Computer-aided discovery of aminopyridines as novel JAK2 inhibitors.

The Janus kinase 2 (JAK2)-mediated signaling pathway plays an important role in controlling cell survival, proliferation, and differentiation. In recent years, genetic, biological, and physiological evidence has established JAK2 inhibitors as effective chemotherapeutic agents for the treatment of many different cancers. For this reason, we sought to identify novel small molecule inhibitors of JAK2. Using Surflex-Dock software, we tested 3010 compounds with known chemical structures in silico for their ability to interact with the JAK2 ATP-binding pocket. We selected the 10 highest-scoring compounds and tested their abilities to inhibit JAK2 activity in vitro. Compound 1a (ethyl 1-(5-((3-methoxyphenyl)carbamoyl)-3-nitropyridin-2-yl)piperidine-4-carboxylate) was identified. Optimization of 1a using docking studies led to the discovery of compounds 1b and 1d, potent JAK2 inhibitors. Furthermore, as V-shaped kinase inhibitors can curve around the protein backbone and access deep into the pocket, we developed a new series of compounds with a non-linear sulfonamide bond. Nine compounds were prepared and evaluated for JAK2 inhibitory effects. Compounds 7e (IC50=6.9µM) and 7h (IC50=12.2µM) showed better JAK2 inhibition, validating our design approach. This study successfully applied virtual screening for hit discovery, and a docking study for hit optimization. In addition, a novel approach to drug discovery, combining structure- and shape-based drug design, facilitated the design of more potent JAK2 inhibitors. The methods provide a guide for future development of inhibitors targeting JAK2 and other kinases.

Structure-based virtual screening and identification of a novel androgen receptor antagonist.

Hormonal therapies, mainly combinations of anti-androgens and androgen deprivation, have been the mainstay treatment for advanced prostate cancer because the androgen-androgen receptor (AR) system plays a pivotal role in the development and progression of prostate cancers. However, the emergence of androgen resistance, largely due to inefficient anti-hormone action, limits the therapeutic usefulness of these therapies. Here, we report that 6-(3,4-dihydro-1H-isoquinolin-2-yl)-N-(6-methylpyridin-2-yl)nicotinamide (DIMN) acts as a novel anti-androgenic compound that may be effective in the treatment of both androgen-dependent and androgen-independent prostate cancers. Through AR structure-based virtual screening using the FlexX docking model, fifty-four compounds were selected and further screened for AR antagonism via cell-based tests. One compound, DIMN, showed an antagonistic effect specific to AR with comparable potency to that of the classical AR antagonists, hydroxyflutamide and bicalutamide. Consistent with their anti-androgenic activity, DIMN inhibited the growth of androgen-dependent LNCaP prostate cancer cells. Interestingly, the compound also suppressed the growth of androgen-independent C4-2 and CWR22rv prostate cancer cells, which express a functional AR, but did not suppress the growth of the AR-negative prostate cancer cells PPC-1, DU145, and R3327-AT3.1. Taken together, the results suggest that the synthetic compound DIMN is a novel anti-androgen and strong candidate for useful therapeutic agent against early stage to advanced prostate cancer.

Structure-based discovery of pyrazolamides as novel ERRγ inverse agonists.

Estrogen-related receptor-gamma (ERRγ) is an orphan nuclear receptor with high structural similarity to estrogen receptors (ERα and ß). The endogenous ligand of the receptor has yet to be identified. Only two classes of molecules-stilbene (diethylstilbestrol, 4-hydroxytamoxifen, and GSK5182) and flavonol (kaempferol) have been known to modulate the transcriptional activity of the receptor to date. Further, these agents lack selectivity to ERRγ suggesting the need for a new inverse agonist. Thus, virtual screening was used to identify pyrazolamide 7 as a novel ERRγ inverse agonist. Structure-based diversification and optimization of the compound further led to the identification of derivative 19 as a potent inverse agonist of ERRγ with selectivity over other nuclear receptors including those of ERR family. Pyrazolamide 19 exhibits strong affinity towards ERRγ and inhibits the expression of hepcidin, fibrinogen and gluconeogenic genes, which suggests that these compounds may have antimicrobial, anti-coagulant and antidiabetic activities.

