Home About us Contact
|
Home About us Contact | ||
|
|
||
Aflatoxin B1 (aflatoxin + b1)
Terms modified by Aflatoxin B1 Selected AbstractsProtective Effect of Ebselen on Aflatoxin B1 -Induced Cytotoxicity in Primary Rat HepatocytesBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2000Cheng-Feng Yang Recent studies have shown that aflatoxin B1 enhances reactive oxygen species formation and causes oxidative damage, which may ultimately contribute to the cytotoxicity and carcinogenic effect of aflatoxin B1. Ebselen, 2-phenyl-1,2-benzoisoseleazol-3(H)-one, a synthetic seleno-organic compound has been shown to possess glutathione peroxidase-like activity and free radical scavenging ability. Thus present study was designed to investigate the protective effect of ebselen on aflatoxin B1 -induced cytotoxicity in primary rat hepatocytes. Aflatoxin B1 -induced cytotoxicity and lipid peroxidation were determined by lactate dehydrogenase leakage and malondialdehyde generation, respectively. Intracellular reactive oxygen species level was measured using the fluorescent probe 2,,7,-dichlorofluorescin diacetate, and the intracellular reduced glutathione concentration was determined with a fluorometric method. Ebselen was found to display a dose-dependent protective effect on lactate dehydrogenase leakage and malondialdehyde generation caused by aflatoxin B1 exposure. The results also demonstrate that ebselen efficiently inhibits the intracellular reactive oxygen species formation in aflatoxin B1 -treated hepatocytes in a dose and time-dependent manner. It was also noted that ebselen was able to increase the intracellular reduced glutathione concentration, both in the control and in aflatoxin B1 -treated hepatocytes. The protection of ebselen against aflatoxin B1 cytotoxicity, however, was not affected by lowering the concentration of intracellular reduced glutathione. The overall data indicate that ebselen possesses a potent protective effect against aflatoxin B1 -induced cytotoxicity, and the main mechanism involved in the protection may be its strong capability in inhibiting intracellular reactive oxygen species formation and preventing oxidative damage. [source] Is correction for protein concentration appropriate for protein adduct dosimetry?CANCER SCIENCE, Issue 2 2007Hypothesis, clues from an aflatoxin B1-exposed population Protein adducts are useful biomarkers for assessing exposure, metabolism and risk of carcinogens. Aflatoxin B1,albumin adducts (AAA) and protein carbonyl content (PCC) have long been used for assessing aflatoxin exposure and oxidative stress to proteins, and the quantitative data are almost exclusively expressed per mg protein. Given the large variation in protein concentrations in plasma among populations, this may not be the most appropriate method. The objective was to test the hypothesis that AAA and PCC should be expressed per mL plasma in population studies. AAA and PCC were analyzed among 402 subjects from three regions of China with a gradient in hepatocellular carcinoma (HCC) mortality ranging from 21 to 97 per 100 000. When biomarker values were expressed per mL plasma, the AAA level was significantly associated with plasma PCC (r = 0.262, P < 0.001), and adjusted levels of AAA and PCC paralleled HCC mortalities in the three regions, suggesting a role for aflatoxin-related oxidative stress in hepatocarcinogenesis in this population. In addition, there were statistically significant associations between both protein biomarkers, expressed per mL plasma, and the levels of alanine aminotransferase and aspartate aminotransferase in hepatitis B virus-infected subjects, suggesting roles for aflatoxin exposure, oxidative stress and hepatitis B virus infection in the development of HCC. The present data suggest that interindividual variation in plasma protein concentration may influence the dosimetry and relevant interpretation of protein biomarkers. (Cancer Sci 2007; 98: 140,146) [source] The determination of aflatoxins in spices by immunoaffinity column extraction using HPLCINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2005Cavit Bircan Summary Seventy-five samples of different spices marketed in Turkey were purchased from bazaars, herbal shops and supermarkets. Equal amounts of paprika, chilli, black peppers and cumin were purchased and used to test and compare the amount of aflatoxin contamination. Two different analytical methods were examined for their efficacy by adding a known amount of aflatoxin to the blank samples of paprika. Twenty-seven paprika, all the chilli powder and four ground black pepper samples were contaminated with aflatoxin B1 in the