Medicine: Tree frog hope for Alzheimer's

A South American tree frog is helping British chemists develop a super-painkiller that may also offer hope to sufferers of Alzheimer's disease. The scientists are copying the molecular structure of a poison secreted from the skin of the brightly coloured tree frog Epipedobates tricolor.

Using the natural substance epibatidine as a starting point they have created designer compounds with enormous medical potential.

John Malpass and his team from the University of Leicester are co-operating with a major drug company on the research, which holds out the possibility of producing a painkiller 200 times more powerful than morphine but without the usual side-effects.

Because it works in an entirely different way from morphine and other opiates it may also provide an effective treatment for Alzheimer's disease, by boosting memory.

Naturally occurring epibatidine cannot be used because it is so toxic. But it is possible to create safe compounds by copying its chemical structure and modifying it and combining it with other molecules.