Levels of five mycotoxins in grains harvested in Atlantic Canada as measured by high performance liquid chromatography

Revisión: Implicaciones toxicológicas y nutricionales de la toxina T-2 / Review: Toxicological and nutritional implications of T-2 toxin

Trichothecenes are mycotoxins produced by species of the genus Fusarium. These toxins are associated with health problems in humans and animals. The most common trichothecenes in cereals are deoxynivalenol, HT-2 toxin, diacetoxyscirpenol, nivalenol, neosolaniol and T-2 toxin; the latter is the most widely studied because it is easy to produce in the laboratory. The effects of T-2 toxicosis include dermatonecrosis, reduced body weight and efficiency of food utilization, severe diarrhoea, haemorrhage, necrosis of the upper alimentary tract, anaemia, immuno suppression ; and in birds, poor feathering. This paper reviews the latest information about the occurrence, chemical characteristics, toxicity, metabolic alterations, biotransformation and detoxifi cation methods of the T-2 toxin.

Analytical Methods for Trichothecenes Surveillance — An Overview Over the Period 1990—2000

This article reviews some aspects of analytical methods used to determine the occurrence of type A and B trichothecenes in grains and foodstuffs and their trends during the decade 1999—2000. A pronounced tendency to use extraction solvents less toxic than chloroform became evident. There was not a prevalent clean up process that pointed there were problems to obtain good recoveries of those mycotoxins. Taking into account the mean values of contamination found in the literature and the provisional maximum tolerable daily intake, a methodology suitable for a surveillance work should have a limit of quantification not greater than 50 μg/kg for deoxynivalenol and less than 10 μg/kg for T-2 and HT-2 toxins. Therefore, gas chromatography or thin layer chromatography could be used for type B trichothecenes while for type A trichothecenes, gas chromatography with electron capture or mass spectrometric detectors is the mandatory quantification method.

A survey of free and conjugated deoxynivalenol in the 2008 corn crop in Ontario, Canada

BACKGROUND

Deoxynivalenol (DON, vomitoxin), one of the most important mycotoxins produced by many Fusarium species, is found as a common contaminant of crops worldwide. Recent studies have described the presence of conjugated forms of DON (glycosides and fatty acid). The aim of the current study was therefore to investigate the natural occurrence of free and conjugated DON in Canadian corn.

RESULTS

Free and conjugated DON was determined by gas chromatography-mass spectrometry (GC-MS) and enzyme-linked immunosorbent assay (ELISA) in 86 corn samples collected from the 2008 crop in Ontario, Canada. Free DON concentrations determined by ELISA were similar to values determined in most samples using GC-MS. Conjugated DON was detected in 72 samples. Levels of free DON ranged from 0.17 to 14.00 µg g(-1) using GC-MS. The highest levels of free DON were found in corn samples from the southern and southwestern regions of Ontario, while samples from eastern regions were less contaminated. Conjugated DON was found mainly in corn from the east-central region, with five of six samples showing high levels of conjugated DON (up to 43% increase in DON following acid hydrolysis). Low levels of conjugated DON (≤ 10% increase in DON following acid hydrolysis) were detected in the majority of corn samples from the southwestern region (nine of 19 samples) and from the central region (16 of 36 samples).

CONCLUSION

The current survey emphasizes the frequency of conjugated DON in Ontario grown corn and the potential challenges in understanding the hazard posed by DON-contaminated foodstuffs and feedstuffs.

Deoxynivalenol and zearalenone in Fusarium-contaminated wheat in Mexico City

Fusarium spp. invasion causes head blight, a destructive disease in the world's main wheat-growing areas, and deoxynivalenol (DON) and zearalenone (ZEA) contamination in cereal-based products. No data are available on the relationship between Fusarium spp. on commercial wheat samples in Mexico City and the presence of mycotoxins. A total of 30 wheat samples were subject to a PCR method involving genes of the trichothecene and zearalenone biosynthesis pathways to detect the presence of Fusarium. Detection and quantification of DON and ZEA was performed using liquid chromatography coupled to UV detection. PCR indicated the presence of the Tri5 and PKS4 genes in 16.7 and 23.3% of samples, respectively. DON and ZEA contamination was found in 51.2 and 71.4% of samples, respectively, where a positive amplification was obtained. This work presents up-to-date information on mycotoxin contamination in Mexico, where improved contamination/exposure data and firm control/monitoring measures are needed.

Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone: An oestrogenic mycotoxin

Zearalenone (ZEA) is a mycotoxin produced mainly by fungi belonging to the genus Fusarium in foods and feeds. It is frequently implicated in reproductive disorders of farm animals and occasionally in hyperoestrogenic syndromes in humans. There is evidence that ZEA and its metabolites possess oestrogenic activity in pigs, cattle and sheep. However, ZEA is of a relatively low acute toxicity after oral or interperitoneal administration in mice, rat and pig. The biotransformation for ZEA in animals involves the formation of two metabolites alpha-zearalenol (alpha-ZEA) and beta-zearalenol (beta-ZEA) which are subsequently conjugated with glucuronic acid. Moreover, ZEA has also been shown to be hepatotoxic, haematotoxic, immunotoxic and genotoxic. The exact mechanism of ZEA toxicity is not completely established. This paper gives an overview about the acute, subacute and chronic toxicity, reproductive and developmental toxicity, carcinogenicity, genotoxicity and immunotoxicity of ZEA and its metabolites. ZEA is commonly found on several foods and feeds in the temperate regions of Europe, Africa, Asia, America and Oceania. Recent data about the worldwide contamination of foods and feeds by ZEA are considered in this review. Due to economic losses engendered by ZEA and its impact on human and animal health, several strategies for detoxifying contaminated foods and feeds have been described in the literature including physical, chemical and biological process. Dietary intakes of ZEA were reported from few countries from the world. The mean dietary intakes for ZEA have been estimated at 20 ng/kgb.w./day for Canada, Denmark and Norway and at 30 ng/kgb.w./day for the USA. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) established a provisional maximum tolerable daily intake (PMTDI) for ZEA of 0.5 microg/kg of body weight.

Occurrence of deoxynivalenol (vomitoxin) in processed cereals and pulses in Turkey

The aim was to investigate the occurrence of deoxynivalenol (DON) in cereal and pulse products in Turkey. DON was detected using high-performance liquid chromatography (HPLC) with ultraviolet detection at 220 nm and positive results greater or equal to 0.60 ppm were confirmed by thin layer chromatography (TLC). An acetonitrile-water (21:4 v/v) extract of the sample was cleaned up on a column packed with alumina-Celite-charcoal (0.35 + 0.25 + 0.40 g). The detection limits for DON were 3 ng/injection (0.10 ppm) and 50 ng/spot (0.60 ppm) for HPLC and TLC, respectively. Eighty-three commercially available cereal and pulse product samples collected from markets and street bazaars were analysed. The recovery rates for boiled, pounded wheat and rice spiked with added DON (1 ppm) were 80.9% (SD 8.37, n=5) and 72.3% (3.85, n=5), respectively. DON was detected in six (8.82%) of 68 cereal and in none of 15 pulse products. The maximum detected amount was 2.67 ppm in a corn flour sample.

Effects of the tricothecene mycotoxin diacetoxyscirpenol on egg production of broiler breeders

Three experiments were conducted to determine the effects of 4,15-diacetoxyscirpenol (DAS) on egg quality and egg production of broiler breeders. In Experiment 1, feed containing 0, 1.25, 2.5, or 5.0 mg DAS/ kg was fed from 67 to 69 wk of age followed by a 3-wk recovery period on a slat-litter floor. In Experiment 2, individually caged broiler breeder females were studied from 23 to 31 wk of age. The basal diet containing 0, 5, 10, or 20 mg DAS/kg was fed from 25 to 27 wk of age. In Experiment 3, individually caged broiler breeder hens were studied from 23 to 32 wk of age. DAS was fed at levels of 0 (basal), 5, 10, and 20 mg DAS/kg for 2 wk beginning at Week 24, followed by the basal breeder diet for 7 wk. Egg production was not affected by levels of up to 5 mg DAS/kg in the older hens of Experiment 1. When fed from 25 to 27 wk of age in Experiment 2, DAS decreased egg production at the 20 mg/kg level only. When fed from 24 to 25 wk of age in Experiment 3, DAS had no significant effect on egg production or egg quality. Short-term consumption of DAS at levels that might naturally occur appears to have little effect on broiler breeder egg production.