range of 0.5,116.4, 1.6,80.4 and 0.3,1.2 ,g kg,1 respectively. Twenty-three (30%) paprika and chilli powder samples were above the regulatory limits used in the European Union. No aflatoxin contamination was detected in the cumin samples at a detection limit of 0.2 ,g kg,1. [source] Control of Aspergillus section Flavi growth and aflatoxin accumulation by plant essential oilsJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2008R. Bluma Abstract Aims:, The antifungal effect of Pimpinella anisum (anise), Pëumus boldus (boldus), Mentha piperita (peppermint), Origanum vulgare (oregano) and Minthosthachys verticillata (peperina) essential oils against Aspergillus section Flavi (two isolates of Aspergillus parasiticus and two isolates of Aspergillus flavus) was evaluated in maize meal extract agar at 0·982 and 0·955 water activities, at 25°C. Methods and Results:, The percentage of germination, germ-tube elongation rate, growth rate and aflatoxin B1 (AFB1) accumulation at different essential oils concentrations were evaluated. Anise and boldus essential oils were the most inhibitory at 500 mg kg,1 to all growth parameters of the fungus. These essential oils inhibited the percentage of germination, germ-tube elongation rate and fungal growth. AFB1 accumulation was completely inhibited by anise, boldus and oregano essential oils. Peperina and peppermint essential oils inhibited AFB1 production by 85,90% in all concentrations assayed. Conclusions:, Anise and boldus essential oils could be considered as effective fungitoxicans for Aspergillus section flavi. Significance and Impact of the Study:, Our results suggest that these phytochemical compounds could be used alone or in conjunction with other substances to control the presence of aflatoxigenic fungi in stored maize. [source] Control of Aspergillus growth and aflatoxin production using antioxidants at different conditions of water activity and pHJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2003A. Nesci Abstract Aims: The effect of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB) and propyl paraben (PP) (at concentrations of 1, 10 and 20 mmol l,1) on germination, growth and aflatoxin B1 production by Aspergillus section Flavi was evaluated. Methods and Results: Studies on the percentage of spore germination, elongation rate, growth rate and aflatoxin B1 production were carried out in vitro in relation to water activity (aw) at 0·982, 0·937, 0·809 and 0·747 values. At 0·809 and 0·747aw values none of the isolates was able to germinate. Overall, PP and BHA were the antioxidants most effective at inhibiting germination of both species. In the presence of the lowest concentration of BHA and PP (1 mmol l,1) the conidial germination percentage ranged from 2 to 19% after 15 h of incubation at the highest water activity tested. BHA and PP at 10,20 mmol l,1 completely inhibited conidial germination. The antioxidants more efficient in controlling Aspergillus elongation rate were PP, BHT and BHA. All strains were much more sensitive to all antioxidants tested on the percentage of spore germination and growth rate at 0·937aw. The antioxidants PP and BHA completely inhibited aflatoxin B1 production by all strains when added at 1 mmol l,1. Decreased aflatoxin B1 levels in comparison with the control, were observed with BHT at 1, 10 and 20 mmol,1 with the strain T20 at 0·982aw. In contrast, stimulation was observed with the antioxidant THB at 10 and 20 mmol l,1 at 0·937aw with the strains T20 and T23. The effect of BHA and PP at 1 mmol l,1 on lag phase and growth rate was maintained in the pH range between 6 and 8. At all pH values the inhibitory effect of BHA was higher than PP. No aflatoxin B1 was detected at all pH values. Conclusions: The data show that BHA and PP could be considered as effective fungitoxicants for A. flavus and A. parasiticus. Significance and Impact of the Study: The information obtained show promise for controlling growth and aflatoxin B1 in stored maize. Futher studies should be carried out to examine the potential for antioxidants, such as BHA and PP to effectively control both growth and aflatoxin production. [source] In vitro evaluation of the chemoprotective action mechanisms of leontopodic acid against aflatoxin B1 and deoxynivalenol-induced cell damageJOURNAL OF APPLIED TOXICOLOGY, Issue 1 2009Stefano Costa Abstract Several in vitro studies showed that free radical scavengers possess chemopreventive properties against mycotoxin-induced cell damage which are at least partially associated with the induction of phase II detoxifying enzymes and antioxidant enzymes like glutathione S -transferase (GST) and