nodularin

Nodularin is a hepatotoxic cyanotoxin produced by cyanobacteria of the genus Nodularia, most commonly found in freshwater and brackish water blooms. Nodularin is a cyclic peptide toxin, structurally related to microcystins, and the Nodularia-derived nodularin-R is the most studied form. It is commonly detected in lakes and coastal ecosystems affected by cyanobacterial blooms, particularly under nutrient-rich, warm, and stagnant conditions.

The toxin inhibits serine/threonine protein phosphatases 1 and 2A in liver cells, leading to increased protein phosphorylation, cytoskeletal disruption, and hepatocellular damage. Clinically, nodularin exposure can cause liver dysfunction and, in severe cases, liver failure in humans and animals; acute exposure is of greatest concern through ingestion of contaminated drinking water or recreational water, or through eating contaminated aquatic organisms. Dermal exposure is considered less significant.

Detection and regulation: nodularin is detected by analytical methods such as LC-MS/MS and immunoassays (ELISA). Drinking water guidelines and health advisories for nodularin vary by country, with some jurisdictions setting maximum allowable concentrations; regulatory actions typically include monitoring and source-water management during blooms.

Ecology and management: nodularin production occurs during cyanobacterial blooms; environmental factors include nutrient enrichment, warm temperatures, and stratified water bodies. Monitoring programs and water-treatment processes such as coagulation, filtration, and adsorption are used to reduce nodularin levels in drinking water.