Evaluation of the efficacy of a feed additive to ameliorate the toxic effects of 4,15-diacetoxiscirpenol in growing chicks

The possible protective effect of a feed additive (Mycofix) against the toxic effects of 4,15-diacetoxiscirpenol (DAS) in growing broiler chickens was investigated in a 21-d fully randomized trial consisting of seven dietary treatments (control with no DAS or Mycofix added, 1 ppm DAS alone, 1 ppm DAS supplemented with 0.75 g/kg Mycofix, 1 ppm DAS supplemented with 1.5 g/kg Mycofix, 2 ppm DAS alone, 2 ppm DAS supplemented with 0.75 g/kg Mycofix, and 2 ppm DAS supplemented with 1.5 g/kg Mycofix). When no feed additive was included, both levels of dietary DAS significantly decreased BW and feed intake and caused oral lesions, with the effect of 2 ppm DAS being more severe. When 1 ppm DAS was added to the diet, supplementation of Mycofix protected against the adverse effects of DAS on feed intake and BW at both levels of inclusion (0.75 and 1.5 g/kg); however, no protection against oral lesions was obtained by Mycofix supplementation. This finding suggests that the adverse effect of DAS on performance is not due to the oral lesions per se but it is likely the result of the systemic absorption of the mycotoxin. When 2 ppm dietary DAS was present in the diet, only partial protection on BW and feed intake was obtained by Mycofix supplementation. More studies are required to determine if a higher dose of Mycofix could be capable of counteracting the adverse effects of 2 ppm dietary DAS on chicken performance.

Liquid chromatographic determination of toxigenic secondary metabolites produced by Fusarium strains

Various liquid chromatographic methods used in the analysis of mycotoxins (zearalenone, trichothecenes and fumonisins) produced by Fusarium species were compared in this work. The results demonstrate the suitability of modern clean-up procedures employing multifunctional MycoSep and immunoaffinity columns although these methods are more expensive than conventional methodologies for clean-up. HPLC with both fluorescence and photodiode array detection is a suitable technique for the analysis of toxic secondary metabolites produced by Fusarium species; different derivatisation strategies have been studied to improve the sensitivity of the technique because of the low concentration of these metabolites in contaminated food. The utility of the proposed methodology was assessed in cereal cultures of various Fusarium strains.

Comparison of mycotoxin profiles among cereal samples from eastern Canada

The relative susceptibilities of major cereal species to mycotoxin contamination have rarely been studied in eastern Canada or elsewhere. The concentration of 13 mycotoxins in 673 corn (Zea mays L.), 99 wheat (Triticum aestivum L.), 116 barley (Hordeum vulgare L.), and 73 oat (Avena sativa L.) samples collected from eastern Canada from 1991 to 1998 crops were compared. Deoxynivalenol (DON) was found to be the most common mycotoxin in all four species. DON contamination was more frequent but less severe in corn than in wheat and barley, and it was least frequent and least severe in oats. Wheat and barley were equally susceptible to DON contamination. The DON content of 8.9% of the corn, 31.3% of the wheat, 22.4% of the barley, and 1.4% of the oat samples exceeded 1 mg·kg-1, the maximum tolerance level recommended for swine feed. Contamination with zearalenone, T-2, HT-2, diacetoxyscirpenol, ochratoxin A, nivalenol, fumonisins, 3-acetyl DON, or 15-acetyl DON was minor in eastern Canada and varied from species to species. Fusarenon X, 15-monoacetoxyscirpenol, and neosolaniol were not detected. Equally significant, approximately one third of the corn and barley samples were contaminated with two to seven mycotoxins. The presence of two or more mycotoxins could have additive or synergistic effects on the toxicity. Measures to reduce DON contamination are needed for corn, wheat, and barley.Key words: Fusarium, mycotoxins, corn, wheat, barley, oats.

