The taxanes are diterpenes produced by the plants of the genus Taxus

Taxus

Taxus is a genus of yews, small coniferous trees or shrubs in the yew family Taxaceae. They are relatively slow-growing and can be very long-lived, and reach heights of 1-40 m, with trunk diameters of up to 4 m...

(yews). As their name suggests, they were first derived from natural sources, but some have been synthesized artificially. Taxanes include paclitaxel

Paclitaxel

Paclitaxel is a mitotic inhibitor used in cancer chemotherapy. It was discovered in a U.S. National Cancer Institute program at the Research Triangle Institute in 1967 when Monroe E. Wall and Mansukh C. Wani isolated it from the bark of the Pacific yew tree, Taxus brevifolia and named it taxol...

 (Taxol) and docetaxel (Taxotere). Paclitaxel was originally derived from the Pacific yew tree.

Taxanes have been used to produce various chemotherapy

Chemotherapy

Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

 drugs. The principal mechanism of action of the taxane class of drugs is the disruption of microtubule

Microtubule

Microtubules are a component of the cytoskeleton. These rope-like polymers of tubulin can grow as long as 25 micrometers and are highly dynamic. The outer diameter of microtubule is about 25 nm. Microtubules are important for maintaining cell structure, providing platforms for intracellular...

 function. Microtubules are essential to cell division, and taxanes stabilize GDP

Guanosine diphosphate

Guanosine diphosphate, abbreviated GDP, is a nucleoside diphosphate. It is an ester of pyrophosphoric acid with the nucleoside guanosine. GDP consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase guanine....

-bound tubulin

Tubulin

Tubulin is one of several members of a small family of globular proteins. The most common members of the tubulin family are α-tubulin and β-tubulin, the proteins that make up microtubules. Each has a molecular weight of approximately 55 kiloDaltons. Microtubules are assembled from dimers of α- and...

 in the microtubule, thereby inhibiting the process of cell division — a "frozen mitosis

Mitosis

Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...

". Thus, in essence, taxanes are mitotic inhibitor

Mitotic inhibitor

A mitotic inhibitor is a drug that inhibits mitosis, or cell division. These drugs disrupt microtubules, which are structures that pull the cell apart when it divides...

s. In contrast to the taxanes, the vinca alkaloids

Vinca alkaloids

Vinca alkaloids are a set of anti-mitotic and anti-microtubule agents which were originally derived from the Periwinkle plant Catharanthus roseus.Vinca alkaloids are used in the treatment of cancer...

 destroy mitotic spindle

Mitotic spindle

In cell biology, the spindle fibers are the structure that separates the chromosomes into the daughter cells during cell division. It is part of the cytoskeleton in eukaryotic cells...

s. Both taxanes and vinca alkaloids are, therefore, named spindle poison

Spindle poison

A spindle poison, also known as a spindle toxin, is a poison which disrupts cell division by affecting the protein threads which connect the centromere regions of chromosomes, known as spindles.Some spindle poisons:* Mebendazole* Colchicine...

s or mitosis poisons, but they act in different ways. Taxanes are also thought to be radiosensitizing

Radiosensitivity

Radiosensitivity is the relative susceptibility of cells, tissues, organs or organisms to the harmful effect of ionizing radiation. Cells are least sensitive when in the S phase, then the G1 phase, then G2 phase and the most sensitive in the M phase of the cell cycle...

.

Taxanes are difficult to synthesize because of their numerous chiral centres — Taxol has 11 of these. Taxanes present difficulties in formulation

Formulation

Formulation may refer to:* Clinical formulation* Formulations * Formulation science* Pharmaceutical formulation:** Galenic formulation* Pesticide formulation...

as medicines because they are poorly soluble in water.