The minimum single emetic doses of deoxynivalenol and 15-acetyldeoxynivalenol in groups of three Yorkshire pigs weighing 10-15 kg were 0.050 and 0.075 mg/kg bw, respectively, when given either by gavage or ip. After gavage, 3 of 15 pigs given the 15-acetyl metabolite and 4 of 15 given deoxynivalenol showed emesis at all doses from 20-200 ug/kg bw. After ip administration, 9 of 15 pigs showed emesis at all doses. The NOELs were 0.025 mg/kg bw for deoxynivalenol and 0.050 mg/kg bw for the 15-acetyl metabolite after either oral intubation or ip injection...
Deoxynivalenol (DON) requires no activation for toxicity, though susceptibility may reflect individual variations in detoxification. This study reports the measurement of un-metabolised urinary DON (free DON) and DOM-1 in samples previously analyzed for the combined measure of free DON+DON-glucuronide (fD+DG), with a concentration >5 ng/mL, for 34 UK adults. Four consecutive daily urine samples were analyzed from twenty-two individuals, whilst from 12 individuals only a single sample was analyzed. The mean (median) concentration of urinary fD+DG in this sub-set was 17.8 ng/mL (13.8 ng/mL), range 5.0-78.2 ng/mL. In 23/34 (68%) individuals, free DON was detected, mean 2.4 ng/mL; range 0.5-9.3 ng/mL. Urinary DOM-1 was detected in 1/34 (3%) of individuals; present at /about/ 1% of urinary fD+DG concentration for that individual. The concentration of fD+DG combined was significantly correlated with urinary free DON (p<0.001, R(2)=0.65), but not with the percentage of free DON to fD+DG (p=0.615, R(2)=0.01), suggesting that the level of DON exposure did not affect the metabolism to DG within the range observed. In this survey most individuals had no detectable urinary DOM-1 and 68% did not detoxify all of the ingested DON to DON-glucuronide...
Deoxynivalenol-3-beta-D-glucoside (D3G), a plant phase II metabolite of the Fusarium mycotoxin deoxynivalenol (DON), occurs in naturally contaminated wheat, maize, oat, barley and products thereof. Although considered as a detoxification product in plants, the toxicity of this substance in mammals is currently unknown. A major concern is the possible hydrolysis of the D3G conjugate back to its toxic precursor mycotoxin DON during mammalian digestion. /The authors/ used in vitro model systems to investigate the stability of D3G to acidic conditions, hydrolytic enzymes and intestinal bacteria, mimicking different stages of digestion. D3G was found resistant to 0.2 M hydrochloric acid for at least 24 hr at 37 °C, suggesting that it will not be hydrolyzed in the stomach of mammals. While human cytosolic beta-glucosidase also had no effect, fungal cellulase and cellobiase preparations could cleave a significant portion of D3G. Most importantly, several lactic acid bacteria such as Enterococcus durans, Enterococcus mundtii or Lactobacillus plantarum showed a high capability to hydrolyze D3G. Taken together these data indicate that D3G is of toxicological relevance and should be regarded as a masked mycotoxin.
Cultures of 20% w/w suspensions of rat cecal contents were incubated anaerobically with [(14)C]deoxynivalenol at a concentration of 35 ug/mL for up to 24 hr. A standard-co-elution method involving high-performance liquid chromatography (HPLC) was used to quantify the proportions of radiolabel associated with deoxynivalenol and with the de-epoxidated form. The latter represented 1.3% of the administered radiolabel immediately after addition of deoxynivalenol, 29% at 7 hr, and 90% at 24 hr; 60% co-eluted with deoxynivalenol at 7 hr and 2% at 24 hr. ...Deoxynivalenol was not converted to the de-epoxy metabolite in cultures of the contents of pig large intestine (including caecum, but not otherwise specified) in another study in which 1 mL of a 1-ug/mL solution of deoxynivalenol was added to 2 g of large intestinal contents and incubated anaerobically for 96 hr. Nearly complete recovery of intact deoxynivalenol was reported. The intestinal contents of chickens treated identically showed nearly complete conversion of deoxynivalenol to the de-epoxy metabolite after 96 hr. After 24 hr of incubation, the rate of conversion was 56% of an applied concentration of 0.014 ug/mL, 69% of 0.14 ug/mL, and 70% of 1.4 ug/mL. Similarly, 35% of the applied deoxynivalenol was metabolized to the de-epoxy metabolite in bovine rumenal fluid after 96 hr of incubation.
