Determination of aflatoxin B1levels in Iranian rice by ELISA method

Mycotoxins in Rice Correlate with Other Contaminants? A Pilot Study of the Portuguese Scenario and Human Risk Assessment

Rice is the second most important cereal crop and is vital for the diet of billions of people. However, its consumption can increase human exposure to chemical contaminants, namely mycotoxins and metalloids. Our goal was to evaluate the occurrence and human exposure of aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEN), and inorganic arsenic (InAs) in 36 rice samples produced and commercialized in Portugal and evaluate their correlation. The analysis of mycotoxins involved ELISA, with limits of detection (LODs) of 0.8, 1 and 1.75 μg kg^-1 for OTA, AFB1, and ZEN, respectively. InAs analysis was carried out by inductively coupled plasma mass spectrometry (ICP-MS; LOD = 3.3 μg kg^-1). No sample showed contamination by OTA. AFB1 was present in 2 (4.8%) samples (1.96 and 2.20 μg kg^-1), doubling the European maximum permitted level (MPL). Concerning ZEN, 88.89% of the rice samples presented levels above the LOD up to 14.25 µg kg^-1 (average of 2.75 µg kg^-1). Regarding InAs, every sample presented concentration values above the LOD up to 100.0 µg kg^-1 (average of 35.3 µg kg^-1), although none surpassed the MPL (200 µg kg^-1). No correlation was observed between mycotoxins and InAs contamination. As for human exposure, only AFB1 surpassed the provisional maximum tolerable daily intake. Children were recognized as the most susceptible group.

Characterization and mechanism of aflatoxin degradation by a novel strain of Trichoderma reesei CGMCC3.5218

Aflatoxins, which are produced mainly by Aspergillus flavus and A. parasiticus, are recognized as the most toxic mycotoxins, which are strongly carcinogenic and pose a serious threat to human and animal health. Therefore, strategies to degrade or eliminate aflatoxins in agro-products are urgently needed. We investigated 65 Trichoderma isolates belonging to 23 species for their aflatoxin B₁ (AFB₁)-degrading capabilities. Trichoderma reesei CGMCC3.5218 had the best performance, and degraded 100% of 50 ng/kg AFB₁ within 3 days and 87.6% of 10 μg/kg AFB₁ within 5 days in a liquid-medium system. CGMCC3.5218 degraded more than 85.0% of total aflatoxins (aflatoxin B₁, B₂, G₁, and G₂) at 108.2–2323.5 ng/kg in artificially and naturally contaminated peanut, maize, and feed within 7 days. Box–Behnken design and response surface methodology showed that the optimal degradation conditions for CGMCC3.5218 were pH 6.7 and 31.3°C for 5.1 days in liquid medium. Possible functional detoxification components were analyzed, indicating that the culture supernatant of CGMCC3.5218 could efficiently degrade AFB₁ (500 ng/kg) with a ratio of 91.8%, compared with 19.5 and 8.9% by intracellular components and mycelial adsorption, respectively. The aflatoxin-degrading activity of the fermentation supernatant was sensitive to proteinase K and proteinase K plus sodium dodecyl sulfonate, but was stable at high temperatures, suggesting that thermostable enzymes or proteins in the fermentation supernatant played a major role in AFB₁ degradation. Furthermore, toxicological experiments by a micronucleus assay in mouse bone marrow erythrocytes and by intraperitoneal injection and skin irritation tests in mice proved that the degradation products by CGMCC3.5218 were nontoxic. To the best of our knowledge, this is the first comprehensive study on Trichoderma aflatoxin detoxification, and the candidate strain T. reesei CGMCC3.5218 has high efficient and environment-friendly characteristics, and qualifies as a potential biological detoxifier for application in aflatoxin removal from contaminated feeds.

