An Overview of Ochratoxin A

Author: Pallavi K. (IG: @journeyofa.researcher)

SCG ID: 0707202014

The subsidiary effects of environmental pollutants have piqued considerable interests of the scientific community in the recent past, particularly due to the concerns relating to their effects on human and animal health. Mycotoxins, the toxins produced by organisms of the fungal kingdom are important compounds in this category of pollutants. These compounds are hard to define and challenging to classify. Mycotoxins are known to be highly noxious and are known for their hepatotoxicity, nephrotoxicity, neurotoxicity, immunotoxicity etc. (Bennett & Klatch, 2003). Ochratoxins are a group of mycotoxins produced by several different fungi of Aspergillus and Penicillium species, and can be divided into three types: A, B and C. Of these, Ochratoxin A (OTA) is the most potent and is produced by Aspergillus ochraceus, A. carbonarius, A. niger and Penicillium verrucosum.

OTA is a mycotoxin well known for its food contaminating abilities. Formed during the storage of food items such as crops, human exposure to this toxin can occur by consumption of contaminated food commodities, such as cereals and cereal products, coffee beans, dry vine fruits, wine and grape juice, spices and liquorice etc (WHO, 2018). OTA is almost 10 times more toxic than Ochratoxin B & C, occurs in the greatest frequency in natural environment, and can easily contaminate food and water. Since it's present in a variety of food products, including some fruits and vegetables, knowingly or unknowingly we all are consuming it. But it mostly goes unnoticed because its effect is not shown till after years of consumption.

OTA is a particularly notorious toxin as it is stable chemically and thermally, and hence, it can't be eliminated during food processing. Studies have shown that the main target of OTA is kidney and it mainly causes nephrotoxicity (Abid et al 2003). Now, let's learn more about the Ochratoxin A toxicity in humans.

Ochratoxin A toxicity in humans:

As we know, OTA is carcinogenic in humans and animals. Its main target in humans is the kidney, as it is known to cause nephrotoxicity. It is also known to cause other adverse effects like immunotoxicity, hepatotoxicity, neurotoxicity etc and it can inhibit the macromolecular synthesis and mitochondrial respiration and can increase lipid peroxidation (Kuiper-Goodman and Scott, 1989). According to The International Agency for Research on Cancer (IARC), OTA has been classified in Group 2B, a possible human carcinogen. OTA has been suspected to cause various nephropathies since the 1970s including chronic interstitial nephropathy (CIN) and Balkan Endemic Nephropathy (BEN) (Barnes et al, 1977; Abid et al, 2003)

OTA causes cell death by creating oxidative stress, a common phenomenon that occurs in the body because of imbalance in between free radicals and antioxidants. These free radicals are oxygen-containing molecules that have an uneven number of electrons in their outer shell which makes them very unstable. Oxidative stress can damage proteins, cells and DNA, and cause ageing and other health conditions like diabetes, cancer, and severe disorders including neurodegenerative diseases such as Alzheimer's etc (Medical News Today, 2019).

Ways to minimize the risk from Ochratoxin A or any mycotoxin (according to guidelines from World Health Organization, 2018):

Buy grains and nuts as fresh as possible.
Make sure you store your food properly- keep away from insects, dry and not too warm.
Don't keep food materials for extended periods before being used.
Inspect whole grains (especially corn, sorghum, wheat, rice), dried figs and nuts such as peanuts, pistachio, almond, walnut, coconut, Brazil nuts and hazelnuts which are all regularly contaminated with aflatoxins for evidence of mould, and discard any that look mouldy, discoloured, or shrivelled.
Ensure a diverse diet – this not only helps to reduce mycotoxins exposure but also improves nutrition.

References:

Abid, S., Hassen, W., Achour, A., Skhiri, H., Maaroufi, K., Ellouz, F., Creppy, E., & Bacha, H. (2003). Ochratoxin A and human chronic nephropathy in Tunisia: is the situation endemic?. Human & experimental toxicology, 22(2), 77–84. https://doi.org/10.1191/0960327103ht328oa
Barnes, J. M., Austwick, P. K., Carter, R. L., Flynn, F. V., Peristianis, G. C., & Aldridge, W. N. (1977). Balkan (endemic) nephropathy and a toxin-producing strain of Penicillium verrucosum var cyclopium: An experimental model in rats. Lancet (London, England), 1(8013), 671–675.
Bennett, J. W., & Klich, M. (2003). Mycotoxins. Clinical Microbiology Reviews,16(3), 497–516. doi:10.1128/cmr.16.3.497-516.2003
Kuiper-Goodman, T., & Scott, P. M. (1989). Risk assessment of the mycotoxin ochratoxin A. Biomedical and environmental science: BES, 2(3), 179–248.
Mycotoxins. (2018). Retrieved July 4, 2020, from https://www.who.int/news-room/fact-sheets/detail/mycotoxins
What is oxidative stress? Effects on the body and how to reduce. (2019). Retrieved from https://www.medicalnewstoday.com/articles/324863