Alex Ciegler

Role of lactone ring of aflatoxin B1 in toxicity and mutagenicity

Cleavage of the lactone ring of aflatoxin B1 results in a nonfluorescent compound that has greatly reduced biological activity. Mutagenicity, as measured by the Ames test, is reduced 450-fold compared to that of B1, and toxicity, as measured by the chick embryo test, is reduced 18-fold.

Fungi that produce mycotoxins: conditions and occurrence.

The occurrence of mycotoxins, in agricultural commodities is a worldwide problem with almost all commodities being potentially susceptible to contamination under the proper conditions. The genera of fungi most implicated are Aspergillus, Penicillium and Fusarium, although the potential for toxin production varies considerably within any given species.Conditions that affect toxin production include fungal strain variation, genetic susceptibility of the host plant or commodity, moisture content, commodity composition, temperature, aeration, microbial population and stress factors. There is undoubtedly interaction between these factors so that laboratory studies involving limited variables can only, at best, approximate field conditions.Natural contamination with mycotoxins has been reported for most of the major agricultural commodities in the world including corn, wheat, rice, millet, barley, oats, sorghum, peanuts, beans, copra, some fruits and nuts and various forages; strangely, soybeans do not appear to be involved to any major extent. The major mycotoxins on commodities reported to date include aflatoxin, the trichothecenes, ochratoxin, citrinin, zearalenone, sporidesmins and some tremorgens. However, laboratory studies have shown that the fungi are capable of producing hundreds of toxic chemicals, most of which are not included in routine analyses. In addition, since toxin effects are often insidious and may go undetected, the true dimensions of the mycotoxin problem are unknown.

Preliminary study of mycoflora and mycotoxins in grain dust from New Orleans area grain elevators.

Dust particles arising from disintegration of grain during handling and shipping may be inhaled by exposed barge and elevator workers. Since the normal grain mycoflora usually contain mycotoxin-producing fungi, these toxins could be natural contaminants of grain dust. Known mycoflora of commercial grain include species of Penicillium, Aspergillus, and Fusarium-fungi that may produce ochratoxins, aflatoxins and zearalenone. A procedure was developed to extract simultaneously these toxins from grain dust. Initial extraction with methylene chloride and water was followed by specific cleanup procedures for each toxin and then by thin layer chromatographic quantitation. In 50-g samples the lowest level of detection for zearalenone was 50 ng of zearalenone/g of dust, for ochratoxin, 10 ng/g and for aflatoxin, 5 ng/g. Dust samples were collected at various locations in two grain elevators and their associated transfer facilities in the New Orleans area. Large amounts of dust that had settled upon floors, machinery and ledges were tested, as well as that which had been collected by dust control systems. Samples were analyzed for aflatoxins, ochratoxin A, and zearalenone. None of the 15 samples contained any detectable amount of aflatoxins or ochratoxin A, but 10 of the 15 samples contained zearalenone at levels from 25 to 100 ng/g.

Fungal competition and mycotoxin production on corn

Aflatoxin and secalonic acid D production in corn in laboratory and field by mixed cultures ofPencillium oxalicum andAspergillus flavus orA. parasiticus was lower than production by the pure cultures. However, mixed culture of these molds withFusarium spp. did not affect mycotoxin production.

The protective role of glutathione in penicillic acid-induced hepatotoxicity in male mice and possible involvement of an active metabolite

Abstract In addition to being carcinogenic, penicillic acid (PA) has been reported to be an hepatotoxin. The present study was undertaken to investigate the effects of PA on hepatic function in male ICR mice. Levels of hepatic glutathione (GSH) were decreased as early as 15 min with maximal depletion between 30 and 60 min after a single ip dose of PA (90 mg/kg). The reduction in heptic GSH was dose dependent with more than 83% depletion at the highest dose level. GSH levels in extrahepatic tissues (kidney, heart, and lung) were, for the most part, not affected by PA. Oxidized GSH was not altered in the tissues examined. A dose- and time-dependent increase in serum glutamic-pyruvic transaminase (SGPT), serum glutamic-oxalacetic transaminase (SGOT), and plasma bilirubin but not in alkaline phosphatase was observed in PA-treated mice. Plasma concentrations of sulfobromophthalien and serum indocyanine green were increased in PA-treated mice. While cysteine pretreatment protected PA-treated mice against depletion of hepatic GSH, against elevation of SGPT and SGOT and against increased sulfobromophthalien and indocyanine green retention, diethylmaleate pretreatment enhanced these effects. Phenobarbital, but not 3-methylcholanthrene pretreatment, potentiated the elevation of SGPT; neither pretreatment had an effect on PA-induced hepatic GSH depletion. These results supported the suggestion that PA is hepatotoxic and that GSH protects against PA hepatotoxicity.

