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Combretastatin A-4 inhibits cell growth and metastasis in bladder cancer cells and retards tumour growth in a murine orthotopic bladder tumour model
BACKGROUND AND PURPOSE Bladder cancer is a highly recurrent cancer after intravesical therapy, so new drugs are needed to treat this cancer. Hence, we investigated the anti-cancer activity of combretastatin A-4 (CA-4), an anti-tubulin agent, in human bladder cancer cells and in a murine orthotopic bladder tumour model. EXPERIMENTAL APPROACH Cytotoxicity of CA-4 was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, propidium iodide (PI) staining assay and clonogenic survival assay. In vivo microtubule assembly assay, cell cycle analyses, Western blot and cell migration assay were used to study the mechanism of CA-4. The effect of intravesical CA-4 therapy on the development of tumours was studied in the murine orthotopic bladder tumour model. KEY RESULTS CA-4 inhibited microtubule polymerization in vivo. Cytotoxic IC50 values of CA-4 in human bladder cancer cells were below 4 nM. Analyses of cell-cycle distribution showed CA-4 obviously induced G2-M phase arrest with sub-G1 formation. The analyses of apoptosis showed that CA-4 induced caspase-3 activation and decreased BubR1 and Bub3 in cancer cells. In addition to apoptosis, CA-4 was also found to induce the formation of multinucleated cells. CA-4 had a significantly reduced cell migration in vitro. Importantly, the in vivo study revealed that intravesical CA-4 therapy retarded the development of murine bladder tumours. CONCLUSIONS AND IMPLICATIONS These data demonstrate that CA-4 kills bladder cancer cells by inducing apoptosis and mitotic catastrophe. It inhibited cell migration in vitro and tumour growth in vivo. Hence, CA-4 intravesical therapy could provide another strategy for treating superficial bladder cancers.
Shen, Cheng-Huang,Shee, Jia-Jen,Wu, Jin-Yi,Lin, Yi-Wen,Wu, Jiann-Der,Liu, Yi-Wen
p. 2008 - 2027
(2010)
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Dual-targeting antitumor conjugates derived from platinum(IV) prodrugs and microtubule inhibitor CA-4 significantly exhibited potent ability to overcome cisplatin resistance
Here we report that three platinum(IV) prodrugs containing a tubulin inhibitor CA-4, as dual-targeting platinum(IV) prodrug, were synthesized and evaluated for antitumor activity using MTT assay. Among them, complex 9 exhibited the most potent antitumor activity against the tested cancer lines including cisplatin resistance cancer cells, and simultaneously displayed lower toxicity compared to cisplatin, respectively. Moreover, complex 9, in which was conjugated to an inhibitor of tubulin at one axial position of platinum(IV) complex, could effectively enter the cancer cells, and significantly induce cell apoptosis and arrest the cell cycle in A549 cells at G2/M stage, and dramatically disrupt the microtubule organization. In addition, mechanism studies suggested that complex 9 significantly induced reactive oxygen species (ROS) generation and decreased mitochondrial trans-membrane potential (MMP) in A549 cells, and effectively induced activation of caspases triggering apoptotic signaling through mitochondrial dependent apoptosis pathways.
Huang, Xiaochao,Wang, Meng,Wang, Chungu,Hu, Weiwei,You, Qinghong,Yang, Yong,Yu, Chunhao,Liao, Zhixin,Gou, Shaohua,Wang, Hengshan
(2019)
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Combretastatin A-4 Analogue: A Dual-Targeting and Tubulin Inhibitor Containing Antitumor Pt(IV) Moiety with a Unique Mode of Action
Three new Pt(IV) complexes comprising a combretastatin A-4 analogue were designed and synthesized. The resulting antitumor Pt(IV) complexes could significantly improve the antiproliferative activity and overcome the drug resistance of cisplatin in vitro. Interestingly, these novel compounds not only can carry the DNA binding Pt(II) warhead into the cancer cells but also have a small molecule fragment that can inhibit tubulin polymerization. Among them, complex 13, which was attached to an inhibitor of tubulin at one axial position of Pt(IV) octahedral coordination sphere, could effectively enter cancer cells, arrest the cell cycle in HepG-2 cancer cells at G2/M phases, and induce activation of caspases triggering apoptotic signaling via the mitochondrial-dependent apoptosis pathways. Moreover, complex 13 has the ability to effectively inhibit the tumor growth in the HepG-2 xenograft model without causing significant loss of animal body weight in comparison with cisplatin.
Huang, Xiaochao,Huang, Rizhen,Gou, Shaohua,Wang, Zhimei,Liao, Zhixin,Wang, Hengshan
p. 2132 - 2148
(2016)
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New efficient synthesis of combretastatin A-4 via Colvin rearrangement
A new four-step approach for the synthesis of anticancer agent combretastatin A-4 (CA-4) has been developed. The method includes the Colvin rearrangement of the benzophenone derivative phenstatin to the key diarylalkyne followed by stereoselective semi-reduction to CA-4 in good overall yield.
Petrov, Ognyan I.,Gerova, Mariana S.,Chanev, Christo D.,Petrova, Katya V.
p. 3711 - 3715
(2011)
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A protecting group-free synthesis of the antineoplastic agent combretastatin A4
The synthesis of combretastatin A4 (CA4) from commercially available inexpensive materials has been achieved via the Wittig reaction followed by irradiation of the (Z)/(E)-CA4 reaction mixture with sunlight. The method resulted in (Z)-CA4 in high yield. This method does not require protection of the phenolic hydroxy group. The synthesis is operationally simple and cost-efficient.
Guo, Xiaotao,Zhang, Dan,Yu, Zhifang,Liu, Tianzhen,Li, Dachang,Li, Chunbao
p. 229 - 230
(2011)
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Design, Synthesis, and in vitro and in vivo Evaluations of (Z)-3,4,5-Trimethoxystyrylbenzenesulfonamides/sulfonates as Highly Potent Tubulin Polymerization Inhibitors
Newer therapeutics can be developed in drug discovery by adopting the strategy of scaffold hopping of the privileged scaffolds from known bioactive compounds. This strategy has been widely employed in drug-discovery processes. Structure-based docking studies illustrate the basic underlying concepts and reveal that interactions of the sulfonamide group and hydrophobic interactions are crucial. On the basis of this strategy, over 60 synthetic analogues were synthesized and evaluated for their cytotoxicity against the NCI panel of 60 human cancer cell lines; the majority of these compounds exhibited promising cytotoxicity with GI50 values ranging between 18 and 50 nm. Among these compounds, (Z)-N-[2,3-dimethoxy-5-(3,4,5-trimethoxystyryl)phenyl]-4-methoxybenzenesulfonamide (7 a) and (Z)-N-[2-hydroxy-3-methoxy-6-(3,4,5-trimethoxystyryl)phenyl]-4-methoxybenzenesulfonamide (9 a) were found to be potent. Similar results were obtained against three human cancer cell lines with IC50 values ranging between 0.04 and 3.0 μm. Studies aimed at elucidating the mechanism of action of these new analogues revealed that they inhibited the in vitro polymerization of tubulin and disorganized the assembly of microtubules in HeLa and MCF-7cancer cells. Lead compounds 7 a and 9 a displayed notable in vivo antitumor activity in a HeLa tumor xenograft model. Our studies have resulted in the identification of a scaffold that can target tubulin polymerization, which should have significant potential toward the development of new antitumor drugs.
Mahesh, Rasala,Nayak, Vadithe Lakshma,Babu, Korrapati Suresh,Riyaz, Syed,Shaik, Thokhir Basha,Kumar, Gajjela Bharth,Mallipeddi, Prema Latha,Reddy, Challa Ratna,Shekar, Kunta Chandra,Jose, Jedy,Nagesh, Narayana,Kamal, Ahmed
p. 678 - 700
(2017)
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Synthesis and in Vitro Bioactivity of Polyunsaturated Fatty Acid Conjugates of Combretastatin A-4
Combretastatin A-4 (CA-4) (1) is a plant-derived anticancer agent binding to the tubulin colchicine site. Polyunsaturated fatty acids (PUFAs) are readily taken up by cancer cells and have been used to improve cell targeting. In the present study, four CA-4-PUFA conjugates were synthesized by coupling combretastatin A-4 (1) with several polyunsaturated fatty acids. The conjugates (2a-d) were characterized using spectroscopic methods. Their cytotoxicity was evaluated against human breast cancer cells (MCF-7), and the inhibition of tubulin polymerization was determined in vitro. All conjugates influenced tubulin polymerization, with the arachidonic acid conjugate (2c) displaying cytotoxicity similar in potency to the natural product CA-4 (1).
Ojike, Fredrick O.,Lavignac, Nathalie,Casely-Hayford, Maxwell A.
p. 2101 - 2105
(2018)
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The synthesis of (E) and (Z)-combretastatins A-4 and a phenanthrene from Combretum caffrum
The synthesis of the trans stilbene E-combretastatin A-4 has been achieved via a Horner-Wittig reaction of (3,4,5- trimethoxybenzyl)diphenylphosphine oxide. The anticancer drug Z- combretastatin A-4 was prepared by the hydroboration/protonation of a diaryl- alkyne.
Lawrence, Nicholas J.,Ghani, Fazni Abdul,Hepworth, Lucy A.,Hadfield, John A.,McGown, Alan T.,Pritchard, Robin G.
p. 1656 - 1660
(1999)
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Synthesis and Cytotoxicity Studies of Stilbene Long-Chain Fatty Acid Conjugates
A series of 16 conjugates of the tubulin polymerization inhibitor combretastatin A4 (CA-4) and other functionally related stilbene with four 18-carbon fatty acids, namely, stearic, oleic, linoleic, and linolenic acids, have been synthesized in good yields. These new derivatives have been evaluated against the KB-3-1 (human epidermoid carcinoma), NCI-H460 (human lung cancer), HEK293 (human embryonic kidney), and MCF-7 (human breast adenocarcinoma) cell lines for antiproliferative activity, with the exhibited cytotoxic activities comparable with those of CA-4 and colchicine. Compounds 22 and 23, CA-4 conjugates of linoleic and linolenic acids, respectively, were determined to have exhibited the most active in vitro assays, with compound 23 exhibiting very similar activity to the parent compound against the NCI-H460 cell line. Our studies further delineated the structurally required Z-geometry of the stilbene moiety and that conjugation of the less active E-stilbenes with the most active fatty acid had minimal or no improvement in their respective activities.
Brown, David P.,Chen, Zhe-Sheng,Narayanan, Silpa,Wong, Thomas
(2020)
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Heterobimetallic Pd/Mn and Pd/Co complexes as efficient and stereoselective catalysts for sequential Cu-free Sonogashira coupling–alkyne semi-hydrogenation reactions
A series of heterobimetallic PdII/MII complexes (MII = Mn, Co) were synthesised and tested as precatalysts for sequential Sonogashira coupling–alkyne semi-hydrogenation reactions to form Z-aryl alkenes. The carbometalated heterobimetallic PdII/CoII complex CoPdL3′ demonstrated an apparent cooperative effect compared to the corresponding monometallic counterparts. This compound was identified as a potent single-molecule catalyst for the one-pot Cu-free Sonogashira coupling of aryl bromides with terminal alkynes followed by chemo- and stereoselective semi-hydrogenation of the alkyne intermediate using NH3·BH3 as a hydrogen source. Furthermore, different aromatic substrates have been tested to show the generality of the reaction for the synthesis of Z-alkenes, including biologically active combretastatin A-4. In addition, the homogeneous nature of the catalytically active species was demonstrated.
Baweja, Saral,Clauss, Reike,Gelman, Dmitri,Hey-Hawkins, Evamarie
p. 1344 - 1356
(2022/02/03)

