Xiaowu Dong

Recent Development and SAR Analysis of Colchicine Binding Site Inhibitors

Microtubules are cytoskeletal components that play important roles in a number of cellular processes. Colchicine binding site inhibitors (CSIs) is one major class of tubulin polymerization inhibitors, inhibiting microtubule polymerization and blocking cell proliferation at metaphase during mitosis. Many CSIs were discovered or designed and synthesized as anticancer agents in the past several years and great progress had been made. Here, we discuss the insights gained so far relevant to the mechanism of CSIs and their common pharmacophore. The recent development of CSIs with their biological activity and structure-activity relationship (SAR) are also reviewed.

Radical aryl migration enables diversity-oriented synthesis of structurally diverse medium/macro- or bridged-rings

Medium-sized and medium-bridged rings are attractive structural motifs in natural products and therapeutic agents. Due to the unfavourable entropic and/or enthalpic factors with these ring systems, their efficient construction remains a formidable challenge. To address this problem, we herein disclose a radical-based approach for diversity-oriented synthesis of various benzannulated carbon- and heteroatom-containing 8–11(14)-membered ketone libraries. This strategy involves 1,4- or 1,5-aryl migration triggered by radical azidation, trifluoromethylation, phosphonylation, sulfonylation, or perfluoroalkylation of unactivated alkenes followed by intramolecular ring expansion. Demonstration of this method as a highly flexible tool for the construction of 37 synthetically challenging medium-sized and macrocyclic ring scaffolds including bridged rings with diverse functionalities and skeletons is highlighted. Some of these products showed potent inhibitory activity against the cancer cell or derivative of human embryonic kidney line in preliminary biological studies. The mechanism of this novel strategy is investigated by control experiments and DFT calculations.

Abrogation of Akt signaling by Isobavachalcone contributes to its anti-proliferative effects towards human cancer cells

Akt signaling pathway has attracted much attention as a promising target for cancer therapeutics. Herein, we report that Isobavachalcone (IBC), a natural chalcone, potently abrogates Akt signaling and exerts anti-proliferative effects on several human cancer cell lines. Modeling results from the Sybyl/FlexiDock program suggest that IBC potentially binds to the ATP-binding pocket of Akt, which is confirmed by the observations that IBC inhibits Akt1 kinase in vitro. Further studies reveal that IBC significantly abates Akt phosphorylation at Ser-473 and Akt kinase activity in cells, which subsequently leads to inhibition of Akt downstream substrates and evokes significant levels of apoptosis associated with mitochondria pathway.

Alkenyl/Thiol-Derived Metal-Organic Frameworks (MOFs) by Means of Postsynthetic Modification for Effective Mercury Adsorption

The synthesis of new functionally diverse alkenyl-derived Cr-MIL-101s (MIL=material of Institute Lavoisier) was realized by a novel and convenient postsynthetic modification (PSM) protocol by means of the carbon-carbon bond-forming Mizoroki-Heck reaction. The new PSM protocol demonstrates a broad scope of substrates with excellent tolerance of functionality under mild reaction conditions. Moreover, a new metal-organic framework (MOF) that bears both alkenyl and thiol side chains prepared by means of the tandem PSM method has shown excellent adsorbent ability in removing mercury ions from water.

Synergistic Antitumor Activity of Gemcitabine and ABT-737 In Vitro and In Vivo through Disrupting the Interaction of USP9X and Mcl-1

The Bcl-2 antagonist ABT-737 targets Bcl-2/Bcl-xL, but not Mcl-1, which may confer resistance to this agent in various cancers with high levels of Mcl-1. Here, we showed that the combination of gemcitabine and ABT-737 exhibited synergistic cytotoxicity and induced significant apoptosis in multiple cancer types, including lung, renal, bladder, and prostate cancers. The enhanced apoptosis induced by gemcitabine plus ABT-737 was accompanied by the greater extent of mitochondrial depolarization, caspases-3 activation, and PARP cleavage in 95-D and 5637 cell lines. Importantly, in ABT-737–resistant cancer cells, the interaction between USP9X and Mcl-1, which was increased by ABT-737 treatment, could be disrupted by gemcitabine, thus resulting in enhanced ubiquitination and the subsequent degradation of Mcl-1 and ultimately in the synergism of these two drugs. Moreover, the increased anticancer efficacy of gemcitabine combined with ABT-737 was further validated in a human lung cancer 95-D xenograft model in nude mice. Taken together, our data first showed the synergistic anticancer capabilities achieved by combining gemcitabine and ABT-737 and, second, opened new opportunities to use antiapoptotic Bcl-2 family members, which drive tumor cell resistance in current anticancer therapies, therapeutically. Mol Cancer Ther; 10(7); 1264–75. ©2011 AACR.

