English yew tree

Heaton et al. have reported the supercritical fluid chromatography of taxicin I and taxicin II extracted by supercritical fluid extraction of Taxu baccata, the English yew tree [41]. They compared capillary- and packed- column SFC and concluded that packed-column SFC was better than capil4 lary-column SFC for quantitative analysis of these compounds. Capillary SFC was done on either a biphenyl or carbowax column with unmodified carbon dioxide as the mobile phase. The packed-column SFC was performed on a nitrile column with a mobile phase consisting of a methanol gradient with carbon dioxide. 

Initial studies with taxd were carried out with material isolated from the bark of the Pacific yew tree, but stripping the bark killed these magnificent trees. Taxol can now be synthesized in four steps from a compound isolated from the needles of the common English yew tree. 

Taxol was the most triumphant new anticancer drug developed in the last few decades. It resulted from a drive to screen thousands of synthesized compounds and plant extracts, financed by the National Cancer Institute (Georg et al. 1994, Suffness 1995, Goodman and Walsh 2001). Taxol is extracted from the bark of the Pacific yew tree, or Taxus brevifoli, found in the Pacific Northwest, and has been proven effective against intractable breast and ovarian cancers. It is now produced by semi-synthetic methods from the needles of the common ornamental tree English Yew, or Taxus baccata. We will discuss taxol in greater detail in Chapter 2. 

Regarded as the tree of death by the Greeks and used to prepare arrow poison by the Celts, the yew tree has been associated with death and poisoning for centuries (68,69). The English yew, Taxus baccata was used to make funeral wreaths and it was believed that one could die by merely standing beneath the boughs of the tree. 

One example of the use of renewable feedstocks is the extraction of a precursor of the anticancer compound paclitaxel (Taxol) from the needles of English yew shrubs. Taxol was originally discovered in the bark of Pacific yew trees, but in quantities so small that large amounts of bark would have to be stripped, killing trees the replacements for which require 200 years to grow and mature. A published 40-step chemical synthesis of taxol was also not practical commercially. The needles of the English yew shrub are rapidly renewable. Bristol-Meyers Squibb, partnering with the National Cancer Institute in 1991, developed a semisynthetic process based upon the paclitaxel precursor and put it into... 

Taxol is difficult to synthesize because of its many functional groups and 11 asymmetric centers. Chemists have made the synthesis a lot easier by allowing the common English yew shrub to carry out the first part of the synthesis. A precursor of the drug is extracted from the shrub s needles, and the precursor is converted to Taxol in a four-step procedure in the laboratory. Thus, the precursor is isolated from a renewable resource, whereas the drug itself could be obtained only by killing a slow-growing tree. This is an example of how chemists have learned to synthesize compounds jointly with nature. 

The Lycian tow was made of the cornel-tree those of the Ethiopians of the palm-tree. The horn of the antelope was used in tne East for bows, at least as far b k as the si of Troy, and is still employed for the puipose. Hie English long-bow was made of yew or ash. 

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