Design, synthesis and biological evaluation of combretastatin A-4 sulfamate derivatives as potential anti-cancer agents
A series of combretastatin A-4 (CA-4) sulfamate derivatives were synthesized and their structure-activity relationship on tubulin, arylsulfatase and tumor cell antiproliferation inhibition was studied. Among them, compound 16a showed excellent potency as well as CA-4 under the same conditions against six tumor cells including HTC-116, HeLa, HepG2, MGC803, MKN45 and MCF-7 cells, respectively. Molecular docking revealed that several important hydrogen bond interactions were formed between the sulfamate group of 16a and the colchicine binding site of tubulin and steroid sulfatase respectively. Although compound 16a was less active than CA-4 in regard to its in vitro activity as an inhibitor of tubulin polymerization, it was effective as an inhibitor of arylsulfatase. This novel combretastatin A-4 sulfamate derivative has the potential to be developed as a dual inhibitor of tubulin polymerization and arylsulfatase for cancer therapy.
Huang, Jinwen,Huang, Leilei,Li, Yingzi,Nie, Hui,Song, Lixing,Wu, Fanhong
supporting information
p. 1374 - 1380
(2021/09/30)

Orchid heterocyclic derivative as well as preparation method and application thereof
The invention relates to a lansamine heterocyclic derivative as well as a preparation method and application thereof. Wherein, X is O or NH. R Is one of a furanyl heterocyclic substituent, a thiophenyl heterocyclic substituent, a thiazolyl heterocyclic substituent, a pyrimidinyl heterocyclic substituent, a pyridazinyl heterocycle substituent, an indolyl heterocyclic substituent, and an indolyl heterocyclic substituent. The preparation method comprises the following steps: carrying out condensation reaction on crude orchid and a carboxylic acid compound containing the substituent R. Or, 4 - methoxy -3 - nitrobenzaldehyde and 3,trimethoxy - triphenyl benzyl bromide salt is used as a raw material, and after Wittig reaction and reduction reaction, the tetracarboxylic acid compound containing the substituent R is subjected to a condensation reaction. Compared with the prior art, heterocyclic compounds such as crude orchid and nicotinic acid are connected through an ester bond to form a twin medicine, and a new way is provided for improving the pharmacological activity of the crude orchid.
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Paragraph 0081-0085

(2021/10/16)

