Taxol (paclitaxel) is a complex fuctionalized diterpene isolated from the bark of the Pacific Yew tree (Taxus Brevitola) native to Northwest America.
Historically, Native American tribes used yew brews to treat rheumatism, fever, and arthritis, but it wasnt until the 1960s that the anticancer qualities were discovered.
Taxol was first isolated from Yew bark in 1962 as part of the National Cancer Institute (NCI) program in search of natural products exhibiting anticancer activity. Over 100,000 compounds were extracted from over 35,000 plant species, but Taxol proved to be most useful.
Because roughly 6 trees must be sacrificed to treat one patient, many efforts are underway to improve availability and to increase synthetic yields of Taxol.
Three "total" syntheses have been carried out to date, the Holton, Nicholau and Danishefsky routes but these are continuously being updated to increase efficiency and yields.
How Taxol works as an anticancer drug:
Taxol is a potent compound that targets rapidly dividing cancer cells and prevents them from replicating. A large number of microtubules are formed at the start of cell division, and as cell division comes to an end, these microtubules are normally broken down into tubulin. Taxol binds to the microtubules and inhibits their depolymerization into tubulin. This means that Taxol blocks a cell's ability to break down the mitotic spindle during mitosis (cell division). With the spindle still in place the cell can't divide into daughter cells and therefore the cancer cant spread.
Molecular Structure: http://biotech.icmb.utexas.edu/botany/tax.html
Taxus Brevifolia image: http://www.21cep.com/9top/story.htm
Yew Foliage Image: http://biotech.icmb.utexas.edu/botany/yewhist.html