紫杉醇的合成进展

紫杉醇是一种重要的抗癌药物,它具有复杂新颖的化学结构,为三环二萜类化合物.本文综述了紫杉醇的半合成和紫杉烷环的各种合成方法.     

Peptidomimetics and metalloprotease inhibitors as anticancer drugs

Peptidomimetics with three types, as the structural or functional mimetics of natural active peptides, can preserve the bioactivity and improve the bioavailability and the specificity towards the targets of the lead peptides. Peptidomimetics of high bioactivity can be designed through various ways including conformation restriction, modification and non-peptide design. Recently the concentration on the development of cancer chemotherapeutic drugs was transferred from cytotoxic drugs to target-based drugs, and many proteases and peptidases that play key roles in the process of tumor genesis and development was discovered, which means that peptidomimetics as potential cancer chemotherapeutic drugs should be paid close attention to. Our laboratory has focused on the development of small-molecule peptidomimetic inhibitors of APN, MMPs and HDACs as target-based anticancer agents. These three zinc-dependent metalloproteinases play very important roles in the process of tumor genesis, invasion, metastasis, angiogenesis and matrix degradation, so small-molecule peptidomimetic inhibitors based on them would be quite potential in the development of chemotherapeutic drugs with high selectivity. Supported by the National High Technology Research and Development Program of China (863 Project) (Grant No. 2007AA02Z314), the National Natural Science Foundation of China (Grant Nos. 90713041 & 30772654), and the Doctoral Fund of Ministry of Education of China (Grant No. 20060422029)     

Magnetic microcapsules for targeted delivery of anticancer drugs

To achieve targeted distribution of anticancer drugs with sustained activity, ferromagnetic ethylcellulose microcapsules containing an anticancer drug, mitomycin C (FM-MMC-mc), were prepared by a method based on phase separation principles. Two prototypes of FM-MMC-mc were made: one with the drug as the core and zinc ferrite on its capsular surface (outer type); the other with both the drug and zinc ferrite as the core (inner type). Both preparations provided a sustained-release property and a sensitive response to conventional magnetic force, although certain differences in the release rate of drug, magnetic responsiveness, and particle size were found between the two dosage forms. Animal studies showed that the magnetic microcapsules could be magnetically controlled in the artery and urinary bladder. VX2 tumors in the rabbit hind limb and urinary bladder were successfully treated with magnetic control of FM-MMC-mc. Pharmacokinetic study revealed that the targeting of the microcapsules markedly enhanced the drug absorption into the surrounding tissues for a prolonged period of time. The results indicate the feasibility and effectiveness of the magnetic microcapsules as a targeted drug delivery system.     

First total synthesis of a novel amide alkaloid derived from Aconitum taipeicum and its anticancer activity

A concise total synthesis of a naturally occurring 3-isopropyl-tetrahydropyrrolo[1, 2-a]pyrimidine-2, 4(1H, 3H)-dione (ITPD) isolated from Aconitum taipeicum with a three-step approach was depicted in this study for the first time. Two key intermediates, diethyl isopropylmalonate (2) and pyrrolidin-2-amine (3), being synthsesised separately from initial diethyl malonate (4) and 3, 4-dihydro-2H-pyrrol-5-amine (5), were utilised to obtain the compound entitled ITPD. ITPD showed a promising anticancer activity in vitro on SMMC-7721 cell lines. Flow cytometry and cell cycle analysis revealed that ITPD could induce apoptosis and cell cycle arrest in S phase. The occurrence of apoptosis possibly attributed to the mechanism that ITPD could mediate the mitochondrial pathway through activating caspase-3/9 and increasing the ratio of Bax/Bcl-2 to finally trigger cell apoptosis and DNA damage. Collectively, the possibility to produce sufficient quantity of synthetic ITPD provided the base for further bio-evaluation in vivo and in vitro. The bioactive assay suggested that it may be a potential candidate for further chemical optimisation and use in cancer therapy.     

Towards a total synthesis of the new anticancer agent mensacarcin: synthesis of the carbocyclic core

A synthesis of the carbocyclic core associated with the new anticancer agent mensacarcin (1) is reported. The strategy involves the synthesis of several novel highly substituted aromatic compounds, such as 12 and 23. The lithium derivative of 12 readily engages in a nucleophilic addition to benzaldehyde 4 to provide the diphenylcarbinol rac-15. The analogous benzyl ether rac-16 undergoes an intramolecular Heck reaction to provide the required tetrahydroanthracene rac-17, which can be transformed into the key tricyclic methyl ether rac-20. In a second approach, the lithium derivative of 21 is added to the hexasubstituted benzaldehyde 23 to give the diphenylcarbinol rac-35. Subsequent methylation to rac-36 followed by an intramolecular Heck reaction provides tricycle rac-37. Similarly, the oxidised compound 40 provides an electronically more suitable intramolecular Heck partner to afford compound 41. Further transformations of these substrates leads to rac-43, which incorporates the core structure of mensacarcin (1).     