Evaluation: There is inadequate evidence in humans for the carcinogenicity of toxins derived from Fusarium graminearum. There is inadequate evidence in experimental animals for the carcinogenicity of deoxynivalenol. Overall evaluation: Toxins derived from Fusarium graminearum, F. culmorum and F. crookwellense are not classifiable as to their carcinogenicity to humans (Group 3).
Deoxynivalenol (DON) and fumonisins (FB) are the most frequently encountered mycotoxins produced by Fusarium species and most commonly co-occur in animal diets. These mycotoxins were studied for their toxicity in piglets on several parameters including plasma biochemistry, organ histopathology and immune response. Twenty-four 5-wk-old animals were randomly assigned to four different groups, receiving separate diets for 5 wk, a control diet, a diet contaminated with either DON (3 mg/kg) or FB (6 mg/kg) or both toxins. At days 4 and 16 of the trial, the animals were subcutaneously immunized with ovalbumin to assess their specific immune response. The different diets did not affect animal performance and had minimal effect on hematological and biochemical blood parameters. By contrast, DON and FB induced histopathological lesions in the liver, the lungs and the kidneys of exposed animals. The liver was significantly more affected when the two mycotoxins were present simultaneously. The contaminated diets also altered the specific immune response upon vaccination as measured by reduced anti-ovalbumin IgG level in the plasma and reduced lymphocyte proliferation upon antigenic stimulation. Because cytokines play a key role in immunity, the expression levels of IL-8, IL-1beta, IL-6 and macrophage inflammatory protein-1beta were measured by RT-PCR at the end of the experiment. The expression of these four cytokines was significantly decreased in the spleen of piglets exposed to multi-contaminated diet. Taken together, our data indicate that ingestion of multi-contaminated diet induces greater histopathological lesions and higher immune suppression than ingestion of mono-contaminated diets.
Beauvericin (BEA), deoxynivalenol (DON) and T-2 toxin (T-2) are important food-borne mycotoxins that have been implicated in human health. In this study, the acute toxicity of individual and combined mycotoxins (BEA, DON and T-2) were tested in immortalized hamster ovarian cells (CHO-K1) at 24, 48 and 72 hr of exposure, by the tetrazolium salt (MTT) and neutral red (NR) assays. The IC50 values obtained for all mycotoxins by the MTT and NR assays ranged from 0.017 to 12.08 uM and from 0.042 to 17.22 uM, respectively. Both, individual and combined mycotoxins demonstrated a significant cytotoxic effect in CHO-K1 cells in a dose-dependent manner. When mycotoxins were assayed individually, T-2 showed the strongest IC50 values (from 0.017 to 0.052 uM), by both endpoints tested, followed by DON (0.53-2.30 uM) and BEA, showing this last one, the weakest IC50 values (from 2.77 to 17.22 uM). On the other hand, cytotoxicity interactions were evaluated by the isobologram method. In acute binary tests, DON+BEA (CI=1.60-25.07) and DON+T-2 (CI=1.74-7.71) showed antagonism at 24, 48 and 72 hr of exposure. By contrast, the binary BEA+T-2 combination (CI=0.35-0.78) showed synergism at all time of exposure tested. The tertiary BEA+DON+T-2 combination demonstrated synergism effect (CI=0.47-0.86) after 24 and 48 hr of exposure; however moderate antagonistic effect (CI=1.14-1.60) was presented after 72 hr of exposure at the lower doses. These results provide quantitative evidence regarding potentially important interactions between BEA, DON and T-2 depending of the time of exposure. The combination index-isobologram equation method can serve as a useful tool in food risk assessment. Due to the potent toxic effects of BEA, DON and T-2, its combined exposure might be an important trigger for development of several diseases in humans, from the mycotoxicological point of view, especially after long period of exposure time.
