Washington, Aug 17 - Deep in Africa's Kalahari desert lies the Devil's Claw, a plant that may hold the key to effective treatments for arthritis, tendonitis and other illnesses that affect millions each year.

In the US, Devil's Claw extracts are in phase-II clinical trials for the treatment of hip and knee arthritis. Other promising uses are not far behind.

But while the demand for these beneficial compounds is increasing, the supply of natural Devil's Claw is dwindling, thanks to years of drought, which have pushed the plant towards extinction.

Scientists have now successfully reproduced active ingredients in the Devil's Claw. Their technique may eventually lead to the development of 'bio-factories' that could produce huge quantities of rare plant extracts quickly and at little cost.

Milen I. Georgiev, a scientist who organises and teaches environment protection courses and schools in Bulgaria, pointed out that for thousands of years, native populations in southern Africa have used the Devil's Claw as a remedy for a huge number of ailments, including fever, diarrhoea and blood diseases.

Today, there are dozens of medicinal and herbal products around the world that are based on chemicals derived from the plant.

In particular, studies suggest that two chemicals -- iridoid glycosides harpagoside and harpagide -- may have beneficial effects in the treatment of degenerative rheumatoid arthritis, osteoarthritis, tendonitis, and other conditions, Georgiev said.