Aplysiatoxin

Aplysiatoxin is a cyanotoxin

Cyanotoxin

Cyanotoxins are toxins produced by bacteria called cyanobacteria . Cyanobacteria are found almost everywhere, but particularly in lakes and in the ocean where, under certain conditions, they reproduce exponentially to form blooms. Blooming cyanobacteria can produce cyanotoxins in such...

 produced by certain cyanobacteria species. It is used as a defensive secretion to protect these cyanobacteria from predation by fish, being a potent irritant

Irritation

Irritation or exacerbation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant...

 and carcinogen

Carcinogen

A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...

, by acting as a powerful activator of Protein kinase C

Protein kinase C

Protein kinase C also known as PKC is a family of enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins. PKC enzymes in turn are activated by signals such as increases in...

. While this action has a tumour-promoting effect, protein kinase C activation can be medically beneficial for some other applications, and synthetic analogues of aplysiatoxin have ironically been reseached for anti-cancer effects.