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1.

Background

Receptor tyrosine kinases (RTK) act through dimerization. Previously it was thought that only bivalent ligands could be agonistic, whereas monovalent ligands should be antagonistic. This notion changed after the demonstration that monovalent ligands can be agonistic, including our report of a small molecule monovalent ligand “D3” that is a partial agonist of the NGF receptor TrkA. A bivalent “D3-linker-D3” was expected to increase agonism.

Methods

Dimeric analogs were synthesized and tested in binding, biochemical, and biological assays.

Results

One analog, 1-ss, binds TrkA with higher affinity than D3 and induces or stabilizes receptor dimers. However, 1-ss exhibited antagonistic activity, through two mechanisms. One mechanism is that 1-ss blocks NGF binding, unlike D3 which is non-competitive. Inhibition of NGF binding may be due to the linker of 1-ss filling the inter-receptor space that NGF traverses before docking. In a second mechanism, 1-ss acts as a pure antagonist, inhibiting NGF-independent TrkA activity in cells over-expressing receptors. Inhibition is likely due to 1-ss “freezing” the TrkA dimer in the inactive state.

Conclusions

Dimerization of an RTK can result in antagonism, through two independent mechanisms.

General significance

we report a small molecule monovalent agonist being converted to a bivalent antagonist.  相似文献   

2.

Background

Among adenosine receptors (ARs) the A2B subtype exhibits low affinity for the endogenous agonist compared with the A1, A2A, and A3 subtypes and is therefore activated when concentrations of adenosine increase to a large extent following tissue damages (e.g. ischemia, inflammation). For this reason, A2B AR represents an important pharmacological target.

Methods

We evaluated seven 1-benzyl-3-ketoindole derivatives (79) for their ability to act as positive or negative allosteric modulators of human A2B AR through binding and functional assays using CHO cells expressing human A1, A2A, A2B, and A3 ARs.

Results

The investigated compounds behaved as specific positive or negative allosteric modulators of human A2B AR depending on small differences in their structures. The positive allosteric modulators 7a,b and 8a increased agonist efficacy without any effect on agonist potency. The negative allosteric modulators 8b,c and 9a,b reduced agonist potency and efficacy.

Conclusions

A number of 1-benzyl-3-ketoindole derivatives were pharmacologically characterized as selective positive (7a,b) or negative (8c, 9a,b) allosteric modulators of human A2B AR.

General significance

The 1-benzyl-3-ketoindole derivatives 79 acting as positive or negative allosteric modulators of human A2B AR represent new pharmacological tools useful for the development of therapeutic agents to treat pathological conditions related to an altered functionality of A2B AR.  相似文献   

3.

Aim

The development of anticancer drugs with specific targets is of prime importance in modern biology. This study investigates the angiopreventive and in vivo tumor inhibition activities of novel synthetic benzophenone–benzimidazole analogs.

Main methods

The multistep synthesis of novel benzophenone–benzimidazole analogs (8a–n) allowing substitution with methoxy, methyl and halogen groups at different positions on the identical chemical backbone and the variations in the number of substituents were synthesized and characterized. The newly synthesized compounds were further evaluated for cytotoxic and antiproliferative effects against Ehrlich ascites carcinoma (EAC) cells. The potent lead compounds were further assessed for antiangiogenic effects in a CAM model and a tumor-induced vasculature in vivo model. The effect of angioprevention on tumor growth was verified in a mouse model.

Key findings

The cytotoxicity studies revealed that compounds 8f and 8n are strongly cytotoxic. Analyzing the structure–activity relationship, we found that an increase in the number of methyl groups in addition to methoxy substitution at the para position of the benzoyl ring in compound 8n resulted in higher potency compared to 8f. Furthermore, neovessel formation in in vivo systems, such as the chorioallantoic membrane (CAM) and tumor-induced mice peritoneum models, was significantly suppressed and reflected the tumor inhibition observed in mice.

Significance

These results suggest the potential clinical application of compound 8n as an antiangiogenic drug for cancer therapy.  相似文献   

4.

