A compound found in a medicinal tea brewed from the bark of a tree could help fight AIDS, scientists have found.

The tea used by tribal healers on the South Pacific island of Samoa to treat hepatitis contains the compound prostratin, extracted from the bark of the mamala tree.

Scientists have found a way to isolate the compound and synthesise it so it is 100 times more potent.

The new version of prostratin shows promise in laboratory tests for both preventing HIV from infecting human cells and awakening dormant HIV viruses that are hiding inside human latently infected cells.

Latent HIV cell reservoirs are untouchable by today`s antiviral medicines. Antiviral medicines reduce active virus levels in patients` blood and keep patients healthy.
But when patients stop the medication, the hibernating HIV in reservoirs awakens to resupply active virus. Prostratin flushes HIV out of its cellular sanctuaries so that antiviral drugs can attack and hopefully eradicate the HIV from the body.

Speaking at the American Chemical Society`s meeting in Indianapolis, Paul A Wender from Stanford University described efficient new ways of making prostratin.

Wender and colleagues first developed a way to make the tea ingredient, prostratin, in large amounts from readily available ingredients.

He described how that initial synthesis broke down a major barrier to probing prostratin`s antiviral effects. Until then, scientists had to extract prostratin from the bark of the Samoan mamala tree, and only tiny and variable amounts were so obtained.

Samoa is where another scientist, Paul Cox, in 1987 heard a native healer praise mamala bark tea as a remedy for viral hepatitis. It led scientists at the National Cancer Institute to analyse the bark and identify prostratin as a key ingredient.

Wender`s synthesis of prostratin opened the door to research on the substance and enabled his team to change prostratin`s architecture.

"We now have made synthetic variants of prostratin, called analogs, that are 100 times more potent than the natural product," Wender said.

Wender`s group also synthesised bryostatin, a substance that occurs naturally in sea creatures called bryozoans, and appears even more effective for AIDS and have applications for Alzheimer`s disease and cancer.

"Bryostatin has shown great promise in laboratory experiments as the basis for development of potentially transformative medicines for cancer, Alzheimer`s disease and the eradication of HIV/AIDS," Wender said.

Researchers have designed simpler and more readily synthesised analogs of bryostatin which are up to 1,000-fold more potent in flushing HIV out of its hiding places than prostratin.