glutathione peroxidase (GPx). The aim of this project was to study the chemopreventive effects of leontopodic acid (LA), a potent natural occurring free radical scavenger isolated from the aerial parts of Leontopodium alpinum. Different mycotoxins were evaluated in two different cell lines on the basis of their specific toxicity: aflatoxin B1 (AFB1) on HepG2 cells and deoxynivalenol (DON) on U937 cells. Cell viability and reactive oxygen species concentration were determined, and the effects of pre-treatment with LA on these parameters were investigated together with the GST and GPx activity as well as the concentration of reduced glutathione. The results show that LA protects U937 cells from DON-induced cell damage but not HepG2 cells from AFB1. Moreover LA is able to enhance GPx activity in U937, but not GST activity in HepG2. We hypothesize that the increase in detoxifying enzymes is probably the main mechanism of antioxidant mediated chemoprevention. Copyright © 2008 John Wiley & Sons, Ltd. [source] Reduction of Aflatoxins by Extrusion-Cooking of Rice MealJOURNAL OF FOOD SCIENCE, Issue 7 2006Miren Castells ABSTRACT:, The objective of this work was to determine the reduction of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) as a function of initial moisture content of samples (24%, 27%, and 30%), barrel temperature (140, 170, and 200 °C), and residence time (30 to 70 s) when artificially contaminated rice meal was extrusion-cooked. Extruded and unextruded samples were analyzed by high-performance liquid chromatography (HPLC). Extrusion-cooking was observed to reduce aflatoxin (AF) content, which ranged from 51% to 95% depending on the type of AF and the studied variables. Only in the case of AFG2 was it found that the higher the temperature, the higher the moisture content, and the longer the residence time, the greater the reduction. Moisture content had a significant influence on reducing AFB2, AFG1, and AFG2 whereas it was not a significant factor affecting the levels of AFB1. Regardless of the type of AF, the lowest reductions were achieved at a temperature of 140 °C. Even though theoretically greater losses would be expected at highest temperature, AFB1 and AFB2 were more reduced by 170 °C than by 200 °C while AFG1 reductions were not statistically different when processing at 170 °C and 200 °C. The decrease of AF followed 1st-order kinetics; the fastest treatment in reducing AF was that at 200 °C when samples containing AFG2 were wetted to 24% and when samples containing AFB1, AFB2, and AFG1 were hydrated to 27%. By contrast, the slowest treatments were observed at a barrel temperature of 140 °C. [source] Quality and Functional Characteristics of Chungkukjang Prepared with Various Bacillus sp.JOURNAL OF FOOD SCIENCE, Issue 4 2005Isolated from Traditional Chungkukjang ABSTRACT: Bacillus circulans, Brevibacillus brevis, B. licheniformis, B. coagulans, B. subtilis, and B. sterothermophillus were isolated and identified from chungkukjangs (Korean traditional soybean paste fermented for a few day). Chungkukjang was prepared on a laboratory scale with soybeans and the isolated strains. Characteristics of the chungkukjangs including slime material content, free amino acid content, sensory qualities, and antimutagenicity were determined. The content of slime material, which is an important indicator of the quality of chungkukjang, was highest in B. licheniformis -inoculated chungkukjang, andlowestin B. sterothermophillus -inoculated chungkukjang. The total content of glycine, glutamic acid, aspartic acid, and arginine, which contribute a savory taste to chungkukjangs, was highest in B. licheniformis-inoculated chungkukjang. The content of leucine, which gives a bitter taste, was highest inB. brevis -inoculated chungkukjang. Sensory evaluation revealed that chungkukjangs made using B. licheniformis and B. subtilishad a weak bitter taste and strong sweet and savory taste and good color, so their overall acceptability was high. Chungkukjang fermented with B. circulans and B. licheniformis inhibited N-Methyl-N,-nitro-N-nitrosoguanidine (MNNG) mutagenicity by more than 80%. B. licheniformis-inoculated chungkukjang exhibited the highest antimutagenicity against and aflatoxin B1 (AFB1) and MNNG. These results suggest that using B. licheniformis to ferment chungkukjang increases the antimutagenic properties and improves the sweet and savory taste by increasing glycine, glutamic acid, aspartic acid, and arginine concentrations. [source] Aflatoxin contamination of consumer milk caused by contaminated rice by-products in compound cattle feedJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2009Erik