Alternaria mycotoxins: an overview of chemical characterization, producers, toxicity, analysis and occurrence in foodstuffs

Microfungiof the genus Alternariaare ubiquitous pathogens and saprophytes. Many species of the genus Alternariacommonly cause spoilage of various food crops in the field or post-harvest decay. Due to their growth even at low temperatures, they are also responsible for spoilage of these commodities during refrigerated transport and storage. Several Alternariaspecies are known producers of toxic secondary metabolites - Alternaria mycotoxins. A. alternata produces a number of mycotoxins, including alternariol, alternariolmonomethyl ether, altenuene, altertoxins I, II, III, tenuazonic acidand other less toxic metabolites. Tenuazonic acidis toxic to several animal species, e.g. mice, chicken, dogs. Alternariol, alternariolmonomethyl ether, altenuene and altertoxin I are not very acutely toxic. There are several reports on the mutagenicity and genotoxicity of alternariol, and alternariolmonomethyl ether. Alternariolhas been identified as a topoisomerase I and II poison which might contribute to the impairment of DNA integrity in human colon carcinoma cells. Analytical methods to determine Alternariatoxins are largely based on procedures, involving cleanup by solvent partitioning or solid phase extraction, followed by chromatographic separation techniques, in combination with ultraviolet, fluorescence, electrochemical and mass spectroscopic detection. A large number of Alternariametabolites has been reported to occur naturally in food commodities (e.g. fruit, vegetables, cereals and oil plants). Alternariol, alternariolmonomethyl ether and tenuazonic acidwere frequently detected in apples, apple products, mandarins, olives, pepper, red pepper, tomatoes, tomato products, oilseed rape meal, sunflower seeds, sorghum, wheat and edible oils. Alternarioland alternariolmonomethyl ether were detected in citrus fruit, Japanese pears, prune nectar, raspberries, red currant, carrots, barley and oats. Alternariolmonomethyl ether and tenuazonic acidwere detected in melon. Natural occurrence of alternariolhas been reported in apple juice, cranberry juice, grape juice, prune nectar, raspberry juice, red wine and lentils.