Mycotoxins. Natural Toxins. mycotoxins. zootoxins. bacterial toxins. plant toxins. phycotoxins

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1 Mycotoxins Robert A. Samson CBS KNAW Fungal Biuodiversity Centre, Utrecht What is a mycotoxin Which mycotoxins are important Description of some important mycotoxins Mycotoxins in indoorenvironments Natural Toxins mycotoxins zootoxins bacterial toxins plant toxins phycotoxins

2 994 Holy fire lysergic acid derivatives Claviceps purpurea 5 Mycotoxins are natural products by fungi that evoke a toxic response when introduced in low concentration to higher vertebrates and other animals by a natural route. Some mycotoxins have multiple effects and may cause phytotoxic and antimicrobial syndromes in addition to animal toxicity From: J.W.Bennett - Mycopathologia 100: 3-5, 1987

3 Effect Mycotoxins Hepatotoxic, hepatocarcinogenic aflatoxins, sterigmatocystin Teratogenic aflatoxins, ochratoxins Neurotoxic citreoviridin, patulin, cyclopiazonic acid, roquefortin Nephrotoxic ochratoxins, citrinin, viomellein, xanthomegnin Immunosuppressive aflatoxins, ochratoxins, trichothecenes Dermatotoxic trichotecenes Emetic vomitoxin (deoxynivalenol) Oestrogenic zearalenone Tremorgenic penitrem A, fumitremorgens Photosensitization sporidezmins, viomellein Hallucinogenic ergotoxins Mycotoxin Carcinogenic to IARC Humans Animals group Aflatoxin B 1, B 2, G 1, G 2 C C 1 Aflatoxin M 1 C C 2B Ochratoxin A L C 2B Zearalenone - L - Patulin - L 3 Fumonisin B 1 L L 2B T-2 toxin L C 3 DON, NIV Fusarin C - C 2B Toxic secondary metabolites produced by fungi Ochratoxin A Gliotoxin Rugulosin Moniliformin Citrinin Trichothecenes Fusaproliferin Food Fumonisins Beauvericin PR Toxin Zearalenone Penitrem A Patulin Aflatoxins

4 Mycotoxins are mostly small molecules which are produced as secondary metabolites by many species of fungi They occur in food and in indoor environments At present more than 450 mycotoxins are known Most mycotoxins are chemically stable Mycotoxins occur everywhere Important are the aflatoxins, Fusarium-toxins, ochratoxin, patulin and sterigmatocystin Mycotoxins are often imported in (sub)tropical food products and feedstuffs 1. Aspergillus spp. 2. Penicillium spp. 3. Fusarium spp. 4. Alternaria spp. 5. Stachybotrys spp 1. aflatoxins 2. trichothecenes and other Fusarium toxins 3. ochratoxins 4. patulin 5. sterigmatocystin

5 Aflatoxin s B 1, B 2, G 1 and G 2 Aspergillus flavus Aspergillus parasiticus Aspergillus nomius O O Aflatoxin B1 O O O OCH 3 Decaketide derivatives Main producers: Aspergillus flavus, A. parasiticus, A. nomius (A. ochraceoroseus, Emericella species, A. bombycis, A. pseudotamarii) Occurrence: Peanut, tree nuts Corn Cotton Spices Red pepper Rice, cereals

6 Acute toxic hepatitis 1974, India (108 deaths from contaminated corn) 1981, 2004, 2006, Kenya, (>150 deaths) Chronic aflatoxicosis cirrhosis, liver cancer Mozambique, South Africa, China Reye syndrome (?) Kwashiorkor (?) The Kenya outbreak of aflatoxicosis people in Kenyan villages got ill; 127 died, including many children

7 Product (for direct human comsumption) Pistachios, peanuts, nuts, dried fruits, cereals B 1 g/kg Σafla g/kg M 1 g/kg Spices Milk, milk products Infant formulae and follow-on formulae, including infant milk and follow-on milk Baby foods and processed cereal based foods for infants and young children Dietary foods for special medical purposes intended specifically for infants Peanuts sold at a market in Indonesia 20 21

8 22 Secondary Primary Primary FOOD FEED Mycotoxicoses Aflatoxin M 1 : the milk-aflatoxin Approx. 1-6 % of the aflatoxin B 1 in animal feedstuffs appears as aflatoxin M 1 in milk A seasonal trend is noted in many surveys, with lower levels occurring in summer months The toxin is found in human breast milk, sometimes at rather high levels in samples from(sub-) tropical regions

9 20 µg/kg 15 µg/kg µg/kg 5 5 µg/kg 21 2 µg/kg 29 1 µg/kg 1 number of countries 25 Aflatoxin M 1 in milk 15 µg/kg 5 µg/kg µg/kg µg/kg µg/kg 34 not detectable 1 number of countries 26 sesquiterpene compounds tetracyclic and macrocyclic trichothecenes T-2 toxin, diacetoxyscirpenol, deoxynivalenol and nivalenol are the most important Main producers: Fusarium acuminatum, F. crookwellense, F. culmorum, F. equiseti, F. graminearum (G. zeae), F. lateritium, F. poae, F. sambucinum (G. pulicaris), F. solani, F. sporotrichioides

10 Fusarium graminearum Tetracyclic: Nivalenol Deoxynivalenol T-2 toxin HT-2 toxin Diacetoxyscirpenol Triacetoxyscirpendiol Fusarenone X Macrocyclic: Verrucarin A, B, J Roridin A, D, E, H Satratoxins Many Others (29+)

