Molecular Recognition and Imaging of Human Telomeric G-Quadruplex DNA in Live Cells: A Systematic Advancement of Thiazole Orange Scaffold To Enhance Binding Specificity and Inhibition of Gene Expression.

A series of fluorescent ligands, which were systematically constructed from thiazole orange scaffold, was investigated for their interactions with G-quadruplex structures and antitumor activity. Among the ligands, compound 3 was identified to exhibit excellent specificity toward telomere G4-DNA over other nucleic acids. The affinity of 3-Htg24 was almost 5 times higher than that of double-stranded DNA and promoter G4-DNA. Interaction studies showed that 3 may bind to both G-tetrad and the lateral loop near the 5'-end. The intracellular colocalization with BG4 and competition studies with BRACO19 reveal that 3 may interact with G4-structures. Moreover, 3 reduces the telomere length and downregulates hTERC and hTERT mRNA expression in HeLa cells. The cytotoxicity of 3 against cancer cells (IC50 = 12.7-16.2 µM) was found to be generally higher than noncancer cells (IC50 = 52.3 µM). The findings may support that the ligand is telomere G4-DNA specific and may provide meaningful insights for anticancer drug design.

Dealkenylative Alkenylation: Formal σ-Bond Metathesis of Olefins.

The dealkenylative alkenylation of alkene C(sp3 )-C(sp2 ) bonds has been an unexplored area for C-C bond formation. Herein 64 examples of ß-alkylated styrene derivatives, synthesized through the reactions of readily accessible feedstock olefins with ß-nitrostyrenes by ozone/FeII -mediated radical substitutions, are reported. These reactions proceed with good efficiencies and high stereoselectivities under mild reaction conditions and tolerate an array of functional groups. Also demonstrated is the applicability of the strategy through several synthetic transformations of the products, as well as the syntheses of the natural product iso-moracin and the drug (E)-metanicotine.

A new fluorescent probe for sensing of biothiols and screening of acetylcholinesterase inhibitors.

A new N2O-type BODIPY probe (LF-Bop) has been proposed for the selective and sensitive detection of biologically relevant small molecular thiols. This detection is based on the Michael addition reaction between the thiol and nitrostyrene groups in the probe, which decreases the quenching effect from the nitro group, thus resulting in the recovery of the deep-red fluorescence from the BODIPY structure. The results show that LF-Bop is able to detect all tested free thiols through a fluorescence turn-on assay. The lowest limit of detection (LOD) for glutathione was found to be down to nanomolar levels (220 nM). Based on this probe, we have developed a new fluorescence assay for the screening of acetylcholinesterase inhibitors. In total, 11 natural and synthetic alkaloids have been evaluated. Both experimental measurements and theoretical molecular docking results reveal that both natural berberine and its synthetic derivative dihydroberberine are potential inhibitors of acetylcholinesterase.

Stereoselective Activity of 1-Propargyl-4-styrylpiperidine-like Analogues That Can Discriminate between Monoamine Oxidase Isoforms A and B.

The resurgence of interest in monoamine oxidases (MAOs) has been fueled by recent correlations of this enzymatic activity with cardiovascular, neurological, and oncological disorders. This has promoted increased research into selective MAO-A and MAO-B inhibitors. Here, we shed light on how selective inhibition of MAO-A and MAO-B can be achieved by geometric isomers of cis- and trans-1-propargyl-4-styrylpiperidines. While the cis isomers are potent human MAO-A inhibitors, the trans analogues selectively target only the MAO-B isoform. The inhibition was studied by kinetic analysis, UV-vis spectrum measurements, and X-ray crystallography. The selective inhibition of the MAO-A and MAO-B isoforms was confirmed ex vivo in mouse brain homogenates, and additional in vivo studies in mice show the therapeutic potential of 1-propargyl-4-styrylpiperidines for central nervous system disorders. This study represents a unique case of stereoselective activity of cis/trans isomers that can discriminate between structurally related enzyme isoforms.

Synthesis, G-Quadruplex DNA binding and cytotoxic properties of naphthalimide substituted styryl dyes.

