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Bridging converts a noncytotoxic nor-paclitaxel derivative to a cytotoxic analogue by constraining it to the T-Taxol conformation.

ABSTRACT: The synthesis of the bridged A-nor-paclitaxel 4 has been achieved from paclitaxel in a key test of the T-Taxol conformational hypothesis. Although the unbridged A-nor-paclitaxel 3 is essentially noncytotoxic, the bridged analogue 4 is strongly cytotoxic. This result provides strong evidence for the T-Taxol conformation as the bioactive tubulin-binding conformation of paclitaxel.

SUBMITTER: Tang S

PROVIDER: S-EPMC2562586 | biostudies-literature | 2006 Aug

REPOSITORIES: biostudies-literature

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Bridging converts a noncytotoxic nor-paclitaxel derivative to a cytotoxic analogue by constraining it to the T-Taxol conformation.

Tang Shoubin S Yang Chao C Brodie Peggy P Bane Susan S Ravindra Rudravajhala R Sharma Shubhada S Jiang Yi Y Snyder James P JP Kingston David G I DG

Organic letters 20060801 18

The synthesis of the bridged A-nor-paclitaxel 4 has been achieved from paclitaxel in a key test of the T-Taxol conformational hypothesis. Although the unbridged A-nor-paclitaxel 3 is essentially noncytotoxic, the bridged analogue 4 is strongly cytotoxic. This result provides strong evidence for the T-Taxol conformation as the bioactive tubulin-binding conformation of paclitaxel. ...[more]

PMID: 16928054

Similar Datasets

Synthesis and bioactivity of a side chain bridged paclitaxel: A test of the T-Taxol conformation.

Project description:A knowledge of the bioactive tubulin-binding conformation of paclitaxel (Taxol()) is crucial to a full understanding of the bioactivity of this important anticancer drug, and potentially also to the design of simplified analogs. The bioactive conformation has been shown to be best approximated by the T-Taxol conformation. As a further test of this conclusion, the paclitaxel analog 4 was designed as a compound which has all the chemical functionality necessary for activity, but which cannot adopt the T-Taxol conformation. The synthesis and bioassay of 4 confirmed its lack of activity, and thus provided further support for the T-Taxol conformation as the bioactive tubulin-binding conformation.

| S-EPMC2684938 | biostudies-literature

Design and synthesis of de novo cytotoxic alkaloids by mimicking the bioactive conformation of paclitaxel.

Project description:Novel paclitaxel-mimicking alkaloids were designed and synthesized based on a bioactive conformation of paclitaxel, that is, REDOR-Taxol. The alkaloid 2 bearing a 5-7-6 tricyclic scaffold mimics REDOR-Taxol best among the compounds designed and was found to be the most potent compound against several drug-sensitive and drug-resistant human cancer cell lines. MD simulation study on the paclitaxel mimics 1 and 2 as well as REDOR-Taxol bound to the 1JFF tubulin structure was quite informative to evaluate the level of mimicking. The MD simulation study clearly distinguishes the 5-6-6 and 5-7-6 tricyclic scaffolds, and also shows substantial difference in the conformational stability of the tubulin-bound structures between 2 and REDOR-Taxol. The latter may account for the large difference in potency, and provides critical information for possible improvement in the future design of paclitaxel mimics.

| S-EPMC2943045 | biostudies-literature

Design and synthesis of simplified taxol analogs based on the T-Taxol bioactive conformation.

Project description:A series of compounds designed to adopt a conformation similar to the tubulin-binding T-Taxol conformation of the anticancer drug paclitaxel has been synthesized. Both the internally bridged analogs 37-39, 41 and the open-chain analogs 27-29 and 43 were prepared. The bridged analogs 37-39 and 41 were synthesized by Grubbs' metatheses of compounds 30-32 and 33, which, in turn, were prepared by coupling ?-lactams 24-26 with alcohols 22 and 23. Both the bridged and the open-chain analogs showed moderate to good cytotoxicity.

| S-EPMC3225578 | biostudies-literature

Transcription profiling of mouse lymphoma L5178Y cells treated with Taxol (Paclitaxel) ILSI-HESI Genotoxicity Study - Taxol

Project description:Mouse lymphoma L5178Y cells are treated with Taxol (Paclitaxel) [CAS:33069-62-4;CHEBI:7887] and harvested at 4 and 24 hours for analysis.

