Mycotoxins Aspergillus Toxins Lecture 12 PDF

Made with Xodo PDF Reader and Editor Mycotoxins Aspergillus toxins Lecture 12 Mohamed Nasr El-Deen Gomaa Professor of Marine Toxicology  Made with Xodo PDF Reader and Editor Aspergillus toxins 2. Ochratoxins  Made with Xodo PDF Reader and Editor 2. Ochratoxins ...

Made with Xodo PDF Reader and Editor Mycotoxins Aspergillus toxins Lecture 12 Mohamed Nasr El-Deen Gomaa Professor of Marine Toxicology  Made with Xodo PDF Reader and Editor Aspergillus toxins 2. Ochratoxins  Made with Xodo PDF Reader and Editor 2. Ochratoxins  Made with Xodo PDF Reader and Editor What is Ochratoxins Producing organisms Aspergillus ochraceus A saprotrophic and pathogenic fungi with broom like shape. Optimum growth temperature at 25ºC. Consist of Hypha, conidia, and sclerotia Hyphal growth produces mycelia. They also have both sexual and asexual forms of reproduction. Asexual reproduction produces conidia spore and sclerotia, and sexual reproduction produces sclerotia. The conidia is responsible of the colony color from pale yellow to brownish.  Made with Xodo PDF Reader and Editor What is Ochratoxins Various exposure methods Contamination occurs pre-harvest and post-harvest. Human exposure can occur through consumption of contaminated food and food products, mainly grain, coffee, and dried grapes. Also through contaminated animal feed that affect animals and affect humans after consumption of contaminated animal products. Direct contact with fungus through water-damaged houses and heating ducts.  Made with Xodo PDF Reader and Editor What is Ochratoxins chemical structure Composed of 2 parts Isocoumarin nucleus Connected by an amide bond with an L-phenylalanine (a key active site for its toxic and carcinogenic activities) L-phenylalanine Isocoumarin  Made with Xodo PDF Reader and Editor What is Ochratoxins chemical structure 3 natural isoforms ( A, B and C) Ochratoxin A (OTA) is the most abundant and toxic. OTA has a low MW (403Da) OTA contains a covalently bound chlorine atom in the isocoumarin acetyl derivative ring, which is absent in Ochratoxin B (OTB). Ochratoxin C (OTC) is an acetyl derivative that in biological systems is rapidly hydrolyzed to generate OTA.  Made with Xodo PDF Reader and Editor What is Ochratoxins Toxicity Exert toxic effects on animals and human beings. Dogs and pigs are the most susceptible animals to OTA. Oral LD50 values in mg/kg bw ranged 46 - 58.3 in mouse 20 - 30.3 in rat. 3.9 in rat neonate 0.2 in dog, 1 in pig 3.3 in chicken  Made with Xodo PDF Reader and Editor What is Ochratoxins Toxicity The diseases caused by the consumption of ochratoxins are known as ochratoxicoses. Kidney and Liver are the primary target organs OA–DNA adducts were found in kidney, liver, and several other organs of mice and rats with OA. Resulting in nephrotoxicity and hepatotoxicity Chronic ochratoxicosis leads to kidney and liver cancer, immune suppression and other pathological conditions. Acute ochratoxicosis leads to death.  Made with Xodo PDF Reader and Editor What is Ochratoxins Regulations Eurapean Food Safety Agency established in 2006 the "tolerable weekly intake" (TWI) of ochratoxin A at 120 ng/kg body weight. This equivalent to a tolerable daily intake (TDI) of 14 ng/kg body weight. The estimated tolerable dosage in humans is 0.2 to 4.2 ng/kg body weight.  Made with Xodo PDF Reader and Editor What is Ochratoxins Regulations USFDA considers a TDI of 5 ng/kg body weight. The USFDA has no regulations around Ochratoxins. The EU allows 2-10 µg/kg of Ochratoxin A in food. The EU has established a maximum limit (ML) of 15 μg/kg for ochratoxin A in nutmeg, ginger, pepper and turmeric. Also EU set ML of 20 μg/kg in chilli and paprika  Made with Xodo PDF Reader and Editor Thank you