G-Quadruplex DNAs, formed by G-rich DNA sequences in human genes, are promising targets for design of cancer drugs. In this study, two naphthalimide substituted styryl dyes with different sizes of aromatic groups were synthesized. The spectral analysis showed that the dye X-2 with a large aromatic group formed aggregates in buffer solution displaying very weak fluorescence intensity, and disaggregated in the presence of G-Quadruplex DNAs with large intensity enhancements (up to ~1800 fold). Moreover, X-2 displayed good selectivity to G-Quadruplex DNAs. In contrast, dye X-3 with the smaller aromatic group had much lower fluorescence enhancements and poor selectivity to G-Quadruplex DNAs, suggesting that the suitably sized aromatic ring was essential for the interaction with G-Quadruplex. Further binding studies suggested that X-2 mainly bound on G-quartet surface through end-stacking mode. Cytotoxicity assay showed that both of the two dyes showed good anti-proliferative activities against the cancer cell lines and less cytotoxicity in non-malignant cell lines, which were better than a standard drug 5-fluorouracil. In addition, living cell imaging was also studied and demonstrated the potential applications of the new dye X-2 in bioassays and cell imaging.

The synthesis and anticancer activity of 2-styrylquinoline derivatives. A p53 independent mechanism of action.

A series of styrylquinolines was designed and synthesized based on the four main quinoline scaffolds including oxine, chloroxine and quinolines substituted with a hydroxyl group or chlorine atom at the C4 position. All of the compounds were tested for their anticancer activity on wild-type colon cancer cells (HCT 116) and those with a p53 deletion. Analysis of SAR revealed the importance of electron-withdrawing substituents in the styryl part and chelating properties in the quinoline ring. The compounds that were more active were also tested on a panel of four cancer cell lines with mutations in TP53 tumor suppressor gene. The results suggest that styrylquinolines induce cell cycle arrest and activate a p53-independent apoptosis. The apparent mechanism of action was studied for the most promising compounds, which produced reactive oxygen species and changed the cellular redox balance.

Tuning the selectivity of N-alkylated styrylquinolinium dyes for sensing of G-quadruplex DNA.

Selective and sensitive detection of G-quadruplex DNA structures is an important issue and attracts extensive interest. To this end, numerous small molecular fluorescent probes have been designed. Here, we present a series of N-alkylated styrylquinolinium dyes named Ls-1, Ls-2 and Ls-3 with varying side groups at the chain end. We found that these dyes exhibited different binding behaviors to DNAs, and Ls-2 with a sulfonato group at the chain end displayed sensitivity and selectivity to G-quadruplex DNA structures in vitro. The characteristics of this dye and its interaction with G-quadruplex DNA were comprehensively investigated by means of UV-vis spectrophotometry, fluorescence, circular dichroism and molecular docking. Furthermore, confocal fluorescence images and MTT assays indicated dye Ls-2 could pass through membrane and enter the living HepG2 cells with low cytotoxicity.

Design, synthesis, and biological activities of 1-aryl-(3-(2-styryl)phenyl)prop-2-en-1-ones.

A moderate elevation in reactive oxygen species (ROS) levels can generally be controlled in normal cells, but may lead to death of cancer cells as the ROS level in cancer cells is already elevated. Therefore, a ROS-generating compound can act as a selective chemotherapeutic agent for cancer cells that does not affect normal cells. In our previous study, a compound containing a Michael acceptor was selectively cytotoxic to cancer cells without affecting normal cells; therefore, we designed and synthesized 26 compounds containing a Michael acceptor. Their cytotoxicities against HCT116 human colon cancer cell lines were measured by using a clonogenic long-term survival assay. To derive the structural conditions required to obtain stronger cytotoxicity against cancer cells, the relationships between the half-maximal cell growth inhibitory concentration values of the synthesized compounds and their physicochemical properties were evaluated by Comparative Molecular Field Analysis and Comparative Molecular Similarity Indices Analysis. It was confirmed that the compound with the best half-maximal cell growth inhibitory concentration triggered apoptosis through ROS generation, which then led to stimulation of the caspase pathway.

Synthesis, Antiproliferative and Pro-Apoptotic Effects of Nitrostyrenes and Related Compounds in Burkitt's Lymphoma.

