- GABAa receptor ligands often interact with binding sites in the transmembrane domain and in the extracellular domain—can the promiscuity code be cracked?
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Many allosteric binding sites that modulate gamma aminobutyric acid (GABA) effects have been described in heteropentameric GABA type A (GABAA) receptors, among them sites for benzodiazepines, pyrazoloquinolinones and etomidate. Diazepam not only binds at the high affinity extracellular “canonical” site, but also at sites in the transmembrane domain. Many ligands of the benzodiazepine binding site interact also with homologous sites in the extracellular domain, among them the pyrazoloquinolinones that exert modulation at extracellular α+/β? sites. Additional interaction of this chemotype with the sites for etomidate has also been described. We have recently described a new indole‐based scaffold with pharmacophore features highly similar to pyrazoloquinolinones as a novel class of GABAA receptor modulators. Contrary to what the pharmacophore overlap suggests, the ligand presented here behaves very differently from the identically substituted pyrazoloquinolinone. Structural evidence demonstrates that small changes in pharmacophore features can induce radical changes in ligand binding properties. Analysis of published data reveals that many chemotypes display a strong tendency to interact promiscuously with binding sites in the transmembrane domain and others in the extracellular domain of the same receptor. Further structural investigations of this phenomenon should enable a more targeted path to less promiscuous ligands, potentially reducing side effect liabilities.
- Ernst, Margot,Iorio, Maria Teresa,Koniuszewski, Filip,Mihovilovic, Marko D.,Rehman, Sabah,Schnürch, Michael,Scholze, Petra,Simeone, Xenia,Vogel, Florian Daniel
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Read Online
- Insights into supramolecular assembly formation of diethyl aryl amino methylene malonate (DAM)derivatives assisted via non-covalent interactions
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The crystal structures of four derivatives of diethyl 2-(((aryl)amino)methylene)malonate (DAM)have been studied by single crystal X-ray diffraction. The molecular structures of all the four derivatives were found to be in co-planar conformation. The detailed analysis of molecular conformation in four derivatives reveals the presence of a common strong intramolecular N–H?O hydrogen bonding, forming a ring of graph-set motif S1 1 (6). The effect of chloro and nitro substitution on their relative strengths of hydrogen bonding are analyzed here. Particularly, in compound 1, additional intramolecular hydrogen bonding between –NO2 and N–H was observed that results in the formation of another six-membered chelate ring. On the other hand in case of compound 3, we have observed type-I Cl?Cl interaction for the first time in this class of compounds. Further, Hirshfeld surface has been generated that is mapped with dnorm shape index and curvedness to summarize the weak interactions and examine the molecular shapes in all four derivatives. Effect of nitro (1 and 2)and chloro (3 and 4)substitution on the C?H, N?O and C?O interaction is highlighted in molecular contour and 2D fingerprint plots.
- Shaik, Althaf,Angira, Deekshi,Thiruvenkatam, Vijay
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Read Online
- Crystal Packing Modulation of the Strength of Resonance-Assisted Hydrogen Bonds and the Role of Resonance-Assisted Pseudoring Stacking in Geminal Amido Esters: Study Based on Crystallography and Theoretical Calculations
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A detailed experimental and theoretical investigation of a series of substituted geminal amido esters (ethyl (2E)-3-(arylamino)-2-(arylcarbamoyl)prop-2-enoate, AME-1-8) leading to the identification of a unique angularly fused pseudotricyclic (S(6),S(6),S(6)) ring system stabilized by an intramolecular resonance-assisted hydrogen bond (RAHB) and a non-RAHB are presented in addition to weak intermolecular interactions. An analysis of X-ray and theoretical models reveals that the strength of the intramolecular RAHB (N1-H1N···O1) varies in a wide range (6.9-11.4 kcal mol-1) due to crystal-packing constraints arising from different aromatic ring substitutions. However, the effect is less significant and the strength differs only in a narrow range (8.2-9.9 kcal mol-1) in the case of non-RAHB. The downfield shift (δ~12.3) observed for the N-Haniline signal in 1H NMR spectra of AME-1-8 is due to the presence of intramolecular RAHB. A PIXEL energy analysis suggests that the molecular dimer formed by stacking of RAHB pseudorings is found to be strong (Etot = -14.4 to -17.9 kcal mol-1), and this dimer forms the basic motif in most of the structures reported herein. A detailed analysis of the isostructurality suggests that the basic motif exists in most of the structural combinations. The weak intermolecular C-H···O, C-H···Cl, and C-H···πinteractions play a vital role in the stabilization of these crystal structures, as evaluated by PIXEL and Bader's quantum theory of atoms in molecules approach (QTAIM). A lattice energy analysis suggests that the Coulombic contribution and total lattice energies are higher in the para-substituted compounds (AME-2, AME-5, and AME-8) in comparison to the other isomeric compounds. Further, the crystal packing of these compounds is analyzed on the basis of the energy frameworks. It shows that most of the crystals show similar 3D topologies, suggesting that these compounds may have similar mechanical behavior.
