cells by suppressing the transcript levels of JAK1, STAT1 and OAS3. AFB1 also decreased the accumulation of STAT1 protein.

CONCLUSION

The inhibition of the type I IFN anti-cancer response pathway by AFB1 suggest a novel mechanism by which AFB1 may induce hepatocellular carcinoma in humans.

Aflatoxins: A Global Concern for Food Safety, Human Health and Their Management

The aflatoxin producing fungi, Aspergillus spp., are widely spread in nature and have severely contaminated food supplies of humans and animals, resulting in health hazards and even death. Therefore, there is great demand for aflatoxins research to develop suitable methods for their quantification, precise detection and control to ensure the safety of consumers' health. Here, the chemistry and biosynthesis process of the mycotoxins is discussed in brief along with their occurrence, and the health hazards to humans and livestock. This review focuses on resources, production, detection and control measures of aflatoxins to ensure food and feed safety. The review is informative for health-conscious consumers and research experts in the fields. Furthermore, providing knowledge on aflatoxins toxicity will help in ensure food safety and meet the future demands of the increasing population by decreasing the incidence of outbreaks due to aflatoxins.

Occupational aflatoxin exposure among feed mill workers in Nigeria

There are indications that significant levels of mycotoxins may be absorbed from inhaled fungal spores. The problem is likely to be most serious with aflatoxins. Indoor airborne fungi in three feed mills in south-western Nigeria were assayed using Sabouraud dextrose agar and coconut agar medium. Fungi isolated include Aspergillus flavus, Rhizopus spp., Aspergillus fumigatus, Aspergillus candidus, Aspergillus niger and Aspergillus terreus with incidence rates of 61, 15, 12, 5, 5 and 2%, respectively. Amount and type of aflatoxins produced in Sabouraud dextrose broth by aflatoxigenic strains of A. flavus isolated at the three mills were strain dependent. Exposure of feed mill workers to aflatoxins was assessed by HPLC analysis of blood samples. Subjects from different occupational groups served as a control group. The mean concentrations of aflatoxin B1, B2, G1 and G2 in blood samples of the feed mill workers varied from 73.4-189.2, <0.1-0.5, 0.3-1.9 and <0.1-3.4 ng/ml, respectively. There was a significant difiference between the mills regarding blood aflatoxin levels of the workers; poorly ventilated mills resulted in higher blood aflatoxin B1 levels. Aflatoxin B1 was not detected in the blood samples of the control group; mean concentrations of aflatoxin B2, G1 and G2 detected in this group varied from <0.1-0.3, 0.4-1.5 and <0.1-0.3 ng/ml, respectively. Results from the present study showed that ventilation of feed mills is an important issue that should be considered to lower the risk of aflatoxin exposure among feed mill workers.

In vitro inhibitory effect of aflatoxin B1 on acetylcholinesterase activity in mouse brain

Growing concern on the problem of mycotoxins in the alimentary chain underlines the need to investigate the mechanisms explaining the cholinergic effects of aflatoxin B(1) (AFB(1)). We examined the effect of AFB(1), a mycotoxin produced by Aspergillus flavus, on mouse brain acetylcholinesterase (AChE) and specifically on its molecular isoforms (G(1) and G(4)) after in vitro exposure. AFB(1) (from 10(-9) to 10(-4)M), inhibited mouse brain AChE activity (IC(50) = 31.6 x 10(-6)M) and its G(1) and G(4) molecular isoforms in a dose-dependent manner. Michaelis-Menten parameters indicate that the K(m) value increased from 55.2 to 232.2% whereas V(max) decreased by 46.2-75.1%. The direct, the Lineweaver-Burk and the secondary plots indicated a non-competitive-mixed type antagonism, induced when the inhibitor binds to the free enzyme and to the enzyme-substrate complex. AFB(1)-inhibited AChE was partially reactivated by pyridine 2-aldoxime (2-PAM) (10(-4)M) but the AChE-inhibiting time courses of AFB(1) (10(-4)M) and diisopropylfluorophosphate (DFP) (2 x 10(-7)M) differed. Overall these data suggest that AFB(1) non-competitively inhibits mouse brain AChE by blocking access of the substrate to the active site or by inducing a defective conformational change in the enzyme through non-covalent binding interacting with the AChE peripheral binding site, or through both mechanisms.

