VOA常速英語：從非洲樹上尋得藥物

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Scientists are looking at traditional African medicine for possible treatments for Alzheimer’s and Parkinson’s disease. The Salk Institute for Biological Studies is analyzing the leaves and bark of a tree that grows on an island nation off the coast of West Africa.

On S?o Tomé and Príncipe, traditional healers have used the Voacanga africana tree for hundreds of years. It’s a small tree that produces yellow or white flowers that turn into berries with seeds. The seeds and bark have been used as a poison, aphrodisiac and a psychedelic. But traditional healers knew it somehow affected those believed to have brain disorders.

Pamela Maher, senior staff scientist at the Salk Institute’s Cellular Neurobiology Lab, said, “We have developed over the years a variety of -- what are called – phenotypic assays that mimic different aspects of what goes wrong in the aging brain. And we have thought for a number of years that plants that have been used in traditional medicines might offer a new source of potential therapeutic compounds for neurodegenerative diseases.”

These include Alzheimer’s, Parkinson’s, as well as degeneration that occurs following a stroke. It’s estimated as many as five-million Americans are living with Alzheimer’s, which causes a half-million deaths each year.

“Right now there really are no good treatments for any neurodegenerative disease. And so we thought that by combining our phenotypic assays that can screen for potentially therapeutic compounds with new potential sources of therapeutic compounds might be a wonderful combination.” said Maher.

Serendipity caused researchers to focus on the Voacanga africa tree. While visiting his family in Portugal, Maher’s associate, Antonio Currais, met Maria do Madureira, a researcher studying herbal medicine on S?o Tomé and Príncipe for many years. They developed tests to find medicinal properties in plants.

Maher said, “We were focusing on plant extracts that were used in traditional medicine, either specifically for brain disorders or were known to have anti-inflammatory activity. And it’s now known a lot of neurological diseases – or almost all of them – involve some degree of inflammation.”

The researchers found that the anti-inflammatory properties of the tree extracts were mostly due to one molecule called voacamine. No tests have been done on animals yet. But this is the molecule that potentially could lead to a synthetic drug for brain illnesses.

“It was much more potent than we had expected something to be. So this showed that our approach for identifying these types of compounds works,” she said.

Maher added that there are many potential sources of drugs in native plants around the world. Most of them have never been tested. She said since you cannot test every plant, the best approach is to “use the knowledge that’s been around for thousands of years to help pick and choose what to study.”