BACKGROUND: Cancers of the lymphatic cells (lymphomas) account for approximately 12% of malignant diseases worldwide. The nitrostyrene scaffold is identified as a lead target structure for the development of particularly effective compounds targeting Burkitt's lymphoma (BL). OBJECTIVES: The aims of the curent study were to synthesise a panel of nitrostyrene compounds and to evaluate their activity in Burkitt's lymphoma (BL). METHODS: A panel of structurally varied compounds were designed and synthesised using Henry Knoevenagel condensation reactions. Single crystal X-Ray analysis confirmed the E configuration for six examples of these novel structures. A number of nitrostyrene-related compounds were also investigated including 1,3-bis(aryl)-2-nitropropenes together with heterocyclic scaffolds containing the nitrovinyl pharmacophore such as 3-nitro-2-phenyl-2H-chromenes. The antiproliferative activities of the compounds were evaluated using the BL cell lines EBV- MUTU-1 and EBV+ DG- 75 (chemoresistant) to establish preliminary structure-activity relationships. RESULTS: Lead compounds with optimized nitrostyrene scaffolds and 3-nitro-2-phenyl-2Hchromene structures were successfully established with typical IC50 values of 0.45 µM and 0.47 µM in MUTU-1 cells and 1.41 µM and 1.92 µM, respectively, in DG-75 cells. The mechanism of cell death was identified as apoptotic and the lead compound was found to elicit comparable apoptotic effects to Taxol in Burkitt's lymphoma cell lines MUTU-1 and DG-75. CONCLUSION: This class of pharmaceutically active compounds with potential for the treatment of Burkitt`s lymphoma suggest a potential role for nitrostyrene based agents in chemotherapy.

Bis-pyridylethenyl benzene as novel backbone for amyloid-ß binding compounds.

Detection of cerebral ß-amyloid (Aß) by targeted contrast agents is of great interest for in vivo diagnosis of Alzheimer's disease (AD). Partly because of their planar structure several bis-styrylbenzenes have been previously reported as potential Aß imaging agents. However, these compounds are relatively hydrophobic, which likely limits their in vivo potential. Based on their structures, we hypothesized that less hydrophobic bis-pyridylethenylbenzenes may also label amyloid. We synthesized several bis-pyridylethenylbenzenes and tested whether these compounds indeed display improved solubility and lower LogP values, and studied their fluorescent properties and Aß binding characteristics. Bis-pyridylethenylbenzenes showed a clear affinity for Aß plaques on both human and murine AD brain sections. Competitive binding experiments suggested a different binding site than Chrysamine G, a well-known stain for amyloid. With a LogP value between 3 and 5, most bis-pyridylethenylbenzenes were able to enter the brain and label murine amyloid in vivo with the bis(4-pyridylethenyl)benzenes showing the most favorable characteristics. In conclusion, the presented results suggest that bis-pyridylethenylbenzene may serve as a novel backbone for amyloid imaging agents.

Surface Modification of Polydivinylbenzene Microspheres with a Fluorinated Glycopolymer Using Thiol-Halogen Click Chemistry.

Distillation-precipitation polymerization of divinylbenzene was applied to obtain uniform-sized polymeric microspheres. The microspheres were then modified with polypentafluorostyrene chains utilizing surface-initiated atom transfer radical polymerization techniques. The hydrophobic fluoropolymer-coated microsphere was then converted to a hydrophilic biopolymer by performing thiol-halogen click chemistry between polypentafluorostyrene and 1-thio-ß-D-glucose sodium salt. The semi-fluorinated glycopolymer showed good binding ability with Concanavalin A as determined by confocal microscopy and turbidity experiments.

Neuroprotective effects of (E)-3,4-diacetoxystyryl sulfone and sulfoxide derivatives in vitro models of Parkinson's disease.

(E)-3,4-dihydroxystyryl aralkyl sulfones and sulfoxides have been reported as novel multifunctional neuroprotective agents in previous studies, which as phenolic compounds display antioxidative and antineuroinflammatory properties. To further enhance the neuroprotective effects and study structure-activity relationship of the derivatives, we synthesized their acetylated derivatives, (E)-3,4-diacetoxystyryl sulfones and sulfoxides, and examined their neuroprotective effects in vitro models of Parkinson's disease. The results indicate that (E)-3,4-diacetoxystyryl sulfones and sulfoxides can significantly inhibit kinds of neuron cell injury induced by toxicities, including 6-OHDA, NO, and H2O2. More important, they show higher antineuroinflammatory properties and similar antioxidative properties to corresponding un-acetylated compounds. Thus, we suggest that (E)-3,4-diacetoxystyryl sulfones and sulfoxides may have potential for the treatment of neurodegenerative disorders, especially Parkinson's disease.

