Vomitoxin, also known as deoxynivalenol (DON), is a type B trichothecene, an

epoxy Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also co ...

- sesquiterpenoid. This

mycotoxin A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic secondary metabolite produced by organisms of kingdom Fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' ...

occurs predominantly in grains such as

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...

, oats, rye, and

corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...

, and less often in

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...

sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many other ...

, and

triticale Triticale (; × ''Triticosecale'') is a hybrid of wheat (''Triticum'') and rye (''Secale'') first bred in laboratories during the late 19th century in Scotland and Germany. Commercially available triticale is almost always a second-generation ...

. The occurrence of deoxynivalenol is associated primarily with '' Fusarium graminearum'' (''Gibberella zeae'') and '' F. culmorum'', both of which are important plant

pathogens In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a ger ...

which cause fusarium head blight in wheat and gibberella or fusarium ear blight in corn. The incidence of fusarium head blight is strongly associated with moisture at the time of flowering (anthesis), and the timing of rainfall, rather than the amount, is the most critical factor. However, increased amount of moisture towards harvest time has been associated with lower amount of vomitoxin in wheat grain due to leaching of toxins. Furthermore, deoxynivalenol contents are significantly affected by the susceptibility of cultivars towards ''Fusarium'' species, previous crop, tillage practices, and fungicide use. It occurs abundantly in grains in

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...

due to heavy rainfall. ''F. graminearum'' grows optimally at a temperature of 25 °C and at a

water activity Water activity (''aw'') is the partial vapor pressure of water in a solution divided by the standard state partial vapor pressure of water. In the field of food science, the standard state is most often defined as pure water at the same tempe ...

above 0.88. ''F. culmorum'' grows optimally at 21 °C and at a water activity above 0.87. The geographical distribution of the two species appears to be related to temperature, ''F. graminearum'' being the more common species occurring in warmer climates. Deoxynivalenol has been implicated in incidents of mycotoxicoses in both humans and farm animals.

Mechanism of action

Vomitoxin belongs to a class of mycotoxins ( trichothecenes) which are strong inhibitors of protein synthesis; exposure to vomitoxin causes the brain to decrease its uptake of the amino acid tryptophan and, in turn, its synthesis of

serotonin Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and va ...

. Reduced levels of serotonin are believed to be responsible for the anorexic effects of DON and other trichothecenes. Irritation of the gastrointestinal tract may also play a role in reducing food intake, and may also partially explain the high incidence of paraesophageal stomach ulcers observed in sows during food refusal. In humans DON is extensively glucuronidated and excreted via urine.

In food

When compared to other trichothecene mycotoxins which can form in grains and forages, vomitoxin is relatively mild. Reduced feed intake, with its accompanying decrease in performance, is the only symptom of vomitoxin toxicity

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to ani ...

producers will likely encounter. This response to vomitoxin appears to occur through the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

. * Human foods: Vomitoxin is not a known

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...

, unlike

aflatoxin Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...

. Large amounts of grain with vomitoxin would have to be consumed to pose acute toxicity in humans. Currently, the chronic effects of low-dose exposure are unknown. The U.S. Food and Drug Administration has established a level of 1 ppm (parts per million) restriction of vomitoxin. * Companion animals: Dogs and cats are restricted to 5 ppm and of grains and grain

byproduct A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be consid ...

s and the grains are not to exceed 40% percent of the diet. * Livestock and farm animals: In animals and livestock, vomitoxin causes a refusal to feed and lack of weight gain when fed above advised levels. Restrictions are set at 10 ppm for

poultry Poultry () are domesticated birds kept by humans for their eggs, their meat or their feathers. These birds are most typically members of the superorder Galloanserae (fowl), especially the order Galliformes (which includes chickens, qu ...

and ruminating

beef Beef is the culinary name for meat from cattle (''Bos taurus''). In prehistoric times, humankind hunted aurochs and later domesticated them. Since that time, numerous breeds of cattle have been bred specifically for the quality or quantit ...

and feedlot cattle older than four months. Ingredients may not exceed 50% of the animal's diet.

Dairy cow Dairy cattle (also called dairy cows) are cattle bred for the ability to produce large quantities of milk, from which dairy products are made. Dairy cattle generally are of the species ''Bos taurus''. Historically, little distinction was mad ...

feed limits are set at 2 ppm.

Biosynthesis

References

External links

A comprehensive review on vomitoxin

Microbiology of Animal Feeds
{{Authority control Mycotoxins Epoxides Spiro compounds Alcohols Ketones Trichothecenes