- Venkatesan, Perumal,Thamotharan, Subbiah,Percino, M. Judith,Ilangovan, Andivelu
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p. 779 - 798
(2021/01/13)
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- Interaction of a Triantennary Quinoline Glycoconjugate with the Asialoglycoprotein Receptor
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Targeted intracellular delivery is an efficient strategy for developing therapeutics against cancer and other intracellular infections. Nonspecific drug delivery shows limited clinical applications owing to high dosage, cytotoxicity, nonspecific action, h
- Palit, Subhadeep,Banerjee, Sayanika,Mahata, Tridib,Niyogi, Sougata,Das, Tanusree,Sova Mandi, Chandra,Chakrabarti, Partha,Dutta, Sanjay
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p. 2211 - 2216
(2021/05/10)
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- Design, synthesis, in vitro and in silico studies of novel 4-oxoquinoline ribonucleoside derivatives as HIV-1 reverse transcriptase inhibitors
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Human immunodeficiency virus type 1 (HIV-1) is a public health problem that affects over 38 million people worldwide. Although there are highly active antiretroviral therapies, emergence of antiviral resistant strains is a problem which leads to almost a million death annually. Thus, the development of new drugs is necessary. The viral enzyme reverse transcriptase (RT) represents a validated therapeutic target. Because the oxoquinolinic scaffold has substantial biological activities, including antiretroviral, a new series of 4-oxoquinoline ribonucleoside derivatives obtained by molecular hybridization were studied here. All synthesized compounds were tested against human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT), and 9a and 9d displayed the highest antiviral activities, with IC50 values of 1.4 and 1.6 μM, respectively. These compounds were less cytotoxic than AZT and showed CC50 values of 1486 and 1394 μM, respectively. Molecular docking studies showed that the most active compounds bound to the allosteric site of the enzyme, suggesting a low susceptibility to the development of antiviral resistance. In silico pharmacokinetic and toxicological evaluations reinforced the potential of the active compounds as anti-HIV candidates for further exploration. Overall, this work showed that compounds 9a and 9d are promising scaffold for future anti-HIV-1 RT drug design.
- Forezi, Luana da S.M.,Ribeiro, Mariana M.J.,Marttorelli, Andressa,Abrantes, Juliana L.,Rodrigues, Carlos R.,Castro, Helena Carla,Souza, Thiago Moreno L.,Boechat, Fernanda da C.S.,de Souza, Alessandra M.T.,de Souza, Maria Cecília B.V.
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- 3-(Benzo[: D] thiazol-2-yl)-4-aminoquinoline derivatives as novel scaffold topoisomerase i inhibitor via DNA intercalation: Design, synthesis, and antitumor activities
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Twenty-seven 3-(benzo[d]thiazol-2-yl)-4-aminoquinoline derivatives have been designed and synthesized as topoisomerase I inhibitors. The in vitro anti-proliferation evaluation against four human cancer cell lines (MGC-803, HepG-2, T24, and NCI-H460) and one normal cell line (HL-7702) indicated that most of them exhibited potent cytotoxicity. Among them, 5a was identified as the most promising candidate with a low IC50 value of about 2.20 ± 0.14 and was selected for further exploration. Spectroscopic analyses and agarose-gel electrophoresis assays indicated that 5a could interact with DNA and strongly inhibit topoisomerase I (Topo I). Further screening of the Topo I activity of compounds 5b, 5c, 5e, 5f, 5h, 5i, 5j, 5l, and 5n suggested that some of the compounds might exert quite a different cytotoxicity profile to that of 5a. Molecular modeling studies confirmed that 5a adopts a unique mode to interact with DNA and Topo I. Other molecular mechanistic studies suggested that the treatment of MGC-803 cells with 5a induces S phase arrest, up-regulates the pro-apoptotic protein, down-regulates the anti-apoptotic protein, activates caspase-3, and subsequently induces mitochondrial dysfunction so as to induce cell apoptosis. The in vivo efficiency of 5a was also evaluated on MGC-803 xenograft nude mice and the relative tumor growth inhibition was 42.4percent at 12 mg kg-1 without an obvious loss in the body weight. This journal is
- Chen, Nan-Ying,Gu, Zi-Yu,Li, Xiao-Juan,Liao, Hao-Ran,Mo, Dong-Liang,Pan, Cheng-Xue,Su, Gui-Fa,Yuan, Jing-Mei,Zhang, Guo-Hai
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p. 11203 - 11214
(2020/07/15)
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- Design, synthesis and 2D QSAR study of novel pyridine and quinolone hydrazone derivatives as potential antimicrobial and antitubercular agents
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The increased development of highly resistant bacterial strains and tuberculosis, constitute a serious public health threat, highlighting the urgent need of novel antibacterial agents. In this work, two novel series of nicotinic acid hydrazone derivatives (6a-r) and quinolone hydrazide derivatives (12a-l) were synthesized and evaluated as antimicrobial and antitubercular agents. The synthesized compounds were evaluated in vitro for their antibacterial, antifungal and antimycobacterial activities. Compounds 6f and 6p bearing the 3,4,5- (OCH3)3 and 2,5-(OCH3)2 benzylidene motifs were the most potent and as antibacterial, antifungal (MIC: 0.49–1.95 μg/mL) and (MIC: 0.49–0.98 μg/mL) respectively and antimycobacterial activity (MIC = 0.76 and 0.39 μg/mL) respectively. Besides, several derivatives, 6e, 6h, 6l-6o, 6q, 6r, 12a, 12b, 12e, 12h, 12k and 12l, exhibited significant antibacterial and antifungal activities with MIC values ranging from 1.95 to 7.81 μg/mL, they also displayed excellent to good activity against Mycobacterium tuberculosis with MIC range from 0.39 to 3.12 μg/mL. In addition, some of the most active compounds were tested for cytotoxic activities against human lung fibroblast normal cells (WI-38) and displayed low toxicity. Moreover, 2D-QSAR models to characterize the descriptors controlling the observed activities, were generated and validated.