An Amine-Assisted Ionic Monohydride Mechanism Enables Selective Alkyne cis-Semihydrogenation with Ethanol: From Elementary Steps to Catalysis
The selective synthesis of Z-alkenes in alkyne semihydrogenation relies on the reactivity difference of the catalysts toward the starting materials and the products. Here we report Z-selective semihydrogenation of alkynes with ethanol via a coordination-induced ionic monohydride mechanism. The EtOH-coordination-driven Cl- dissociation in a pincer Ir(III) hydridochloride complex (NCP)IrHCl (1) forms a cationic monohydride, [(NCP)IrH(EtOH)]+Cl-, that reacts selectively with alkynes over the corresponding Z-alkenes, thereby overcoming competing thermodynamically dominant alkene Z-E isomerization and overreduction. The challenge for establishing a catalytic cycle, however, lies in the alcoholysis step; the reaction of the alkyne insertion product (NCP)IrCl(vinyl) with EtOH does occur, but very slowly. Surprisingly, the alcoholysis does not proceed via direct protonolysis of the Ir-C(vinyl) bond. Instead, mechanistic data are consistent with an anion-involved alcoholysis pathway involving ionization of (NCP)IrCl(vinyl) via EtOH-for-Cl substitution and reversible protonation of Cl- ion with an Ir(III)-bound EtOH, followed by β-H elimination of the ethoxy ligand and C(vinyl)-H reductive elimination. The use of an amine is key to the monohydride mechanism by promoting the alcoholysis. The 1-amine-EtOH catalytic system exhibits an unprecedented level of substrate scope, generality, and compatibility, as demonstrated by Z-selective reduction of all alkyne classes, including challenging enynes and complex polyfunctionalized molecules. Comparison with a cationic monohydride complex bearing a noncoordinating BArF- ion elucidates the beneficial role of the Cl- ion in controlling the stereoselectivity, and comparison between 1-amine-EtOH and 1-NaOtBu-EtOH underscores the fact that this base variable, albeit in catalytic amounts, leads to different mechanisms and consequently different stereoselectivity.
Huang, Zhidao,Wang, Yulei,Leng, Xuebing,Huang, Zheng
supporting information
p. 4824 - 4836
(2021/04/07)

Stereoselective Bromoboration of Acetylene with Boron Tribromide: Preparation and Cross-Coupling Reactions of (Z)-Bromovinylboronates
The mechanism of acetylene bromoboration in neat boron tribromide was studied carefully by means of experiment and theory. Besides the syn-addition mechanism through a four-center transition state, radical and polar anti-addition mechanisms are postulated, both triggered by HBr, which is evidenced also to take part in the Z/E isomerization of the product. The proposed mechanism is well supported by ab initio calculations at the MP2/6-31+G? level with Ahlrichs' SVP all-electron basis for Br. Implicit solvation in CH2Cl2 has been included using the PCM and/or SMD continuum solvent models. Comparative case studies have been performed involving the B3LYP/6-31+G? with Ahlrichs' SVP for Br and MP2/Def2TZVPP levels. The mechanistic studies resulted in development of a procedure for stereoselective bromoboration of acetylene yielding E/Z mixtures of dibromo(bromovinyl)borane with the Z-isomer as a major product (up to 85%). Transformation to the corresponding pinacol and neopentyl glycol boronates and stereoselective decomposition of their E-isomer provided pure (Z)-(2-bromovinyl)boronates in 57-60% overall yield. Their reactivity in a Negishi cross-coupling reaction was tested. An example of the one-pot reaction sequence of Negishi and Suzuki-Miyaura cross-couplings for synthesis of combretastatin A4 is also presented.
Polá?ek, Jan,Paciorek, Jan,Sto?ek, Jakub,Semrád, Hugo,Munzarová, Markéta,Mazal, Ctibor
p. 6992 - 7000
(2020/06/05)

Microtubule inhibitors containing immunostimulatory agents promote cancer immunochemotherapy by inhibiting tubulin polymerization and tryptophan-2,3-dioxygenase
A combination therapeutic regimen via introducing tryptophan 2,3-dioxygenase inhibitors into microtubule inhibitors was performed and evaluated for their antitumor activity. Thereinto, HT2, composed of combretastatin A-4 (CA-4) and tryptophan-2,3-dioxygenase (TDO) inhibitor by a linker, displayed the most potent activity with 10-fold higher than its parent CA-4 against HepG2, A549 and HCT-116 cancer cell lines. Mechanism studies suggested that HT2 inhibited tubulin polymerization and cell migration, caused G2 phase arrest, induced apoptosis by mitochondrial mediated apoptotic pathway, concurrent depolarized the mitochondria membrane potentials and caused reactive oxygen species (ROS) production in HepG2 cells. Moreover, HT2 could enhance T-cell immune responses in vitro by releasing a TDO inhibitor to suppress TDO expression and blockade kynurenine production. As expected, HT2 could remarkably promote the antitumor activity of CA-4 in either immunocompetent H22 or immunodeficient A549 tumor xenograft models without observable toxic effects. More importantly, HT2 increased the level of splenic and tumor-infiltrated T cells and in turn effectively boosted the inhibition effect in H22 xenografted tumor growth. Collectively, this immunochemotherapeutic strategy can be applied to promote chemotherapeutic effect.
Hua, Shixian,Chen, Feihong,Gou, Shaohua
supporting information

(2019/12/11)

Dual-functional conjugates improving cancer immunochemotherapy by inhibiting tubulin polymerization and indoleamine-2,3-dioxygenase
A series of novel conjugates comprising tublin and IDO inhibitors were designed, synthesized and evaluated for their antiproliferative activity. Among them, HI5, composed of combretastatin A-4 (CA-4) and (D)-1-methyltryptophan (D-MT) by a linker, exhibited the most potent antitumor activity, in particular with higher IC50 value (0.07 μM) than CA-4 (0.21 μM) against HeLa cancer cell line. Mechanism studies indicated that HI5 can inhibit tubulin polymerization and cell migration, cause G2/M phase arrest, concurrent induce apoptosis via the mitochondrial dependent apoptosis pathway and cause reactive oxidative stress generation in HeLa cells. Furthermore, HI5 can inhibit IDO expression and decrease kynurenine production, leading to stimulating T cells activation and proliferation to enhance antitumor immunity in vitro. Interestingly, HI5 can effectively limit the tumor growth in the HeLa xenograft mice models without causing significant loss of body weight. Consequently, such a conjugation can be a potent and safe immunochemotherapeutic method for improving cancer therapy.
Chen, Feihong,Gou, Shaohua,Hua, Shixian,Wang, Xinyi
supporting information

(2020/01/21)