In vitro antitumor mechanism of (E)-N-(2-methoxy-5-(((2,4,6-trimethoxystyryl)sulfonyl)methyl)pyridin-3-yl)methanesulfonamide.

ON01910.Na [sodium (E)-2-(2-methoxy-5-((2,4,6-trimethoxystyrylsulfonyl)methyl)phenylamino)acetate; Rigosertib, Estybon], a styryl benzylsulfone, is a phase III stage anticancer agent. This non-ATP competitive kinase inhibitor has multitargeted activity, promoting mitotic arrest and apoptosis. Extensive phase I/II studies with ON01910.Na, conducted in patients with solid tumors and hematologic cancers, demonstrate excellent efficacy. However, issues remain affecting its development. These include incomplete understanding of antitumor mechanisms, low oral bioavailability, and unpredictable pharmacokinetics. We have identified a novel (E)-styrylsulfonyl methylpyridine [(E)-N-(2-methoxy-5-((2,4,6-trimethoxystyrylsulfonyl)methyl)pyridin-3-yl)methanesulfonamide (TL-77)] which has shown improved oral bioavailability compared with ON01910.Na. Here, we present detailed cellular mechanisms of TL-77 in comparison with ON01910.Na. TL-77 displays potent growth inhibitory activity in vitro (GI50 < 1µM against HCT-116 cells), demonstrating 3- to 10-fold greater potency against tumor cell lines when compared with normal cells. Cell-cycle analyses reveal that TL-77 causes significant G2/M arrest in cancer cells, followed by the onset of apoptosis. In cell-free conditions, TL-77 potently inhibits tubulin polymerization. Mitotically arrested cells display multipolar spindles and misalignment of chromosomes, indicating that TL-77 interferes with mitotic spindle assembly in cancer cells. These effects are accompanied by induction of DNA damage, inhibition of Cdc25C phosphorylation [indicative of Plk1 inhibition], and downstream inhibition of cyclin B1. However, kinase assays failed to confirm inhibition of Plk1. Nonsignificant effects on phosphoinositide 3-kinase/Akt signal transduction were observed after TL-77 treatment. Analysis of apoptotic signaling pathways reveals that TL-77 downregulates expression of B-cell lymphoma 2 family proteins (Bid, Bcl-xl, and Mcl-1) and stimulates caspase activation. Taken together, TL-77 represents a promising anticancer agent worthy of further evaluation.

Synthesis and biological evaluation of 5-nitropyrimidine-2,4-dione analogues as inhibitors of nitric oxide and iNOS activity.

Fifty two compounds based on 5-nitropyrimidine-2,4-dione moiety have been synthesized and evaluated for their inhibitory potency on the production of nitric oxide. Among them, compound 36 inhibited the production of nitric oxide (IC50 : 8.6 µm) on lipopolysaccharide-induced RAW 264.7 cells and inducible nitric oxide synthase activity (IC50 : 6.2 µm), as well as exerted no potential cytotoxicity (IC50 > 80.0 µm). Docking study confirmed that compound 36 was an inducible nitric oxide synthase inhibitor with perfect binding to the active site of inducible nitric oxide synthase. At a dose of 10 mg/kg, oral administration of 36 possessed protective properties in carrageenan-induced paw edema of male ICR mice.

Design, synthesis and biological evaluation of naphthostyril derivatives as novel protein kinase FGFR1 inhibitors.

New class of FGFR1 kinase inhibitors with naphthostyril heterocycle has been identified. A series of N-phenylnaphthostyril-1-sulfonamides has been synthesized and tested in vitro. It was revealed that the most active compound N-(4-hydroxyphenyl)naphthostyril-1-sulfonamide inhibited FGFR1 with IC50 of 2 µM. In our preliminary studies, N-phenylnaphthostyril-1-sulfonamides demonstrated selectivity of FGFR1 inhibition and antiproliferative activity on cancer cell line. N-phenylnaphthostyril-1-sulfonamides have a good potential for further development as anticancer agents.

