The Purification of Taxus Extract by SepaBean™ Machine

Meiyuan Qian, Yuefeng Tan, Bo Xu
Application R&D Center

Introduction
Taxus (Taxus chinensis or Chinese yew) is a wild plant protected by the country. It is a rare and endangered plant left behind by the Quaternary glaciers. It is also the only natural medicinal plant in the world. Taxus is distributed in the temperate zone of the northern hemisphere to the mid-subtropical region, with about 11 species in the world. There are 4 species and 1 variety in China, namely Northeast Taxus, Yunnan Taxus, Taxus, Tibetan Taxus and Southern Taxus. These five species are distributed in Southwest China, South China, Central China, East China, Northwest China, Northeast China and Taiwan. Taxus plants contain a wide variety of chemical components, including taxanes, flavonoids, lignans, steroids, phenolic acids, sesquiterpenes and glycosides. The famous anti-tumor drug Taxol (or Paclitaxel) is a kind of taxanes. Taxol has unique anticancer mechanisms. Taxol can “freeze” microtubules by combing with them and prevent microtubules from separating chromosomes at the time of cell division, thus leading to the death of dividing cells, especially rapidly proliferating cancer cells[1]. Furthermore, by activating macrophages, Taxol causes a decrease in TNF-α (tumor necrosis factor) receptors and release of TNF-α, thereby killing or inhibiting tumor cells[2]. Moreover, Taxol can induce apoptosis by acting on the apoptotic receptor pathway mediated by Fas/FasL or activating the cysteine protease system[3]. Due to its multiple target anticancer effect, Taxol is widely used in the treatment of ovarian cancer, breast cancer, non-small cell lung cancer (NSCLC), gastric cancer, esophageal cancer, bladder cancer, prostate cancer, malignant melanoma, head and neck cancer, etc[4]. Especially for advanced breast cancer and advanced ovarian cancer, Taxol has an outstanding curative effect, therefore it is known as “the last line of defense for cancer treatment”.

Taxol is the most popular anticancer drug in the international market in recent years and is considered to be one of the most effective anticancer drugs for humans in the next 20 years. In recent years, with the explosive growth of population and cancer incidence, the demand for Taxol has also increased significantly. Currently, Taxol required for clinical or scientific research is mainly extracted directly from Taxus. Unfortunately, the content of Taxol in plants is quite low. For example, the Taxol content is only 0.069% in the bark of Taxus brevifolia, which is generally considered to have the highest content. For the extraction of 1 g of Taxol, it requires about 13.6 kg of Taxus bark. Based on this estimate, it takes 3 – 12 Taxus trees which are more than 100 years old to treat an ovarian cancer patient. As a result, a large number of Taxus trees have been cut down, resulting in near extinction for this precious species. In addition, Taxus is very poor in resources and slow in growth, which makes it difficult for further development and utilization of Taxol.

At present, the total synthesis of Taxol has been successfully completed. However, its synthetic route is very complex and high-cost, making it have no industrial importance. The semi-synthetic method of Taxol is now relatively mature and is considered to be an effective way to expand the source of Taxol in addition to artificial planting. Briefly, in the semi-synthesis of Taxol, the Taxol precursor compound which is relatively abundant in Taxus plants is extracted and then converted into Taxol by chemical synthesis. The content of 10-deacetylbaccatin Ⅲ in the needles of Taxus baccata can be up to 0.1%. And the needles are easy to regenerate comparing with the barks. Therefore, the semi-synthesis of Taxol based on 10-deacetylbaccatin Ⅲ is attracting more and more attention from researchers[5] (as shown in Figure 1).

Figure 1. The semi-synthetic route of Taxol based on 10-deacetylbaccatin Ⅲ.

In this post, the Taxus plant extract was purified by a flash preparative liquid chromatography system SepaBean™ machine in combination with SepaFlash C18 reversed-phase (RP) flash cartridges produced by Santai Technologies. The target product meeting the purity requirements was obtained and can be used in subsequent scientific research, offering a cost-effective solution for the rapid purification of this kind of natural products.