A promising anti-cancer substance has been found in a Borneo shrub by researchers for an Australian pharmaceutical firm, while a chemical found in latex produced by a tree appears to be effective against the replication of HIV, the report said.

In the bark of another species of tree, the researchers discovered a previously unknown substance which in laboratory tests appeared to kill the human malaria parasite, it added.

In all, it said, 422 new plant species had been discovered in Borneo -- shared by Malaysia, Indonesia and Brunei -- in the last 25 years and many others were believed to be there which could have medicinal applications.

But "all these promising discoveries could eventually be lost if the disappearing rainforests of the heart of Borneo are not adequately protected," the WWF said. "More forest destruction could well deny science the opportunity to discover and develop further potential sources of life-saving medication," it quoted Murray Tait, vice president of Drug Delivery at Cerylid Biosciences, the Australian company that identified the anti-cancer compound, as saying.

Borneo's forest cover has shrunk to 50 percent of its territory today from 75 percent in the mid-1980s, the report said.