NQO1-selective activated prodrugs of combretastatin A-4: Synthesis and biological evaluation
Tumor-specific prodrug treatment renders the exclusive delivery of antitumor agents with the lowest untoward effects. In this work, we reported the synthesis and biological assessment of four NQO1-activatable combretastatin A-4 prodrugs constituted by active drug CA-4, different self-immolating linkers, and NQO1-responsive trigger groups. The in vitro antiproliferative activities showed that prodrug 4 displayed greater selective toxicity toward the tumor cells that overexpressed NQO1, taxol-resistant A549 cells, hypoxia-exposed A549 and HepG2 cells, and incurred lower damage to normal cells in comparison with combretastatin A-4, prodrugs 1, 2, and 3. Moreover, based on a mechanistic study, NQO1 triggered prodrug 4 to effectively liberate the parent drug combretastatin A-4 and kill tumor cells. Furthermore, we also demonstrated that prodrug 4 exerted a stronger anticancer effect and greater safety than combretastatin A-4 under in vivo conditions. Hence, from the above results, NQO1 can be used as a specific delivery system for releasing anticancer agents; besides, prodrug 4 can serve as a candidate lead for developing specific anticancer agents.
Li, Manping,Li, Sen,Li, Yue,Ma, Xin,Qu, Yan,Wu, Liqiang,Zhang, Chong
(2020/09/04)

A 2-step synthesis of Combretastatin A-4 and derivatives as potent tubulin assembly inhibitors
A series of combretastatin derivatives were designed and synthesised by a two-step stereoselective synthesis by use of Wittig olefination followed by Suzuki cross-coupling. Interestingly, all new compounds (2a-2i) showed potent cell-based antiproliferative activities in nanomolar concentrations. Among the compounds, 2a, 2b and 2e were the most active across three cancer cell lines. In addition, these compounds inhibited the polymerisation of tubulin in vitro more efficiently than CA-4. They caused cell cycle arrest in G2/M phase further confirming their ability to inhibit tubulin polymerisation.
Barnes, Natalie G.,Parker, Anthony W.,Ahmed Mal Ullah, Amjed A.,Ragazzon, Patricia A.,Hadfield, John A.
(2020/08/14)

Synthesis, Biological Evaluation, and Molecular Docking of Combretastatin and Colchicine Derivatives and their hCE1-Activated Prodrugs as Antiviral Agents
Recent studies indicate that tubulin can be a host factor for vector-borne flaviviruses like dengue (DENV) and Zika (ZIKV), and inhibitors of tubulin polymerization such as colchicine have been demonstrated to decrease virus replication. However, toxicity limits the application of these compounds. Herein we report prodrugs based on combretastatin and colchicine derivatives that contain an ester cleavage site for human carboxylesterase, a highly abundant enzyme in monocytes and hepatocytes targeted by DENV. Relative to their parent compounds, the cytotoxicity of these prodrugs was reduced by several orders of magnitude. All synthesized prodrugs containing a leucine ester were hydrolyzed by the esterase in vitro. In contrast to previous reports, the phenylglycine esters were not cleaved by human carboxylesterase. The antiviral activity of combretastatin, colchicine, and selected prodrugs against DENV and ZIKV in cell culture was observed at low micromolar and sub-micromolar concentrations. In addition, docking studies were performed to understand the binding mode of the studied compounds to tubulin.
Richter, Michael,Boldescu, Veaceslav,Graf, Dominik,Streicher, Felix,Dimoglo, Anatoli,Bartenschlager, Ralf,Klein, Christian D.
p. 469 - 483
(2019/02/01)

Prodrug Activation by a Viral Protease: Evaluating Combretastatin Peptide Hybrids to Selectively Target Infected Cells
Infections with flaviviruses such as dengue virus (DENV) are prevalent throughout tropical regions worldwide. Replication of these viruses depends on tubulin, a host cell factor that can be targeted to obtain broad-spectrum antiviral agents. Targeting of tubulin does, however, require specific measures to avoid toxic side-effects. Herein, we report the synthesis and biological evaluation of combretastatin peptide hybrids that incorporate the cleavage site of the DENV protease to allow activation of the tubulin ligand within infected cells. The prodrug candidates have no effect on tubulin polymerization in vitro and are 20-2000-fold less toxic than combretastatin A-4. Several of the prodrug candidates were cleaved by the DENV protease in vitro with similar efficiency as the natural viral substrates. Selected compounds were studied in DENV and Zika virus replication assays and had antiviral activity at subcytotoxic concentrations.
Richter, Michael,Leuthold, Mila M.,Graf, Dominik,Bartenschlager, Ralf,Klein, Christian D.
supporting information
p. 1115 - 1121
(2019/08/20)

Copper-catalysed, diboron-mediated: Cis -dideuterated semihydrogenation of alkynes with heavy water
Methods to incorporate deuterium atoms into organic molecules are valuable for the pharmaceutical industry. Here, we found that diboron reagents can efficiently mediate the transfer of two D atoms from heavy water directly onto alkynes through copper-catalysed cis-selective semihydrogenation. Avoiding the use of costly and flammable D2 gas, this safe and practical process can proceed with excellent chemoselectivity and stereoselectivity. Utilizing the present method as the key step, the formal asymmetric total synthesis of d2-deuterium-labeled cis-combretastatin A4 is demonstrated. Mechanistic studies suggest that monoborylation of alkynes is the key step for this semihydrogenation process.
Han, Xiaowei,Hu, Jiefeng,Chen, Cheng,Yuan, Yu,Shi, Zhuangzhi
p. 6922 - 6925
(2019/06/18)

Pt(IV) prodrugs containing microtubule inhibitors displayed potent antitumor activity and ability to overcome cisplatin resistance
It is well-known that cisplatin exhibited a broad spectrum of anticancer activities against many solid tumors, but its severe toxicity and drug resistance have largely limited wider clinical applications. Various strategies have been tried to discover new Pt (II) drugs with at least equal activity as well as low toxicity compared to cisplatin, but the inherent problem remains unsolved. Here we report that Pt (IV) complexes comprising a CA-4 analogue, as dual-targeting Pt (IV) prodrug, were synthesized and evaluated for anti-proliferative activity using MTT assay. Among them, complex 19 displayed most potent activity against the tested cancer cell lines, and simultaneously exhibited better cell selectivity between cancer cells and normal cells than that of cisplatin. Mechanism studies revealed that complex 19 effectively induced cell cycle arrest at the G2/M phase and dramatically disrupted the microtubule organization. Moreover, complex 19 significantly induced cell apoptosis and decreased MMP. Importantly, complex 19 significantly inhibited tumor growth in SK-OV-3 xenograft model in vivo without apparent toxicity.
Li, Lingxue,Huang, Xiaochao,Huang, Rizhen,Gou, Shaohua,Wang, Zhimei,Wang, Hengshan
supporting information
p. 666 - 679
(2018/07/29)