Compuestos sintéticos del tipo de estirilquinolinas con actividades leishmanicida y citotóxica / Styrylquinolines-type synthetic compounds with leishmanicidal and cytotoxic activities

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Synthesis of a 3-(α-styryl)benzo[b]-thiophene library via bromocyclization of alkynes and palladium-catalyzed to sylhydrazones cross-couplings: evaluation as antitubulin agents.

A library of functionalized 3-(α-styryl)-benzo[b]thiophenes, endowed with a high level of molecular diversity, was efficiently synthesized by applying a synthetic sequence that allowed introduction of various substituents on aromatic A, B, and C-rings. The strategy developed involves the synthesis of 3-bromobenzo[b]thiophene derivatives through a bromocyclization step of methylthio-containing alkynes using N-methylpyrrolidin-2-one hydrotribromide reagent (MPHT). Further coupling of 3-bromobenzothiophenes under palladium-catalysis with N-tosylhydrazones efficiently furnished 2-aryl-3-(α-styryl)benzo[b]thiophene derivatives. The antiproliferative properties of target compounds were studied. Among them, compound 5m has demonstrated submicromolar cytotoxic activity against HCT-116 cell line, and inhibited the polymerization of tubulin at micromolar level comparable to that of CA-4.

Discovery of (E)-3-((styrylsulfonyl)methyl)pyridine and (E)-2-((styrylsulfonyl)methyl)pyridine derivatives as anticancer agents: synthesis, structure-activity relationships, and biological activities.

ON01910.Na is a highly effective anticancer agent that induces mitotic arrest and apoptosis. Clinical studies with ON01910 in cancer patients have shown efficacy along with an impressive safety profile. While ON01910 is highly active against cancer cells, it has a low oral availability and requires continuous intravenous infusion or multiple gram doses to ensure sufficient drug exposure for biological activity in patients. We have identified two novel series of styrylsulfonyl-methylpyridines. Lead compounds 8, 9a, 18 and 19a are highly potent mitotic inhibitors and selectively cytotoxic to cancer cells. Impressively, these compounds possess excellent pharmaceutical properties and two lead drug candidates 9a and 18 demonstrated antitumor activities in animal models.

Improved flavodoxin inhibitors with potential therapeutic effects against Helicobacter pylori infection.

Helicobacter pylori (Hp) infection affects one-half of the human population and produces a variety of diseases from peptic ulcer to cancer. Current eradication therapies achieve modest success rates (around 70%), resistance to the antibiotics of choice is on the rise, and vaccination has not proved to be successful yet. Using an essential Hp protein, flavodoxin, as target, we identified three low-molecular-weight flavodoxin inhibitors with bactericidal anti-Hp properties. To improve their therapeutic indexes, we have now identified and tested 123 related compounds. We have first tested similar compounds available. Then we have designed, synthesized, and tested novel variants for affinity to flavodoxin, MIC for Hp, cytotoxicity, and bactericidal effect. Some are novel bactericidal inhibitors with therapeutic indexes of 9, 38 and 12, significantly higher than those of their corresponding leads. Developing novel Hp-specific antibiotics will help fighting Hp resistance and may have the advantage of not generally perturbing the bacterial flora.

Synthesis and neuroprotective effect of E-3,4-dihydroxy styryl aralkyl ketones derivatives against oxidative stress and inflammation.

E-3,4-Dihydroxy styryl aralkyl ketones as well as their 3,4-diacetylated derivatives as the analogues of neuroprotective agent CAPE were designed and synthesized for improving stability and lipid solubility. The neuroprotective activities of target compounds 10a-g and 11a-g were tested by three models in vitro, including 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity, neuronal protecting effect against damage induced by H2O2 in PC12 cells and nitric oxide suppression effect in BV2 microglial cells. The results demonstrated that compounds 10f and 11f exhibited the most potent neuroprotective effect against oxidative stress and inflammation, which is higher than that of the lead compound CAPE.