Fumonisins: isolation, chemical characterization and biological effects
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W C Gelderblom1, W F Marasas, R Vleggaar
1Research Institute for Nutritional Diseases, SAMRC, Tygerberg, South Africa.
Abstract:
The fumonisin B mycotoxins (FB1 and FB2) have been purified and characterized from corn cultures of Fusarium moniliforme strain MRC 826. Fumonisin B1 (FB1), the major fumonisin produced in culture, has been shown to be responsible for the major toxicological effects of the fungus in rats, horses and pigs. Recent investigations on the purification of compounds with chromatographic characteristics similar to FB1 have led to the identification of two new fumonisins, FB3 and FB4. Fumonisins A1 and A2, the N-acetyl derivatives of FB1 and FB2 respectively, were also purified and shown to be secondary metabolites of the fungus. Short-term carcinogenesis studies in a rat liver bioassay indicated that over a period of 15 to 20 days, at dietary levels of 0.05-0.1%, FB2 and FB3 closely mimic the toxicological and cancer initiating activity of FB1 and thus could contribute to the toxicological effects of the fungus in animals. In contrast, no biological activity could be detected for FA1 under identical experimental conditions. These studies and others have indicated that the fumonisin B mycotoxins, although lacking mutagenicity in the Salmonella test or genotoxicity in the DNA repair assays in primary hepatocytes, appear to induce resistant hepatocytes similar to many known hepatocarcinogens.
Insights
Fumonisin B mycotoxins (FB1-FB4) from Fusarium moniliforme were purified and characterized. FB2 and FB3 mimic FB1's toxicological and cancer-initiating activity, suggesting their contribution to fungal toxicity in animals.
Area of Science:
- Mycology
- Toxicology
- Biochemistry
Background:
- Fusarium moniliforme produces fumonisin B mycotoxins (FB1, FB2).
- FB1 is the primary toxin responsible for toxicological effects in rats, horses, and pigs.
- Previous research identified FB1 and FB2, necessitating further characterization of related compounds.
Purpose of the Study:
- To purify and characterize fumonisin B mycotoxins (FB1-FB4) and related compounds (FA1, FA2) from Fusarium moniliforme.
- To evaluate the toxicological and cancer-initiating activity of newly identified fumonisins (FB3, FB4) and related compounds (FA1, FA2).
- To assess the contribution of these mycotoxins to the overall toxicity of the fungus.
Main Methods:
- Purification and characterization of fumonisin B mycotoxins (FB1-FB4) and related compounds (FA1, FA2) using chromatographic techniques.
- Short-term carcinogenesis studies utilizing a rat liver bioassay.
- Assessment of mutagenicity using the Salmonella test and genotoxicity using DNA repair assays in primary hepatocytes.
Main Results:
- Fumonisin B mycotoxins FB1, FB2, FB3, and FB4 were purified and characterized.
- Fumonisins A1 and A2 (N-acetyl derivatives of FB1 and FB2) were identified as secondary metabolites.
- FB2 and FB3 demonstrated toxicological and cancer-initiating activity similar to FB1 in rat liver bioassays.
- FA1 showed no detectable biological activity under experimental conditions.
- Fumonisins induced resistant hepatocytes, a characteristic of known hepatocarcinogens, despite lacking mutagenicity or genotoxicity.
Conclusions:
- FB2 and FB3 contribute to the toxicological effects of Fusarium moniliforme in animals.
- The fumonisin B mycotoxins possess hepatocarcinogenic potential by inducing resistant hepatocytes.
- Further investigation into the mechanisms of fumonisin-induced toxicity and carcinogenesis is warranted.