The ability of cyproheptadine, a serotonin antagonist at the serotonin2 receptor and a known appetite stimulant, to attenuate the adverse effect of deoxynivalenol was investigated in 3 trials with 21-day-old male ICR mice weighing 15-18 g. Groups of 10 mice received diets containing combinations of cyproheptadine and deoxynivalenol (purity, 99%), providing doses of deoxynivalenol of 4-16 mg/kg (equivalent to 0.6-2.4 mg/kg bw/day) and of cyproheptadine of 1.2-20 mg/kg (equivalent to 0.19-3 mg/kg bw). Cyproheptadine was administered in the feed for 2 days before addition of deoxynivalenol, and the two agents were then administered concurrently for 12 days. Cyproheptadine effectively offset the reduction in feed intake caused by deoxynivalenol, but only at certain doses. At a dose of deoxynivalenol of 4 mg/kg of feed, the optimal dose of cyproheptadine was 1.2-2.5 mg/kg of feed; at 8 mg/kg of feed, cyproheptadine was required at 2.5 mg/kg of feed; at 12 mg/kg of feed, the required dose of cyproheptadine was 2.5-5.0 mg/kg feed; and at 16 mg/kg of feed, cyproheptadine at 5-10 mg/kg feed was required. At lower doses of cyproheptadine (5 mg/kg of feed), alone or in combination with the lowest dose of deoxynivalenol tested, a modest increase in weight gain was noted, but this was not seen at higher concentrations of deoxynivalenol. /It was/ concluded that serotininergic mechanisms probably mediate the deoxynivalenol-induced reduction in feed intake. The finding that cyproheptadine significantly attenuated the effect of deoxynivalenol indicates the involvement of the serotonin2 receptor in this process.
Groups of 3-6 pigs weighing 60 kg were used to study the health effects of purified deoxynivalenol and ochratoxin A in their feed, singly or in combination, and the presence of residues 90 days after intake. The pigs received diets containing ochratoxin A at 0.1 mg/kg with deoxynivalenol at 1 mg/kg, equivalent to 0.004 mg of ochratoxin A and 0.04 mg of deoxynivalenol/kg bw, respectively; ochratoxin A alone at 0.1 mg/kg; or deoxynivalenol alone at 1 mg/kg. Two controls received feed containing neither ochratoxin A nor deoxynivalenol. The pigs that received mycotoxins in their feed did not show clinical or hematological changes. The pigs that received both mycotoxins had hyperemia in the gastric mucosa, and changes in the tubular epithelium were observed in one animal in each treated group. Few pathological lesions were found, but the Committee noted that there were few animals in the study. The observed antibody titres against pseudorabies (Aujeszky disease or "mad itch"), as a measure of effects on the immune system, suggest that non-specific defense mechanisms were not affected. The mean concentration of ochratoxin A in the kidneys of animals treated with both toxins was about 50% higher than that in the group given ochratoxin A alone, indicating a possible interaction. The concentration of ochratoxin A also appeared to be slightly increased in muscle of animals receiving both mycotoxins.
Metabolic studies have been carried out on animals, principally with T-2 toxin, but a few with /deoxynivalenol/ (DON). These trichothecenes are rapidly absorbed from the alimentary tract... . The toxins are distributed fairly evenly without marked accumulation in any specific organ or tissue. Trichothecenes are metabolically transformed to less toxic metabolites by such reactions as hydrolysis, hydroxylation, de-epoxidation, and glucuronidation. Trichothecenes, such as T-2 toxin and DON, are rapidly eliminated in the feces and urine. ...In the rat, 25% of DON was eliminated in the urine and 65% in the feces, 96 hr after dosing.
