Taxanes present difficulties in formulation as medicines because they are poorly soluble in water.
As their name suggests, taxanes were first derived from natural sources, but some have been synthesized artificially. Paclitaxel was originally derived from the Pacific yew tree. Taxanes are difficult to synthesize because of their numerous chiral centres — taxol has 11 of these.
Recently, the presence of taxanes in the shells and leaves of Corylus avellana (the common hazel plant) has been reported.
The principal mechanism of action of the taxane class of drugs is the disruption of microtubule function. Microtubules are essential to cell division, and taxanes stabilize GDP-bound tubulin in the microtubule, thereby inhibiting the process of cell division as depolymerization is prevented. Thus, in essence, taxanes are mitotic inhibitors. In contrast to the taxanes, the vinca alkaloids prevent mitotic spindle formation through inhibition of tubulin polymerization. Both taxanes and vinca alkaloids are, therefore, named spindle poisons or mitosis poisons, but they act in different ways. Taxanes are also thought to be radiosensitizing.
Hongdoushans A-C are oxygenated taxane diterpenes, isolated from the wood of Taxus wallichiana. Hongdoushan A (C29H44O7), hongdoushan B (C27H40O7), and hongdoushan C (C27H42O6) are reported to have anticancer activity in vitro.