Mycotoxins

Mycotoxins are toxic metabolic products of moulds. About 200 different toxins are known; they are produced by slightly more than 300 fungal species. Purely linguistically the term "mycotoxin" is to be distinguished from the term "fungal poison". Fungal toxins (above all phallatoxins, amantinins) are formed by large fungi and here in their fruiting bodies.

Mycotoxins are toxic for humans (even for animals at the same temperature) even in small doses. In Central Europe the importance of mycotoxins is increasing. This is caused by food imports from areas with a warm and humid climate. They are threatened by mould infestation at all stages of production, from agricultural production to food processing and storage. In addition, toxin-forming moulds, especially Fusarium (see below Fusarium), spread in temperate latitudes.

The most important mycotoxin groups and their formers are:

• Mycotoxins of Claviceps species (group of ergot alkaloids)
• Mycotoxins of Fusarium species (zearalenone; fusarenone)
• Mycotoxins from Penicillium species (luteoskyrin, patulin)
• Mycotoxins of Aspergillus species (aflatoxins, sterigmatocystine, ochratoxin). Aflatoxins, are a frequent cause of food poisoning. However, they can also cause unspecific health problems such as headaches, aching limbs and irritation of the mucous membranes via the ambient air.

Mycotoxins can be grouped into the following groups of substances:

• Ethyl alcohol - Saccharomyces cerevisiae (beer, wine)
• Aflatoxins
• Alternaria toxins, such as Alternariol (AOH), Alternariol monomethyl ether (AME), Altenuene and Tenuazonic acid
• Cephalosporin
• Chaetomin
• Citrinin
• Fumonisins (Fusarium verticilloides; mainly found in maize, have carcinogenic and neurotoxic effects)
• Fusarium toxins see below Fusarium
• Gliotoxin
• Griseofulvin
• Ergot alkaloids -s.u. Secale cornutum
• Mycophenolic acid - Penicillium roqueforti
• Ochratoxins (e.g. ochratoxin A; in cereals and cereal products)
• Patulin - Penicllium spp. (in mouldy fruit varieties)
• Penicillin
• Penitrem A
• Roquefortin C
• Satratoxin
• Sterigmatocystin
• Tenuazonic acid
• trichothecenes, such as deoxynivalenol (DON), nivalenol, T-2 toxin
• Viomellein
• Verrucosidine
• Verruculogen
• Xanthomegnin
• Zearalenone (bind to estrogen receptor)

Almost all mycotoxins are stable to heat and acids. Aflatoxins are destroyed e.g. by UV light other mycotoxins are destroyed by alkaline solutions. The mycotoxins are not destroyed by cooking and frying mouldy food.

The maximum levels for certain mycotoxins valid in Germany can be found in the Regulation for the Limitation of Contaminants in Foodstuffs (Contaminants Regulation). Due to the carcinogenic effect of aflatoxins, a general maximum level for all foodstuffs not regulated by Regulation (EC) No. 1881/2006 is also laid down in the national regulation. In addition, there are maximum levels for ochratoxin A in dried fruit and figs.

Furthermore, moulds cause a poor indoor climate through the release of volatile organic compounds (microbiologically produced VOCs, so-called MVOCs), which are usually associated with a musty smell. This can lead to unspecific impairments, such as irritation of mucous membranes and headaches. Concrete hazards have not yet been conclusively researched, however, and also depend strongly on the type of fungus present.

The MVOCs released by moulds with an irritant effect are mainly alcohols, esters, aldehydes and ketones. Substances such as geosmin, 1-octen-3-ol or 3-methylfuran cause the typical mold odor in rooms. With the proof of 2-Methyl-1-propanol, 2-Methyl-1-butanol and Dimethyldisulfide in the ambient air a mold-affection is present with high probability since these connections are characteristic metabolic products of molds.

1. Khetan S et al (2017) Urinary tract infection due to Fusarium oxysporum in an immunocompetent patient with chronic kidney disease. J Biomed Res. doi: 10.7555/JBR.32.20160128. https://www.ncbi.nlm.nih.gov/pubmed/29569576
2. Ortiz J et al (2018) Multiple mycotoxin exposure of infants and young children via breastfeeding and complementary/weaning foods consumption in Ecuadorian highlands. Food Chem Toxicol 118:541-548.
3. Ratnaseelan AM et al (2018) Effects of Mycotoxins on Neuropsychiatric Symptoms and Immune Processes. Clin Ther pii: S0149-2918(18)30229-7.
4. Ordinance on the limitation of contaminants in foodstuffs (Kontaminanten-Verordnung - KmV.

Listing of the most important mycotoxins:

• Aflatoxins (Aspergillus flavus), on nuts and oilseeds - toxic and carcinogenic to the liver
• Alternariol (Alternaria alternata, Alternaria solani), on fruit, vegetables, tobacco, millet, nuts; mutagenic
• Cephalosporin (Cephalosporium acremonium), antibiotic
• Chaetomin (Chaetomium species) nephrotoxic, antibiotic effect on gram-positive bacteria
• Citrinin (Aspergillus ochraceus, Penicillium citrinum), on cereals, hepatotoxic, nephrotoxic, carcinogenic
• Deoxynivalenol (DON) (Fusarium culmorum, Fusarium graminearum, see below Fusarium), on cereals, gastrointestinal irritant
• Fumagillin(Aspergillus fumigatus), inhibits angiogenesis, antibiotic
• Fumonisins (Fusarium species - Fusarium verticilloides) mainly on maize, possibly carcinogenic, teratogenic
• fusarenone (Fusarium species), on cereals, possibly carcinogenic
• Fusaric acid (Fusaria species), growing on cereals, low toxicity, antibiotic
• Gliotoxin (Aspergillus species, Gliocladium fimbriatum), cytotoxic, immunosuppressive
• Griseofulvin (Penicillium grisefulvum), antibiotic
• Kojic acid (Aspergillus and Penicillium species), maize and other feedstuffs, low mutagenic, moderately antibiotic
• Luteoskyrin (Penicillium islandicum) on rice, toxic to liver and carcinogenic to liver?)
• Mycophenolic acid (see also mycophenolate mofetil)
• Ochratoxins (Aspergillus ochraceus) on cereals and green coffee, nephrotoxic
• Ochratoxin A (OTA) (Aspergillus ochraceus, Penicillium viridicatum), on peanuts, maize, wheat, cottonseed meal, nephrotoxic, carcinogenic
• Patulin (Penicillium articae, Penicillium claviformi) on apples and apple products, toxic to stomach mucosa
• Roquefortin (Penicillium roqueforti, Penicillium commune) on rice flour and other foodstuffs, neurotoxic, paralytic
• Sterigmatocystin (Aspergillus nidulans) on cereals, toxic to the liver and carcinogenic to the liver)
• T-2 toxin - trichothecenes - (including Fusarium) on cereals, haematotoxic
• Xanthomegnin (Aspergillus, Penicillium, Trichophyton and Microsporum species) on meat, hepatotoxic
• Zearalenone(Fusarium) on maize, cereals, nuts, estrogenic effect, infertility, questionable carcinogenicity