Although deoxynivalenol appeared in the blood within 30 min after intake by sheep, the systemic bioavailability was only 7.5%. A single dose of 5 mg/kg bw of deoxynivalenol was administered by oral intubation to four 1-yr-old male sheep, and repeated blood samples were taken over 30 hr. Deoxynivalenol and the de-epoxy metabolite were determined by GC with electron capture detection (ECD). No deoxynivalenol or the de-epoxy metabolite could be detected in plasma within the 30-hr observation period. Three male sheep were given a single iv dose of deoxynivalenol at 0.5 mg/kg bw, with blood sampling and analysis as after oral dosing. Systemic bioavailability was calculated from the ratio of the integrated area under the concentration-time curve times the dose for both oral and iv administration. <0.3% of the oral dose and <2% of the iv dose was detected in plasma as the de-epoxy metabolite. Free deoxynivalenol accounted for an average of 24.8% of the absorbed dose measured in blood; the remainder was made up of the de-epoxy metabolite or the glucuronide conjugate of deoxynivalenol. The oral absorption rate of deoxynivalenol in sheep was approximately 7% on the basis of recovery rates from urine and bile collected over 36 hr from two sheep given 5 mg/kg bw of deoxynivalenol orally. Deoxynivalenol and the de-epoxy metabolite were analysed by GC/ECD. An average of 6.9% of the administered dose was recovered from urine and 0.11% from bile. Glucuronide-conjugated de-epoxy metabolite was the only form detected in bile (detection limit, 0.1 mg, corresponding to 0.04% of the administered dose). An average of 1.3% of the administered dose was recovered from urine as the de-epoxy metabolite or its conjugate, and 5.7% was recovered as deoxynivalenol or its conjugate.
In contrast to the low bioavailability seen in sheep and cows, relatively high bioavailability was observed in pigs. Blood, urine, bile, and feces were collected over 24 hr after an intragastric dose of 0.6 mg/kg bw of [(14)C]deoxynivalenol or an iv dose of 0.3 mg/kg bw. The proportions of radiolabel were assumed to represent those of administered deoxynivalenol, and the validity of this assumption was confirmed by GC/MS, which showed very little metabolism or conjugation. On the basis of measurements of the integrated area under the concentration-time curve for three animals treated intravenously and three treated intragastrically, the average systemic bioavailability of deoxynivalenol in pigs was estimated to be 55%. Approximately 95% of the administered dose was recovered as deoxynivalenol... .
Although the absolute bioavailability of deoxynivalenol has not been measured in rats, 25% of an oral dose of 10 mg/kg bw was recovered in urine at 96 hr, suggesting that the absorption rate in rats may be higher than in sheep or cows. HPLC and GC/MS analysis indicated that 25% of the radiolabel in 0-24 hr urine was associated with unchanged deoxynivalenol and 10% with the de-epoxy metabolite. Similarly, 4.5 and 4.4% of an orally administered dose of 6 mg/kg bw was recovered in the urine of Wistar rats as free deoxynivalenol and the de-epoxy metabolite, respectively, within 96 hr.
Structure−Activity Relationships of Trichothecene Toxins in an Arabidopsis thaliana Leaf Assay
摘要：
Many Fusarium species produce trichothecenes, sesquiterpene epoxides that differ in patterns of oxygenation and esterification at carbon positions C-3, C-4, C-7, C-8, and C-15. For the first comprehensive and quantitative comparison of the effects of oxygenation and esterification on trichothecene phytotoxicity, we tested 24 precursors, intermediates, and end products of the trichothecene biosynthetic pathway in an Arabidopsis thaliana detached leaf assay. At 100 mu M, the highest concentration tested, only the trichothecene precursor trichodiene was nontoxic. Among trichothecenes, toxicity varied more than 200-fold. Oxygenation at C-4, C-8, C-7/8, or C-15 was, on average, as likely to decrease as to increase toxicity. Esterification at C-4, C-8, or C-15 generally increased toxicity. Esterification at C-3 increased toxicity in one case and decreased toxicity in three of eight cases tested. Thus, the increase in structural complexity along the trichothecene biosynthetic pathway in Fusarium is not necessarily associated with an increase in phytotoxicity.