Nordkvist Abstract BACKGROUND: Elevated levels of aflatoxin M1 were observed in routine checks of consumer milk in southern Sweden in early 2006. A trace-back study revealed contaminated milk from several farms, and a total of 68 farms were banned from delivering milk to dairies for shorter or longer periods. The maximum level of aflatoxin M1 in a single sample from an individual farm was 257 ng kg,1 fresh milk. RESULTS: Aflatoxin analyses of commercial compound feed revealed that the contamination originated from the ingredient rice feed meal, a by-product from the preparation of Basmati rice for human consumption. Up to 56 µg kg,1 of aflatoxin B1 was found in rice feed meal at one feed mill. CONCLUSION: The present example shows that an aflatoxin-contaminated minor feed ingredient included at less than 10% (w/w) of compound cattle feed can significantly contaminate the milk produced. This emphasises the need for effective monitoring of the feed chain of food-producing animals in order to prevent food contamination. Copyright © 2008 Society of Chemical Industry [source] Antimutagenic and antioxidant activities of cascalote (Caesalpinia cacalaco) phenolicsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2004Rafael A Veloz-García Abstract There is an increasing awareness and interest in the antioxidant behaviour and potential health benefits of phenolic acids. The identification of novel sources of phenolic acids has been also of scientific interest. Cascalote (Caesalpinia cacalaco) pods are known to be a good source of ,tannins', the name by which industry in Mexico recognizes phenolic extract. Phenolics were determined as gallic acid equivalents g,1. The antimutagenic activity against aflatoxin B1 and the antioxidant activity, using two different methods, of the extract were also evaluated. Gallic acid accounts for almost 90% of the phenolic extract of cascalote, the remaining 10% was tannic acid. Antimutagenic activity of cascalote phenolics was dose-dependent, showing an inhibition level of 64.42% at the highest dose assayed. Antioxidant and antiradical activities were also dose-dependent. The highest antioxidant activity showed by cascalote phenolics was 73.5%, higher than that of Trolox. The highest antiradical activity of cascalote phenolics was 75.3%, higher than that of BHT and Trolox. Cascalote pods are an outstanding source of gallic and tannic acids. Copyright © 2004 Society of Chemical Industry [source] Inhibition of aflatoxin B1 production of Aspergillus flavus, isolated from soybean seeds by certain natural plant productsLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2006Y.L. Krishnamurthy Abstract Aims:, The inhibitory effect of cowdung fumes, Captan, leaf powder of Withania somnifera, Hyptis suaveolens, Eucalyptus citriodora, peel powder of Citrus sinensis, Citrus medica and Punica granatum, neem cake and pongamia cake and spore suspension of Trichoderma harzianum and Aspergillus niger on aflatoxin B1 production by toxigenic strain of Aspergillus flavus isolated from soybean seeds was investigated. Methods and Results:, Soybean seed was treated with different natural products and fungicide captan and was inoculated with toxigenic strain of A. flavus and incubated for different periods. The results showed that all the treatments were effective in controlling aflatoxin B1 production. Captan, neem cake, spore suspension of T. harzianum, A. niger and combination of both reduced the level of aflatoxin B1 to a great extent. Leaf powder of W. somnifera, H. suaveolens, peel powder of C. sinensis, C. medica and pongamia cake also controlled the aflatoxin B1 production. Conclusions:, All the natural product treatments applied were significantly effective in inhibiting aflatoxin B1 production on soybean seeds by A. flavus. Significance and Impact of the Study:, These natural plant products may successfully replace chemical fungicides and provide an alternative method to protect soybean and other agricultural commodities from aflatoxin B1 production by A. flavus. [source] Liver carcinogen aflatoxin B1 as an inducer of mitotic recombination in a human cell lineMOLECULAR CARCINOGENESIS, Issue 3 2001Peter Markus Stettler Abstract The mycotoxin aflatoxin B1 (AFB1) is one of the most potent rodent and human liver carcinogens. Upon cytochrome P450,specific metabolism, it induces mutations as well as mitotic recombination events in in vitro systems. We have found that in the lower eukaryote yeast, the recombinagenic activity of AFB1 surpasses its mutagenic activity, and we speculated on possible consequences in terms of the mechanism of liver carcinogenesis. In