Nodularin

Nodularin is a hepatotoxin and tumor promoter produced by the cyanobacteria Nodularia spumigena. It is a cyclic pentapeptide and is toxic to the liver due to inhibition of protein phosphatases 1 and 2A.

Structure

Nodularin is a cyclic pentapeptide, meaning it consists of five amino acids linked in a ring structure. The amino acids in nodularin are L-arginine, D-β-methylaspartic acid, N-methyldehydroalanine, D-erythro-β-methylaspartic acid, and Adda (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid).

Toxicity

Nodularin is a potent inhibitor of protein phosphatases 1 and 2A, which are essential for many cellular processes in the liver. This inhibition leads to an increase in phosphorylation of proteins, disrupting normal cell function and leading to cell death. Nodularin is also a tumor promoter, meaning it can stimulate the growth of existing tumors.

Exposure and effects

Humans can be exposed to nodularin through ingestion, inhalation, or skin contact with contaminated water during algal blooms of Nodularia spumigena. Symptoms of acute exposure include nausea, vomiting, diarrhea, abdominal pain, hepatitis, and kidney damage. Chronic exposure can lead to liver cancer.

Detection and treatment

Nodularin can be detected in water samples using liquid chromatography-mass spectrometry. There is currently no specific antidote for nodularin poisoning, and treatment is supportive, focusing on relieving symptoms and preventing further exposure.

See also

• Microcystin
• Cylindrospermopsin
• Anatoxin-a

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