Background

Aspartic proteases Cathepsin (Cath) E and D are two different proteases, but they share many common characteristics, including molecular weight, catalytic mechanism, substrate preferences, proteolytic conditions and inhibition susceptibility. To define the biological roles of these proteases, it is necessary to elucidate their substrate specificity. In the present study, we report a new peptide–substrate that is only sensitive to Cath E but not Cath D.

Methods

Substrate e, Mca-Ala-Gly-Phe-Ser-Leu-Pro-Ala-Lys(Dnp)-DArg-CONH2, designed in such a way that due to the close proximity of a Mca-donor and a Dnp-acceptor, near complete intramolecular quenching effect was achieved in its intact state. After the proteolytic cleavage of the hydrophobic motif of peptide substrate, both Mca and Dnp would be further apart, resulting in bright fluorescence.

Results

Substrate e showed a 265 fold difference in the net fluorescence signals between Cath E and D. This Cath E selectivity was established by having -Leu**Pro- residues at the scissile peptide bond. The confined cleavage site of substrate e was confirmed by LC-MS. The catalytic efficiency (Kcat/KM) of Cath E for substrate e was 16.7 μM1 S1. No measurable catalytic efficiency was observed using Cath D and no detectable fluorescent changes when incubated with Cath S and Cath B.

Conclusions

This study demonstrated the promise of using the developed fluorogenic substrate e as a selective probe for Cath E proteolytic activity measurement.

General significance

This study forms the foundation of Cath E specific inhibitor development in further studies.  相似文献   

5.

Background

G-quadruplexes are promising therapeutic targets for small molecules. In general, the introduction of steady positive charges through the in situ alkylation of nitrogen atoms within potential G-quadruplex ligands can significantly improve their quadruplex binding and stabilization abilities. However, our previous studies on bisaryldiketene derivatives showed that the derivative M4, whose central piperidone moiety is quaternized, exhibits a poor G-quadruplex stabilization ability.

Methods

To clarify this unusual finding, CD, ITC, UV and NMR analyses were performed to determine the binding behaviors of M4 and its non-quaternized analog M2 to G-quadruplex DNA [d(TGGGT)]4. Molecular modeling approaches were also employed to help illustrate ligand–quadruplex DNA interactions.

Results

The CD melting and ITC analyses revealed that M2 exhibited much stronger stabilization and binding abilities to [d(TGGGT)]4 compared to M4. Moreover, the CD and ITC analyses in combination with UV, NMR and MD simulations revealed that M2 tended to be end-stacked on the G-quartet, whereas M4 tended to be bound in the groove region. Analysis of the electrostatic potential showed that the charged surface of M4 was more positive than that of M2 and other reported ligands that bind to the G-quadruplex via end-stacking interactions.

Conclusions

The results indicated that the different positively charged surfaces of M2 and M4 might be the key reason for their different binding modes. These different binding modes also lead to different binding affinities and stabilization abilities for [d(TGGGT)]4.

General significance

These results provide new clues for the rational design of G-quadruplex-binding small molecules with steady positive charges.  相似文献   

6.

Background

Endangered plant species are a vital resource for exploring novel drug prototypes. A Korean endangered plant Rhododendron brachycarpum G. Don is a broad-leaved shrub native to northern Korea and central Japan. The high mobility group box 1 protein (HMGB1) could be a specific target for the discovery of novel antiseptic agents.

Methods

Gauge-invariant atomic orbital (GIAO) NMR chemical shift calculations were applied for investigation of stereochemical details with accuracy improved by application of DP4 analysis. In vitro antiseptic mechanisms were investigated utilizing immunofluorescence staining, ELISA and cell–cell adhesion assay. Cecal ligation and puncture (CLP) operation was employed to evaluate in vivo potential alleviating severe sepsis and septic shock.

Results

The first bicyclic megastigmane glucoside rhododendroside A (1) along with known megastigmane glucosides (25) were isolated from the leaves of R. brachycarpum. The structure of 1 was established by NMR analysis as well as comparison of the experimental chemical shifts with those of computed values employing DP4 application. In the CLP operation model that simulates severe sepsis, rhododendroside A (1) improved the survival rate up to 60%.