this study we investigated whether the recombinagenic activity of AFB1 also would be identified in human cells. To address this question, we followed the fate of a heterozygous thymidine kinase (tk) allele in the human lymphoblastoid cell line TK6 upon exposure to AFB1. Individual mutants that had lost tk activity were subjected to loss of heterozygosity analysis of the tk locus and its flanking markers. Fluorescence in situ hybridization analysis on chromosome 17 also was performed. In parallel, a similar analysis was performed on TK6 cells exposed to the alkylating agent N -nitrosomethylurea, a well-known classic point mutagen. Our analysis showed a difference in the molecular mechanism leading to inactivation of the tk allele upon exposure to these two mutagens. In AFB1 -exposed cells the fraction of recombination-derived mutants predominated, whereas in N -nitrosomethylurea,exposed cells the fraction of point mutants was higher. Thus, the recombinagenic activity of AFB1 previously identified in a lower eukaryote also was found in the human cell line TK6. Our data support the hypothesis that mitotic recombination represents a central mechanism of action in AFB1 -induced liver carcinogenesis. © 2001 Wiley-Liss, Inc. [source] Occurrence of certain mycotoxins in corn and corn-based products and thermostability of fumonisin B1 during processingMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 4 2003A. M. Abd Alla El-Sayed Abstract A total of 57 samples of corn and corn-based products collected from various districts of Egypt were analyzed for Fusarium mycotoxins (T-2, diacetoxyscripenol (DAS( deoxynivalenol (DON) and fumonisin B1 (FB1) and aflatoxins. FB1 was detected in about 80%, 53.85%, 33.3%, and 28.57% of yellow corn, corn meal, white corn, and popcorn samples, respectively. The levels of FB1 ranged from 10 to 780 ,g/kg. T-2 and DAS were detected in 5% and 10% of yellow corn samples, respectively, and DON was detected in white corn and popcorn samples at levels of 28.8 and 10.1 ,g/kg, respectively. Starch samples were found to be free from Fusarium mycotoxins. Baking balady bread at 450°C/min reduced FB1 to 72.4% while baking Franco bread at 250°C/20 min reduced FB1 to 57.4%. Boiling of macaroni and corn in water completely removed FB1 from contaminated samples. On the other side, corn flakes samples were found to be contaminated with aflatoxins B1 and G1 at levels ranging from 6 to 10 ppm, whereas 2.9% of samples were contaminated with aflatoxin B1 > 35 ppm and G1 > 16 ppm. [source] Development of a liquid chromatography/time-of-flight mass spectrometric method for the simultaneous determination of trichothecenes, zearalenone and aflatoxins in foodstuffsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2006Hiroki Tanaka A liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) method based on time-of-flight MS (TOFMS) with a real-time reference mass correction technique was developed for the simultaneous determination of Fusarium mycotoxins (nivalenol, deoxynivalenol, fusarenon X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, HT-2 toxin, T-2 toxin, diacetoxyscirpenol, zearalenone) and Aspergillus mycotoxins (aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2) in corn, wheat, cornflakes and biscuits. Samples were cleaned up with a MultiSep #226 column. Detection of the mycotoxins was carried out in exact mass chromatograms with a mass window of 0.03,Th. Calibration curves were linear from 2 to 200,ng,·,mL,1 for trichothecenes and zearalenone, and 0.2 to 20,ng,·,mL,1 for aflatoxins, by 20,µL injection. The limits of detection ranged from 0.1 to 6.1,ng,·,g,1 in foodstuffs analyzed in this study. The LC/TOFMS method was found to be suitable for the screening of multiple mycotoxins in foodstuffs rapidly and with high sensitivity, and its performance was demonstrated for the confirmation for target mycotoxins. Copyright © 2006 John Wiley & Sons, Ltd. [source] Growth and hepatopancreas performances of gibel carp fed diets containing low levels of aflatoxin B1AQUACULTURE NUTRITION, Issue 4 2010D. HAN Abstract The effects of aflatoxin B1 (AFB1) on growth, physiological responses and histological changes were investigated in juvenile gibel carp (Carassius auratus gibelio). Triplicate groups of gibel carp (3.53 ± 0.02 g) were fed seven semipurified diets (Diet 1 to 7) containing 3.20, 5.37, 7.08, 9.55, 12.70, 17.90 and 28.60 ,g AFB1 kg,1 diet for 3 months. The results showed fish weight gain fed Diet 6 was 112.6% of that of control group (Diet 1) after 3 months, but there was no significant difference of weight gain between fish fed Diet 7 and the control