In the biosynthesis of Fusarium trichothecenes, the C-3 hydroxyl group of isotrichodermol must be acetylated by TRI101 for subsequent pathway genes to function. Despite the importance of this 3-O-acetylation step in biosynthesis, Tri101 is both physically and evolutionarily unrelated to other Tri genes in the trichothecene gene cluster. To gain insight into the evolutionary history of the cluster, we purified recombinant TRI3 (rTRI3), one of the two cluster gene-encoded trichothecene O-acetyltransferases, and examined to determine whether this 15-O-acetyltransferase can add an acetyl to the C-3 hydroxyl group of isotrichodermol. When a high concentration of rTRI3 was used in the assay (final concentration, 50 μm), we observed 3-O-acetylation activity against isotrichodermol that was more than 105 times less efficient than the known 15-O-acetylation activity against 15-deacetylcalonectrin. The rTRI3 protein also exhibited 4-O-acetylation activity when nivalenol was used as a substrate; in addition to 15-acetylnivalenol, di-acetylated derivatives, 4,15-diacetylnivalenol, and, to a lesser extent, 3,15-diacetylnivalenol, were also detected at high enzyme concentrations. The significance of the trace trichothecene 3-O-acetyltransferase activity detected in rTRI3 is discussed in relation to the evolution of the trichothecene gene cluster.
Methylthiodeoxynivalenol (MTD), a novel derivative of the trichothecene mycotoxin deoxynivalenol (DON), was prepared by applying a reliable procedure for the formal Michael addition of methanethiol to the conjugated double bond of DON. Structure elucidation revealed the preferred formation of the hemiketal form of MTD by intramolecular cyclisation between C8 and C15. Computational investigations showed a negative total reaction energy for the hemiketalisation step and its decrease in comparison with theoretical model compounds. Therefore, this structural behaviour seems to be a general characteristic of thia-Michael adducts of type B trichothecenes. MTD was shown to be less inhibitory for a reticulocyte lysate based in vitro translation system than the parent compound DON, which supports the hypothesis that trichothecenes are detoxified through thia-adduct formation during xenobiotic metabolism.
Characterization of Deoxynivalenol–Glutathione Conjugates Using Nuclear Magnetic Resonance Spectroscopy and Liquid Chromatography–High-Resolution Mass Spectrometry
作者：Ana Stanic、Silvio Uhlig、Morten Sandvik、Frode Rise、Alistair L. Wilkins、Christopher O. Miles
DOI：10.1021/acs.jafc.6b02853
日期：2016.9.14
identities were not confirmed due to a lack of standards. We have synthesized DON–GSH conjugates in alkaline solution. The major products 2 and 5 were isolated and their structures determined by massspectrometry and NMR spectroscopy as GSH adducts at C-13 and C-10 (via epoxide and Michael addition, respectively) of 1. Other Michael addition products were also tentatively identified by LC-MS. Concentrations
MIXTURES CONTAINING 1,1,1,3,3,3-HEXAFLUOROBUTENE AND 1-CHLORO-3,3,3-TRIFLUOROPROPENE
申请人：Honeywell International Inc.
公开号：EP2447310A2
公开（公告）日：2012-05-02
The present invention relates to mixtures of 1,1,1,3,3,3-hexafluorobutene (1336mzzm) and 1-chloro-3,3,3-trifluoropropene (1233zd). The blends are useful as blowing agents for polymer foam, solvents, aerosol propellants and heat transfer media.