A Simple, Sensitive Method for Detection of Vomitoxin (Deoxynivalenol) Using Reversed Phase, High Performance Liquid Chromatography

Abstract Vomitoxin, a trichothecene mycotoxin produced by Fusarium graminearum, can be measured at levels as low as 5-10 ppb in contaminated corn by reversed phase, high performance liquid chromatography on Partisil 10 ODS-2 eluted with acetonitrile-water and detection at 214 nm. Corn extracts were initially purified by preparative thin layer chromatography on silica gel. Optimal separations of vomitoxin from other components in a sample of contaminated corn were achieved with 25% or less acetonitrile in water in which vomitoxin elutes with k′ > 1.06. Using 25% acetonitrile in water, the minimum detectable amount was 1.5 ng and the relationship between peak height and amount of vomitoxin was linear over the range 1-30 ng. Although resolution was greater when less acetonitrile was present in the eluant, sensitivity was somewhat lower.

Chapter 11 - Effect of High-Energy Radiation on Lignocellulose Conversion

The practice of high energy irradiation of biomass to increase its utility is reviewed. The effects of high energy radiation on lignocellulosics with respect to changes in chemical and physical properties, sugar yield, digestibility to acid and enzymatic hydrolysis, and possible utilization of irradiated biomass were investigated. The primary effect of irradiation on cellulose is chain cleavage with ensuing decomposition of the formed carbohydrates resulting in formation of acid and reducing groups. The solubility of irradiated cellulose is increased in water and in alkaline solution. Solubilized products include a homologous series of cellodextrins and other low molecular weight compounds but very little glucose. The radiation effect on cellulose is generally noticeable at or above 1 Mrad and is proportional to the radiation dose. The possible use of nuclear wastes in the form of Cs-137 in conversion of lignocellulose is also discussed.

The inability of Fusarium species extracts to induce dieback in pines

Cultures of F. moniliforme var. subglutinans, F. moniliforme, F. lateritium, F. equiseti, F. semitectum and F. solani from pine and F. moniliforme and F. graminearum from southern U.S. corn were grown on rice and corn, extracted, and checked for toxicity in mice, chicken embryos, and pine seedlings, and for mutagenicity by the Ames test. While extracts from both fungal groups contained toxins, none of the extracts induced dieback in pine seedlings. Almost all of the cultures isolated from corn in contrast to those from pine, were mutagenic. Thin-layer chromatography did not detect T-2 toxin, moniliformin, or vomitoxin, indicating that these toxins do not elicit dieback symptoms in pine.

Curvularin from Penicillium baradicum baghdadi NRRL 3754, and biological effects

Curvularin, a fungal metabolite similar in chemical structure to zearalenone, a potent estrogen, was tested for its estrogenic effects to gilts. No estrogenicity was observed to 60 kg gilts after feeding curvularin per os at a rate of 10 mg per day for 5 days. Curvularin was also nontoxic to mice and chick embryo.

14C-Labeled aflatoxin B1 prepared with yeastlike cultures of Aspergillus parasiticus.

A simple method was developed to produce 14C-labeled aflatoxin B1 by using the yeastlike phase of Aspergillus parasiticus NRRL 2999. Yeastlike cultures resulted from absence of manganese in a synthetic medium. Sodium acetate-1-14C had a 0.22% average incorporation; sodium acetate-1,2-14C, 0.70%. The average yield of labeled B1 was 10 mg/500 ml medium with an average specific activity of either 63.3 mCi/mole (C-1 label) or 194.3 mCi/mole (C-1, 2 label).