Conclusions

Our results exhibit that R. brachycarpum may produce a unique scaffold that is developed into a drug lead mitigating HMGB1-induced vascular pro-inflammatory stimuli and thus alleviating severe sepsis and related manifestations.

General significance

Discovery of new drug leads would warrant conservation efforts of endangered species.  相似文献   

7.
8.

Background

Farnesyl pyrophosphate synthase (FPPS) is a key regulatory enzyme in the biosynthesis of cholesterol and in the post-translational modification of signaling proteins. It has been reported that non-bisphosphonate FPPS inhibitors targeting its allosteric binding pocket are potentially important for the development of promising anti-cancer drugs.

Methods

The following methods were used: organic syntheses of non-bisphosphonate quinoline derivatives, enzyme inhibition studies, fluorescence titration assays, synergistic effect studies of quinoline derivatives with zoledronate, ITC studies for the binding of FPPS with quinoline derivatives, NMR-based HAP binding assays, molecular modeling studies, fluorescence imaging assay and MTT assays.

Results

We report our syntheses of a series of quinoline derivatives as new FPPS inhibitors possibly targeting the allosteric site of the enzyme. Compound 6b showed potent inhibition to FPPS without significant hydroxyapatite binding affinity. The compound showed synergistic inhibitory effect with active-site inhibitor zoledronate. ITC experiment confirmed the good binding effect of compound 6b to FPPS, and further indicated the binding ratio of 1:1. Molecular modeling studies showed that 6b could possibly bind to the allosteric binding pocket of the enzyme. The fluorescence microscopy indicated that these compounds could get into cancer cells.

Conclusions

Our results showed that quinoline derivative 6b could become a new lead compound for further optimization for cancer treatment.

General significance

The traditional FPPS active-site inhibitors bisphosphonates show poor membrane permeability to tumor cells, due to their strong polarity. The development of new non-bisphosphonate FPPS inhibitors with good cell membrane permeability is potentially important.  相似文献   

9.

Background

Altered cellular bioenergetics and oxidative stress are emerging hallmarks of most cancers including pancreatic cancer. Elevated levels of intrinsic reactive oxygen species (ROS) in tumors make them more susceptible to exogenously induced oxidative stress. Excessive oxidative insults overwhelm their adaptive antioxidant capacity and trigger ROS-mediated cell death. Recently, we have discovered a novel class of quinazolinediones that exert their cytotoxic effects by modulating ROS-mediated signaling.

Methods

Cytotoxic potential was determined by colorimetric and colony formation assays. An XF24 Extracellular Flux Analyzer, and colorimetric and fluorescent techniques were used to assess the bioenergetics and oxidative stress effects, respectively. Mechanism was determined by Western blots.

Results

Compound 3a (6-[(2-acetylphenyl)amino]quinazoline-5,8-dione) was identified through a medium throughput screen of ~ 1000 highly diverse in-house compounds and chemotherapeutic agents for their ability to alter cellular bioenergetics. Further structural optimizations led to the discovery of a more potent analog, 3b (6-[(3-acetylphenyl)amino]quinazoline-5,8-dione) that displayed anti-proliferative activities in low micromolar range in both drug-sensitive and drug-resistant cancer cells. Treatment with 3b causes Akt activation resulting in increased cellular oxygen consumption and oxidative stress in pancreatic cancer cells. Moreover, oxidative stress induced by 3b promoted activation of stress kinases (p38/JNK) resulting in cancer cell death. Treatment with antioxidants was able to reduce cell death confirming ROS-mediated cytotoxicity.

Conclusion

In conclusion, our novel quinazolinediones are promising lead compounds that selectively induce ROS-mediated cell death in cancer cells and warrant further preclinical studies.