Cilostazol reduces MCP-1-induced chemotaxis and adhesion of THP-1 monocytes by inhibiting CCR2 gene expression.

The chemotaxis and adhesion of monocytes to the injured endothelium in the early atherosclerosis is important. Cilostazol, a specific phosphodiesterase type III inhibitor, is known to exhibit anti-atherosclerotic effects mediated by different mechanisms. This study aimed to investigate the modulating effect of cilostazol on the MCP-1-induced chemotaxis and adhesion of monocytes. The gene expression of CCR2, the major receptor of MCP-1 in THP-1 monocytes, was also analyzed. The chemotaxis of monocytes toward MCP-1 was investigated using the transwell filter assay. Cilostazol dose-dependently inhibited the MCP-1-induced chemotaxis of monocytes which was shown to be cAMP-dependent. Using western blot analysis and flow cytometry method, we demonstrated the decrease of CCR2 protein at the cell membrane of monocytes by cilostazol treatment. Results from RT/real-time PCR confirmed the decrease of CCR2 mRNA expression by cilostazol which was also mediated by cAMP. Similar inhibition was also noted in human peripheral monocytes. The post-CCR2 signaling pathways including p44/42 and p38 MAPK were examined by western blot analysis. Result confirmed the inhibitory effect of cilostazol on the phosphorylation of p44/42 and p38 MAPK after MCP-1 stimulation. The activation of monocytes after MCP-1 treatment exhibited enhanced adhesion to vascular endothelial cells which was dose-dependently suppressed by cilostazol. Together, cilostazol was demonstrated, for the first time, to inhibit the CCR2 gene expression and MCP-1-induced chemotaxis and adhesion of monocytes which might therefore reduce the infiltration of monocytes during the early atherosclerosis. The present study provides an additional molecular mechanism underlying the anti-atherosclerotic effects of cilostazol.

Design and synthesis of 4-amino-2-phenylquinazolines as novel topoisomerase I inhibitors with molecular modeling.

4-Amino-2-phenylquinazolines 7 were designed as bioisosteres of 3-arylisoquinolinamines 6 that were energy minimized to provide stable conformers. Interestingly, the 2-phenyl ring of 4-amino-2-phenylquinazolines was parallel to the quinazoline ring and improved their DNA intercalation ability in the DNA-topo I complex. Among the synthesized 4-amino group-substituted analogs, 4-cyclohexylamino-2-phenylquinazoline 7h exhibited potent topo I inhibitory activity and strong cytotoxicity. Interestingly, consistency was observed between the cytotoxicities and topo I activities in these quinazoline analogs, suggesting that the target of 4-amino-2-phenylquinazolines is limited to topo I. Molecular docking studies were performed with the Surflex-Dock program to afford the ideal interaction mode of the compound into the binding site of the DNA-topo I complex in order to clarify the topo I activity of 7h.

Design, synthesis and docking study of 5-amino substituted indeno[1,2-c]isoquinolines as novel topoisomerase I inhibitors.

Various 5-amino group-substituted indeno[1,2-c]isoquinolines 7a-f were synthesized based on the previous QSAR study as rigid structures of 3-arylisoquinolines. Amino group-substituted compounds, especially 5-piperazinyl indeno[1,2-c]isoquinoline 7f, displayed potent topoisomerase I inhibitory activity as well as cytotoxicities against five different tumor cell lines. A Surflex-Dock docking model of 7f was also studied.

Synthesis of benzo[3,4]azepino[1,2-b]isoquinolin-9-ones from 3-arylisoquinolines via ring closing metathesis and evaluation of topoisomerase I inhibitory activity, cytotoxicity and docking study.

Benzo[3,4]azepino[1,2-b]isoquinolinones were designed and developed as constraint forms of 3-arylisquinolines with an aim to inhibit topoisomerase I (topo I). Ring closing metathesis (RCM) of 3-arylisoquinolines with suitable diene moiety provided seven membered azepine rings of benzoazepinoisoquinolinones. Spectral analyses of these heterocyclic compounds demonstrated that the methylene protons of the azepine rings are nonequivalent. The shielding environment experienced by these geminal hydrogens differs unusually by 2.21ppm. As expected, benzoazepinoisoquinolinones displayed potent cytotoxicity. However, cytotoxic effects of the compounds were not related to topo I inhibition which is explained by non-planar conformation of the rigid compounds incapable of intercalating between DNA base pairs. In contrast, flexible 3-arylisoquinoline 8d attains active conformation at drug target site to exhibit topo I inhibition identical to cytotoxic alkaloid, camptothecin (CPT).

