Taxus brevifolia

Taxotere [114977-28-5] Taxus brevifolia Taxus breviofolia Taylor cells Taylors borate... 

A new antitumor drug, taxol, has been isolated from the bark of Taxus brevifolia, the Pacific yew tree. Like vinblastine and colchicine, taxol inhibits cell replication by acting on microtubules. Unlike these other antimitotic drugs, however, taxol stimulates microtubule polymerization and stabilizes microtubules. 

Taxus baccata 656 Taxus brevifolia 655 Tebbe reagent 703 telomerization 354 ff. a-terpineol 5 tertiary radicals 409, 413 tether, disposable 664 tetrahedrane 12... 

Taxanes (paclitaxel, docetaxel) are derivatives of yew tree bark (Taxus brevifolia). They stabilize microtubules in the polymerized state leading to nonfunctional microtubular bundles in the cell. Inhibition occurs during G2- and M-phases. Taxanes are also radiosensitizers. Unwanted effects include bone marrow suppression and cumulative neurotoxicity. 

Anticancer drugs originally extracted from the cortex of Taxus brevifolia or Taxus baccata. They block cell division by inhibiting tubulin depolymerization. Two... 

F.14 Paclitaxel, which is extracted from the Pacific yew tree Taxus brevifolia, has antitumor activity for ovarian and breast cancer. It is sold under the trade name Taxol. On analysis, its mass percentage composition is 66.11% C, 6.02% H, and 1.64% N, with the balance being oxygen. What is the empirical formula of paclitaxel ... 

Wani MC, Taylor HL, Wall ME, Coggon P, McPhail AT. Plant antitumor agents. VI. The isolation and structure of taxol, a novel antileukemic and antitumor agent from Taxus brevifolia. J Am Chem Soc 1971 93 2325-7. 

FIGURE 11.2 (a) Photocopy and densitogram of PLC of and extract of Taxus brevifolia (needles), system Si02/CHCl3 + B +... 

A fine example of such a semi-synthesis is the preparation of the anti-cancer drug paclitaxel (Taxol ), a relatively scarce compound from Taxus brevifolia. Here, the natural and better accessible 10-deacetylbaccatin III, isolated from the leaves of Taxus baccata, provides the complicated ring system of paclitaxel, including all substituents with the right stereostructure (Scheme 5.1). In just four reaction steps [5] paclitaxel is obtained from 10-deacetylbaccatin III. 

Taxol i is a naturally occurring substance isolated from the Pacific yew tree Taxus brevifolia), which has been approved for clinical treatment of cancer patients. Taxol enhances polymerization of tubuhn and the consequent formation of stable microtubules, inhibiting cellular mitosis. 

Taxol (Paclitaxel) 137, a natural product derived from the bark of the Pacific yew, Taxus brevifolia [213-215], and the hemisynthetic analogue Docetaxel (Taxotere) 138, two recent and promising antitumour agents, have been the matter of extensive in vivo and in vitro animal metabolic studies. The major metabolites of taxol excreted in rat bile [216] were identified as a C-4 hydroxylated derivative on the phenyl group of the acyl side chain at C-13 (139), another aromatic hydroxylation product at the mefa-position on the benzoate group at C-2 (140) and a C-13 deacylated metabolite (baccatin III, 142) the structure of six minor metabolites could not be determined. The major human liver microsomal metabolite, apparently different from those formed in rat [217], has been identified as the 6a-hydroxytaxol (141) [218, 219]. A very similar metabolic pattern was... 

Paclitaxel, from the bark of the pacific yew (Taxus brevifolia), inhibits disassembly of microtubules and induces atypical ones. Docetaxel is a semisynthetic derivative. 

Paclitaxel (21), formerly known as taxol , is a nitrogen-containing diterpenoid compound isolated from the bark of Taxus brevifolia Nutt. (Pacific yew). As an anticancer agent, paclitaxel acts as a tubulin stabilizer and leads to cell cycle arrest.Since paclitaxel was originally isolated from the bark of the slow-growing species, 77 brevifolia, sourcing was a major obstacle in the development of this drug and its introduction into the market.However, as described later in this chapter, this has now been overcome. 