General significance

Since 3b (6-[(3-acetylphenyl)amino]quinazoline-5,8-dione) exerts Akt-dependent ROS-mediated cell death, it might provide potential therapeutic options for chemoresistant and Akt-overexpressing cancers.  相似文献   

10.
Two new coordination polymers [Cd(dps)2Cl2] (1) and [Co(dps)2(H2O)2]·(abs)2(H2O)2 (2) (dps = 4, 4′-dipyridylsulfide, Habs = 4-amino benzenesulfonic acid) have been synthesized under similar conditions and characterized by elemental analysis, fluorescence spectra and single crystal X-ray diffraction. Compound 1 displays a dps-bridged 2D puckered, grid-like layer, which is further linked by C-H?Cl hydrogen bonds to form a 3D supramolecular architecture. Compound 2 shows a dps-bridged double-stranded chain structure, which is extended by N-H?O and O-H?O hydrogen bonds generating a 3D network. Solid-state fluorescence results reveal that both complexes can emit strong emission bands, at 467 nm and 518 nm for 1 and 344 nm for 2, respectively. Magnetic measurements show that there are weak antiferromagnetic interactions between the adjacent Co(II) ions in 2.  相似文献   

11.
Six antimony adducts with N-donor neutral ligands (1,10-phenanthroline, 4,4′-bipyridine) have been obtained following the reaction of antimony halides with phenanthroline and 4,4′-bipyridine. By changing the solvent and stoichiometry, we obtained six different complexes, Sb(phen)Cl3 (1), Sb(phen)Br3 (2), Sb2(phen)4Br8 (3) and Sb(bpy)Cl3 (4), Sb(bpy)2Cl3 (5), Sb(bpyH · bpyH2)Br6 (6) (where phen = 1,10-phenanthroline, bpy = 4,4′-bipyridine). All the complexes have been characterized via elemental analysis, FT-IR and NMR (1H, 13C) spectroscopy. The crystal structures of complexes 2, 3 and 6 have been determined by X-ray single crystal diffraction.The structural analysis show that the coordination sphere around antimony atom in complex 2 is a distorted square pyramid, coordinated by three bromine atoms and two nitrogen atoms from phen. In complex 3, the central antimony atom is six-coordinated through four bromine atoms and two nitrogen atoms forming a distorted octahedral geometry. Besides that, there are also uncoordinated 1,10-phenanthroline bonded by hydrogen bonds and π-π stacking interactions, which is rarely observed in previous reports. The crystal structure of complex 6 consists of bpyH · bpyH2 trications and hexabromoantimonate trianions. The antimony atom in the anion has a distorted octahedral environment. Additionally, all complexes present a 3D framework built up by N-H?Br, C-H?Br and C-H?Cl weak hydrogen bonds interactions.  相似文献   

12.
13.
Using the ‘Click Protocol’ the new ligands 1-(cyclohexyl)-4-(2-pyridyl)-1,2,3-triazole (1), 1-(2-trifluoromethyl phenyl)-4-(2-pyridyl)-1,2,3-triazole (2), 1-(4-hexyl phenyl)-4-(2-pyridyl)-1,2,3-triazole (3), 1-(2-mercaptomethyl phenyl)-4-(2-pyridyl)-1,2,3-triazole (4) and 1-(4-N,N-dimethylamino phenyl)-4-(2-pyridyl)-1,2,3-triazole (5) were prepared by reacting 2-ethynylpyridine with the corresponding azides. In the next step the ligands were reacted with suitable palladium and platinum precursors to yield the cis-dichloro-palladium complexes 1a-4a and platinum complexes 1b-4b. Investigation of the molecular structure of the free ligands 1 and 5 reveals the formation of infinite chains in the 3D structure which are governed by hydrogen bonds between the triazole units. Likewise the 3D structure of 1a shows infinite chains which are held together by multiple remarkably short C-H?Cl-Pd contacts. Electrochemical investigation of the free ligands by cyclic voltammetry showed irreversible reduction processes at highly negative potential. Upon metal complexation huge anodic shifts of the reduction potential were observed. To further characterize the electronic properties of all the compounds UV-Vis spectra were also analyzed.  相似文献   

