A mycotoxin is a toxic secondary metabolite produced by organisms of the fungus kingdom and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' is usually reserved for the toxic chemical products produced by fungi that readily colonize crops.
Commonly known as hellebores, the Eurasian genus Helleborus consists of approximately 20 species of herbaceous or evergreen perennial flowering plants in the buttercup family Ranunculaceae, within which it gave its name to the tribe of Helleboreae. Despite names such as "winter rose", "Christmas rose" and "Lenten rose", hellebores are not closely related to the rose family (Rosaceae). Many hellebore species are poisonous.
T-2 Mycotoxin is a trichothecene mycotoxin. It is a naturally occurring mold byproduct of Fusarium spp. fungus which is toxic to humans and animals. The clinical condition it causes is alimentary toxic aleukia and a host of symptoms related to organs as diverse as the skin, airway, and stomach. Ingestion may come from consumption of moldy whole grains. T-2 can be absorbed through human skin. Although no significant systemic effects are expected after dermal contact in normal agricultural or residential environments, local skin effects can not be excluded. Hence, skin contact with T-2 should be limited.
Macrocycles are often described as molecules and ions containing a twelve or more membered ring. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry.
Yellow rain was the subject of a 1981 political incident in which the United States Secretary of State Alexander Haig accused the Soviet Union of supplying T-2 mycotoxin to the Communist states in Vietnam, Laos and Cambodia for use in counterinsurgency warfare. Refugees described many different forms of "attacks", including a sticky yellow liquid falling from planes or helicopters, which was dubbed "yellow rain". The U.S. government alleged that over ten thousand people had been killed in attacks using these supposed chemical weapons. The Soviets denied these claims and an initial United Nations investigation was inconclusive.
Stachybotrys chartarum, also known as black mold or toxic black mold, is a variety of microfungus that produces its conidia in slime heads. It is sometimes found in soil and grain, but the mold is most often detected in cellulose-rich building materials from damp or water-damaged buildings. S. chartarum was originally discovered on the wall of a house in Prague in 1837 by Czech mycologist August Carl Joseph Corda. It requires very high moisture levels in order to grow and is associated with wet gypsum material and wallpaper.
Aglaonema is a genus of flowering plants in the arum family, Araceae. They are native to tropical and subtropical regions of Asia and New Guinea. They are known commonly as Chinese evergreens.
Trichothecenes are a very large family of chemically related mycotoxins produced by various species of Fusarium, Myrothecium, Trichoderma, Trichothecium, Cephalosporium, Verticimonosporium, and Stachybotrys. Trichothecenes are a class of sesquiterpenes. The most important structural features causing the biological activities of trichothecenes are the 12,13-epoxy ring, the presence of hydroxyl or acetyl groups at appropriate positions on the trichothecene nucleus, and the structure and position of the side-chain. They are produced on many different grains like wheat, oats or maize by various Fusarium species such as F. graminearum, F. sporotrichioides, F. poae and F. equiseti.
The avermectins are a series of drugs and pesticides used to treat parasitic worms and insect pests. They are a group of 16-membered macrocyclic lactone derivatives with potent anthelmintic and insecticidal properties. These naturally occurring compounds are generated as fermentation products by Streptomyces avermitilis, a soil actinomycete. Eight different avermectins were isolated in four pairs of homologue compounds, with a major (a-component) and minor (b-component) component usually in ratios of 80:20 to 90:10. Other anthelmintics derived from the avermectins include ivermectin, selamectin, doramectin, eprinomectin, and abamectin.
Mycotoxicology is the branch of mycology that focuses on analyzing and studying the toxins produced by fungi, known as mycotoxins. In the food industry it is important to adopt measures that keep mycotoxin levels as low as practicable, especially those that are heat-stable. These chemical compounds are the result of secondary metabolism initiated in response to specific developmental or environmental signals. This includes biological stress from the environment, such as lower nutrients or competition for those available. Under this secondary path the fungus produces a wide array of compounds in order to gain some level of advantage, such as incrementing the efficiency of metabolic processes to gain more energy from less food, or attacking other microorganisms and being able to use their remains as a food source.