As will be mentioned further in this chapter, the discovery of the anticancer drug, paclitaxel (21), was soon followed by sourcing issues due to the low yield of this compound in the source plant, Taxus brevifolia Nutt. This led to the semisynthesis of paclitaxel (21), from a precursor molecule, 10-deacetylbaccatin III, readily available from the leaves of Taxus baccata L., a renewable source with high yields of this compound.Docetaxel (37) is a second taxane class anticancer drug and is a semisynthetic derivative of paclitaxel (21). ... 

Podophyllotoxin (38) Podophyllum peltatum L.), colchicine (9) Colchicum autumnale L.), vinblastine (4), and vincristine (5) Catharan-thus roseus (L.) G. Don] are standard microtubule-destabilizing agents used in cancer research. Paclitaxel (21), from Taxus brevifolia Nutt., acts as a promoter of stabilization of microtubules and causes mitotic arrest in an unusual fashion. ... 

Paclitaxel (21) was originally obtained from the bark of the Pacific yew, Taxus brevifolia Nutt. However, as the tree takes 200 years to mature, stripping the bark to produce this compound for the market was not sustainable. A better source of naturally occurring paclitaxel has not been found in other species and the total synthesis, on the other hand,... 

Stierle A, Strobel G, Stierle D, Grothaus P, Bignami G, The search for a taxol-producing microorganism among the endophytic fungi of the pacific yew, Taxus brevifolia, JNat Prod 58 1315-1324, 1995. 

Stierle A, Stierle D, Strobel G, Bignami G, Grothaus P, Endophytic fungi of pacific yew Taxus brevifolia) as a source of taxol, taxanes and other pharmacophores, in Bioregulators for Crop Protection and Pest Control, American Chemical Society, Washington DC, pp. 64—77, 1994. 

The NCI scientists discovered that extracts of the bark and needles of a yew tree, Taxus brevifolia of the Pacific Northwest, killed trunor cells. Fresh samples were obtained from the forests in the state of Washington in August 1962. Paclitaxel was first isolated from yew tree extract in 1967, and retested on cells in the laboratory. After it was found to be effective in tests on animals with tmnors, paclitaxel was studied in a large munber of human cancer patients and finally approved by the Food and Drug Administration (FDA) in 1992 for use in treating cancer in people. 

Taxol Terpenoid Ovarian, breast cancer Taxus brevifolia (western yew tree)... 

The diterpenoid taxol (Figure 1.12) was first isolated from the pacific yew tree (Taxus brevifolia) in the late 1960s. Its complete structure was elucidated by 1971. Difficulties associated with the subsequent development of taxol as a useful drug mirror those encountered during the development of many plant-derived metabolites as drug products. Its low solubility made taxol difficult to formulate into a stable product, and its low natural abundance required large-scale extraction from its native source. 

Pacific yew, Taxus brevifolia Nutt., Taxaceae, Gymn. 

The alkaloid ester paclitaxel (7.93) is a natural product derived from the western yew (Taxus brevifolia) and European yew (Taxus baccata). This agent functions as a mitotic spindle by causing excessive tubulin polymerization. Paclitaxel has demonstrated considerable clinical utility in ovarian and breast cancer. 

It is an alkaloid ester derived from the western yew Taxus brevifolia. 

Nature has been a potential source of therapeutic agents for thousands of years. An impressive number of modem dmgs have been derived from natural sources. Over the last century, a number of top selling dmgs have been developed from natural products. Anticancer dmg vincristine from Vinca rosea, narcotic analgesic morphine from Papaver somniferum, antimalarial dmg artemisinin from Artemisia annua, anticancer dmg Taxol from Taxus brevifolia and antibiotic peniciUins from Penicillium ssp. are just a few examples. 

One of the simplest and most significant of the diterpenes is phytol, a reduced form of geranylgeraniol, which constitutes the lipophilic side-chain of the chlorophylls. Phytol also forms a part of vitamin E (tocopherols) and K molecules. Vitamin A is also a 20-carbon-containing compound, and can be regarded as a diterpene. However, vitamin A is formed from a cleavage of a tetraterpene. Among the medicinally important diterpenes, paclitaxel, isolated from Taxus brevifolia (family Taxaceae), is one of the most successful anticancer drugs of modern time. 

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