Aspergillus Toxins Quiz

Study Notes

Ochratoxins are produced by the fungus Aspergillus ochraceus.
Aspergillus ochraceus grows best at 25°C and produces a variety of toxins, including ochratoxins, through sexual and asexual reproduction.
Aspergillus ochraceus is a saprotrophic and pathogenic fungus that can contaminate food and animal feed.
Ochratoxins can contaminate food and animal feed during pre-harvest and post-harvest stages.
The most prevalent ochratoxin is Ochratoxin A (OTA), which is a potent toxin known for its carcinogenic and nephrotoxic properties.
Ochratoxins can affect humans through consumption of contaminated food, animal products, and water.
Direct contact with Aspergillus ochraceus in water-damaged buildings can also pose a health risk.

Ochratoxins are composed of two parts: an isocoumarin nucleus and an L-phenylalanine molecule connected by an amide bond.
L-phenylalanine is critical for the toxic and carcinogenic activities of ochratoxins.
Several isoforms of ochratoxins can be produced with Ochratoxin A (OTA) being the most abundant and toxic isoform.
Ochratoxin B (OTB) lacks the chlorine atom present in OTA.
Ochratoxin C (OTC) is an acetyl derivative that rapidly hydrolyzes to generate OTA.

Ochratoxins have toxic effects on both animals and humans.
Dogs and pigs are especially vulnerable to the effects of OTA.
The lethal dose (LD50) of OTA varies across species, with dogs and neonate rats exhibiting the highest sensitivity.
Ochratoxicoses, diseases caused by ochratoxin consumption, primarily target the kidneys and liver.
Ochratoxin A (OTA) can bind to DNA, leading to the formation of adducts in various organs, including the kidneys, liver, and brain.
Chronic exposure to ochratoxin A leads to kidney and liver cancer, immune suppression, and other health issues.
Acute exposure to high levels of ochratoxin A can be fatal.

In 2006, the European Food Safety Authority established a "tolerable weekly intake" (TWI) of 120 ng/kg body weight for ochratoxin A.
This translates to a tolerable daily intake (TDI) of 14 ng/kg body weight.
The estimated tolerable dosage in humans ranges from 0.2 to 4.2 ng/kg body weight.
The US Food and Drug Administration (FDA) has no official regulations around ochratoxins, but they consider a TDI of 5 ng/kg body weight.
Regulations around ochratoxin A levels in food vary between countries, with the EU setting maximum limits (ML) for certain food products.
For instance, the EU limits ochratoxin A levels to 15 µg/kg in nutmeg, ginger, pepper, and turmeric, and to 20 µg/kg in chili and paprika.

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