14.
[Pd(sac)(terpy)](sac)·4H2O (1), [Pt(sac)(terpy)](sac)·5H2O (2), [PdCl(terpy)](sac)·2H2O (3) and [PtCl(terpy)](sac)·2H2O (4) (sac = saccharinate, and terpy = 2,2′:6′,2″-terpyridine) have been synthesized and characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR. In 1 and 2, a tridentate terpy ligand together with an N-coordinated sac ligand form the square-planar geometry around the palladium(II) or platinum(II) ions, while one sac anion remains outside the coordination sphere as a counter-ion. X-ray single crystal studies show that the [M(sac)(terpy)]+ ions in 1 and 2 reside in the centers of a hydrogen bonded honeycomb network formed by the uncoordinated sac ions and the lattice water molecules. Complexes 3 and 4 are isostructural and consist of a [M(Cl)(terpy)]+ cation, a sac anion and two lattice water molecules. The [M(Cl)(terpy)]+ ions interact with each other via M-M and π-π stacking interactions and these π interacted units are assembled to a 2D network by water bridges involving the sac ions and lattice water molecules. Convenient synthetic paths for 1-4 are also presented, and spectral, luminescence and thermal properties were discussed.  相似文献   

15.
Four new triorganotin complexes of 3-amino-5-mercapto-1,2,4-triazole with the type of R3Sn(SC2N3HNH2-3) (R = Me, 1; n-Bu, 2; Ph, 3; PhCH2, 4) have been synthesized. All the complexes have been characterized by elemental analysis, IR, 1H NMR and 13C NMR spectra. Complexes 1, 3 and 4 have been characterized by X-ray crystallography analyses too. The geometry about Sn of complex 1 is distorted trigonal bipyramidal and the supramolecular structures of complex 1 has been found consist of channels built up by intermolecular N-H?N hydrogen bonding. The geometry of tin atoms in complexes 3 and 4 are distorted tetrahedron and 1D polymers connected by intermolecular N-H?N hydrogen bonding or N-H?N and N-H?S hydrogen bonding. Additionally, 1D polymer of complex 3 aggregated in 2D layer by intermolecular N-H?S hydrogen bonding.  相似文献   

16.
Four new Cu(II) complexes [Cu(pzda)(2,2′-bpy)(H2O)] · 2.5H2O (1), [Cu(pzda)(phen)(H2O)] · H2O (2), [Cu(pzda)(4,4′-bpy)] · H2O (3) and [Cu(pzda)(bpe)0.5(H2O)] (4) were synthesized by hydrothermal reactions of copper salt (acetate or sulphate) with pyrazine-2,6-dicarboxylic acid (H2pzda), and 2,2′-bipyridine (2,2′-bpy), 1,10-phenanthroline (phen), 4,4′-bipyridine (4,4′-bpy) or 1,2-bis(4-pyridyl)-ethane (bpe), respectively. For 1 and 2, they are both monomeric entities which are further assembled into 3D supramolecular networks by hydrogen bonds and π-π stacking interactions. Complex 3 has a 2D metal-organic framework which is connected into 3D supramolecular network by hydrogen bonds. However, for 4, the bpe ligand bridges two Cu(II) ions into binuclear unit, and then the binuclear molecules are assembled into 3D supramolecular network by hydrogen bonds between the coordination water molecule and the carboxylate oxygen atoms. The thermal decomposition mechanism of complexes 1 and 2 cooperated with powder XRD at different temperatures is discussed. The results reveal that once liberation of water molecules takes place the supramolecular network of 1 and 2 collapses.  相似文献   

17.
9-Nickelafluorenyllithium (1) reacted with iodine and then with various CpxM complexes (Cpx = Cp, Cp, M = Na, Mg, Li) in different solvents. The products (π-allyl complexes), isolated from these reactions, were formed via addition of the biphenyl ligand to the Cp ring originally bonded to the Ni atom. Stereospecifity of the reactions depended on the used solvent. π-Allyl compounds 2, 3 and 4 were characterized by X-ray single crystal analysis.  相似文献   

