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Drug From Chestnut May Stop AIDS Virus

August 29, 1987

SEATTLE (AP) _ A drug extracted from the seeds of an Australian chestnut tree appears to halt reproduction of the AIDS virus in the test tube, says a Fred Hutchinson Cancer Research Center scientist.

The drug, castanospermine, has been approved by the National Cancer Institute for tests in animals, and was selected as the institute’s lead ″natural substance″ drug for use against AIDS, virologist Larry Rohrschneider said Friday.

Considerably more testing would be required before it would be tried in humans; Rohrschneider said this could be in about a year if all goes well.

The test tube results came in a Harvard University laboratory headed by Dr. William Haseltine, a leading AIDS researcher, he said.

″At the right level (dose), the drug completely prevented the spread of the virus,″ Rohrschneider said.

The experiments were conducted under contract by Harvard because the Seattle group doesn’t work with the virus that causes acquired immune deficiency syndrome.

New test tube studies are examining the substance’s effectiveness in combination with AZT, the only AIDS-fighting drug currently fully approved by the Food and Drug Administration, said Rohrschneider.

That combination may be particularly effective, Rohrschneider speculated, because castanospermine acts late in the life cycle of the virus, and AZT acts early in its life cycle.

Rohrschneider learned of the seed extract while doing basic research into how normal cells become cancerous. He picked several new drugs with a known effect on carbohydrate metabolism in cells. One was a compound extracted from locoweed, and he learned from scientific literature that castanospermine had a similar chemical structure and had been shown to be effective against a virus related to the AIDS virus.

He obtained seed pods of the chestnut tree, known as a ″black bean″ in Australia, from Brisbane Botanic Gardens.

The Fred Hutchinson center, which holds patents on the drug for use against AIDS and cancers, is negotiating with two major drug companies to take over development, testing and production.

Scientists at Cornell University and University of California-Berkeley also are studying the seed extract, Rohrschneider said.

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