2004-02-13 | E-TOXM-9 | biostudies-arrayexpress

Recent advances in the study of the bioactive conformation of taxol.

Project description:Paclitaxel is one of the most important chemotherapeutic drugs in the fight against cancer. This minireview covers the recent advances in the study of the bioactive conformation of paclitaxel in tubulin/microtubules. The tubulin-bound structure of paclitaxel has been studied by means of photoaffinity labeling, cryo-electron microscopy, solid-state NMR, molecular modeling, MD simulations and the synthesis of conformationally restrained analogues and paclitaxel mimics. The bioactive conformation of paclitaxel is important since it could provide critical information that would allow the design of novel analogues with simpler structures and/or increased potency against cancer.

| S-EPMC3072276 | biostudies-literature

Conjugation of Aspergillus flavipes Taxol with Porphyrin Increases the Anticancer Activity of Taxol and Ameliorates Its Cytotoxic Effects.

Project description:Taxol is one of the potential anticancer drugs; however, the yield of Taxol and its cytotoxicity are common challenges. Thus, manipulating the Taxol biosynthetic pathway from endophytic fungi, in addition to chemical modification with biocompatible polymers, is the challenge. Four fungal isolates, namely, Aspergillus flavipes, A. terreus, A. flavus, and A. parasiticus, were selected from our previous study as potential Taxol producers, and their potency for Taxol production was evaluated in response to fluconazole and silver nitrate. A higher Taxol yield was reported in the cultures of A. flavipes (185 µg/L) and A. terreus (66 µg/L). With addition of fluconazole, the yield of Taxol was increased 1.8 and 1.2-fold for A. flavipes and A. terreus, respectively, confirming the inhibition of sterol biosynthesis and redirecting the geranyl phosphate pool to terpenoids synthesis. A significant inhibition of ergosterol biosynthesis by A. flavipes with addition of fluconazole was observed, correlating with the increase on Taxol yield. To increase the Taxol solubility and to reduce its cytotoxicity, Taxol was modified via chemical conjugation with porphyrin, and the degree of conjugation was checked from the Thin layer chromatography and UV spectral analysis. The antiproliferative activity of native and modified Taxol conjugates was evaluated; upon porphyrin conjugation, the activity of Taxol towards HepG2 was increased 1.5-fold, while its cytotoxicity to VERO cells was reduced 3-fold.

| S-EPMC7024149 | biostudies-literature

Effects of Piperazine Derivative on Paclitaxel Pharmacokinetics.

Project description:Paclitaxel (PTX) is an anticancer agent that is used to treat many cancers but it has a very low oral bioavailability due, at least in part, to the drug efflux transporter, P-glycoprotein (P-gp). Therefore, this study was performed to enhance oral bioavailability of PTX. In this study, we investigated the effects of several piperazine derivatives on P-gp function in vitro. Compound 4 was selected as the most potent P-gp inhibitor from the in vitro results for examining the pharmacokinetic (PK) changes of PTX in rats. Compound 4 increased the AUCinf of PTX without alterations in the Cmax value. The elimination half-life was extended and the oral clearance decreased. Additionally, the Tmax was delayed or widened in the treatment groups. Therefore, the bioavailability (BA) of PTX was improved 2.1-fold following the co-administration of 5 mg/kg of the derivative. A piperazine derivative, compound 4, which was confirmed as a substantial P-gp inhibitor in vitro increased the BA of PTX up to 2-fold by a lingering absorption, in part due to inhibition of intestinal P-gp and a low oral clearance of PTX. These results suggest that co-administering compound 4 may change the PK profile of PTX by inhibiting P-gp activity in the body.

| S-EPMC6359037 | biostudies-literature

Synthetic paclitaxel-octreotide conjugate reversing the resistance of A2780/Taxol to paclitaxel in xenografted tumor in nude mice.