Synthesis of Bromoundecyl Resorc[4]arenes and Applications of the Cone Stereoisomer as Selector for Liquid Chromatography
As an extension of our studies on the multifaceted properties of C-alkylated resorc[4]arenes, we planned to immobilize on a solid support resorc[4]arenes with C11-long side chains in the lower rim. To this purpose, we synthesized two conformationally diverse resorc[4]arenes containing a bromoundecyl moiety in the four axial pendants. The cone stereoisomer 6a (30% yield) was selected for the reaction with an aminopropylated silica gel (APSG) obtained from spherical Kromasil Si 100, 5 μm particles, to give the corresponding immobilized SP-C11-resorc[4]arene system. The resulting polar-embedded stationary phase was fully characterized and investigated in the HPLC discrimination of the E/Z stereoisomers of naturally occurring and semisynthetic combretastatins, a family of (Z)-stilbene anticancer drugs. The chair stereoisomer 6b (20% yield), when submitted to X-ray diffraction analysis, showed a noteworthy self-assembly in the crystal lattice, with intercalated hydrophobic and polar layers as a result of intermolecular Br···O halogen bond interactions, according to a unique stacking motif. The potential and versatility of the SP-C11-resorc[4]arene stationary phase were shown as well in the separation of highly polar natural products (namely, flavonoids), under reversed-phase (RP) conditions, and of fullerenes C60 and C70, by using apolar solvents as mobile phases.
Corradi, Silvia,Mazzoccanti, Giulia,Ghirga, Francesca,Quaglio, Deborah,Nevola, Laura,Massera, Chiara,Ugozzoli, Franco,Giannini, Giuseppe,Ciogli, Alessia,D'Acquarica, Ilaria
p. 7683 - 7693
(2018/06/11)

CO2-Catalyzed oxidation of benzylic and allylic alcohols with DMSO
CO2-catalyzed transition-metal-free oxidation of alcohols has been achieved. Earlier, several methodologies have been explored for alcohol oxidations based on transition-metal catalysts. However, owing to the cheaper price, easy separation and nontoxicity, transition-metal-free systems are in high demand to the pharmaceutical industries. For this reason, various primary and secondary alcohols have been selectively oxidized to the corresponding carbonyl compounds using CO2 as a catalyst in the presence of different functional groups such as nitrile, nitro, aldehyde, ester, halogen, ether, and so on. At the end, transition-metal-free syntheses of pharmaceuticals have also been achieved. Finally, the role of CO2 has been investigated in detail, and the mechanism is proposed on the basis of experiments and DFT calculations.
Riemer, Daniel,Mandaviya, Bhavdip,Schilling, Waldemar,G?tz, Anne Charlotte,Kühl, Torben,Finger, Markus,Das, Shoubhik
p. 3030 - 3034
(2018/04/14)

Contra-Thermodynamic, Photocatalytic E→Z Isomerization of Styrenyl Boron Species: Vectors to Facilitate Exploration of Two-Dimensional Chemical Space
Designing strategies to access stereodefined olefinic organoboron species is an important synthetic challenge. Despite significant advances, there is a striking paucity of routes to Z-α-substituted styrenyl organoborons. Herein, this strategic imbalance is redressed by exploiting the polarity of the C(sp2)?B bond to activate the neighboring π system, thus enabling a mild, traceless photocatalytic isomerization of readily accessible E-α-substituted styrenyl BPins to generate the corresponding Z-isomers with high fidelity. Preliminary validation of this contra-thermodynamic E→Z isomerization is demonstrated in a series of stereoretentive transformations to generate Z-configured trisubstituted alkenes, as well as in a concise synthesis of the anti-tumor agent Combretastatin A4.
Molloy, John J.,Metternich, Jan B.,Daniliuc, Constantin G.,Watson, Allan J. B.,Gilmour, Ryan
supporting information
p. 3168 - 3172
(2018/02/26)

Design, synthesis, and biological evaluation of novel combretastatin A-4 thio derivatives as microtubule targeting agents
A series of novel combretastatin A-4 (CA-4) thio derivatives containing different molecular cores, namely α-phenylcinnamic acids (core 1), (Z)-stilbenes (core 2), 4,5-disubstituted oxazoles (core 3), and 4,5-disubstituted N-methylimidazoles (core 4), as cis-restricted analogues were designed and synthesized. They were selected with the use of a parallel virtual screening protocol including the generation of a virtual combinatorial library based on an elaborated synthesis protocol of CA-4 analogues. The selected compounds were evaluated for antiproliferative activity against a panel of six human cancer cell lines (A431, HeLa, MCF7, MDA-MB-231, A549 and SKOV) and two human non-cancer cell lines (HaCaT and CCD39Lu). Moreover, the effect of the test compounds on the inhibition of tubulin polymerization in vitro was estimated. In the series studied here, oxazole-bridged analogues exhibited the most potent antiproliferative activity. Compounds 23a, 23e, and 23i efficiently inhibited tubulin polymerization with IC50 values of 0.86, 1.05, and 0.85 μM, respectively. Thio derivative 23i, when compared to its oxygen analogue 23j, showed a 5-fold higher inhibitory impact on tubulin polymerization. Compounds 23e and 23i, which showed both best cytotoxic and antitubulin activity, were further studied in terms of their effect on cell cycle distribution and proapoptotic activity. Compound 23e induced a statistically significant block of the cell cycle at the G2/M phase in A431, HaCaT, HeLa, MCF-7, MDA-MB-231, and SKOV-3 cells to an extent comparable to that observed in CA-4. In HeLa and SKOV-3 cells incubated with 23i, a concentration-dependent block of the G2/M phase was observed. The proapoptotic effect of 23e and 23i in A431, HaCaT, MCF-7, MDA-MB-231, and SKOV-3 was demonstrated with ELISA assay and double staining with Annexin V-FITC/PI. The results indicated that compound 23e and 23i may serve as novel lead compounds in research on more effective anticancer agents.
Stefański, Tomasz,Mikstacka, Renata,Kurczab, Rafa?,Dutkiewicz, Zbigniew,Kucińska, Ma?gorzata,Murias, Marek,Zielińska-Przyjemska, Ma?gorzata,Cichocki, Micha?,Teubert, Anna,Kaczmarek, Mariusz,Hogendorf, Adam,Sobiak, Stanis?aw
p. 797 - 816
(2018/01/03)

CA-4 antitumor drug, synthesizing method and application thereof
The invention discloses a CA-4 antitumor drug, a synthesizing method and an application thereof. The CA-4 antitumor drug is formed in the manner of introducing the alkoxy or fluorine-containing alkoxy into 4' site of natural product combretastatin and functionally chemical modifying 3' site thereof. The CA-4 antitumor drug disclosed by the invention has higher capacity of restraining tubulin gathering and can be used for anti-tumor therapy.
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(2018/03/01)

A method for the synthesis of hydroxy [...] composition of the new method (by machine translation)
The present invention discloses a new method for the synthesis of hydroxy [...] compound. The claimed method is: in the organic solvent, under a certain temperature, ammonium formate/through the palladium catalytic removal of benzyl protecting group system, to obtain hydroxyl [...] compound. The method has the mild reaction conditions, the operation is simple, small reagent toxicity, safety, high yield, wide range of application, low cost, relatively suitable for mass production and the like. (by machine translation)
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Paragraph 0083-0084

(2017/08/27)