Virtual screening and synthesis of quinazolines as novel JAK2 inhibitors.

JAK2 is an important target in multiple processes associated with tumor growth. In this study, virtual screening was employed for hit compound identification with chemical libraries using SurflexDock. Subsequently, hit optimization for potent and selective candidate JAK2 inhibitors was performed through synthesis of diverse C-1 substituted quinazoline derivatives. A novel compound 5p, (6,7-dimethoxyquinazolin-4-yl)naphthalen-1-ylamine, was thus obtained. JAK2 inhibitory activity of 5p was 43% at 20µM and this was comparable to AG490, a representative JAK2 inhibitor. Moreover, 5p showed a positive correlation between JAK2 inhibition and cytotoxicity; 5p treatment in HT-29 cells strongly inhibited JAK2 activation and subsequent STAT3 phosphorylation, reduced anti-apoptotic protein levels, and finally induced apoptosis. This suggests that compound 5p is a candidate inhibitor of JAK2 and its downstream STAT3 signaling pathway for antitumor therapy. In the docking model, the quinazoline template of 5k, the lead compound, occupied a hydrophobic region such as Leu856, Leu855, Ala880, Leu932 and Gly935, and the highly conserved hydrogen bond was created by 6-OMe of the ring template, which binds to the NH of Arg980. Moreover, hydrophobic interactions were identified between morpholine moiety and the hydrophobic region formed by Leu855, Ala880, Tyr931, Val911 and Met929. Also, compound 5k more strongly inhibited JAK2 phosphorylation in mouse embryonic stem cells than AG490. Our study shows the successful application of virtual screening for lead discovery and we propose that the novel compound 5p can be an effective JAK2 inhibitor candidate for further antitumor agent research.

Coupled-cavity concept applied to a highly compact single-frequency laser operating in the 2 µm spectral region.

We present a highly compact and cost-efficient Tm:YAP laser setup supporting single-frequency operation at a significantly high efficiency. The coupled-cavity concept was used to design a single-frequency laser operating at 1990 nm. Single-frequency output power of 784 mW was obtained when the absorbed pumping power was 2.4 W. The optical-to-optical efficiency was 33%, and the slope efficiency was 52%.

Ellagic Acid, the Active Compound of Phyllanthus urinaria, Exerts In Vivo Anti-Angiogenic Effect and Inhibits MMP-2 Activity.

This study aimed to assess the potential anti-angiogenic mechanism of Phyllanthus urinaria (P. urinaria) and characterize the major compound in P. urinaria that exerts anti-angiogenic effect. The water extract of P. urinaria and Ellagic Acid were used to evaluate the anti-angiogenic effect in chorioallantoic membrane (CAM) in chicken embryo and human vascular endothelial cells (HUVECs). The matrix metalloproteinase-2 (MMP-2) activity was determined by gelatin zymography. The mRNA expressions of MMP-2, MMP-14 and tissue inhibitor of metalloproteinase-2 (TIMP-2) were analyzed by reverse transcription polymerase chain reaction (RT-PCR). Level of MMP-2 proteins in conditioned medium or cytosol was determined by western blot analysis. We confirmed that P. urinaria's in vivo anti-angiogenic effect was associated with a reduction in MMP-2 activity. Ellagic acid, one of the major polyphenolic components as identified in P. urinaria by high performance liquid chromatography mass spectrometry (HPLC/MS), exhibited the same anti-angiogenic effect in vivo. Both P. urinaria and Ellagic Acid inhibited MMP-2 activity in HUVECs with unchanged mRNA level. The mRNA expression levels of MMP-14 and TIMP-2 were not altered either. Results from comparing the change of MMP-2 protein levels in conditioned medium and cytosol of HUVECs after the P. urinaria or Ellagic Acid treatment revealed an inhibitory effect on the secretion of MMP-2 protein. This study concluded that Ellagic Acid is the active compound in P. urinaria to exhibit anti-angiogenic activity and to inhibit the secretion of MMP-2 protein from HUVECs.

