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Pacific Yew Background
In the 1950's the American Cancer Institute (ACI) initiated a wide spread screening program of substances, and extracted from a wide spectrum of pre-targeted materials in the hope that ACI could find out some anti-cancer agents. Over 110,000 extracts from plant species were tested over a 21 year period (1960-1981). The Pacific Yew tree as one of the major target of interests due to the local population (most of them are native American) had relatively low cancer cases compared with other US geographic areas. The findings showed that an extract from the bark of the Pacific Yew (Taxus) was the most promising anti-cancer agent.
The Pacific Yew, belonging to one of the Taxus family, is a slow growing evergreen tree (shrub). The genus Taxus is distributed mainly over the temperate zones of the northern hemisphere. Ecologists have isolated 7 different species of taxus worldwide. There are 7 major species about Taxus Yew trees, and hundreds of cultivars around the world.
The historical fact about the native American who drank Pacific Yew Tea, chewed Pacific Yew tips (leaves), drank the extract from Pacific Yew, and walked in the Pacific Yew forest to breath the fresh air, etc. All of above life-style practices contributed the low rate of cancer cases in that geographic area. A complex chemical compound was discovered in the bark of Pacific Yew called Taxol at that time that showed the most promising in wide spectrum of cancer-curing treatments. Today, TaxolŽ is Bristol-Myers Squibb's registered trademark for paclitaxel. Paclitaxel is commonly referred to as 'Taxol' in the press and conversation; the term will be used here.
It is logical to assume, besides Taxol, there are other chemical compounds, or the combinations of some chemical compounds also would be good anti-cancer agents. Today, numerous research projects and scientific study in the worldwide scientific community are surrounding the research subjects of Taxol, Taxol derivitives, Taxane (the raw material of Taxol), and similar chemical compounds in the hope to find the better treatment for various cancers.
One of the main blocks in the development of Taxol as an anti-cancer agent at that time was the difficulty in obtaining sufficient quantities of the compound from its nature source. Taxol only constitutes 0.01-0.03% of the dry weight of the inner bark of the Pacific Yew Tree. This means vast amount of the yew tree are needed to isolate even small amounts of the Taxol compound, and the supply became one major issue due to slow-grow of all Taxus family. Hence, It was difficult to commercialize this Taxol from its nature resource.
Based up actual field experience at that time,
2000-3000 mature yew trees ----> 9000 kg dried inner bark ---> 1 kg Taxol
Consequently, it was commercial unfeasible to cut large amount of nature yew trees in order to treat just several cancer patients.
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