Fumonisin B1

Fumonisin B1 is the most prevalent member of a family of toxins, known as fumonisins, produced by several species of Fusarium molds, such as Fusarium verticillioides, which occur mainly in maize (corn), wheat and other cereals. Fumonisin B1 contamination of maize has been reported worldwide at mg/kg levels. Human exposure occurs at levels of micrograms to milligrams per day and is greatest in regions where maize products are the dietary staple. Fumonisin B1 is the most prevalent member of a family of toxins, known as fumonisins, produced by several species of Fusarium molds, such as Fusarium verticillioides, which occur mainly in maize (corn), wheat and other cereals. Fumonisin B1 contamination of maize has been reported worldwide at mg/kg levels. Human exposure occurs at levels of micrograms to milligrams per day and is greatest in regions where maize products are the dietary staple. Fumonisin B1 is hepatotoxic and nephrotoxic in all animal species tested. The earliest histological change to appear in either the liver or kidney of fumonisin-treated animals is increased apoptosis followed by regenerative cell proliferation. While the acute toxicity of fumonisin is low, it is the known cause of two diseases which occur in domestic animals with rapid onset: equine leukoencephalomalacia and porcine pulmonary oedema syndrome. Both of these diseases involve disturbed sphingolipid metabolism and cardiovascular dysfunction. In 1970, an outbreak of leukoenchephalomalacia (ELEM) in horses in South Africa was associated with the contamination of corn with the fungus Fusarium verticillioides. It is one of the most prevalent seed-borne fungi associated with corn. Another study was done on the possible role of fungal toxins in the etiology of human esophageal cancer in a region in South Africa. The diet of the people living in this area was homegrown corn and F. verticillioides was the most prevalent fungus in the corn consumed by the people with high incidence of esophageal cancer. Further outbreaks of ELEM and people in certain regions with high incidence of esophageal cancer led to more research on F.verticillioides. Soon they found experimentally that F.verticillioides caused ELEM in horses and porcine pulmonary edema in pigs. It was found to be highly hepatotoxic and cardiotoxic in rats. In 1984 it was shown that the fungus was hepatocarcinogenic in rats. The chemical nature of the metabolite(s) causing all this had still not been discovered in 1984. After discovery of the carcinogenicity of the fungus, isolation and chemical characterization of the mycotoxin(s) and carcinogen(s) produced by F.verticillioides was urgent. It wasn't until 1988 that the chemical nature of the carcinogen was unraveled. Fumonisin B1 and fumonisin B2 were isolated from cultures of F.verticillioides at PROMEC (Programme on Mycotoxins and Experimental Carcinogenesis). The structures were elucidated in collaboration with the CSIR(Council for Scientific and Industrial Research). Now approximate 15 different fumonisins are discovered, the most important ones being fumonisin B1, B2 and B3.