Aflatoxins in Cereals and Cereal-Based Products: Occurrence, Toxicity, Impact on Human Health, and Their Detoxification and Management Strategies

Cereals and cereal-based products are primary sources of nutrition across the world. However, contamination of these foods with aflatoxins (AFs), secondary metabolites produced by several fungal species, has raised serious concerns. AF generation in innate substrates is influenced by several parameters, including the substrate type, fungus species, moisture content, minerals, humidity, temperature, and physical injury to the kernels. Consumption of AF-contaminated cereals and cereal-based products can lead to both acute and chronic health issues related to physical and mental maturity, reproduction, and the nervous system. Therefore, the precise detection methods, detoxification, and management strategies of AFs in cereal and cereal-based products are crucial for food safety as well as consumer health. Hence, this review provides a brief overview of the occurrence, chemical characteristics, biosynthetic processes, health hazards, and detection techniques of AFs, along with a focus on detoxification and management strategies that could be implemented for food safety and security.

Development and Validation of an Automated Magneto-Controlled Pretreatment for Chromatography-Free Detection of Aflatoxin B1 in Cereals and Oils through Atomic Absorption Spectroscopy

A chromatography-free detection of aflatoxin B1 (AFB1) in cereals and oils through atomic absorption spectroscopy (AAS) has been developed using quantum dots and immunomagnetic beads. A magneto-controlled pretreatment platform for automatic purification, labeling, and digestion was constructed, and AFB1 detection through AAS was enabled. Under optimal conditions, this immunoassay exhibited high sensitivity for AFB1 detection, with limits of detection as low as 0.04 μg/kg and a linear dynamic range of 2.5–240 μg/kg. The recoveries for four different food matrices ranged from 92.6% to 108.7%, with intra- and inter-day standard deviations of 0.7–6.3% and 0.6–6.9%, respectively. The method was successfully applied to the detection of AFB1 in husked rice, maize, and polished rice samples, and the detection results were not significantly different from those of liquid chromatography-tandem mass spectrometry. The proposed method realized the detection of mycotoxins through AAS for the first time. It provides a new route for AFB1 detection, expands the application scope of AAS, and provides a reference for the simultaneous determination of multiple poisonous compounds (such as mycotoxins and heavy metals).

Exposure to multiple mycotoxins in domestic and imported rice commercially traded in Tehran and possible risk to public health

Mycotoxins are secondary fungi metabolites that induce acute and chronic toxic effects in humans and animals. In the present study, nine mycotoxins including aflatoxins (AFB1, AFB2, AFG1 and AFG2), fumonisins (FB1 and FB2), Ochratoxin A (OTA), deoxynivalenol (DON), and zearalenone (ZEN) were determined in one hundred rice samples collected from Tehran using high performance liquid chromatography (HPLC) with fluorescence or photodiode array detector. In addition, possible risk to public health was investigated by assessing dietary exposure through rice consumption, the margin of exposure (MOE), respective risk of cancer and hazard index (HI) of the monitored mycotoxins in children and adults. The higher mean levels were determined for DON (102.22 μg.Kg-1), followed by FB1 (85.00 μg.Kg-1). For the rests of mycotoxins the levels did not exceed 20 μg.Kg-1. The estimated AFB1 intake for the adults and children through rice consumption exceeds the safe levels established for both carriers and non-carriers of hepatitis B virus. The mean and median determined exposure levels of OTA, DON ZEN and FB1, were found lower than the Provisional Maximum Tolerable Daily Intake (PMTDI) value for both adults and children of Tehran that consuming domestic and imported rice. The mean HI for adults and median HI for adults and children were below one, and mean HI for children was close to one. All the mean, median and maximum MoE values were <10,000 in adults and children, indicating a risk due to AFB1 exposure through rice consumption in Tehran. In addition, the calculated mean cancer risk in adult and child populations of Tehran were 0.27 and 0.64 cases per year per 105 individuals, respectively, that shows population in Tehran could be at risk of cancer due to AFB1 exposure through rice consumption as calculated. So further studies are necessary for the monitoring mycotoxins in rice and different food products as well as estimating average dietary exposure and cumulative exposure assessment of mycotoxins for main foods in IR Iran.