Comparison of extraction and clean-up procedures for analysis of zearalenone in corn, rice and wheat grains by high-performance liquid chromatography with photodiode array and fluorescence detection

The aim of this work was the optimization of some procedures usually used in the analysis of zearalenone (ZEA) in corn and other cereals by high-performance liquid chromatography (HPLC) with photodiode array and/or fluorescence detection. The comparison of five extraction solvents is presented. Three solid-phase extraction cartridges (C-18, silica, Florisil) and immuno-affinity columns were also compared to obtain the best recovery of the mycotoxin with the minimal presence of co-extractives in the chromatograms. Mixtures of methanol-1% aqueous NaCl (80.20 or 60:40 v/v) were the best extraction solvents. Florisil provided higher recovery of ZEA than C-18, and silica proved unsuitable. The immuno-affinity column was very efficient in cleaning the extracts, but its sample capacity was lower than that of SPE columns due to saturation. The mobile phase (methanol-water 80:20 v/v) gave a low retention time for ZEA (approximately 5 min), high sensitivity and acceptable separation between this mycotoxin and alpha-zearalenol. The optimized protocol is straightforward, provides high ZEA recoveries in spiked corn (mean 102.4%), has an acceptable sensitivity and has a lack of interference with fluorescence detection (detection limit 4 ng ZEA g(-1) corn). The photodiode array detector was useful, except at very low ZEA levels, to confirm the identity of the mycotoxin. The method was applied to search for ZEA accumulation in corn, wheat and rice grains inoculated with selected strains of Fusarium graminearum, F. oxysporum and method was applied to search for ZEA accumulation in corn, wheat and rice grains inoculated with selected strains of Fusarium graminearum, F. oxysporum and F. culmorum.

Accumulation of type A trichothecenes in maize, wheat and rice by Fusarium sporotrichioides isolates under diverse culture conditions

Toxigenic isolates of Fusarium sporotrichioides were tested for the production of type A trichothecenes (T-2 toxin, HT-2 toxin, diacetoxyscirpenol and neosolaniol) when grown on three substrates (maize, rice and wheat) under various conditions of temperature and water activity in the laboratory for 3 weeks. Trichothecenes were determined by high-performance liquid chromatography with fluorescence detection, after derivatisation with coumarin-3-carbonyl chloride. This is the first time this analytical method has been applied to an extensive study of trichothecene accumulation. With minor exceptions, greater trichothecene production occurred when samples were incubated at 20 degrees C and moistened with 35% water (water activity 0.990) although incubation conditions affected the substrates studied in different ways. No correlation between the different pairs of trichothecenes was found except for neosolaniol and diacetoxyscirpenol (r=0.56). Principal component analysis results show that the data points can be grouped in three rough clusters related to cereal type, which points out that the composition of these cereals can influence the production of type A trichothecenes.

Occurrence of T-2 toxin in processed cereals and pulses in Turkey determined by HPLC and TLC

The purpose of this study was to investigate the T-2 toxin level of contaminated cereal and pulse products in Turkey. T-2 toxin was detected using high performance liquid chromatography (HPLC) with UV detection at 208 nm and thin layer chromatography (TLC) was used for confirmation of the T-2 toxin-contaminated samples (> or = 1 ppm). The recovery was 93 +/- 3.3% (SD 3.29, n = 5) for chickpea spiked with a known amount of T-2 toxin (1 ppm). The detection limits for T-2 toxin for HPLC and TLC were 25 ng per injection and 50 ng per spot, respectively. A total of 50 commercially available cereal and pulse product samples, collected from markets and street bazaars, were analysed. Incidences of T-2 toxin detected in cereal and pulse products were 23.5% and 31.2%, respectively and the maximum detected amount was 1.9 ppm in a sample of dried beans. The incidence of toxin-contaminated specimens is not so low relative to the volume of specimens produced.

Determination of T-2 toxin in grain and grain products by HPLC and TLC

The purpose of this study was to investigate the T-2 toxin contaminated grain and grain products consumed especially by Turkish population. The T-2 toxin was detected using the high performance liquid chromatography (HPLC) with UV detector at 208 nm and the identify of T-2 was further confirmed by thin layer chromatography (TLC). The recovery was 91 +/- 4.24% for corn flour fortified with the known amount of T-2 toxin (1 ppm). The detection limits of T-2 toxin for the HPLC and the TLC were 25 ng and 50 ng, respectively. A total of 30 commercially available grain and grain product samples were analyzed. Two corn flour samples were found to contain detectable levels of T-2 toxin at a level of 1.60 ppm and 4.08 ppm.