Application of ring-closing metathesis for the synthesis of benzo[3,4]azepino[1,2-b]isoquinolin-9-ones.

Cycloaddition reaction between toluamides and benzonitriles was applied to prepare the 3-arylisoquinolines, and their chemical transformation to the dienes 4 was performed. The ring-closing metathesis (RCM) reaction afforded the desired heterocyclic compounds, benzo[3,4]azepino[1,2-b]isoquinolinones 5 in good yield.

Degradation of the internal elastic laminae in vein grafts of rats with aortocaval fistulae: potential impact on graft vasculopathy.

The internal elastic lamina (IEL) of vein grafts may be modified when exposed to arterialized hemodynamics. We investigated changes of the IEL in the inferior vena cava (IVC) of rats with aortocaval fistulae (ACF). In the IVC of ACF rats, both a markedly increased flow velocity and a mildly increased pressure were demonstrated. In the lower segment where hemodynamic changes were prominent, neointimal hyperplasia was prominently found. The IEL of the IVC in sham-operated rats, observed by confocal microscopy, was composed of parallel elastic fibers. In ACF rats, the IEL degenerated progressively after surgery. The elastic fibers were stretched and gradually became sparse, a change that was more prominent in the lower segment. Eight weeks after surgery, the IEL hardly existed in some areas of the lower segment. Electron microscopy revealed decreased densities and diameters of elastic fibers. Reverse transcriptase-polymerase chain reaction analysis revealed an up-regulation of potent elastases, cathepsins K and S, and matrix metalloproteinase-2 in the IVC of ACF rats. Results of immunohistochemical studies localized cathepsin expression predominantly to the luminal endothelium lining the IEL, suggesting involvement of elastinolysis in the degradation of the IEL. We demonstrated the degradation of the IEL in the vein graft of ACF rats, especially in the segment exposed to prominent hemodynamic changes. IEL degradation may contribute to the development of neointimal hyperplasia in vein grafts.

Synthesis, in vitro and in vivo evaluation of 3-arylisoquinolinamines as potent antitumor agents.

In the search for potent water-soluble 3-arylisoquinolines, several 3-arylisoquinolinamines were designed and synthesized. Various substituted 3-arylisoquinolinamines exhibited strong cytotoxic activity against eight different human cancer cell lines. In particular, C-6 or C-7 dimethylamino-substituted 3-arylisoquinolinamines displayed stronger potency than the lead compound 7a. Interestingly, compounds 7b and 7c showed more effective activity against paclitaxel-resistant HCT-15 human colorectal cancer cell lines when compared to the original cytotoxic cancer drug, paclitaxel. We analyzed the cell cycle dynamics by flow cytometry and found that treatment of human HCT-15 cells with 3-arylisoquinolinamine 7b blocked or delayed the progression of cells from G0/G1 phase into S phase, and induced cell death. Treatment with compound 7b also significantly inhibited the growth of tumors and enhanced tumor regression in a paclitaxel-resistant HCT-15 xenograft model.

Propylthiouracil, independent of its antithyroid effect, decreases VSMC collagen expression.

Propylthiouracil (PTU), in addition to its antithyroid effect, is recently found to have a potent antiatherosclerotic effect. Because collagen accumulation is the major contributor to the growth of atherosclerotic lesions and the neointimal formation after arterial injury, the aim of this study is to investigate the impact of PTU on collagen regulation. In the rat carotid injury model, PTU administration reversed the up-regulation of collagen in the neointima induced by balloon injury. In vitro, vascular smooth muscle cells (VSMCs), the main origin of arterial collagen, were treated with PTU. Propylthiouracil caused a concentration-dependent decrease in collagen I and III steady-state protein and mRNA levels, as determined by immuno-cytochemistry, Western, and/or Northern blot analyses. Transient transfection experiments using rat type I collagen promoter construct showed that PTU failed to affect collagen gene transcription in VSMCs. Actinomycin D studies demonstrated that the half-life of collagens mRNA decreased with PTU treatment, suggesting that PTU down-regulates collagen expression predominantly at the post-transcriptional level. Taken together, these data suggest that PTU inhibits VSMC collagen production via destabilization of collagen mRNA that contributes to its beneficial effect on atherogenesis and neointimal formation after arterial injury. However, whether the destabilization of collagen may induce plaque rupture in PTU-treated arteries merits further investigation.

