ÁñÁ«ÊÓƵ

Hundreds of natural chemicals that could protect the skin from damaging ultraviolet rays have gone unnoticed by Western scientists because they only grow in the tropics, the British Association heard.

Monique Simmonds, of the Royal Botanical Gardens at Kew in London, said that scientists are finding that flavinoids in tropical plants can protect against skin cancer. Some have been used for centuries by tribes as face paints.

"There is increased interest in flavinoids because of their potential use in cancer. They are in higher concentrations in plants exposed to high ultra-violet levels," she said. "There is concern with the breakdown of the ozone layer whether some could be used for their protective properties."

The flavinoids take the form of pigments on the surface of the plants. "They have evolved to protect the plant," said Dr Simmonds. There were some promising chemicals but she was looking for industrial sponsorship to continue work.

The discovery illustrates how medical researchers, botanists and biochemists are working together to discover natural medicines.

On malaria medicines, scientists are working urgently to record the knowledge of natural remedies held by the older generations of tribes. "They have knowledge about some of the ailments to do with malaria and a number of plants that can treat symptoms," she said. "But are the plants they are using affecting the causes or are they just anti-fever remedies?"