Evaluation of mycotoxin-contaminated cereals for their use in animal feeds in Hungary

In the period between December 5, 1991 and September 17, 1998, 760 maize, 367 wheat, 119 soybean, 222 barley, 85 bran, 32 triticale, 60 oat, 14 rye and 22 sunflower samples were investigated for the presence and concentration of seven fusariotoxins (T-2 toxin, zearalenone, deoxynivalenol, nivalenol, diacetoxyscirpenol, HT-2 toxin, fusarenone-X) and OTA. The comparison of analytical data with those of the relevant literature revealed that although the incidence rate and/or concentration of Fusarium mycotoxins and OTA in Hungarian-grown cereals is occasionally considerable, the position of the country is not worse that the average of countries. Our findings indicate that soybean tends to be good substrate for trichothecene-producing fungi and the rate of contamination is regarded as substantial. The commodities were assorted into one of three quality categories. The proportion of objectionable samples was only 3.0, 2.2, 2.3 and 1.7% in maize, wheat, barley and soybean samples, respectively. However, this low rate of objection might still be a source of great economic loss. The proportion of objectionable samples was much higher in the case of bran, oat and triticale (7.1, 6.7, and 6.3%, respectively). The results of the present investigation indicate a need for regular screening for mycotoxins of importance and individual appraisal of each commodity from the point of their use in animal feeds.

Determination of type A trichothecenes by high-performance liquid chromatography with coumarin-3-carbonyl chloride derivatisation and fluorescence detection

A method for the analysis of type A trichothecenes T-2 toxin, HT-2 toxin, neosolaniol and diacetoxyscirpenol by high-performance liquid chromatography with fluorescence detection using coumarin-3-carbonyl chloride has been developed. Different parameters concerning the analytical procedure such as stability of both the reagent and derivatised analytes, time and temperature of the derivatisation reaction, were studied and optimised. Three different clean-up procedures (solid-phase extraction with silica gel or C-18 cartridges, and liquid-liquid partition between toluene and dihydrogen phosphate buffer) were tested in order to remove the excess reagent peaks. The last procedure gave the best results when the buffer pH was 3-5.5, and is therefore recommended. Separations were performed on a stainless steel LiChrospher 100 C-18 reversed-phase column with pre-column of the same phase. The mobile phase was acetonitrile/water (65:35, v/v) containing 0.75% acetic acid at a flow-rate of 1.0 ml/min. The proposed method provides good separation between the four trichothecenes and good reproducibility (RSD of calibration standards <5%). The limits of detection of the studied trichothecenes at a signal-to-noise ratio of 3:1, with an injection volume of 20 microl were 10 ng/g sample for T-2 toxin and about 15 ng/g sample for the remaining mycotoxins. The calibration curve was linear between 10 and 2000 ng for the four trichothecenes assayed. The method was applied to the analysis of these mycotoxins in fungal cultures (corn and rice) of Fusarium sporotrichioides, and is also perfectly suitable for the quantification of type A trichothecenes in contaminated cereals.

Quantitative determination and structure elucidation of type A- and B-trichothecenes by HPLC/ion trap multiple mass spectrometry

A method is presented for the quantification and structure confirmation of trichothecenes in wheat by high-performance liquid chromatography combined with multiple mass spectrometry (MS(n)()). Nine type A- and B-trichothecenes were determined (nivalenol, deoxynivalenol, fusarenon-X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, neosolaniol, diacetoxyscirpenol, HT-2 toxin, and T-2 toxin). Extraction was carried out with acetonitrile/water. The extract was purified on a MycoSep column. Quantification was based on an internal standard and atmospheric pressure chemical ionization in the positive ion mode. Recoveries from spiked wheat were in the range of 80-106% at levels of 500 ppb. The limits of quantification for the whole method were between 10 and 100 ppb. Ion adduct formation with ammonium and acetate ions and MS(n) experiments provided information about substitution and fragmentation behavior of the mycotoxins. A scheme has been established for the partial structure elucidation of type A- and B-trichothecenes in fungal cultures.