Occurrence of aflatoxins and fumonisins in preharvest maize from south-western Nigeria

A survey was conducted on the incidence of fungi, and the natural occurrence of aflatoxins and fumonisins in preharvest maize from fields in south-western Nigeria. Mycological examinations revealed the predominance of F. verticillioides (Zea mays) (syn. F. moniliforme), occurring in 89.3% of samples with a mean kernel infection of 49.4%, while Aspergillus flavus was isolated from 65% of samples having a mean kernel infection of 6.8%. Aflatoxin B1 was detected in 18.4% of samples with a mean of 22 micrograms kg-1, while aflatoxins B2, G1 and G2 were present in 7.8, 2.9 and 1% of the samples with mean levels of 10, 8 and 7 micrograms kg-1, respectively, in contaminated samples. Total aflatoxins ranged from 3 to 138 micrograms kg-1 in positive samples, with a mean of 28 micrograms kg-1. Fumonsin B1 was the predominant toxin detected in terms of frequency (78.6% of samples) and quantity (concentration range 70-1780 micrograms kg-1, mean = 495 micrograms kg-1). Fumonisin B2 was detected in 68 samples (66%) with a mean of 114 micrograms kg-1. Fifteen samples were contaminated with both aflatoxins and fumonisins.

Aflatoxin B1and its interconverting metabolite aflatoxicol in milk: the situation in Mexico

Between 1996 and 1998, 580 litres of milk in Mexico were surveyed for aflatoxin B(1) (AFB(1)) and its metabolite aflatoxicol (AFL), which are mutagenic and carcinogenic mycotoxins that interconvert AFB(1)-AFL-AFB(1). The seven most consumed brands from different regions of Mexico included pasteurized and ultrapasteurized milk with four different fat levels: whole fat (28-33 g l(-1)), half-skimmed (10-20 g l(-1)), light (1-4 g l(-1)) and with vegetable oil (33 g l(-1)). Aflatoxins in each sample were concentrated with total aflatoxin immunoaffinity columns and quantitated by high-performance liquid chromatography. A milk sample was considered contaminated if it contained >/=0.05 microg l(-1) AFL. Pasteurization and ultrapasteurization of milk did not control contamination with AFL, which was present in 13% of samples at >/=0.05 microg l(-1) and in 8% at >/=0.5 microg l(-1), with a range of AFL from 0 to 12.4 microg l(-1). AFB(1) was present mainly in traces (0-0.4 microg l(-1)). The safest milk in relation to AFL contamination was imported milk powder with vegetable oil. There was a significant correlation between contamination of milk with AFL and the autumn (p<0.0002); the fat content was not significant.

Aflatoxins in the lungs of children with kwashiorkor and children with miscellaneous diseases in Nigeria

Autopsy lung specimens from 20 children with kwashiorkor and 20 with other miscellaneous diseases, at the Obafemi Awolowo Teaching Hospital complex, Ile-Ife, Nigeria, were analyzed for the presence of aflatoxin using high-performance liquid chromatography. Aflatoxins were detected in 18 children who died from kwashiorkor but only in 13 of those who died from miscellaneous diseases. Of the 10 children, 5 in each group, who died with pneumonia, all had detectable levels of aflatoxins in their lungs. The two children with congestive cardiac failure, one secondary to pneumonia and the other secondary to tuberculous pericarditis, had more than two detectable aflatoxins in their lungs. These findings demonstrate that Nigerian children are exposed to aflatoxins and that high levels can accumulate in lung tissue.