Molecular design, synthesis and docking study of benz[b]oxepines and 12-oxobenzo[c]phenanthridinones as topoisomerase 1 inhibitors.

Benz[b]oxepines 4a-g and 12-oxobenzo[c]phenanthridines 5a-d were designed and synthesized as constrained forms of 3-arylisoquinolines through an intramolecular radical cyclization reaction. Radical cyclization of O-vinyl compounds preferentially led to the 7-endo-trig cyclization pathway to the benz[b]oxepines and 12-oxobenzo[c]phenanthridines through 6-exo-trig path as minor products. Among the synthesized compounds, benz[b]oxepine derivative 4e exhibited potent in vitro cytotoxicity against three different tumor cell lines, as well as topoisomerase 1 inhibitory activity. A Surflex-Dock docking study was performed to clarify the topoisomerase 1 activity of 4e.

Anti-tumor and anti-angiogenic effects of Phyllanthus urinaria in mice bearing Lewis lung carcinoma.

Phyllanthus urinaria, a widely used herb medicine in Asia, was tested for its anti-tumor effect in vivo for the first time. The anti-tumor activity in P. urinaria extract was evaluated by its effect on tumor developed in C57BL/6J mice with implantation of Lewis lung carcinoma cells. The oral administration of P. urinaria to mice caused significant inhibition of tumor development with lower occurrence rate and markedly reduced tumor size. Neither the total body weight of mouse nor the weights of organs including heart, lung, liver, spleen and kidney revealed any difference between two groups, suggesting limited in vivo cytotoxic effect of P. urinaria in mice. TUNEL assay demonstrated the increase of apoptosis in tumor sections prepared from P. urinaria-treated mice compared with control mice. It is worth of note that the neovascularization in tumor was inhibited in P. urinaria-treated mice, which implicated the potential anti-angiogenic effect of P. urinaria. Further study using an in vitro matrix-induced tube formation of HUVECs again confirmed the anti-angiogenic action of P. urinaria. P. urinaria exerted no inhibitory effect on the growth of HUVECs, however, the migration of HUVECs as analyzed using transwell assay was suppressed markedly by P. urinaria in a dose-dependent manner. All together, the present study indicated that P. urinaria extract is an anti-tumor and anti-angiogenic agent, which can be used safely in animals.

Protective effect of propylthiouracil independent of its hypothyroid effect on atherogenesis in cholesterol-fed rabbits: PTEN induction and inhibition of vascular smooth muscle cell proliferation and migration.

BACKGROUND: Propylthiouracil (PTU) is used to treat hyperthyroid patients by its hypothyroid effect. PTU also is found to have potent antioxidant and immunosuppressive effects. These findings suggest that PTU may play a role in the prevention of atherosclerosis. METHODS AND RESULTS: This study evaluates the effect of PTU on atherosclerotic change in rabbits fed a high-cholesterol diet. The pronounced atherosclerotic lesions in the aortas of rabbits fed a 2% cholesterol diet for 12 weeks were significantly attenuated by the concurrent addition of 0.1% PTU to the drinking water. However, exogenous supplementation of thyroid hormone in hypothyroid PTU-treated rabbits did not abrogate the protective effect of PTU on atherogenesis. Immunohistochemical analysis showed that PTU administration apparently reduced the intimal smooth muscle cell/macrophage ratio in the atherosclerotic plaques of rabbits fed a 2% cholesterol diet. In vitro, the addition of PTU to the medium of cultured rat vascular smooth muscle cells led to a dose-dependent inhibition of cell proliferation and migration. Furthermore, this study confirmed that PTU dose-dependently increased expression of PTEN, a tumor suppressor gene known to be involved in the coordinate inhibition of VSMC proliferation and migration. CONCLUSIONS: This study demonstrated that PTU inhibited the development of atherosclerosis through a thyroid-independent mechanism that may be explained, at least in part, by the ability of PTU to inhibit vascular smooth muscle cell proliferation and migration. Furthermore, PTEN induction, via disruption of the phosphatidylinsitol 3-kinase-mediated pathway, plays a crucial role in mediating the inhibitory action on vascular smooth muscle cell proliferation and migration.

