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Read more: 鈥�Drugs with bite: The healing powers of venoms鈥�

DRUG: ShK
SOURCE: Sea anemone
CONDITION: Autoimmune disease

In the warm, shallow waters of the Caribbean Sea, especially in the coral reefs around Cuba, lives a species of sea anemone called Stichodactyla helianthus. In the early 1990s a group of Cuban researchers on a diving expedition collected some specimens to analyse their toxins. The compound they discovered has spawned an experimental drug, ShK, which is about to go into clinical trials for treating multiple sclerosis (Toxicon, ). It also has potential to treat a broad range of autoimmune diseases, including type 1 diabetes and rheumatoid arthritis.

Autoimmune diseases arise when the immune system mistakenly decides that one of the body鈥檚 own tissues is foreign and begins to attack it. In many cases the damage is caused by a particular group of immune cells called effector memory T-cells. These possess a unique ion channel called a Kv1.3 potassium channel without which they cannot function, and it is this channel that ShK targets. 鈥淪hK puts the cork in the bottle,鈥� says Ray Norton at Monash University in Melbourne, Australia, who has been involved in the project since 1996. 鈥淚n the presence of our compound, the cells become immobilised and wither and die.鈥�

Studies in animal models of MS have been a success, and the latest version of the compound is due to start clinical trials in humans by mid-2012. 鈥淚n MS, there鈥檚 a lot of nerve damage 鈥� we can certainly stop further damage,鈥� says Norton. 鈥淭ime will tell whether we can reverse damage that has already happened 鈥� whether the innate repair mechanisms start to win out once the effector memory T-cells are taken out. We are hopeful.鈥�

Quite what such a compound is doing in the sea anemone in the first place is an open question. Possibly it acts to stun the fish that they eat. Ion channel function can vary significantly from species to species, and the ion channel鈥檚 role in fish could be very different from its role in our bodies.