Paclitaxel anticancer agents

Poly(ADP-ribose)polyrmerase (PARP) inhibitors, 42 (2004) 125 P2 Purinoreceptor ligands, 38 (2001) 115 p38 MAP kinase inhibitors, 38 (2001) 1 Paclitaxel, anticancer agent, 32 (1995) 289... 

Other applications include bioequivalent measurements of bromazepam, an anticonvulsant, in human plasma. The lower limit of quantitation (LLOQ) was 1 ng/mL (Gongalves et al. 2005). Kuhlenbeck et al. (2005) studied antitussive agents (dextromethorphan, dextrophan, and guaifenesin) in human plasma LLOQ values were 0.05, 0.05, and 5 ng/mL, respectively. Other compounds studied were nucleoside reverse transcriptase inhibitors, zidovudine (AZT) and lamivudine (3TC) (de Cassia et al. 2004) and stavudine (Raices et al. 2003) in human plasma, and paclitaxel, an anticancer agent, in human serum (Schellen et al. 2000). 

Other anticancer agents have distinct mechanisms paclitaxel and its relatives target microtubules as do the vinca alkaloids. Antiestrogens and antiandrogens target estrogen and androgen receptors. 

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. 

Straubinger, R. M. A. Sharma, U. S. Sharma, and S. V. Balasubramanian. 1995. Pharmacology and antitumor effects of novel Paclitaxel formulations. In Taxane Anticancer Agents, George G. I. et al., eds. ACS Symposium Series 583. Washington, DC American Chemical Society 111-123. 

The answer is c. (Hardman, pp 1260-1262.) Paclitaxel is a large structural molecule that contains a 15-membered taxane ring system. This anticancer agent is an alkaloid derived from the bark of the Pacific yew tree. Its chemotherapeutic action is related to the microtubules in the cell. Paclitaxel promotes microtubule assembly from dimers and causes microtubule stabilization by preventing depolymerization. As a consequence of these actions, the microtubules form disorganized bundles, which decreases... 

In the anticancer area, the use of natural products as direct agents or as novel lead compounds for the generation of synthetic or semisynthetic analogs has proved remarkably productive, and a recent survey showed that 62% of new anticancer agents over the last 10 years have been natural products or agents based on natural product models.7 Examples of clinically important plant-derived natural products are the vinca alkaloids vinblastine (4) and vincristine (5), the podophyllotoxin analogs etoposide (6) and teniposide (7), the diterpenoid paclitaxel (Taxol ) (8), and the camptothedn-derivative topotecan (9). 

Block copolymer micelle formulations of doxorubicin and paclitaxel are both in Phase l/ll trials for the treatment of advanced cancers. Aliabadi and Lavasanifar (2006) recently compiled a review of the clinical status of polymeric micelle systems for anticancer agent delivery. 

Vyas DM and Kadow JF (1995) Paclitaxel a unique tubulin interacting anticancer agent. Prog Med Chem 32, 289-337. 

In this chapter, we describe an account of our research on the chemistry and biology of paclitaxel and taxoid anticancer agents (taxoid = taxol-like compound). The topics covered in this chapter include (i) the development of a practical and efficient method for the semisynthesis of paclitaxel and docetaxel using chiral 3-hydroxy-P-lactams as synthetic intermediates, (ii) structure-activity relationship (SAR) studies of various taxoids that led to the discovery of the extremely potent second-generation taxoids, and (iii) biological and conformational studies with the use of fluorine-containing taxoids as probes. ... 

Our SAR study of paclitaxel analogues on their ability to activate macrophage, inducing the production of NO and TNF, has revealed stark differences in the structural requirements for cytotoxicity vs. macrophage activation. The results warrant a great deal of further study on the possible alternative or auxiliary mechanism of action for paclitaxel and taxoids, which might lead to the discovery of a new series of taxoid anticancer agents with unique mechanism of action. 

The second chapter addresses new facets of the medicinal chemistry of the important anticancer drug Taxol (paclitaxel). Ojima and coworkers explore, in particular, the structure-activity relationship associated with the 3-phenylisoserine side chain, synthetically exploiting their P-Lactam Synthon Method . Their research has led to, among other things, a series of noteworthy second-generation taxoid anticancer agents. 

Many anticancer agents have their origins in pharmacognosy, including paclitaxel, etoposide, and the camptothecin analogues, topotecan and irinotecan, to name just a few. The dolastatins are a unique class of compounds isolated from the Indian Ocean sea-hare Dolabdla auricularia that are referred to as depsipeptides,... 

Paclitaxel is a well-established antiproliferative agent with a microtubule-targeting pharmacologic activity (37,42,43). As an anticancer agent, paclitaxel causes polymerization and stabilization of microtubules (43-45). The stabilization of microtubule dynamics by paclitaxel can interrupt many cellular processes, including cell division, migration, activation, maintenance of cytoskeletal framework, and intracellular as well as transmembrane protein transport (42,46,47). 

Fig. 3 Venn-diagram for selected compounds interacting with the key MDR-related ABC transporters. MDR-substrate anticancer agents. Abbreviations VCR vincristine, VP-16 etoposide, STER steroids, TAM tamoxiphen, TKI-INHIB tyrosin kinase inhibitors e.g. STI-571, DOX doxorubicine or adriamycin, DNR daunorubicin, EPIR epirubicin, MX mitoxantrone, TOPOT topotecan, iridotecan, BISANT bisanthrone, COLCH colchicin, ACT-D actinomycin D, MYTOM mytomycin, TX methotrexate, CPHAM cyclophosphamide, CHLB chlorambucil, CARM carmustine, LCV leucovorin, HUR hydroxy urea, CISPL cisplatin, TAXOL paclitaxel. (Reproduced from [4])...

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