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Baccatin III (baccatin + iii)
Selected AbstractsOxidation of Baccatin III at C14: A Facile Rearrangement of the Baccatin III Core.CHEMINFORM, Issue 43 2007Dinah Dutta Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Expression of an acetyl-CoA synthase and a CoA-transferase in Escherichia coli to produce modified taxanes in vivoBIOTECHNOLOGY JOURNAL, Issue 2 2007Catherine Loncaric Abstract Previous in vitro studies revealed that the 10-deacetylbaccatin III 10,- O -acetyltransferase (DBAT) from Taxus can catalyze the transfer of acetyl, propionyl or n -butyryl from CoA to the C10-hydroxyl of 10-deacetylbaccatin III. Accordingly, Escherichia coli JM109 were transformed to recombinantly express dbat, and this enzyme function was coupled to that of acetyl-CoA synthase (acs, EC 6.2.1.1) expressed from and regulated by genes encoded on the bacterial chromosome. Incubation of the bacteria with 10-deacetylbaccatin III and increasing concentrations of acetic acid revealed an in vivo conversion (,10%) of substrate to natural product baccatin III (C10-acetylated), which was remarkably similar to the relative conversion without acid supplementation. Incubation of the modified E. coli with 5 mM propionic acid, revealed a fivefold increase in the conversion (,13%) of 10-deacetylbaccatin III to 10-deacetyl-10-propionylbaccatin III, compared to ,2% conversion in the absence of exogenous propionate. To produce the butyrylbaccatin III analog in vivo, bacteria were engineered to co-express the dbat and atoAD (EC 2.8.3.8) genes; the latter encodes an acetoacetate: acetyl-CoA CoA-transferase that activates butyrate to butyryl CoA. The bacteria were incubated with 10-deacetylbaccatin III and 25-100 mM butyrate, and a maximum of ,2.6% conversion to 10-butyrylbaccatin III was observed compared to ,0.6% conversion when no exogenous butyrate was supplied. [source] Improved Paclitaxel and Baccatin III Production in Suspension Cultures of TaxusmediaBIOTECHNOLOGY PROGRESS, Issue 3 2002Rosa M. Cusidó A cell suspension culture of Taxus media was established from a stable callus line of this species. The growth rate and production of paclitaxel and baccatin III of this cell suspension were significantly increased during the shake flask culture in its respective optimum media for cell growth and product formation, which were selected after assaying 24 different culture media. The highest yields of paclitaxel (2.09 mg L,1) and baccatin III (2.56 mg L,1) in the production medium rose (factors of 7.0 and 3.0, respectively) in the presence of methyljasmonate (220 ,g g,1 FW). When the elicitor was added together with mevalonate (0.38 mM) and N -benzoylglycine (0.2 mM), the increase in the yields of paclitaxel and baccatin III was even higher (factors of 8.3 and 4.0, respectively). Thereafter, a two-stage culture for cell suspension was carried out using a 5,l stirred bioreactor running for 36 days, the first stage being in the cell growth medium until cells entered their stationary growth phase (12 days) and the second stage being in the production medium supplemented with the elicitor and two putative precursors in the concentrations indicated above. Under these conditions, 21.12 mg L,1 of paclitaxel and 56.03 mg L,1 of baccatin III were obtained after 8 days of culture in the production medium. [source] Synthesis and Biological Evaluation of N -(Arylsulfanyl)carbonyl Analogues of Paclitaxel (Taxol)CHEMISTRY & BIODIVERSITY, Issue 4 2006Bekir Karliga Abstract Four new N -(arylsufanyl)carbonyl paclitaxel analogues (2a,d) were prepared from 7-(triethylsilyl)-protected baccatin III (5). Their cytotoxicities against human ovarian (A2780) and prostate cancer (PC3) cell lines, as well as their tubulin-assembly activities, were determined. In these assays, the new compounds showed rather weak activities, one two orders of magnitude below those of paclitaxel (taxol; 1). The known 3,- N- [(thiophen-2-yl)carbonyl] paclitaxel analogue 3 was also prepared. As previously reported, 3 exhibited strongly improved cytotoxicities and tubulin-assembly activities as compared to paclitaxel (1). [source] | |||||||||||||