FACT SHEET - www.micotoxinas.com.br
Richard Lawley, Leatherhead Food International, Randalls Road, Leatherhead, Surrey KT22 7RY, England
Moniliformin is formed in cereals by a number of Fusarium species that include F. avenaceum. F. subglutinans, and F. proliferatum and occurs as the sodium or potassium salt of 1-hydroxycyclobut-1-ene-3,4-dione. Studies that ascribe moniliformin production to F. moniliforme, which is now called F. verticillioides and does not produce moniliformin, actually tested an aggregate consisting of more than one species. These fungi also commonly produce other important mycotoxins so that moniliformin is frequently present in a mixture of mycotoxins. This mycotoxin has not yet received much attention because it does not appear to be carcinogenic and relatively high amounts appear to be necessary to cause significant toxicological effects. These have been demonstrated in a limited number of animal species. Its stability and fate during processing is also poorly studied so that the degree of consumer exposure is uncertain.
Chemical and Physical Properties
It is an ionic compound forming sodium and potassium salts and is soluble in water and polar solvents. Light yellow crystals. Literature reports pKa-values between 0.0 and 1.7. On heating, moniliformin as the free acid decomposes at 150-153 Deg C without melting. UV maxima are 229 nm and 260 nm in methanol.
Toxicity and Importance
There is a limited amount of data on the effects of moniliformin on mammalian species. The oral LD50 in rodents is approximately 25-50 mg/kg and for day old cockerels 4 mg/kg. The ip. LD50 was 21 and 29 mg/kg respectively for female and male mice. In acute studies, the main lesion appears to be intestinal haemorrhage, but in sub-acute and chronic studies in a variety of avian species and laboratory rodents, the principal target is the heart. It is a potent inhibitor of mitochondrial pyruvate and ketoglutarate oxidation. Data on the effects of moniliformin on reproduction and the foetus and its mutagenic and carcinogenic potential are negative but extremely limited. In a few studies it was found that moniliformin caused chromosomal aberrations. It is cytotoxic for mammalian cells at higher concentrations. In studies in which broiler chicks were fed diets containing 50 mg/kg moniliformin, the birds consumed more feed but put on less weight. They had increased heart and proventriculus (the thin-walled part of the stomach) weights, and decreased mean cell volumes, and the results showed that diets containing moniliformin at this concentration were toxic to chicks fed to market age. Phytotoxic effects have also been observed. In humans, moniliformin has casually been linked with Keshan disease, endemic to certain areas of China.
Some of the published data in which maize containing moniliformin has been fed to animals may need re-evaluation on the basis that contaminated maize may contain a cocktail of toxic Fusarium-derived residues such as fumonisins, zearalenone and trichothecenes.
Products affected and Natural Occurrence
Data on the occurrence of moniliformin in food is scarce. Concentrations up to 12 mg/kg occurred in maize in the Transkei intended for human consumption. More recently, analysis of imported milled maize products, destined for incorporation into animal feed stuffs in the UK, showed 60% of samples contaminated with concentrations up to 4.6 mg/kg moniliformin. It has also been shown to occur in other cereals including wheat, rye and rice. Samples with similar maximum concentrations have been reported in maize from Gambia and South Africa while field samples of maize, oats, wheat, rye and triticale showing visible fungal damage in Poland contained levels ranging from 0.5 to nearly 400 mg/kg. In consumer products, moniliformin has been found in 12 out of 14 corn tortillas examined at levels of 0.022 to 0.1 mg/kg.
Sampling and Analysis
The ionic nature of moniliformin makes its extraction and recovery from biological material difficult so that, until recently, robust methods suitable for reliable surveillance have not been available. Thin layer chromatography with colorimetric detection has been used for its determination. It can be analysed using HPLC using an ion-paired solvent mixture such as acetonitrile and 1% tetrabutylammonium sulphate solution for extraction, and ion-pair HPLC with UV measurement at 229 nm. Ion chromatography is now well established and LC-MS using triethylamine as an ion-pairing agent has been used for moniliformin in maize down to 10 microgrammes/kg. Methodology is covered in more detail in the specialised fact sheet other Fusarium mycotoxins.
Stability and Persistence
The stability of moniliformin in aqueous solution depends on temperature, pH and time. It has been reported to be almost completely destroyed by heating in pH 10 for I hour at 175 Deg C. There is only limited information on its degradation during processing. Moniliformin has been shown to decrease by about 70% in producing corn tortillas from maize.
Legislation and Control
No regulations exist for moniliformin.