group. Alanine aminotransferase (ALT) of fish hepatopancreas fed Diet 7 was significantly higher than the control group (P < 0.05), but no significant difference was observed in ALT activities of the fish fed with more than 10 ,g AFB1 kg,1 (Diet 4, 5, 6 and 7). No significant histological lesions were identified between the control and increasing AFB1 treatments. AFB1 accumulated in hepatopancreas was logarithmically related to the dietary AFB1 levels, and AFB1 also accumulated in muscles and ovaries of gibel carp fed Diet 3 to Diet 7. The present results indicated that fish fed with more than 10 ,g AFB1 kg,1 diet showed impaired physiological responses and more AFB1 residue of muscles and ovaries above the safety limitation of European Union. [source] Histological alterations in the hepatopancreas of Penaeus monodon Fabricius (1798) given aflatoxin B1 -incorporated dietsAQUACULTURE RESEARCH, Issue 11 2009Radhika Gopinath Abstract Aflatoxin is a toxic contaminant produced by toxigenic fungi of the genus Aspergillus during the processing and storage of feeds and feed ingredients. Aflatoxins can cause abnormalities such as poor growth, physiological imbalances and histological changes that result in a reduction in the yield and profitability of shrimp culture. Histological changes in Penaeus monodon sub-adults fed different doses of aflatoxin B1 were studied. The doses of aflatoxin B1 administered in the diets were 50, 100, 150, 500, 1000 and 2000 ppb. At the end of the fourth and the eighth weeks of the experiment, the shrimps were sampled and the cephalothorax was observed for histological changes. Significant changes were observed in the different treatment groups at the fourth and eighth weeks. The severity of pathological changes was proportional to the increase in the concentration of aflatoxin fed to the shrimps. Histological changes in the hepatopancreas were loss of structure of the cells and tubules, nodule formation, cell elongation, desquamation, rounding of cells, fibrosis, necrosis, haemocytic infiltration and cellular inflammation. [source] Protective Effect of Ebselen on Aflatoxin B1 -Induced Cytotoxicity in Primary Rat HepatocytesBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2000Cheng-Feng Yang Recent studies have shown that aflatoxin B1 enhances reactive oxygen species formation and causes oxidative damage, which may ultimately contribute to the cytotoxicity and carcinogenic effect of aflatoxin B1. Ebselen, 2-phenyl-1,2-benzoisoseleazol-3(H)-one, a synthetic seleno-organic compound has been shown to possess glutathione peroxidase-like activity and free radical scavenging ability. Thus present study was designed to investigate the protective effect of ebselen on aflatoxin B1 -induced cytotoxicity in primary rat hepatocytes. Aflatoxin B1 -induced cytotoxicity and lipid peroxidation were determined by lactate dehydrogenase leakage and malondialdehyde generation, respectively. Intracellular reactive oxygen species level was measured using the fluorescent probe 2,,7,-dichlorofluorescin diacetate, and the intracellular reduced glutathione concentration was determined with a fluorometric method. Ebselen was found to display a dose-dependent protective effect on lactate dehydrogenase leakage and malondialdehyde generation caused by aflatoxin B1 exposure. The results also demonstrate that ebselen efficiently inhibits the intracellular reactive oxygen species formation in aflatoxin B1 -treated hepatocytes in a dose and time-dependent manner. It was also noted that ebselen was able to increase the intracellular reduced glutathione concentration, both in the control and in aflatoxin B1 -treated hepatocytes. The protection of ebselen against aflatoxin B1 cytotoxicity, however, was not affected by lowering the concentration of intracellular reduced glutathione. The overall data indicate that ebselen possesses a potent protective effect against aflatoxin B1 -induced cytotoxicity, and the main mechanism involved in the protection may be its strong capability in inhibiting intracellular reactive oxygen species formation and preventing oxidative damage. [source] Mechanisms involved in the chemoprevention of flavonoidsBIOFACTORS, Issue 1-4 2000Marie-HÉLÉNe Siess Flavonoids, widespread in edible plants, have been studied extensively for their anticarcinogenic properties. However, only few studies have been done with these constituents being administered by the dietary route. In our research, the effects of feeding rats with flavone, flavanone, tangeretin, and quercetin were investigated on two steps of aflatoxin B1 (AFB1)-induced hepatocarcinogenesis (initiation and promotion). Nonpolar