Determination of mycotoxins produced by Fusarium isolates from banana fruits by capillary gas chromatography and high-performance liquid chromatography

A method of analysis for trichothecenes (nivalenol, deoxynivalenol, 3- and 15-acetyldeoxynivalenol, diacetoxyscirpenol, neosolaniol, T-2 tetraol, T-2 and HT-2 toxins), zearalenone and zearalenols, and another method for determination of fumonisin B1 are described and applied to cultures of Fusarium isolated from bananas. Both methods were adapted from different techniques of extraction, clean-up and determination of these mycotoxins. The first method involves extraction with methanol-1% aqueous sodium chloride, clean-up of extracts by partition with hexane and dichloromethane, additional solid reversed-phase clean-up and analysis of two eluates by both high-performance liquid chromatography with ultraviolet detection and capillary gas chromatography. The method for fumonisin B1 implies extraction with aqueous methanol, concentration, clean-up with water and methanol on Amberlite XAD-2 column, formation of a fluorescent 4-fluoro-7-nitrobenzofurazan derivative and analysis by high-performance liquid chromatography with fluorescence detection. Both procedures give good limits of detection and recoveries, and are considered suitable for the detection and quantification of the studied toxins in corn and rice cultures of Fusarium spp. isolated from banana fruits.

Multi-year monitoring of Canadian grains and grain-based foods for trichothecenes and zearalenone

Monitoring of Canadian grain crops and foods by the Health Protection Branch for deoxynivalenol (DON, vomitoxin) has been undertaken every year since 1980, when it was found in Ontario soft wheat for the first time (in the 1979 and 1980 crops). Contamination of this wheat crop has varied, with 22-100% incidences in all but 1 year and up to 0.75 micrograms/g for the annual means of positive samples. The Canadian guideline for DON is 2 micrograms/g in uncleaned soft wheat. Western Canadian hard wheat had < 10% incidence of DON in 7 crop years but 11-43% of samples analysed in 10 other years were positive. Wheat foods, including imports, have shown 9-90% incidences with annual mean levels of 0.07-0.58 micrograms/g in positive samples. Consistently high contamination of Ontario corn has been observed (13-100% annual incidences and annual means of positives 0.16-1.4 micrograms/g). Other trichothecenes, namely nivalenol and HT-2 toxin, have been found infrequently in Canadian grains. New analyses of Canadian and imported beers showed low ng/ml levels of DON. Grains destined for food use and corn foods have been analysed for zearalenone from 1986 to 1993. The most contaminated crop was Ontario; annual mean levels in positive samples ranged from 23 to 215 ng/g. Zearalenone has been detected infrequently in wheat, barley and soybeans (< 75 ng/g).

Natural occurrence of deoxynivalenol in wheat, wheat flour and bakery products in Argentina

The objective of this study was to evaluate the natural occurrence of deoxynivalenol (DON) in wheat, wheat flour and different kinds of breads and pastries widely consumed by the population in Argentina. Of 60 wheat samples analysed, 93.3% were contaminated. The average DON contamination level over all samples was 1798 micrograms/kg, and the minimum and maximum values were 100 micrograms/kg and 9250 micrograms/kg, respectively. The wheat flour samples (61 samples) were contaminated with DON at levels ranging from 250 micrograms/kg to 9000 micrograms/kg with an average of 1309 micrograms/kg. The frequency of DON contamination over 42 samples of different bakery products was 92.8%, with levels ranging from 200 micrograms/kg to 2800 micrograms/kg with an average of 464 micrograms/kg. These results suggest a high risk for consumers of wheat products and the need to monitor final products before consumption.

Individual and combined effects of T-2 toxin and DAS in laying hens

1. The individual and combined effects of T-2 toxin and 4,15-diacetoxyscirpenol (DAS) on laying hens were investigated in an experiment consisting of a 2 x 2 completely randomised factorial design with dietary concentrations of 0 and 2 mg/kg T-2 toxin and 0 and 2 mg/kg DAS. 2. Individually, T-2 toxin and DAS induced oral lesions in half of the hens and decreased significantly egg production and food intake. 3. The effects of T-2 toxin and DAS were additive for reduced food consumption and incidence of oral lesions. However, a synergism for reduced egg production was observed during the last experimental period. 4. No effects on body weight were observed during this study. Mild changes in selected plasma enzymes activities and no change in liver malondialdehyde content were detected. 5. The combination of T-2 toxin and DAS was more toxic than the single mycotoxins, for some parameters, and therefore, may pose a greater economic threat to the poultry industry than either of the toxins individually.