Z-Stereoselective Aza-Peterson Olefinations with Bis(trimethylsilane) Reagents and Sulfinyl Imines
Highly stereoselective aza-Peterson olefinations from bench-stable α,α-bis(trimethylsilyl)toluene reagents and N-substituted imines have been achieved using TMSO-/Bu4N+ as Lewis base activator in THF. Remarkably, and for the first time, N-t-butanesulfinyl imines were utilized for the synthesis of Z-stilbenes with excellent selectivities, while N-aryl imines generated E-stilbenes under identical reaction conditions. The protocol proved general for numerous examples with low molecular weight byproducts formed. The origin of the Z-selectivity is proposed to be a result of diastereoselective addition to N-t-butanesulfinyl imines followed by syn-elimination of an in situ formed hypervalent silicate.
Das, Manas,OShea, Donal F.
supporting information
p. 336 - 339
(2016/02/03)

cis-Semihydrogenation of alkynes with amine borane complexes catalyzed by gold nanoparticles under mild conditions
Supported gold nanoparticles catalyze the semihydrogenation of alkynes to alkenes with ammonia borane or amine borane complexes in excellent yields and under mild conditions. Internal alkynes provide cis-alkenes, making this protocol an attractive alternative of the classical Lindlar's hydrogenation.
Vasilikogiannaki, Eleni,Titilas, Ioannis,Vassilikogiannakis, Georgios,Stratakis, Manolis
p. 2384 - 2387
(2015/02/05)

Synthesis and insect antifeedant activity of stilbene derivatives against Brontispa longissima Larvae
Continuing our search for natural product-based compounds for the control of B. longissima Larvae, 25 stilbene analogs were synthesized and evaluated for insect antifeedant activity against third-instar larvae of B. longissima for the first time. Among all the tested compounds, especially compounds 3a, 3c, and 6 showed pronounced antifeedant activities with AFC50 values of 0.218, 0.327, and 0.226 mg/mL, respectively. The different antifeedant activity ranges of these compounds indicated that variation of chemical structures in the stilbene skeleton markedly affected the activity profiles of this compound class, and some important SAR information has been revealed from it. In addition, to understand the structural requirements for antifeedant activities of the 25 synthesized stilbene analogs, a comparative molecular field analysis (CoMFA) model, which yielded the leave-one-out (LOO) cross-validated correlation coefficient (q 2) of 0.533 and a non-cross-validated correlation coefficient (r 2) of 0.929, was constructed. Together, these preliminary results may be useful in guiding further modification of stilbenes in the development of potential new antifeedants.
Liu, Ying-Qian,Li, Xiao-Jing,Zhao, Chun-Yan,Lu, Yan,Li, Wen-Qun,Liu, Zhen-Ling,Feng, Gang,Yang, Liu
p. 2196 - 2206
(2013/07/26)

Amidobenzothiazoles And Process For The Preparation Thereof
The present invention provides a compound of general formulae A useful as potential anti-cancer agents against human cancer cell lines and a process for the preparation thereof. Where in R, R1, R2═H, alkyl, alkoxy, halo, haloalkyl, halomethoxy, nitro and G= Where in R, R1, R2═H, alkyl, alkoxy, halo, haloalkyl, halomethoxy, nitro and G=
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(2013/12/04)

CuI/1,10-phen/PEG promoted decarboxylation of 2,3-diarylacrylic acids: Synthesis of stilbenes under neutral and microwave conditions with an in situ generated recyclable catalyst
A series of trans- or cis-stilbenes have been synthesized in good to excellent yields via a functional group-dependent decarboxylation process from the corresponding 2,3-diaryl acrylic acids in a neutral CuI/1,10-phen/PEG-400 system under microwave conditions. The in situ generation of the recyclable catalytic complex, the use of environmentally benign solvent PEG-400, the operational simplicity, the short reaction times, as well as the functional group-dependent chemo- and stereo-selectivity have made the decarboxylation process a highly efficient and applicable protocol.
Zou, Yong,Huang, Qi,Huang, Tong-Kun,Ni, Qing-Chun,Zhang, En-Sheng,Xu, Tian-Long,Yuan, Mu,Li, Jun
p. 6967 - 6974
(2013/10/08)

Synthesis of Z-(pinacolato)allylboron and Z-(pinacolato)alkenylboron compounds through stereoselective catalytic cross-metathesis
The first examples of catalytic cross-metathesis (CM) reactions that furnish Z-(pinacolato)allylboron and Z-(pinacolato)alkenylboron compounds are disclosed. Products are generated with high Z selectivity by the use of a W-based monoaryloxide pyrrolide (MAP) complex (up to 91% yield and >98:2 Z:E). The more sterically demanding Z-alkenylboron species are obtained in the presence of Mo-based MAP complexes in up to 93% yield and 97% Z selectivity. Z-selective CM with 1,3-dienes and aryl olefins are reported for the first time. The utility of the approach, in combination with catalytic cross coupling, is demonstrated by a concise and stereoselective synthesis of anticancer agent combretastatin A-4.
Kiesewetter, Elizabeth T.,O'Brien, Robert V.,Yu, Elsie C.,Meek, Simon J.,Schrock, Richard R.,Hoveyda, Amir H.
p. 6026 - 6029
(2013/06/05)

Site-specific and far-red-light-activatable prodrug of combretastatin A-4 using photo-unclick chemistry
Although tissue-penetrable light (red and NIR) has great potential for spatiotemporally controlled release of therapeutic agents, it has been hampered because of the lack of chemistry translating the photonic energy to the cleavage of a chemical bond. Recently, we discovered that an aminoacrylate group could be cleaved to release parent drugs after oxidation by SO and have called this photo-unclick chemistry . We demonstrate its application to far-red-light-activated prodrugs. A prodrug of combretastatin A-4 (CA4) was prepared, CMP-L-CA4, where CMP is dithiaporphyrin, a photosensitizer, and L is an aminoacrylate linker. Upon irradiation with 690 nm diode laser, the aminoacrylate linker of the prodrug was cleaved, rapidly releasing CA4 (>80% in 10 min) in CDCl3. In tissue culture, it showed about a 6-fold increase in its IC50 in MCF-7 after irradiation, most likely because of the released CA4. Most significantly, CMP-L-CA4 had better antitumor efficacy in vivo than its noncleavable (NC) analog, CMP-NCL-CA4. This is the first demonstration of the in vivo efficacy of the novel low-energy-light-activatable prodrug using the photo-unclick chemistry.
Bio, Moses,Rajaputra, Pallavi,Nkepang, Gregory,Awuah, Samuel G.,Hossion, Abugafar M. L.,You, Youngjae
supporting information
p. 3936 - 3942
(2013/07/19)

Design, synthesis and biological evaluation of novel aminosaccharide derivatives of combretastatin A-4
Combretastatin A-4 (CA-4), a natural vascular disrupting agent (VDA) with potent anti-cancer activity, is a promising lead compound in drug discovery. In view of the potential application of carbohydrates in medicinal chemistry, we designed and synthesized sixteen novel CA-4 aminosaccharide derivatives. In vitro anti-proliferative studies showed that compounds 7a and 7c significantly inhibited the growth of human umbilical vein endothelia cells (HUVEC) and other four cancer cell lines. Besides, preliminary structure-activity relationship (SAR) was also summarized. 2013 Bentham Science Publishers.
Tang, Yan,Tu, Zhewei,Sun, Jing,Zhu, Xiong,Liu, Kun,He, Shuying,Xu, Yungen
p. 935 - 941
(2013/12/04)