Mycotoxin Contamination of Consumed Rice in Iran: A Review

: Mycotoxin contamination of rice has been introduced as a big challenge for public health in developing countries in numerous studies. Rice consumption is also considered the main source of secondary metabolites in Iran. Given the diversity of climatic conditions in this region as well as unsuitable storage conditions, including high temperature and humidity, rice can be extremely contaminated via various fungi. The current study is a review of the occurrence of mycotoxins in rice in Iran. In this regard, some investigations had revealed that rice could be contaminated by mycotoxins such as aflatoxins (AFTs) (B1, B2, G1, and G2), deoxynivalenol (DON), fumonisin (FM) (B1 and B2), ochratoxin A (OTA), T-2 toxin, and zearalenone (ZEN). Moreover, the amount of mycotoxins in rice was reported in varying ranges in different provinces and regions and normally less than Iranian maximum tolerated dose (MTD). Given the importance of rice in the Iranian diet, it was finally recommended to screen consumed rice to find about fungal contaminations and mycotoxins.

Mapping of quantitative trait loci for traits linked to fusarium head blight in barley

Fusarium head blight (FHB) is a devastating disease occurring in small grain cereals worldwide. The disease results in the reduction of grain yield, and mycotoxins accumulated in grain are also harmful to both humans and animals. It has been reported that response to pathogen infection may be associated with the morphological and developmental traits of the host plant, e.g. earliness and plant height. Despite many studies, effective markers for selection of barley genotypes with increased resistance to FHB have not been developed. In the present study, we investigated 100 recombinant inbred lines (RIL) of spring barley. Plants were examined in field conditions (three locations) in a completely randomized design with three replications. Barley genotypes were artificially infected with spores of Fusarium culmorum before heading. Apart from the main phenotypic traits (plant height, spike characteristic, grain yield), infected kernels were visually scored and the content of deoxynivalenol (DON) mycotoxin was investigated. A set of 70 Quantitative Trait Loci (QTLs) were detected through phenotyping of the mapping population in field conditions and genotyping using a barley Ilumina 9K iSelect platform. Six loci were detected for the FHB index on chromosomes 2H, 3H, 5H, and 7H. A region on the short arm of chromosome 2H was detected in which many QTLs associated with FHB- and yield-related traits were found. This study confirms that agromorphological traits are tightly related to FHB and should be taken into consideration when breeding barley plants for FHB resistance.

Occurrence of mycotoxins in rice consumed by Iranians: a probabilistic assessment of risk to health

Risks based on cancer and non-cancer endpoints, to Iranians from exposure to several mycotoxins (aflatoxin B1, ochratoxin, deoxynivalenol and T-2 toxin) following consumption of rice were evaluated. Point estimates of hazard were made for each mycotoxin and a hazard index (HI) and probabilistic estimates were based on results of Monte Carlo Simulations (MCS). All known 17 peer-reviewed studies, published in databases included in Science Direct, PubMed, Scopus and Web of Science, as well as grey literature published in Google Scholar from 2008 to 2017 were considered. The 95^th and 50^th centiles of Hazard Index (HI) in Iranians due to ingestion of rice were estimated to be 2.5 and 0.5, respectively. The 95^th and 50^th centiles of people with positive surface antigens for hepatitis B (HBsAg+) risk characterisation for AFB₁ in Iranian consumers of rice were 81 and 79.1, respectively. The 95^th and 50^th centiles for risks of Iranians negative for the surface antigen of hepatitis B HBsAg (HBsAg-) were 4.4 and 2.6, respectively. Based on results of the MCS for risks to cancer effects, the 95^th and 50^th centiles of margins of exposure (MOE) were 233 and 231, respectively. Therefore, it is recommended to update agricultural approaches and storage methods and implement monitoring and regulations based on risks to health posed by consumption of rice by the Iranian population.

Concentration and Prevalence of Aflatoxin M1 in Human Breast Milk in Iran: Systematic Review, Meta-Analysis, and Carcinogenic Risk Assessment: A Review

This meta-analysis was designed to review the published reports regarding the concentration and/or prevalence of aflatoxin M₁ (AFM₁) in human breast milk in Iran. The carcinogenic risk for Iranian infants consuming this milk was estimated with the hazard index. The PubMed and Scopus databases and the Scientific Information Database were screened for relevant studies between 1995 and 2017, and 11 of the 112 collected studies were included in the systematic review and meta-analysis. The mean (95% confidence interval) concentration of AFM₁ was 5.85 ng/L (4.54 to 7.15 ng/L), which was lower than the European Union standard (25 ng/L). The mean prevalence of AFM₁ in breast milk in Iran was 42% (11 to 77%). The estimated daily intakes for male and female infants were 0.02 to 5.57 ng/kg and 0.02 to 3.68 ng/kg of body weight per day, respectively. The rank order of estimated daily intake for both male and female infants according to age was 1 week > 1 month > 6 months > 12 months. The hazard index for all age groups of infants in all provinces in Iran was less than 1. Therefore, infants in Iran were not considered at carcinogenic risk from AFM₁ in human breast milk.