Pseudomonas amygdali is a Gram-negative plant pathogenic bacterium. It is named after its ability to cause disease on almond trees. Different analyses, including 16S rRNA analysis, DNA-DNA hybridization, and MLST clearly placed P. amygdali in the P. syringae group together with the species Pseudomonas ficuserectae and Pseudomonas meliae, and 27 pathovars of Pseudomonas syringae/Pseudomonas savastanoi, constituting a single, well-defined phylogenetic group which should be considered as a single species. This phylogenetic group has not been formally named because of the lack of reliable means to differentiate it phenotipically from closely related species, and it is currently known as either genomospecies 2 or phylogroup 3. When it is formally named, the correct name for this new species should be Pseudomonas amygdali, which takes precedence over all the other names of taxa from this group, including Pseudomonas savastanoi, which is and inadequate and confusing name whose use is not recommended.
Myrothecium verrucaria is a species of fungus in the order Hypocreales. A plant pathogen, it is common throughout the world, often found on materials such as paper, textiles, canvas and cotton. It is a highly potent cellulose decomposer.
Satratoxin-H, a trichothecene mycotoxin, is a naturally occurring toxin produced by the ascomycetes Stachybotrys chartarum and Podostroma cornu-damae which is toxic to humans and animals. The clinical condition it causes is known as Stachybotrotoxicosis. It is related to the mycotoxin T-2, but unlike T-2 has not been reported to have been used as a chemical weapon.
Vomitoxin, also known as deoxynivalenol (DON), is a type B trichothecene, an epoxy-sesquiterpenoid. This mycotoxin occurs predominantly in grains such as wheat, barley, oats, rye, and corn, and less often in rice, sorghum, and triticale. The occurrence of deoxynivalenol is associated primarily with Fusarium graminearum and F. culmorum, both of which are important plant pathogens 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 due to heavy rainfall.
Betaenone B, like other betaenones, is a secondary metabolite isolated from the fungus Pleospora betae, a plant pathogen. Its phytotoxic properties have been shown to cause sugar beet leaf spots, which is characterized by black, pycnidia containing, concentric circles eventually leading to necrosis of the leaf tissue. Of the seven phytotoxins isolated in fungal leaf spots from sugar beet, betaenone B showed the least amount of phytotoxicity showing only 8% inhibition of growth while betaenone A and C showed 73% and 89% growth inhibition, respectively. Betaenone B is therefore not considered toxic to the plant, but will produce leaf spots when present in high concentrations (0.33 μg/μL). While the mechanism of action of betaenone B has yet to be elucidated, betaenone C has been shown to inhibit RNA and protein synthesis. Most of the major work on betaenone B, including the initial structure elucidation of betaenone A, B and C as well as the partial elucidation mechanism of biosynthesis, was presented in three short papers published between 1983–88. The compounds were found to inhibit a variety of protein kinases signifying a possible role in cancer treatment.
Diacetylverrucarol is a natural trichothecene produced by the fungus Myrothecium verrucaria. Chemically, it is an acetate derivative of verrucarol.
Podostroma cornu-damae, also known the as poison fire coral, is a species of fungus in the family Hypocreaceae. The fruit bodies of the fungus are highly toxic, and have been responsible for several fatalities in Japan. The fungus contains several trichothecene mycotoxins.
Trichothecium roseum is a fungus in the division Ascomycota first reported in 1809. It is characterized by its flat and granular colonies which are initially white and develop to be light pink in color. This fungus reproduces asexually through the formation of conidia with no known sexual state. Trichothecium roseum is distinctive from other species of the genus Trichothecium in its characteristic zigzag patterned chained conidia. It is found in various countries worldwide and can grow in a variety of habitats ranging from leaf litter to fruit crops. Trichothecium roseum produces a wide variety of secondary metabolites including mycotoxins, such as roseotoxins and trichothecenes, which can infect and spoil a variety of fruit crops. It can act as both a secondary and opportunistic pathogen by causing pink rot on various fruits and vegetables and thus has an economical impact on the farming industry. Secondary metabolites of T. roseum, specifically Trichothecinol A, are being investigated as potential anti-metastatic drugs. Several agents including harpin, silicon oxide, and sodium silicate are potential inhibitors of T. roseum growth on fruit crops. Trichothecium roseum is mainly a plant pathogen and has yet to show a significant impact on human health.
Sirohydrochlorin is a tetrapyrrole macrocyclic metabolic intermediate in the biosynthesis of sirohaem, the iron-containing prosthetic group in sulfite reductase enzymes. It is also the biosynthetic precursor to cofactor F430, an enzyme which catalyzes the release of methane in the final step of methanogenesis.
Nivalenol (NIV) is a mycotoxin of the trichothecene group. In nature it is mainly found in fungi of the Fusarium species. The Fusarium species belongs to the most prevalent mycotoxin producing fungi in the temperate regions of the northern hemisphere, therefore making them a considerable risk for the food crop production industry.
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