flavonoids such as flavone, flavanone and tangeretin administered through the initiation period, decreased the number of ,-glutamyl transpeptidase-preneoplastic foci. In the same conditions of administration, quercetin, a polyhydroxylated flavonoid, showed no protective effect. Moreover, feeding rats with flavanone during the phenobarbital-induced promotion step significantly reduced the areas of placental glutathione S-transferase preneoplastic foci. Quercetin, flavone, and tangeretin, administered in the same conditions, caused no significant effect. Therefore flavanone act as an anti-initiator as well as an anti-promotor. Several mechanisms were involved in the anti-initiating effects of flavone, flavanone, and tangeretin: enhancement of enzymes involved in the detoxication of AFB1 (glutathione S-transferase, UDP-glucuronyl transferase), increase of the formation of AFB1 -glutathione conjugates and inhibition of the binding of AFB1 to DNA. Although the relevance of these data to the human situation remains to be demonstrated, they confirm that several flavonoids administered by the dietary route possess promising chemoprotective effects. [source] Thermal stabilization of the DNA duplex by adducts of aflatoxin B1BIOPOLYMERS, Issue 3 2002Indrajit Giri Abstract The trans-8,9-dihydro-8-(N7-guanyl)-9-hydroxyaflatoxin B1 cationic guanine N7 adduct of aflatoxin B1 thermally stabilizes the DNA duplex, as reflected in increased Tm values upon adduction. The magnitude of the increased Tm value is characteristically 2,3°C. The major rotamer of the neutral guanine N7 adduct trans-8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxy aflatoxin B1 (the FAPY major adduct) exhibits a 15°C increase in Tm in 5,-d(CTATFAPYGATTCA)-3,-5,-d(TGAATCATAG)-3,. Site-specific mutagenesis experiments reveal the FAPY major adduct induces G,T mutations in Escherichia coli at a frequency six times higher than that of the cationic adduct (Smela, M. E.; Hamm, M. L.; Henderson, P. T.; Harris, C. M.; Harris, T. M.; Essigmann, J. M. Proc Natl Acad Sci USA, 99, 6655,6660). Thus, the FAPY major lesion may account substantially for the genotoxicity of AFB1. Structural studies for cationic and FAPY adducts of aflatoxin B1 suggest both adducts intercalate above the 5,-face of the modified deoxyguanosine and that in each instance the aflatoxin moiety spans the DNA helix. Intercalation of the aflatoxin moiety, accompanied by favorable stacking with the neighboring base pairs, is thought to account for the increased thermal stability of the aflatoxin cationic guanine N7 and the FAPY major adducts. However, the structural basis for the large increase in thermal stability of the FAPY major adduct in comparison to the cationic guanine N7 adduct of aflatoxin B1 is not well understood. In light of the site-specific mutagenesis studies, it is of considerable interest. For both adducts, the intercalation structures are similar, although improved stacking with neighboring base pairs is observed for the FAPY major adduct. In addition, the presence of the formamido group in the aflatoxin B1 FAPY major adduct may enhance duplex stability, perhaps via intrastrand sequence-specific hydrogen bonding interactions within the duplex. © 2002 Wiley Periodicals, Inc. Biopolymers (Nucleic Acid Sci) 65: 190,201, 2002 [source] Hepatitis B and C Viruses Infection, Lifestyle and Genetic Polymorphisms as Risk Factors for Hepatocellular Carcinoma in Haimen, ChinaCANCER SCIENCE, Issue 12 2002Shun-Zhang Yu A case-control study was carried out to investigate the impact of factors including virus infection, aflatoxin B1, microcystins, smoking/drinking and dietary habits as well as genetic polymorphisms of aldehyde dehydrogenase 2 (ALDH2) and cytochrome P4502E1 (CYP2E1), on susceptibility to hepatocellular carcinoma (HCC) in Haimen, China. A total of 248 patients with HCC and 248 sex-, age- and residence-matched population-based controls were recruited into the study. Virus infection, and ALDH2 and CYP2E1 gene polymorphisms were assessed in 134 paired cases and controls. By univariate analysis, hepatitis B virus (HBV) infection (odds ratio [OR]=9.75; 95% confidence interval [CI] =4.71,20.2), history of intravenous injection (OR=1.50; 95%CI=1.02,2.22), average income (OR=0.63; 95% CI=0.43,0.92), frequent intake of foods rich in protein, e.g., egg (OR=0.6; 95% CI=0.42,0.87), chicken (OR=0.53; 95% CI=0.35,0.79), pork (OR=0.67; 95% CI=0.46,0.98) and fresh fish (OR=0.58; 95% CI=0.39,0.87) significantly differed between cases and controls. However, peanut intake (OR=0.66; 95% CI=0.43,1.01), source of drinking water, including tap (OR=1.33; 