Rapid detection of aflatoxin B1 by dummy template molecularly imprinted polymer capped CdTe quantum dots

A novel and sensitive fluorescent sensor was synthesized for the rapid and specific recognition of aflatoxin B₁ (AFB1) by our combining molecular imprinting techniques with quantum dot technology. Molecularly imprinted polymers coated CdTe quantum dots (MIP@CdTe QDs) were prepared through the Stöber method with 5,7-dimethoxycoumarin as a dummy template. 3-Aminopropyltriethoxysilane was selected as the functional monomer, and tetraethyl orthosilicate was used as the cross-linking agent. The best molar ratio of 5,7-dimethoxycoumarin to functional monomer to cross-linker was 4:20:15. The MIP@CdTe QD composites were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and fluorescence spectroscopy. Under the optimum conditions, the relative fluorescence intensity of the MIP@CdTe QDs showed adequate linearity with AFB1 concentration over the range from 80 to 400 ng/g. The detection limit is 4 ng/g, according to 3s/K. Finally, the method was successfully applied to the quantitative determination of AFB1 in real samples. The spike recoveries at different spiking levels ranged from 99.20% to 101.78%, which were consistent with those measured by ultrahigh-performance liquid chromatography-mass spectrometry. The method developed for AFB1 detection lays the foundation for rapid detection of trace amounts of other exogenous harmful substances in a complicated matrix.

Aflatoxin M1 in human breast milk in Shahrekord, Iran and association with dietary factors

This survey was conducted to determine the occurrence and levels of aflatoxin M₁ (AFM₁) in 250 breast milk samples of lactating mothers, obtained from urban and rural regions of Shahrekord, Iran. Moreover, the association between AFM₁ occurrence levels and dietary factors was assessed. AFM₁ analysis was carried out using the competitive enzyme-linked immunosorbent assay technique for screening and high-performance liquid chromatography with fluorescence detection (HPLC-FLD) for confirmatory purposes. The toxin was detected in 39 samples (15.6%), ranging from 11.1 to 39.3 ng/l, of which 8 samples (3.2%) had levels above the Iranian national standard limit (25 ng/l). AFM₁ occurrence and levels in breast milk samples obtained from rural regions were significantly higher (P ≤ 0.05) than those obtained from urban ones. It might be due to the different dietary patterns in these regions. It was found that dietary habits with more tendencies to consume bread, rice and non-alcoholic beer beverage significantly increased (P ≤ 0.05) the risk of AFM₁ occurrence in breast milk. In addition, higher consumption of bread, olive and traditional cream significantly increased (P ≤ 0.05) the levels of AFM₁ in breast milk samples. Further investigations should be performed to determine more precisely the association between AFM₁ occurrence and dietary factors and also the risk of infant exposure to this mycotoxin.

Citrinin detection by intensified fluorescence signal of a FRET-based immunosensor using magnetic/silica core-shell

