Case Study Taxol

Taxol®, or paclitaxel, was first extracted from the bark of the pacific yew (Taxus brevifolia) in the 1960s, however it took 21 years until the anticancer drug was available on the market. Today it is used to treat lung-, ovarian- and breast cancer, as well as the AIDS associated Kaposi-sarcoma. Paclitaxel, by binding to a protein called Tubulin, it prevents the disassembly of the spindel microtubules during cell division, ultimately leading to cell death.

There was especially high demand for the substance during clinical trials, so much so, that the T. brevifolia populations were quickly and severely reduced.[1] Because of non-environmentally friendly extraction processes and the over-use of the exploitable Taxus species, the demand for alternative pathways for Taxol arose.

Besides its anti-cancerous properties, the Himalayan yew (Taxus baccata) is used in traditional Unani systems of medicine, as well as by local inhabitants of high-altitude Himalayan regions to treat various diseases, such as bronchitis, coughs, asthma, headache, and insect bites. Different species of the Taxus genus are used for making furniture, carving and as fuel.[3] Due to this wide use and its slow natural regeneration (low pollination rate, long seed dormancy, and weak competitive ability of seedlings) the Taxus genus has experienced a significant reduction in population sizes of several species.
The Taxus brevifolia (native to North America) for example after a reduciton in populations of 30% has been listed as near threatened globally and as endangered in the Himalayan regions by the IUCN.[4]

[1] (McElroy & Jennewein, 2018)

[2] (Gallego-Jara, Lozano-Terol, Sola-Martínez, Cánovas-Díaz, & de Diego Puente, 2020)

[3] (Lanker, Malik, Gupta, & Butola, 2010)

[4] (Thomas, 2013)

Deforestation

Despite methods for synthetic production that have been developed over the last 20 years, extraction from trees continues to be the cheapest and most frequently used approach. Large monocultures and deforestation pose problems. According to Gallego-Jara et al. still today 4 trees have to be cut down to treat one patient with 2g of Taxol®.[5] If not completely cut down, the trees mostly die slowly due to the removal of their bark.[6]

[5] (Gallego-Jara, Lozano-Terol, Sola-Martínez, Cánovas-Díaz, & de Diego Puente, 2020)

[6] (Yuliya, et al., 2023)

Climate Change

Climate Change influences the distribution of plant species by affecting the temperature of habitat areas, therefore leading to migration of vegetative communities. Studies done both in China and Turkey show that multiple species of the Taxus genus are locally endangered due to these habitat changes.[7][8]

[7] (Wu, et al., 2022)

[8] (Evrim Koc, Svenning, & Avci, 2018)

Sustainable Production

Based on the problematic extraction of paclitaxel from yew trees, different biomedical techniques for a more sustainable approach to this natural compound have been postulated. These are based on the use of microorganisms, such as endophytic fungi, the increase of its bioavailability without exerting adverse effects on the health of patients and the minimization of resistance.[9]

[9] (Gallego-Jara, Lozano-Terol, Sola-Martínez, Cánovas-Díaz, & de Diego Puente, 2020)