11 General symptoms: dizziness, headache, shivers, salivation, nausea, impaired vision, dermatotoxicity Alimentary toxic aleukia (Soviet Union, before, during and after the II. World War more than death) "bean-hull" toxicosis (Japan) "red-mold" disease (akakabi, Japan) Feed refusal, emetic effects in animals Oestrogenic polyketide derivative Occurrence: cereals Main producers: F. graminearum, F. culmorum Acts as a sexual hormone in the fungus Effect on swine: vulva swelling vaginal and rectal prolapses irregular estrous cycles embryo development is stopped Suspected to be the causative agent of premature thelarche in young girls in Puerto Rico ( ) and Hungary (1997) Product EU limit ( g/kg) Unprocessed cereals * 100 Unprocessed maize ** 200 Cereal flour* 75 Maize** - flour, -meal, - grits, refined oil 200 Bread, pastries, biscuits, cereal snacks, breakfast cereals maize snacks**, cornflakes**, Processed cereal based food for infants, young children and baby food *except for maize ** if no other limit until 01/07/2007.

12 Discovered in 1988 Producer: Fusarium verticillioides (F. moniliforme=gibberella fujikuroi); endophyte of corn Sphingosin analogs Leucoencephalomalacia in horses (hole in the head disease) Pulmonary edema in pigs Hepatocarcinoma in mouse, rat Esophagal cancer in South Africa (Transkei, Natal), China, Italy Neural tube defects (folic acid uptake) Product EU limit ( g/kg) Unprocessed maize 2000 Maize based products for direct human consumption with the exception of below 400 Maize - flour, -meal, - grits 1000 Processed maize based food for infants, young children and baby food 200

13 Ochratoxin Occurrence of ochratoxins Cereals (wheat, rice, corn) Coffee, cocoa Spices (paprika, curry) Fruits and vegetables Wine, raisins, beer Pulses (soybean) Animal kidney, blood Human blood, milk Ochratoxin A: especially associated with stored cereals in northern countries The main producing fungi are P. verrucosum (temperate or cold climates) and A. westerdijkiae (A. ochraceus (warmer regions) In Europe, some 50 % of the dietary OTA intake comes from cereals(products), other sources include soybeans, green coffee, cocoa beans, wine, beer, spices, dried vine fruit etc. Blood from healthy humans in Europe frequently contains OTA, which confirms a continuous, widespread exposure

14 Airborne Mycotoxins many airborne fungi are known to produce mycotoxins Stachybotrys chartarum, Aspergillus flavus and other species limited data on the presence of mycotoxins in air limited data on toxicological data ß-glucan (component of the fungal cell wall)

15 Not all fungi indoors produce mycotoxins Mycotoxin production depends on the strain and the substrate Mycotoxins can be produced as crystals, volatiles and may be included in the mycelium and spores Mycotoxins might be present in non viable fungal colonies Glucan may also cause inflammatory symptoms Identification of the species indicates the potential mycotoxin hazard produces mycotoxins (e.g. satratoxins) Satratoxins can accumulate to relatively high concentrations in Stachybotrys conidia (Sorensen et al., 1987). Gregory et al. (2004) have localized satratoxin-g in the conidia of S. chartarum. The toxin is predominantly localized in the conidia, with moderate labeling in the apex of the Stachybotrys phialides. The toxin was primarily present along the outer plasma lemma surface and in the inner wall of the conidium. It only showed moderate labeling in the mycelium.

16 Gregory. L., Pestka, J.J., Dearborn, D.G. & Rand, T.G. (2004). Localization of satratoxin-g in Stachybotrys chartarum spores and spore impacted mouse lung using immunocytochemistry. Toxicology Pathology. 32: Metabolite production varies considerably between media, temperature and water activity, so moulds may produce very different metabolites when growing on building materials as compared to laboratory media. On naturally infested materials moulds grow in mixed cultures with other moulds and bacteria which may induce production of other metabolites than in pure cultures. Indoor moulds Growth on building material Toxins on building materials Alternaria spp yes No toxins found Aspergillus flavus Yes but very wet No aflatoxins Aspergillus niger Yes but very wet No toxins found Aspergillus versicolor yes Sterigmatocystin but not produced at aw<0.9 Aspergillus calidoustus Yes but poor No toxins found growth Chaetomium globosum yes Chaetomins and chaetoglobins Cladosporium spp yes No toxins found Penicillium chrysogenum yes No toxins found Stachybotrys chartarum Yes but wet Trichothecenes, satratoxins Ulocladium spp Yes but wet No toxins found

17 Mycotoxin production on building materials is occurring at high a w (>0.9, in the material surface) but only above a w 0.95 significant mycotoxin production will occur Exposure to humans is thought to be by fungal fragments, so the mould can develop first, dries out and later be fragmented Potential species are Stachybotrys chartarum, Chaetomium globosum and Aspergillus versicolor. o Fungi can produce toxic compounds = mycotoxins o Mycotoxins are mostly produced in food, often before harvest o Mycotoxins do not have a direct toxicological effect, but the toxins are stored in the organs and often are the inducers of cancer o In Western countries mycotoxins are strictly regulated but not in developing countries othe significance of mycotoxins in indoor environments should be carefully considered because in many cases these compounds might not be produced on building materials