Detection of sterigmatocystin based on the novel aflatoxin-oxidase/chitosan-single-walled carbon nanotubes/poly-o-phenylenediamine modified electrode / 生物工程学报

A sensitive electrochemical biosensor based on Aflatoxin-Oxidase (AFO) was developed for detection of sterigmatocystin (ST). The enzyme was immobilized on chitosan-single-walled carbon nanotubes (CS-SWCNTs) hybrid film, which attached to the poly-o-phenylenediamine (POPD)-modified Au electrode. The fabricated procedures of the biosensor were characterized with atomic force microscopy (AFM), fourier transform-infrared spectroscopy (FT-IR), and electrochemical impedance spectroscopy (EIS). The cyclic voltammetric results of the biosensor indicated that AFO exhibited a surface-controlled and quasi-reversible electrochemical redox behavior with a formal potential of -0.436 V (vs. Ag/AgCl) in 0.1 mol/L PBS (pH 7.0), which resulted from the direct electron transfer between entrapped AFO and the underlying electrode. The enzymatic electrode exhibited an excellent electrocatalytic response to ST. The linear range of ST determination was from 10 ng/mL to 310 ng/mL with correlation coefficient of 0.997, the detection limit was 3 ng/mL (S/N=3), and the response time was less than 10 seconds. The apparent Michaelis-Menten constant (K(M)app) was estimated to be 7.13 micromol/L. The biosensor had the advantages of good repeatability and stability, remaining 85.6% of its original current value after storage at 4 degrees C for a month, and the RSD for 11 replicate determination of 20 ng/mL ST was 3.9%. This AFO/CS-SWCNTs/POPD/Au modified electrode showed high selectivity and sensitivity in real sample analysis, giving values of recovery in the range of 87.6%-105.5%. The proposed method can be applied to the determination of ST in real samples with satisfactory results.

Spices Mycobiota and Mycotoxins Available in Saudi Arabia and Their Abilities to Inhibit Growth of Some Toxigenic Fungi

The prevalence and population density of the mycobiota of 50 samples belonging to 10 kinds of spices (anise, black pepper, red pepper, black cumin, peppermint, cardamom, clove, cumin, ginger and marjoram) which collected from different places in Jeddah Governorate were studied. The natural occurrence of mycotoxins in those samples was also investigated. Fifteen genera and thirty - one species of fungi in addition to one species variety were isolated and identified during this study. The most common genera were Aspergillus, Penicillium and Fusarium. Aflatoxins (12~40 microg/kg) were detected in the extract of 5 samples of each of anise seeds and black pepper fruits; three samples of black cumin seeds and on sample only of each of peppermint and marjoram leaves out of 5 samples tested of each. Sterigmatocystin (15~20 microg/kg) was detected in some samples of red pepper, cumin and marjoram. The inhibitory effects of 10 kinds of powdered spices were tested against 3 toxigenic isolates of fungi (Aspergillus flavus, A. versicolor and Penicillium citrinum). Clove proved to be antimycotic compounds. It inhibited the growth of the tested toxigenic fungi. Black pepper, peppermint, cardamom, cumin and marjoram completely inhibited aflatoxins production, while black pepper and cardamom also completely inhibited sterigmatocystin production.

Carcinogenic effects of sterigmatocystin and deoxynivalenol in NIH mice / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To further explore the carcinogenic activity of Sterigmatocystin (ST) and the possible synergistic carcinogenic effect of deoxynivalenol (DON) in NIH mice.</p><p><b>METHODS</b>NIH mice were randomly divided into 6 groups, 30 in each. Five groups of mice were given by gastric intubation ST 3 microg/kg, ST 30 microg/kg, ST 3 microg/kg + DON 1.5 microg/kg, ST 30 microg/kg + DON 1.5 microg/kg and DON 1.5 microg/kg respectively, 3 times a week for 24 weeks. The remaining group of mice was given normal saline accordingly, serving as control. All mice were fed with HPLC-confirmed mycotoxin-free food, analysis. The mice were killed and pathologically examined at 58th and 74th weeks.</p><p><b>RESULTS</b>No pathological changes were found in the control group of mice. Adenocarcinoma of lung was observed in 25.0%, 41.7%, 62.5%, 69.2% and 37.5% of mice given ST 3 microg/kg, ST 30 microg/kg, ST 3 microg/kg + DON 1.5 microg/kg, ST 30 microg/kg + DON 1.5 microg/kg and DON 1.5 microg/kg, respectively. In addition, dysplasia of glandular stomach was detected in 50.0%, 58.3%, 37.5%, 53.8% and 25.0% of mice similarly treated.</p><p><b>CONCLUSION</b>Oral administration of ST or DON can induce adenocarcinoma in lung and dysplasia of glandular stomach in NIH mice. There is synergistic carcinogenic effect when both ST and DON are given.</p>