Modification of 3-arylisoquinolines into 3,4-diarylisoquinolines and assessment of their cytotoxicity and topoisomerase inhibition.

Inspired by the initial success of the monoarylisoquinolines and the quest to identify more potent and selective anticancer agents with topoisomerase (topo) inhibitory activity, series of diarylisoquinolines (3,4-diarylisoquinolones and 3,4-diarylisoquinolinamines) were designed and synthesized. Synthesis of these compounds primarily involved lithiated toluamide-benzonitrile cycloaddition, Suzuki coupling, and nucleophilic aromatic substitution reactions. Eight of the derivatives were selectively toxic against human ductal breast epithelial tumor cells (T47D), human prostate cancer cells (DU145), and human colorectal adenocarcinoma cells (HCT-15), but had no effect on normal human breast epithelial cells (MCF10A). The topo inhibitory activities of the diarylisoquinoline compounds were relatively dependent upon their chemical structure. 3,4-Diarylisoquinolones generally did not inhibit topo I and only showed moderate inhibition of topo II. In contrast, several 3,4-diarylisoquinolinamines showed superior topo I inhibitory activity. Isoquinolinamine derivatives had greater affinity for topo I than for topo II. Topo inhibition by 3,4-diarylisoquinolines was further supported by docking models showing intercalative and/or H-bond interactions between these compounds and the DNA/topo(s). An analysis of the correlation between the cytotoxicity and topo inhibition of these compounds indicated that the primary biological target of derivatives with potent cytotoxicity was topo, which in turn establishes diaryl-substituted isoquinolines as a novel class of potential anticancer drugs.

Design, synthesis and systematic evaluation of cytotoxic 3-heteroarylisoquinolinamines as topoisomerases inhibitors.

A series of 3-heteroarylisoquinolinamines were designed, synthesized and evaluated for cytotoxicity, topoisomerases (topos) inhibitory activities and cell cycle inhibition. Several of the 3-heteroarylisoquinolines exhibited selective cytotoxicity against human ductal breast epithelial tumor (T47D) cells over non-cancerous human breast epithelial (MCF-10A) and human prostate cancer (DU145) cells. Most of the derivatives showed greater cytotoxicity in human colorectal adenocarcinoma (HCT-15) cells than camptothecin (CPT), etoposide and doxorubicin (DOX). Generally, 3-heteroarylisoquinolinamines displayed greater affinity for topo I than topo II. 3-Heteroarylisoquinolinamines with greater topo I inhibitory effect exhibited potent cytotoxicity. Piperazine-substituted derivative, 5b, with potent topo I and moderate topo II activities intercalated between DNA bases and interacted with topos through H-bonds at the DNA cleavage site of a docking model. Moreover, flow cytometry indicated that cytotoxic 3-heteroarylisoquinolinamines led to accumulation of human cervical (HeLa) cancer cells in the different phases of the cell cycle before apoptosis. Taken together, 3-heteroarylisoquinolinamines possessed potent cytotoxicity with topos and cell cycle inhibitory activities.

Fluorene-based macromolecular nanostructures and nanomaterials for organic (opto)electronics.

Nanotechnology not only opens up the realm of nanoelectronics and nanophotonics, but also upgrades organic thin-film electronics and optoelectronics. In this review, we introduce polymer semiconductors and plastic electronics briefly, followed by various top-down and bottom-up nano approaches to organic electronics. Subsequently, we highlight the progress in polyfluorene-based nanoparticles and nanowires (nanofibres), their tunable optoelectronic properties as well as their applications in polymer light-emitting devices, solar cells, field-effect transistors, photodetectors, lasers, optical waveguides and others. Finally, an outlook is given with regard to four-element complex devices via organic nanotechnology and molecular manufacturing that will spread to areas such as organic mechatronics in the framework of robotic-directed science and technology.