Plant Could Become Alternative Source of Taxol® Precursor
SAN FRANCISCO, March 29 — The active chemical of the anticancer drug Taxol® has unexpectedly been found in hazelnuts, says a team of researchers at the University of Portland in Portland, Oregon. This is the first report of the potent chemical, generically known as paclitaxel, being found in a plant other than the yew tree. This finding could reduce the cost of the commercial drug and make it more readily available, the investigators say. The study is being presented here today at the 219th national meeting of the American Chemical Society, the world’s largest scientific society.
“This is potentially good news for cancer patients,” says Angela M. Hoffman, Ph.D., associate professor of chemistry in the university’s Department of Chemistry and Physics, and a member of the research team. Taxol® is currently one of the biggest-selling cancer drugs worldwide. An alternative source could stimulate competition among drug manufacturers, which could mean cheaper drug prices, explains Hoffman.
The study began as a search for a compound that made certain hazelnut trees resistant to a plant disease known as Eastern Filbert Blight. A chemical analysis of extracts from these hazelnut trees was conducted. Surprisingly, one of the chemicals identified from the extracts was paclitaxel, says Hoffman. The chemical was isolated from the nuts, branches and shells of the trees, she says.
The U.S. Food and Drug Administration (FDA) has approved Taxol® for the treatment of ovarian cancer, breast cancer and AIDS-related Kaposi’s sarcoma. Researchers originally believed that the drug’s precursor was found only in the bark of the Pacific yew tree, a slow-growing plant found in limited quantities in the Pacific Northwest. As it takes several Pacific yew trees to make a small amount of Taxol® commercially, the trees were once the target of controversy since large scale harvesting could have risked their extinction.
Commercial supplies of Taxol® are now manufactured by a semi-synthetic method that relies on extracts from the leaves of another yew species. Although paclitaxel has been synthesized artificially in the laboratory without using any yew parts, this method is currently too complex and expensive to implement commercially, says Hoffman.
While the supply of Taxol® is generally meeting demand for currently approved cancer treatments and clinical trials, researchers are also finding an increasing number of other medical applications that are boosting demand for it. Clinical studies have shown that the drug is promising for the treatment of psoriasis, polycystic kidney disease, multiple sclerosis and Alzheimer’s, among others.
As demand for the anticancer drug continues to increase, researchers may be wise to consider the hazelnut tree as an alternative source of paclitaxel, Hoffman says. Although the amount of the chemical found in a hazelnut tree is about one-tenth that of the yew (6 to 7 micrograms/gram dry weight of hazel vs. 60 to 70 micrograms/gram dry weight of yew), the effort required to extract paclitaxel from these sources is comparable, she says.
For those who are tempted to run to the store and stockpile hazelnuts, Hoffman urges caution. Based on her chemical analysis of raw hazelnuts, she concludes there is probably not enough paclitaxel in a handful of nuts to make a difference medically. The researcher has not tested roasted nuts, and is skeptical of any significant amounts of the chemical being found in hazelnut-flavored products like coffee, tea and candy.
Hoffman’s work, in addition to being funded by the university, is partially funded by the Oregon Hazelnut Commission.
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