Orally active docetaxel analogue: synthesis of 10-deoxy-10-C-morpholinoethyl docetaxel analogues

Research Advances on Anti-Cancer Natural Products

Malignant tumors seriously threaten people's health and life worldwide. Natural products, with definite pharmacological effects and known chemical structures, present dual advantages of Chinese herbs and chemotherapeutic drug. Some of them exhibit favorable anti-cancer activity. Natural products were categorized into eight classes according to their chemical structures, including alkaloids, terpenoids and volatile oils, inorganic salts, phenylpropanoids, flavonoids and isoflavones, quinone, saponins and polysaccharides. The review focused on the latest advances in anti-cancer activity of representative natural products for every class. Additionally, anti-cancer molecular mechanism and derivatization of natural products were summarized in detail, which would provide new core structures and new insights for anti-cancer new drug development.

Synthesis and biological evaluation of new paclitaxel analogs and discovery of potent antitumor agents

Reaction of 10-deacetylbaccatin III (III) and its 7-TES derivative (IV) with DAST under various conditions resulted in the formation of an array of new fluorinated and non-fluorinated 13-keto taxoid compounds (2a–4a) through a vinylogous pinacol–pinacolone rearrangement. Further fluorination of some of these products (2a, 3a) with NFSi or Selectfluor gave additional derivatives. Sodium borohydride reduction of the 13-keto group of these products (2a, 2b, 3a, 3b, 4a, 8, 9, 11–14) led to a series of 9α-hydroxy taxoid derivatives, which were esterified using the docetaxel side chain employing the corresponding protected β-lactam, followed by deprotection to furnish a library of docetaxel analogs and related compounds. A selected number of synthesized compounds (7, 10, 19a, 19b, 21a, 21b, 23, 27, 29, 34–36) were submitted to the National Cancer Institute (NCI) 60 cell line screening program and tested for cytotoxic properties. Taxoids 19a, 19b, 21a, 21b, 23, 27, 29, 34 and 35 were found to exhibit significant anticancer activity against various cancerous cell lines with 23, 27, and 29 being the most potent compounds, demonstrating GI50 values of ≤5 nM in several assays.

Standard protecting groups create potent and selective kappa opioids: salvinorin B alkoxymethyl ethers

Protection of salvinorin B as standard alkoxyalkyl ethers yielded highly potent kappa opioid receptor agonists. Ethoxymethyl ether 6 is among the most potent and selective kappa agonists reported to date. Fluoroethoxymethyl ether 11 is the first potent, selective fluorinated kappa ligand, with potential use in MRI and PET studies. Further enlargement of the alkoxy group, alkylation of the acetal carbon, or heteroatom substitution all reduced activity. These protecting groups may prove useful in related work not only by enabling the use of harsher synthetic conditions, but potentially by optimizing the potency of the products.

Standard protecting groups create potent and selective kappa opioids: salvinorin B alkoxymethyl ethers

Protection of salvinorin B as standard alkoxyalkyl ethers yielded highly potent kappa opioid receptor agonists. Ethoxymethyl ether 6 is among the most potent and selective kappa agonists reported to date. Fluoroethoxymethyl ether 11 is the first potent, selective fluorinated kappa ligand, with potential use in MRI and PET studies. Further enlargement of the alkoxy group, alkylation of the acetal carbon, or heteroatom substitution all reduced activity. These protecting groups may prove useful in related work not only by enabling the use of harsher synthetic conditions, but potentially by optimizing the potency of the products.

Clinical pharmacokinetics of docetaxel : recent developments

Docetaxel belongs to the class of taxane antineoplastic agents that act by inducing microtubular stability and disrupting the dynamics of the microtubular network. The drug has shown a broad spectrum of antitumour activity in preclinical models as well as clinically, with responses observed in various disease types, including advanced breast cancer and non-small cell lung cancer. The pharmacokinetics and metabolism of docetaxel are extremely complex and have been the subject of intensive investigation in recent years. Docetaxel is subject to extensive metabolic conversion by the cytochrome P450 (CYP) 3A isoenzymes, which results in several pharmacologically inactive oxidation products. Elimination routes of docetaxel are also dependent on the presence of drug-transporting proteins, notably P-glycoprotein, present on the bile canalicular membrane. The various processes mediating drug elimination, either through metabolic breakdown or excretion, impact substantially on interindividual variability in drug handling. Strategies to individualise docetaxel administration schedules based on phenotypic or genotype-dependent differences in CYP3A expression are underway and may ultimately lead to more selective chemotherapeutic use of this agent.

DJ-927, a novel oral taxane, overcomes P-glycoprotein-mediated multidrug resistance in vitro and in vivo

DJ-927 is a novel taxane, which was selected for high solubility, non-neurotoxicity, oral bioavailability, and potent antitumor activity. In this study, we compared the in vitro and in vivo efficacy of DJ-927 with those of paclitaxel and docetaxel. DJ-927 exhibited stronger cytotoxicity than paclitaxel and docetaxel in various tumor cell lines, especially against P-glycoprotein (P-gp)-expressing cells. The cytotoxicity of DJ-927, unlike those of other taxanes, was not affected by the P-gp expression level in tumor cells, or by the co-presence of a P-gp modulator. When intracellular accumulation of the three compounds was compared, intracellular amounts of DJ-927 were much higher than those of paclitaxel or docetaxel, particularly in P-gp-positive cells. In vivo, DJ-927 showed potent antitumor effects against two human solid tumors in male BALB/c-nu/nu mice, and yielded significant life-prolongation in a murine liver metastasis model with male C57BL/6 mice, in which neither paclitaxel nor docetaxel was effective. The results demonstrate the superior efficacy of orally administered DJ-927 over intravenously administered paclitaxel or docetaxel against P-gp-expressing tumors, probably due to higher intracellular accumulation. A phase I clinical trials of DJ-927 is currently ongoing in the US.

A new method for synthesis of 7-deoxytaxane analogues by hydrogenation of delta(6,7)-taxane derivatives

A new method for the synthesis of 7-deoxytaxane analogues has been established through hydrogenation of Delta(6,7)-taxane derivatives. Among several catalysts examined, Pd-C was found to be a most effective catalyst for the preparation of target compound.

New highly active taxoids from 9β-dihydrobaccatin-9,10-acetals. Part 2

To investigate structure-activity relationships of the 9,10-acetal-9beta-dihydro taxoids, we modified the 7-hydroxyl groups of the 9,10-acetonide-3'-(4-pyridyl) analogue to deoxy, methoxy, alpha-F, and 7beta,8beta-methano group. As a result of this study, we found that the 7-deoxy analogue was the strongest among these analogues. In addition, we found that the 7-deoxy-3'-(4-pyridyl) and 7-deoxy-3'-(2-pyridyl) analogues showed stronger activity against cell lines expressing P-glycoprotein than the corresponding 3'-phenyl analogue.