The specific immune-reaction between the anti-citrinin antibody immobilized on the surface of magnetic/silica core–shell (MSCS) and the citrinin–Rho123–BSA conjugate brings the Rho123 fluorophore as an acceptor and the QDs as a donor in close spatial proximity and causes FRET for occurring upon photo-excitation of the QDs. The novelties of this study include: (1) immobilization of the MSCS; (2) large amount of the immobilized QDs, and (3) immobilization of a large amount of Rho123 on the BSA macromolecule. Cd/Te QDs were synthesized by the simultaneous reduction of cadmium chloride and tellurium in the presence of sodium borohydride. Magnetic nanoparticles were synthesized using FeSO₄ and FeCl₃. The prepared magnetic nanoparticles shelled by silica using tetraethoxysilane in the presence of ammonia. Transmission electron microscopy (TEM) analysis was used for investigating shape and monodispersity of the nanoparticles. EDC/NHS was used as a cross linking agent for immobilization of the QDs, conjugation of citrinin to amino groups of BSA, labeling of BSA with Rho123 and also for immobilization of the amino-functionalized MSCS on the immobilized QDs. Immobilization of the anti-citrinin antibody on the surface of the amino-functionalized MSCS was performed by Schiff-base mechanism. By using these three effective strategies, sensitivity of the designed nanobiosensor was incredibly enhanced as a very low limit of detection (up to 0.1 pM). The feasibility of this technique was tested by the detection of citrinin in the spiked human serum. Results showed that there was a linear correlation between the decreased fluorescence intensity of the Rho123 and increased fluorescence intensity of the QDs with increasing concentration of citrinin in the spiked samples in the range of 1–6 pM. According to obtained results, we conclude that this highly sensitive detection scheme is a easy, quick and impressive method that can be used in optical-based nanosensors.

The assessment of anti-tumoral activity of polysaccharide extracted from terrestrial filamentous fungus

Fungal polysaccharides are well-known for the medicinal properties such as antitumor and immunomodulating effects. Hence, this study evaluated antitumor effects of polysaccharide extracted from Fusarium sp. isolated from soil samples of Karaj district, Alborz, Iran along with its taxonomic study. The filamentous fungus strain FK1 was isolated from the soil sample of Karaj, Iran. The strain was identified based on cultural, morphological and 18 S rRNA gene parameters as Fusarium. Further, the strain Fusarium was cultured in fermented broth of modified (PDB) for 10  days at 25 °C. The polysaccharide of strain FK1 was extracted from the mycelium free supernatant by boiling water method and evaluated for antitoxicity effect on two human cancer cell lines: HeLa cell line and Lymphoblastoid cell line (LCL) by MTT method. Findings revealed that water-extracted from mycelia polysaccharide of strain FK1 had the highest cytotoxicity effect against LCL which is the cause of B lymphocyte cancer, at 50  μg/ml concentration dose (114 ± 1.63) followed by 100  μg/ml (105 ± 0.57) and 10  μg/ml (104 ± 0.57), while it did not have a considerable effect on HeLa cell line. Fusarium could be alternative sources as an antitumor component.

Development of an Enzyme-Linked Immunosorbent Assay Method Specific for the Detection of G-Group Aflatoxins

To detect and monitor G-group aflatoxins in agricultural products, we generated class-specific monoclonal antibodies that specifically recognized aflatoxins G₁ and G₂. Of the final three positive and stable hybridomas obtained, clone 2G6 produced a monoclonal antibody that had equal sensitivity to aflatoxins G₁ and G₂, and did not cross-react with aflatoxins B₁, B₂, or M₁. Its IC50 values for aflatoxins G₁ and G₂ were 17.18 ng·mL(-1) and 19.75 ng·mL(-1), respectively. Using this new monoclonal antibody, we developed a competitive indirect enzyme-linked immunosorbent assay (CI-ELISA); the method had a limit of detection of 0.06 ng·mL(-1). To validate this CI-ELISA, we spiked uncontaminated peanut samples with various amounts of aflatoxins G₁ and G₂ and compared recovery rates with those determined by a standard HPLC method. The recovery rates of the CI-ELISA ranging from 94% to 103% were comparable to those of the HPLC (92% to 102%). We also used both methods to determine the amounts of G-group aflatoxins in five peanut samples contaminated by aflatoxin B₁-positive, and their relative standard deviations ranged from 8.4% to 17.7% (under 20%), which demonstrates a good correlation between the two methods. We further used this CI-ELISA to assess the ability of 126 fungal strains isolated from peanuts or field soils to produce G-group aflatoxins. Among these, seven stains producing different amounts of G-group aflatoxins were identified. Our results showed that the monoclonal antibody 2 G6-based CI-ELISA was suitable for the detection of G-group aflatoxins present in peanuts and also those produced by fungi.