New method of synthesis and biological evaluation of some combretastatin A-4 analogues
A series of novel combretastatin A-4 analogues was synthesized in 36-64% yields by Negishi cross-coupling reaction under mild conditions. The prepared compounds exhibit good cytotoxicity against HBL100 epithelial cell lines (IC50=0.022-10.31 ). Georg Thieme Verlag Stuttgart · New York.
Malysheva, Yulia B.,Combes, Sebastien,Fedorov, Alexey Yu.,Knochel, Paul,Gavryushin, Andrei E.
supporting information; experimental part
p. 1205 - 1208
(2012/06/29)

Aryl-aryl interactions as directing motifs in the stereodivergent iron-catalyzed hydrosilylation of internal alkynes
The defined Fe hydride complex FeH(CO)(NO)(Ph3P)2 is highly active as a catalyst for selective hydrosilylation of internal alkynes to vinylsilanes. Depending on the silane employed either E- or Z-selective hydrosilylation products were formed in excellent yields and good to excellent stereoselectivities.
Belger, Christian,Plietker, Bernd
supporting information; experimental part
p. 5419 - 5421
(2012/07/03)

Synthesis and biological evaluation of combretastatin-amidobenzothiazole conjugates as potential anticancer agents
A series of combretastatin-amidobenzothiazole conjugates have been synthesized and evaluated for their anticancer activity. All these compounds exhibited significant anticancer activity and the most potent compound (11a) showed GI50 values ranging 0.019-11 μM. Biological studies such as cell cycle distribution, effect on tubulin polymerization and effect on ERK signalling pathway have been examined in MCF-7 cell line. FACS analysis revealed that these compounds induced cell cycle arrest at G2/M phase. Compound 11a showed significant effect on tubulin polymerization and affected the ERK signalling pathway that result in the decreased levels of ERK1/2, p-ERK and c-Jun proteins. Docking experiments have shown that the active molecules interact and bind well in the ATP binding pocket of ERK protein.
Kamal, Ahmed,Mallareddy, Adla,Janaki Ramaiah,Pushpavalli,Suresh, Paidakula,Kishor, Chandan,Murty,Rao, N. Sankara,Ghosh, Sowjanya,Addlagatta, Anthony,Pal-Bhadra, Manika
p. 166 - 178
(2013/01/15)

Synthesis of novel spin-labelled combretastatin A-4 derivatives as potential antineoplastic agents
Four novel spin-labelled combretastatin A-4 (CA-4) analogues were first synthesised in quantitative yield by reacting CA-4 with the corresponding nitroxyl radical. Their cytotoxic activities against A-549 (human lung cancer) and HePG-2 (human liver cancer) invitro were evaluated, and the results indicated that these derivatives were more cytotoxic than the clinical drug irinotecan.
Li, Xiao-Jing,Yang, Liu,Liu, Ying-Qian,Li, Chong
experimental part
p. 1271 - 1277
(2012/10/18)

Dehydrative fragmentation of 5-hydroxyalkyl-1 h -tetrazoles: A mild route to alkylidenecarbenes
The development of a mild, base-free method for the generation of alkylidenecarbenes is reported. Treatment of 5-hydroxyalkyl-1H-tetrazoles with carbodiimides generates products arising from the 1,2-rearrangement or [1,5]-C-H bond insertion of a putative alkylidenecarbene. Formation of this divalent intermediate is proposed to occur by way of a tetraazafulvene, which undergoes extrusion of 2 mol of dinitrogen. Details of this methodology, its application to the synthesis of combretastatin A-4, and an improved route to 5-hydroxyalkyl-1H-tetrazoles are described.
Wardrop, Duncan J.,Komenda, John P.
p. 1548 - 1551
(2012/06/05)

Hydroxyl substitutional effect on selective synthesis of CIS, trans stilbenes and 3-arylcoumarins through perkin condensation
The substitutional effect in the selective synthesis of cis, trans stilbenes and 3-arylcoumarins has been described. The regio- and geometrical selectivity for synthesis of stilbene derivatives under the Perkin strategy strongly depends on the presence or absence of hydroxyl group as well as their positions in the phenyl ring. As a result, practical synthetic strategies were established for preparing various natural stilbenes including combretastatin A-4, pterostilbene, and resveratrol with satisfactory yields (49.2-63.7%). Copyright Taylor & Francis Group, LLC.
Xiao, Chun-Fen,Zou, Yong,Du, Jian-Li,Sun, Hong-Yi,Liu, Xian-Ke
p. 1243 - 1258
(2012/04/04)

Anticancer effects of the metabolic products of the resveratrol analogue, DMU-212: Structural requirements for potency
The methoxylated trans-stilbene resveratrol analogue, (E)-3,4,5,4′- tetramethoxystilbene (1), has shown promising antiproliferative activity in in vitro cell line and in vivo models. In vivo 1 gives rise to several metabolic products through demethylation or hydroxylation reactions at the stilbene moiety. In the present study we examined the anticancer activity of 1 and the metabolites (E)-3′-hydroxy-3,4,5,4′-tetramethoxystilbene (2), (E)-4′-hydroxy-3,4,5-trimethoxystilbene (3), (E)-4-hydroxy-3,5,4′- trimethoxystilbene (4) and (E)-3-hydroxy-4,5,4′-trimethoxystilbene (5) by means of cell viability testing, cell cycle analysis, immunostaining and Western blotting. Compounds 1 and 2 exhibited submicromolar toxicity in MCF-7 breast adenocarcinoma and HepG2 hepatoma cells, whereas 3, 4 and 5 were inactive in terms of inhibition of cellular proliferation. Incubation with 1 or 2 at 10 μM for 24 h induced apoptosis and G2/M cell cycle arrest in MCF-7 and HepG2 cells. Immunostaining of MCF-7 cells for β-tubulin in the presence of either 1 or 2 revealed shorter localization of the protein around the nucleus, as compared to control cells. Western blot analyses further demonstrated that treatment with either 1 or 2 at concentrations between 30 and 50 μM for 24 h caused a downregulation in the levels of β-tubulin and cyclin D1 expression and an upregulation in the levels of p53 expression in MCF-7 and HepG2 cells. 2 further increased the ratio of mRNA levels of the apoptosis-related genes Bax/Bcl-xL in both MCF-7 and HepG2 cells in a dose-dependent manner. We conclude that 2 inhibits HepG2 and MCF-7 cellular proliferation by inducing apoptosis and G2/M arrest through p53 and Bax/Bcl-xL upregulation. Our findings further demonstrate that trimethoxy substitutions along with the presence of a methoxy group at position 4′ are necessary for retaining the activity of 1.
Androutsopoulos, Vasilis P.,Ruparelia, Ketan C.,Papakyriakou, Athanasios,Filippakis, Harilaos,Tsatsakis, Aristeidis M.,Spandidos, Demetrios A.
experimental part
p. 2586 - 2595
(2011/06/21)