Norrisolide: total synthesis and related studies

A stereoselective synthesis of (+)-norrisolide is presented. This natural product belongs to a family of marine spongiane diterpenes the structure of which is characterized by a fused gamma-lactone-gamma-lactol ring system attached to a bicyclic hydrophobic core. Our studies led to the development of a expedient synthesis of such gamma-lactone-gamma-lactol motifs based on ring expansion of a fused cyclopropyl ester. Highlights of the synthetic strategy toward norrisolide include the coupling of the two bicyclic systems by constructing a sterically demanding C9-C10 bond and the installation of the C19 oxygen at the last step of the synthesis via a Baeyer-Villiger oxidation.     

Analysis of anticancer drugs: a review

In the last decades, the number of patients receiving chemotherapy has considerably increased. Given the toxicity of cytotoxic agents to humans (not only for patients but also for healthcare professionals), the development of reliable analytical methods to analyse these compounds became necessary. From the discovery of new substances to patient administration, all pharmaceutical fields are concerned with the analysis of cytotoxic drugs. In this review, the use of methods to analyse cytotoxic agents in various matrices, such as pharmaceutical formulations and biological and environmental samples, is discussed. Thus, an overview of reported analytical methods for the determination of the most commonly used anticancer drugs is given.     

Towards the synthesis of massadine: a unified strategy for the stereoselective synthesis of the carbocyclic C,D-ring subunit

Massadine is a hexacyclic marine natural product, which belongs to the family of pyrrole-imidazole alkaloids. Herein, we describe a unified approach to the C,D-ring subunit of this sponge metabolite based on the exploitation of a norbornene scaffold for the stereocontrolled construction of massadine's carbon skeleton. Highlights of the sequence presented include the application of a stereospecific norbornyl rearrangement for facile introduction of an oxygen at the C7-position within the norbornene nucleus, a highly regioselective and end group differentiating ozonolytic scission of a C-C double bond, and an oxidative decarboxylation reaction for the installation of the hindered secondary C2-alcohol function. Furthermore, the iterative assembly of the two guanidine entities as well as the implementation of the spirocyclic junction between the C- and the D-rings are described. Collectively, these key transformations permit an entry to an appropriately functionalized carbon framework, which will serve as a starting point for our efforts toward the completion of the synthesis of massadine.     

Review: recent advances and future development of metal complexes as anticancer agents

Since the initial discovery of applications of platinum complexes in the clinical treatment of many kinds of cancers, the efficiency of platinum complexes in inhibiting the proliferation of various types of tumors surprised researchers working on the development of anticancer drugs. Meanwhile, despite the potent clinical treatment patients get from platinum complexes, there are also disadvantages including limited solubility in aqueous media and side effects like ototoxicity, myelosuppression, nephrotoxicity, and poor selectivity toward healthy cells. For this reason, efforts have been made to search for novel solutions. Non-platinum complexes (like Fe, Pd, Ru, Cu, Bi, Zn, etc.) were found with potential anticancer activities. We here review the properties of five metal complexes as anticancer agents and make comparisons among them in biological features and cytotoxic activity. Seeking the interrelation between microstructure and mechanism of anticancer, we hope this review provides distinct insights into future study of anticancer agents.     

Total Synthesis of Camptothecin and Related Natural Products by a Flexible Strategy

A flexible strategy for constructing natural products containing indolizinone or quinolizinone scaffolds and their analogues was developed, which was based on a cascade exo hydroamination followed by spontaneous lactamization. This method was applied in the total synthesis of camptothecin in nine steps in a new ring‐forming approach. It was also used to efficiently prepare five biogenetically or structurally related natural alkaloids, including 22‐hydroxyacuminatine, oxypalmatine, norketoyobyrine, naucleficine, and nauclefine, as well as 35 natural‐product‐like molecules. We believe that this method and the small‐molecule library prepared with it can open new avenues for studying the bioactivity of camptothecin and Nauclea natural products.     

On the remarkable antitumor properties of fludelone: how we got there

Small-molecule natural products are presumably often biosynthesized with a view to optimizing their ability to bind to strategic proteins or other biomolecular targets. Although the ultimate setting in which a drug must function may be very different, the use of such natural products as lead compounds can serve as a significant head start in the hunt for new agents of clinical value. Herein we reveal the synergistic relationship between chemical synthesis and drug optimization in the context of our research program around the epothilones: how synthesis led to the discovery of more-potent epothilone derivatives, and discovery inspired the development of new synthetic routes, thus demonstrating the value of target-directed total synthesis in the quest for new substances of material clinical benefit.     

Total synthesis of complex cyclotryptamine alkaloids: stereocontrolled construction of quaternary carbon stereocenters

Our ability to access the more complex members of the cyclotryptamine family of alkaloids, and to exploit their disparate biological activities, is limited by the synthetic challenge posed by their oligomeric, polyindoline structures. A recurring structural theme within these molecules is the presence of multiple quaternary stereocenters in close proximity to one another. Over the last decade, we have developed a set of transformations that allow rapid access to polyindolines, a number of which exploit the ability of catalytic levels of palladium to orchestrate carbon-carbon bond formation with impressive levels of regio- and stereocontrol. This review tells the story behind the development of this toolbox of synthetic methods, and their validation through the total synthesis of a number of structurally complex cyclotryptamine alkaloids. It also highlights an aspect of asymmetric catalysis that has received little attention, the ability of catalytic asymmetric reactions to selectively elaborate complex, polyfunctional molecules.