What are the ways for humans to obtain paclitaxel?

At present, there are three ways to obtain paclitaxel: 1. Natural extraction, 2. Synthetic, 3. Semi-synthetic and 4. Biological fermentation. The latter three methods mostly stay in the laboratory stage. (1) Taxol biosynthesis: The molecular formula of taxol is C47H5 1NO 14, which is a natural secondary metabolite with terpenoid cyclic structure. It is mainly composed of taxane ring and side chain. It is of great significance to study its biosynthesis for improving the synthesis efficiency, cloning and combination, forming key enzyme genes and increasing the yield of paclitaxel. At present, the key is whether we can find one or two key enzymes and purify and clone their genes. Can gene cloning of Taxus chinensis break through? (2). Chemical synthesis of paclitaxel? According to research and reports, the activity of 10- deacetylbaccatin Ⅲ (baccatin Ⅲ) isolated from Taxus plants is obviously lower than that of paclitaxel, but it can be extracted from Taxus needles. This substance can synthesize paclitaxel through four chemical processes. Great progress has been made in solving the new source of paclitaxel. 1994, an American research group headed by Dr. NICOLAOU reported that paclitaxel was completely synthesized by chemical methods. (3) Microbial synthesis of paclitaxel? STTERLE et al. isolated a parasitic fungus (Taxus angustifolia) from the phloem of Taxus brevifolia. It can produce taxol and related hydrocarbons in a specific culture medium, but at present, the yield is extremely low, so it can not be used in production. Recombinant DNA technology is expected to improve the yield of paclitaxel. Besides bark, root is the organ with the highest taxol content. People use Agrobacterium rhizogenes to soak the explants of Taxus plants to induce rooting. This method does not need exogenous hormones, hairy roots grow rapidly and genetic traits are stable. If we can combine the search for the synthesis of paclitaxel or its similar derivatives, the key enzymes obtained by microbial synthesis and the cloning of Taxus related genes, this method can be broken through. With the introduction of the 5th Beijing Biomedical Development Forum, the development of extracting paclitaxel from plants is summarized as follows: Since the 1960s, the discovery of new anticancer drugs mainly comes from the metabolites of primitive plants, that is, several anticancer chemotherapy reagents currently used, rather than compounds extracted from higher plants. For example: "Catharanthus roseus alkaloids" isolated from Catharanthus roseus? Epipodophyllotoxin derivatives isolated from podophyllum. Camptothecin derivatives isolated from Camptotheca acuminata? So far, the "Taxus ferruginea" component separated from Taxus chinensis has been obtained.