Project description:Peptide hormone-based targeted therapy to tumors has been studied extensively. Our previous study shows that somatostatin receptor expresses high level on drug-resistant human ovarian cancer. The paclitaxel-octreotide conjugate (POC) exhibits enhanced growth inhibition, as well as reduced toxicity, in paclitaxel-resistant human ovarian cancer cells. The aim of this study was to investigate the effect of targeted cytotoxicity and potential reversal mechanism of resistance in paclitaxel-resistant human ovarian cancer cells xenografted into nude mice. The SSTR2 shows higher expression levels in tumor tissue. Moreover, fluorescein-labeled POC displays favorable targeting in tumor cells. POC presents the perfect efficacy in inhibiting tumor growth and exerts lower or no toxic effects on normal tissues. Real-time PCR and Western Blotting has demonstrated that the mRNA and protein expressions of SSTR2 in POC group were significantly higher, while MDR1, α-tubulin, βIII-tubulin, VEGF and MMP-9 were significantly lower than in the other treatment groups and controls. Combined with the previous study in vitro, this study evaluates an effective approach on the treatment of paclitaxel-resistant ovarian cancer which expresses somatostatin receptor SSTR. Our investigation has also revealed the possible molecular mechanism of POC in treating the ovarian cancer, and therefore, provided a theoretical basis for the clinical application of this newly-invented compound.

| S-EPMC5347781 | biostudies-literature

Pharmacokinetic Alteration of Paclitaxel by Ferulic Acid Derivative.

Project description:P-glycoprotein (P-gp) is known to be involved in multidrug resistance (MDR) and modulation of pharmacokinetic (PK) profiles of substrate drugs. Here, we studied the effects of synthesized ferulic acid (FA) derivatives on P-gp function in vitro and examined PK alteration of paclitaxel (PTX), a well-known P-gp substrate drug by the derivative. Compound 5c, the FA derivative chosen as a significant P-gp inhibitor among eight FA candidates by in vitro results, increased PTX AUCinf as much as twofold versus the control by reducing PTX elimination in rats. These results suggest that FA derivative can increase PTX bioavailability by inhibiting P-gp existing in eliminating organs.

| S-EPMC6920777 | biostudies-literature

Transcription profiling of human immature dendritic cells treated with Lipopolysaccharide (LPS) vs Taxol (paclitaxel)

Project description:Generation of monocyte-derived dendritic cells (DC). Immature DC were prepared from peripheral blood mononuclear cells (PBMCs) isolated from whole blood of healthy donors. A minimum of 3 individual donor blood was used for each experiment. PBMCs were incubated with anti-CD14 microbeads (Miltenyi Biotec, Bergish Gladbach, Germany) as specified in the manufacturer's instructions. The isolated monocytes were resuspended at 10^6 cells/ml in medium supplemented with 10% human AB serum, 100 ng/ml GM-CSF (Leucomax; Novartis, Camberley, UK) and 50 ng/ml IL-4 (Peprotech EC Ltd, London, UK), cultured in tissue culture flasks. On day 7 the cells were defined as immature DC with low/intermediate HLA-DR expression. Microarray analysis of the effects of Paclitaxel and LPS on DC. Total RNA was extracted from day 7 DC which had been treated for 2 h with 1 ug/ml LPS or 100 uM paclitaxel for 2 h then washed and returned to culture for 24 h. This was used as a template to generate Cy3-labelled cRNA, using the Low RNA Input Linear Amplification Kit (Agilent). This was used as a probe on the Whole Human Genome Microarray (4x44K) slide (Agilent). Slides were scanned using the Agilent scanner and data extracted using Feature Extraction Software 9.5.3 (Agilent). Subsequent data analysis was performed using GeneSpring GX software.

2009-11-27 | E-MEXP-2465 | biostudies-arrayexpress

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