| dc.description.abstract | Mycophenolic acid (MPA) is a toxic metabolite produced by many Penicillium species among which are P. brevicompactum and P. roqueforti. Byssochlamys nivea, a yeast species, has also been reported to produce MPA.
MPA producing fungi are frequently isolated from maize and grass silage (animal feed) for example P.roqueforti. Byssochlamys species are also responsible for spoilage and degradation of fruits and silages.
P. brevicompactum has been isolated from a wide range of human foods. P. roqueforti is used in the production of blue-veined cheeses, thus MPA has been detected in most of this type of cheese.
Animals are exposed to MPA through the ingestion of contaminated feeds. MPA or majority of MPA producing fungi have been found in animal feed thus could be carried over to human foods of animal origin. MPA has not been detected in milk so far, but up to 0.23mg/kg has been found in sheep muscle tissue. The possibility for MPA occurrence in fruit is high but this has not been extensively studied yet. The major route of for human exposure is therefore dietary.
From the available data, exposure of humans and animals to MPA seems to be considerably high (>0.1mg/day for humans, 900mg/day for cattle and1.8mg/kg body weight for livestock in general). This could have health consequences especially considering that humans and animals are chronically exposed to this compound. The calculated Acceptable Daily Intake (ADI) for humans is 0.195mg and that for cattle is 1.8mg.
Due to the genotoxic nature of MPA (although results of genotoxicity assays are conflicting), the Margin of Exposure (MOE) of MPA for humans has been calculated which is 1000; thus it is a substance with a high risk for which urgent risk management measures are required.
The few clinical studies on animal subjects have also been strictly limited to the acute, rather than chronic, toxin exposure. Chronic exposure studies however will be more relevant to real life situation.
Human exposure to MPA has not been extensively studied, thus there are only a few data on its concentration in human food products. The consumption of blue-veined cheese is a major route of human exposure. However, the cumulative exposure from different food sources which should be of health concern has not been studied.
MPA has a number of therapeutic uses, the most important of which is, its use as an immunosuppressant drug in renal transplant, lupus nephritis, non-infectious ocular inflammation and in the management of difficult inflammatory bowel diseases. | |