95% CI=0.81,2.20), deep well (OR=0.94; 95% CI=0.56,1.55), shallow well (OR=0.85; 95% CI=0.55-,1.30), river (OR=0.95; 95% CI=0.65,1.38), ditch (OR=1.09; 95% CI=0.76,1.55) and pond water (OR=1.0; 95% CI=0.14,7.10) were not significantly associated with risk. Univariate analysis also indicated that the 1,1 genotype of ALDH2 (OR=1.38; 95% CI=0.86,2.23) as well as the Pst1- and Rsa1-digested c1/c1 genotype of CYP2E1 (OR=1.36; 95% CI=0.81,2.28), was slightly more frequent in the case group. On multivariate analysis, HBV infection (OR=13.9; 95% CI=5.78,33.6) and history of intravenous injection (OR=2.72; 95% CI=1.24,6.00) were still associated with significantly increased risk of HCC, while frequent intake of fresh fish (OR=0.32; 95% CI=0.12,0.86) decreased this risk. These findings suggest that whereas peanut intake, water sources as well as genetic polymorphisms in ALDH2 and CYP2E1 do not significantly correlate with the risk of HCC, HBV infection is a main risk factor, and dietary items rich in protein, especially fresh fish, might protect against the risk of HCC in Haimen, China. [source] Interactions of aflatoxin B1 with SRP components can disrupt protein targetingCELL BIOCHEMISTRY AND FUNCTION, Issue 1 2005Jasbir Singh Abstract Spectrofluorimetric studies have revealed that aflatoxin B1 (AFB1) interacts with signal recognition particle (SRP), which acts as an escort for polyribosomes with signal peptides to be transported and bound to the cytoplasmic face of the endoplasmic reticulum (ER). We further report that the binding of AFB1 to SRP is selective as it only binds to two (SRP9 and 14) out of its three constituent polypeptides studied. Binding of AFB1 to proteins is known to alter their conformations. Interactions of AFB1 with SRP polypeptides may generate structural and functional alterations in this particle and hinder secretory protein synthesis. Copyright © 2004 John Wiley & Sons, Ltd. [source] Application of pressurized liquid extraction in the analysis of aflatoxins B1, B2, G1 and G2 in nutsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009Luca Campone Abstract Aflatoxins (AFs) B1, B2, G1 and G2 were extracted from nuts by using pressurized liquid extraction (PLE) and the PLE extracts were analyzed using HPLC with fluorescence detection using photochemical post-column derivatization without further cleanup procedures. Several extraction parameters such as temperature (25, 40, 60 and 80°C), pressure (500, 1000, 1500 and 2000,psi), solvent extraction mixture (acetone, acetonitrile, ethyl acetate and methanol), number of cycles (1 and 2), use of dispersing agents and cell size (5 and 11,mL) were investigated for their effects on the extraction performance. The results showed 60°C, 1500,psi, acetonitrile, one cycle and a cell size of 5,mL as most favorable PLE operating conditions. The proposed analytical method provides LODs below the maximum levels established by European Union regulations and the recoveries of the four AFs were between 77 and 93% at spiking levels of 4, 2 and 0.5,,g/kg for AFB1 and AFG1 and 1, 0.5 and 0.13,,g/kg for AFB2 and AFG2. Validation was carried out using certified reference materials. PLE has been applied for the first time to the analysis of AFs in nuts and offers the possibility for fast simple and accurate quantitative determination of studied mycotoxins. [source] Occurrence of certain mycotoxins in corn and corn-based products and thermostability of fumonisin B1 during processingMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 4 2003A. M. Abd Alla El-Sayed Abstract A total of 57 samples of corn and corn-based products collected from various districts of Egypt were analyzed for Fusarium mycotoxins (T-2, diacetoxyscripenol (DAS( deoxynivalenol (DON) and fumonisin B1 (FB1) and aflatoxins. FB1 was detected in about 80%, 53.85%, 33.3%, and 28.57% of yellow corn, corn meal, white corn, and popcorn samples, respectively. The levels of FB1 ranged from 10 to 780 ,g/kg. T-2 and DAS were detected in 5% and 10% of yellow corn samples, respectively, and DON was detected in white corn and popcorn samples at levels of 28.8 and 10.1 ,g/kg, respectively. Starch samples were found to be free from Fusarium mycotoxins. Baking balady bread at 450°C/min reduced FB1 to 72.4% while baking Franco bread at 250°C/20 min reduced FB1 to 57.4%. Boiling of macaroni and corn in water completely removed FB1 from contaminated samples. On the other side, corn flakes samples were found to be contaminated with aflatoxins B1 and G1 at levels ranging from 6 to 10 ppm, whereas 2.9% of samples were contaminated with aflatoxin B1 > 35 ppm and G1 > 16 ppm. [source] | |||||||||||||||||||