Which blue-green alga is associated with hepatic toxicity?

• A. Microcystis
• B. Spirulina
• C. Anabaena
• D. Oscillatoria

Answer: (A)

Hepatotoxic cyanobacterial toxins are most famously linked to microcystins, which are produced by Microcystis blooms. Microcystins are cyclic peptides that inhibit protein phosphatases 1 and 2A, disrupting the hepatocyte cytoskeleton and leading to liver cell injury. The liver takes up these toxins preferentially, so exposure from contaminated water can cause liver enzyme elevation and potentially serious hepatic damage. Spirulina comes from a different cyanobacterium (Arthrospira) and is not associated with these hepatotoxins. Other genera like Anabaena and Oscillatoria can produce other types of toxins, but the classic association with hepatic toxicity is Microcystis.