ABSTRACT
The emergence of paclitaxel (3) (Taxol®) in 1982 as a highly effective drug for the treat-
ment of refractory ovarian cancer has been rapidly followed by a serious problem related
to the adequate supply of the drug (Cragg and Snader, 1991). Paclitaxel (3) (Figure 7.1)
is a complex diterpenoid which was first isolated from the bark of the Pacific yew, Taxus
brevifolia (Taxaceae), a slow-growing tree mainly found in the Pacific Northwest (Wani et
al., 1971). Paclitaxel (3) is found in the yew’s bark in minute quantities, about 0.017%
dry weight basis (Witherup et al., 1990; Wheeler et al., 1992). The sacrifice of a 100-year-
old tree yielding about 3 kg of bark containing some 300 mg of 3 is required to obtain
approximately a single cancer chemotherapy drug dose (Cragg and Snader, 1991). In
1992, Hauser Chemical Research reported that their current production capacity had
reached 130 kg of 3 which was extracted from 730,000 kg of Pacific yew bark collected
in 1991 (Suffness and Wall, 1995). These data indicate that the extraction of 3 from nat-
urally growing Taxus trees is quite limited compared to the large number of trees which
are needed to obtain a sufficient amount of 3.