18.
Six 2D and 3D supramolecular complexes [Cu(L1)(O2CCH3)2] · H2O (1), [Cu2(L2)22-O2CCH3)2](BF4)2 (2), [Cu2(L1)2(BDC)(NO3)2] · 0.5H2O (3) [Cu2(L2)2(BDC)(NO3)2] (4), [Cu2(L3)2(BDC)(NO3)2] · 0.5H2O (5) and [Cu2(L2)2(BDC)(H2O)2](BDC) · 8H2O (6) (L1 = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine, L2 = 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine, L3 = 4′-phenyl-2,2′:6′,2″-terpyridine, BDC = 1,4-benzenedicarboxylate), have been prepared and structurally characterized by X-ray diffraction crystallography. In complexes 1, 3, and 4, 1D channels are formed through C-H?O and C-H?N hydrogen-bonding interactions, and further linked into 3D structure via C-H?O and O-H?O interactions. Complex 2 is a 2D layer constructed from intermolecular C-H?F and π-π stacking interactions. In the structure of 6, the BDC2− ions and solvent water molecules form a novel 2D layer containing left- and right-handed helical chains via hydrogen-bonds, and an unusual discrete water octamer is formed within the layer. In 2, 4, 6 and [Ag2(L2)2](PF6)2 (7) the bonding types of pendent pyridines of L2 depending on the twist about central pyridines are involved in intramolecular (2 and 4), intermolecular (6) or coordination bonds (7) in-twist-order of 5.8°, 3.7°, 28.2° and 38.0°, respectively. Differently, the pendent pyridines of L1 in 1 and 3 form intermolecular hydrogen bonds despite of distinct corresponding twist angles of 25.1° (1) and 42.6°(3). Meanwhile, π-π stacking interactions are present in 1-6 and responsible for the stabilization of these complexes.  相似文献   

19.
The reaction of [1,3-di(2-methoxy)benzene]triazene, [HL], with Hg(CH3COO)2 and Hg(SCN)2 in methanol as solvent, resulted in the formation of [HgL2] (1) and [HgL(SCN)] (2), respectively. These compounds were characterized by means of X-ray diffraction, FT-IR spectroscopy, CHN and TGA-DTA analysis. In the lattice of the compound 1, the mono-nuclear complexes were connected to dimer structure by intermolecular non-classical C-H···O hydrogen bonds. Also, weak Hg-η2-arene π-interactions link the dimers into 1D supramolecular chains. The compound 2 is a 2D coordination polymer induced by C-H···π stacking interactions between 1D chains produced by weak Hg-η33-arene π-interactions. The results of studies of the stoichiometry and formation of complexes of 1 and 2 in methanol solution were found to be in support of their solid state stoichiometry.  相似文献   

20.
Six new 1-3D coordination polymers of an unsymmetrical angular ligand 3-pyridin-4-ylbenzoate (L), namely, [Ni(L)2(C2H6O2)]n (1), [Cd(L)2(H2O)2]n·4H2O (2), [Zn2(OH)(L)3]n (3), [Fe2(OH)(L)3]n (4), [Ni(L)2(H2O)]n (5) and [Cd(L)2(H2O)]n (6) were hydro(solvo)thermally synthesized. They have abounding structure chemistry ranging from one-dimensional ribbons (1 and 2), and two-dimensional novel helical double-layered frameworks (3 and 4) to three-dimensional CdSO4-topological porous interpenetrating architectures with hydrophilic and hydrophobic channels regularly arraying (5 and 6). The labile conformations and coordination modes of ligand L, which were finely tuned by reaction conditions, perhaps play the key role in the construction of various architectures. Very interestingly, the slight difference in solvent system or temperature resulted in the distinct architectures of nickel(II) complexes 1 and 5 or cadmium(II) complexes 2 and 6. As expected, the unsymmetrical ligand L has a trend to construct metal-organic helixes as observed in 3 and 4. Thermogravimetric analysis of 5 shows the main framework retains stability until a higher temperature 379 °C. The 3D microporous network of 5 can slightly absorb for N2 and Ar. Compounds 2, 3 and 6 emit ligand-centered photoluminescence but with obviously different intensities owing to the structural diversities and coordinating water molecules.  相似文献   

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