Synthesis and biological evaluation of 3,4-diaryl-5-aminoisoxazole derivatives

A series of cis-restricted 3,4-diaryl-5-aminoisoxazoles have been synthesized and evaluated for their biological activities. Among them, compound 11a and 13a displayed potent cytotoxic activities in vitro against five human cancer cell lines with IC(50) values in the low micromolar range and two compounds inhibited tubulin polymerization with IC(50) value of 1.8, and 2.1 microM, respectively, similar to that of CA-4. Compound 13a could arrest at the G2/M phase of the cell cycle at the concentration of 0.1 and 1.0 microM and induce apoptosis at 0.1-1.0 microM.

QSAR study of Akt/protein kinase B (PKB) inhibitors using support vector machine.

A three-class support vector classification (SVC) model with high prediction accuracy for the training, test and overall data sets (95.2%, 88.6% and 93.1%, respectively) was developed based on the molecular descriptors of 148 Akt/protein kinase B (PKB) inhibitors. Then, support vector regression (SVR) method was applied to set up a more accurate model with good correlation coefficient (r(2)) for the training, test and overall data sets (0.882, 0.762 and 0.840, respectively). Enrichment factors (EF) and receiver operating curves (ROC) studies of database screening were also performed either using the SVR model alone or assisted with the SVC model, the results of which demonstrated that the established models could be useful and reliable tools in identifying structurally diverse compounds with Akt inhibitory activity.

Synthesis and biological evaluation of novel flavonoid derivatives as dual binding acetylcholinesterase inhibitors

A new series of flavonoid derivatives have been designed, synthesised and evaluated as acetylcholinesterase inhibitors that could bind simultaneously to the peripheral and catalytic sites of the enzyme. Among them, fifteen derivatives were found to inhibit the enzyme in the micromolar range and isoflavone derivatives possessed more potent inhibitory activity than other flavonoid derivatives. The best compound 9a had its inhibitory activity (IC50 = 0.093μM) in the same range as the reference compound, donepezil (IC50 = 0.025μM). Preliminary structure-activity relationships and a molecular modeling study for 9a have revealed that the isoflavone moiety plays a key role in the interaction of this series of derivatives with AChE by acting as an anchor in its peripheral anionic site.

Synthesis and In-Vitro Antitumor Activities of Some Mannich Bases of 9-Alkyl-1,2,3,4-tetrahydrocarbazole-1-ones

A novel series of 2‐substituted aminomethyl‐9‐alkyl‐1,2,3,4‐tetrahydrocarbazole‐1‐ones 5a–q was synthesized via aminomethylation of 9‐alkyl‐1,2,3,4‐tetrahydrocarbazole‐1‐ones 4a–e with hydrochlorides of the respective amines 6a–m. The structures of these newly synthesized compounds were characterized by 1H‐NMR, MS, and elemental analysis. All the compounds were tested for their cytotoxic activity in vitro against four human tumor cell lines including human non‐small lung cancer cells (A549), human gastric adenocarcinoma (SGC), human colon cancer cell (HCT116), human myeoloid leukemia cells (K562), and one multi‐drug resistant subline (KB‐VCR). Most compounds showed moderate to potent cytotoxic activity against the tested cell lines. Preliminary mechanism research indicated that the most promising compound, 2‐diethylaminomethyl‐9‐methyl‐1,2,3,4‐tetrahydrocarbazole‐1‐one 5c, exhibited a potential inhibitory effect against microtubule.

Design, Synthesis, and Biological Evaluation of Prenylated Chalcones as Vasorelaxant Agents

Five prenylated chalcones and one allylated chalcone were prepared according to the analysis based on support vector machine (SVM) classification model. Most of the synthesized chalcones showed potent vasorelaxant activities through evaluation in aortic rings with the endothelium pre‐contracted by phenylephrine (PE), indicating that the experimental activities were in good agreement with the theoretical ones. Structure‐activity relationship of these compounds showed that the substituent pattern and number of hydroxyl groups were crucial for their vasorelaxant activities and that the replacement of prenyl group with allyl group retained the potent activity.