The primary study on the detection of sterigmatocystin by biologic enzyme electrode modified with the multiwall carbon nanotubes / 生物工程学报

Sterigmatocystin (ST), the secondary metabolite of many kinds of filamentous fungi, is a potent carcinogen structurally related to the aflatoxins (AFT). With similar chemical structure, sterigmatocystion behaves much the homogeneous properties to aflatoxins, both of these mycotoxins exhibit similar biological properties due to their bisfuranoid structure. Since the common, and even heavier pollution, found in foods and feeds-stuff, sterigmatocystion is more harmful than aflatoxins. The reported detection methods of sterigmatocystion included the Thin-layer Chromatography, the High-Performance-Liquid Chromatography, the Enzyme-Linked Immunosorbant Assay and the PCR detection to the toxic gene, however studies about both easy and inexpensive electro-chemical methods have not been found. Our previous studies had discovered that Sterigmatocystin (ST) exist similar sensitivity towards aflatoxin-detoxifizyme (ADTZ), which we had isolated from a fungus, as aflatoxin does. In this work, the preliminary study on electrochemical analysis and determination of ST with triplet electrode enzyme-biosensor system (Ag/AgCl as the reference electrode, Pt and Au as the pair and work electrode, respectively) was carried out. Multiwall-carbon-nanotube (MWNT) had been used to increase the electron transportation on electrode. In the research, the Au electrode was modified by MWNT-immobilized ADTZ, and then the voltammertric behavior of ST was studied by means of cyclic voltammogram analysis and different pulse analysis. Autoprobe CP Research Atomic Force Microscope and TECNAI 10 Transmission Electron Microscope, had been used to detect the MWNT as well as the surface of MWNT-modified ADTZ. The voltammertric behavior of ST was studied by means of cyclic voltammogram analysis and different pulse analysis. The results show that the red-ox peak potential of ST is at the point of -600 mV, the linear detection range is from 8.32 x 10(-5) to 66.56 x 10(-5) mg/mL, the detection limit is at 8.32 x 10(-5) mg/mL, and the response time is 10 seconds. This study provided a good basic work for further research.

Effects of sterigmatocystin, deoxynivalenol and aflatoxin G1 on apoptosis of human peripheral blood lymphocytes in vitro / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To explore the effects of Sterigmatocystin (ST), Deoxynivalenol (DON) and Aflatoxin G1 (AFG1) on apoptosis of human peripheral blood lymphocytes (HPBLs) in vitro and thus to further elucidate the putative roles of these three mycotoxins on human immunosystem.</p><p><b>METHODS</b>The effects of ST, DON and AFG1 on apoptosis of HPBLs were studied with cell culture, flow cytometric (FCM) DNA analysis and DNA agarose gel electrophoresis.</p><p><b>RESULTS</b>DNA agarose gel electrophoresis results showed the characteristic "ladder" pattern of apoptosis in HPBLs treated with ST, DON and AFG1. Flow cytometric DNA analysis revealed that typical subdiploid peaks of apoptosis in DNA histogram could be seen in all groups treated with the three mycotoxins. Significant time-effect and dose-effect relationships were found between the apoptosis rates and treatment time as well as concentrations of the three mycotoxins.</p><p><b>CONCLUSION</b>ST, DON and AFG1 can induce apoptosis of HPBLs in vitro and may have some negative effects on human immunosystem.</p>

Introducción al tema de micotoxinas y micotoxicosis / Introduction to mycotoxins and mycotoxicoses

Se presenta un panorama general sobre las principales micotoxinas y sus efectos sobre la salud humana y animal

Mycoflora and mycotoxins of sunflower [Helianthus annus L] seeds in Egypt II Sterigmatocystin production by thermophilic [or thermotolerant] fungi

Fourteen species and 4 varieties which belong to 10 genera were collected from 36 sunflower seed samples using dilution-plate method on 1% glucose-Czapek's agar at 45°C. Aspergillus [7 species] and Mucor [1 species] were the most prevalent genera. From the preceding genera A. fumigatus, A. nidulans and M. puscillus were extremely dominant. Fifteen isolates which belong to the previous species [A. nidulans and nidulans var. lates] were screened for the production of sterigmatocystin at 28 and 45°C. Thin-layer chromatographic analysis [TLC] revealed that 4 isolates belonging to A. nidulans were positive for the toxin production at 28°C, but none of these isolates tested produced any detectable amount of sterigmatocystin when grown at 45°C. A suitable liquid medium for sterigmatocystin-producing fungi was formulated. Maximum production of sterigmatocystin was obtained at pH 5 and after incubation for 7 days at 28°C using surface cultivation