Practical and green synthesis of combretastatin A-4 and its prodrug CA4P using renewable biomass-based starting materials
A practical and green protocol for the synthesis of vascular disrupting agent combretastatin A-4 (CA4) and its water soluble prodrug CA4P is described. Starting from the biomass-based compound anethole, which is abundantly and sustainably available from Chinese star anise (Illicium verum Hook. f.), the key intermediate 3-hydroxy-4-methoxyphenylacetic acid can be obtained within five steps. Perkin condensation between this acid and another naturally derived compound 3,4,5-trimethoxybenzaldehyde, followed by decarboxylation gives combretastatin A-4 in good overall yield. The phosphate produrg CA4P can be prepared under simple and mild conditions in a sequential one-pot two-step reaction. Georg Thieme Verlag Stuttgart New York.
Chen, Yu,Zou, Yong,Sun, Hong-Yi,Liu, Xian-Ke,Xiao, Chun-Fen,Sun, Jie,He, Shu-Jie,Li, Jun
experimental part
p. 217 - 222
(2011/02/28)

Synthesis and biological evaluation of combretastatin analogs as cell cycle inhibitors of the G1 to S transition in Saccharomyces cerevisiae
A series of Z and E combretastatin A-4 analogs bearing different substituents (OH, F, NO2, NH2, B(OH)2) in the 3′ position were synthesized. These derivatives and Z and E combretastatin A-1 were analysed by monitoring their ability to inhibit cell growth in Saccharomyces cerevisiae. Combretastatin A-1 (2a), A-4 (2b) and compound 2c were found to inhibit yeast growth. Moreover, combretatstatin A-4 (2b) and compound 2c induced a G1 arrest by affecting the synthesis of Clb5 protein, the principal S-phase cyclin. The G1 arrest is coincident with the activation of the stress activated kinase Snf1.
Coccetti, Paola,Montano, Giuseppe,Lombardo, Alessandro,Tripodi, Farida,Orsini, Fulvia,Pagliarin, Roberto
supporting information; experimental part
p. 2780 - 2784
(2010/08/19)

Design and in vitro evaluation of branched peptide conjugates: Turning nonspecific cytotoxic drugs into tumor-selective agents
The use of peptide receptors as targets for tumor-selective therapies was envisaged years ago with the findings that receptors for different endogenous regulatory peptides are overexpressed in several primary and metastatic human tumors, and can be used as tumor antigens. Branched peptides can retain or even increase, through multivalent binding, the biological activity of a peptide and are very resistant to proteolysis, thus having a markedly higher in vivo activity compared with the corresponding monomeric peptides. Oligo-branched peptides, containing the human regulatory peptide neurotensin (NT) sequence, have been used as tumor-specific targeting agents. These peptides are able to selectively and specifically deliver effector units, for cell imaging or killing, to tumor cells that overexpress NT receptors. Results obtained with branched NT conjugated to different functional units for tumor imaging and therapy indicate that branched peptides are promising novel multifunctional targeting molecules. This study is focused on the role of the releasing pattern of drug-conjugated branched NT peptides. We present results obtained with oligobranched neurotensin peptides conjugated to 6-mercaptopurin (6-MP), combretastain A-4 (CA4) and monastrol (MON). Drugs were conjugated to oligo-branched neurotensin through different linkers, and the mode-of-release, together with cytotoxicity, was studied in different human cancer cell lines. The results show that branched peptides are very promising pharmacodelivery options. Among our drug-armed branched peptides, NT4-CA4 was identified as a candidate for further development and evaluation in preclinical pharmacokinetic and pharmacodynamic studies. This peptide-drug exhibits significant activity against pancreas and prostate human cancer cells. Consequently, this derivative is of considerable interest due to the high mortality rates of pancreas neuroendocrine tumors and the high incidence of prostate cancer.
Falciani, Chiara,Brunetti, Jlenia,Pagliuca, Chiara,Menichetti, Stefano,Vitellozzi, Lucia,Lelli, Barbara,Pini, Alessandro,Bracci, Luisa
scheme or table
p. 567 - 574
(2010/12/18)

An efficient microwave-promoted route to (Z)-stilbenes from trans-cinnamic acids: Synthesis of combretastatin A-4 and analogues
cis-Stilbenes were synthesized from trans-cinnamic acids, involving ethylenic-bond bromination and a subsequent one-pot microwave-promoted stereoselective debrominative decarboxylation-Suzuki cross-coupling strategy. This sequence represents a useful way to prepare a variety of combretastatin A-4 derivatives.
Bazin, Marc-Antoine,Jouanne, Marie,El-Kashef, Hussein,Rault, Sylvain
experimental part
p. 2789 - 2794
(2010/03/03)

Synthesis and antitumor-evaluation of cyclopropyl-containing combretastatin analogs
Several derivatives of combretastatin have been prepared bearing a cyclopropyl unit instead of the natural occurring cis-double bond. Final products and synthetic intermediates were evaluated for their cytotoxic properties in two human cancer cell lines.
Fuerst, Rita,Zupko, Istvan,Berenyi, Agnes,Ecker, Gerhard F.,Rinner, Uwe
scheme or table
p. 6948 - 6951
(2010/08/06)

Synthesis of combretastatin A-4 and erianin
A concise route to two anti-tubulin natural products combretastatin A-4 and erianin has been developed. Combretastatin A-4 was obtained by a Perkin reaction between 3-bromo-4-methoxyphenyl acetic acid and 3,4,5- trimethoxybenzaldehyde, hydroxyl transformation, decarboxylation with a high level of cis-selectivity (cis/trans = 95/5), and erianin was obtained by subsequent hydrogenation. The overall yields of combretastatin A-4 and erianin were 37.5 and 30.8%, respectively.
Zou, Yong,Xiao, Chun-Fen,Zhong, Rong-Qing,Wei, Wen,Huang, Wen-Ming,He, Shu-Jie
experimental part
p. 354 - 356
(2009/06/18)

One-pot hydrosilylation-protodesilylation of functionalized diarylalkynes: a highly selective access to Z-stilbenes. Application to the synthesis of combretastatin A-4
An efficient stereoselective synthesis of Z-stilbenes has been developed from diarylalkynes via a new hydrosilylation-protodesilylation process. The scope and limitation of this method is presented to stereoselectively prepare a wide range of (Z)-stilbenes in a one-pot way is presented. A concise application to the preparation of combretastatin A-4 (CA-4), a vascular targeting agent inhibitor of tubulin polymerisation is described.
Giraud, Anne,Provot, Olivier,Hamzé, Abdallah,Brion, Jean-Daniel,Alami, Mouad
p. 1107 - 1110
(2008/09/17)

COMBRETASTATIN DERIVATIVES AND RELATED THERAPEUTIC METHODS
Compounds of the formula (I) wherein R1, R5, R6, R7 and R10 are H, wherein R2, R3, R4 and R8 are OMe, and wherein R9 is -X-CO-R", R" is an unsubstituted or a substituted alkyl, alkenyl or aryl group comprising 5-21 carbon atoms and does not include N, and X is O, S or N, compounds related thereto, and methods for their use, particularly for modulating tumor growth or metastasis in an animal.
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Page/Page column 27-28

(2008/06/13)