- Abdelrahman, Mohamed A.,Salama, Ismail,Gomaa, Mohamed S.,Elaasser, Mahmoud M.,Abdel-Aziz, Marwa M.,Soliman, Dalia H.
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p. 698 - 714
(2017/07/18)
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- 6-substituted-1-((1-substituted phenyl-1,2,3-triazole-4-yl)methyl)-4-carbonylquinoline-3-ethyl formate compound, and preparation and application thereof
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The invention specifically discloses a 6-substituted-1-((1-substituted phenyl-1,2,3-triazole-4-yl)methyl)-4-carbonylquinoline-3-ethyl formate compound, and preparation and application thereof, belonging to the technical field of organic synthesis. The com
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Paragraph 0049; 0050
(2016/10/07)
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- 6-substituted-1-((1-substituted phenyl-1,2,3-triazole-4-yl)methyl)-4-carbonylquinoline-3-carboxylic acid or pharmaceutical salt, preparation and application
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The present invention belongs to the technical field of organic synthesis, and specifically discloses 6-substituted-1-((1-substituted phenyl-1,2,3-triazole-4-yl)methyl)-4-carbonylquinoline-3-carboxylic compounds or a pharmaceutical salt thereof, and prepa
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Paragraph 0052; 0053
(2017/01/23)
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- Invariant and variable intermolecular interactions in functionalized malonic acid half-esters: X-ray, Hirshfeld surface and PIXEL energy analyses
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A series of functionalized malonic acid half-ester derivatives (parent compound MHE-1), with variations in functional groups at different positions on the aromatic ring, have been synthesized and crystal structures are determined at room temperature (296
- Venkatesan, Perumal,Thamotharan, Subbiah,Kumar, Rajendran Ganesh,Ilangovan, Andivelu
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p. 904 - 915
(2015/02/19)
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- Synthesis, cytotoxicity and mechanistic evaluation of 4-oxoquinoline-3- carboxamide derivatives: Finding new potential anticancer drugs
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As part of a continuing search for new potential anticancer candidates, we describe the synthesis, cytotoxicity and mechanistic evaluation of a series of 4-oxoquinoline-3-carboxamide derivatives as novel anticancer agents. The inhibitory activity of compounds 10-18 was determined against three cancer cell lines using the MTT colorimetric assay. The screening revealed that derivatives 16b and 17b exhibited significant cytotoxic activity against the gastric cancer cell line but was not active against a normal cell line, in contrast to doxorubicin, a standard chemotherapeutic drug in clinical use. Interestingly, no hemolytical activity was observed when the toxicity of 16b and 17b was tested against blood cells. The in silico and in vitro mechanistic evaluation indicated the potential of 16b as a lead for the development of novel anticancer agents against gastric cancer cells.
- Forezi, Luana Da S. M.,Tolentino, Nathalia M. C.,De Souza, Alessandra M. T.,Castro, Helena C.,Montenegro, Raquel C.,Dantas, Rafael F.,Oliveira, Maria E. I. M.,Silva Jr., Floriano P.,Barreto, Leilane H.,Burbano, Rommel M. R.,Abrahim-Vieira, Barbara,De Oliveira, Riethe,Ferreira, Vitor F.,Cunha, Anna C.,Boechat, Fernanda Da C. S.,De Souza, Maria Cecilia B. V.
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p. 6651 - 6670
(2014/06/10)
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- Molecular design, synthesis and biological evaluation of 1,4-dihydro-4-oxoquinoline ribonucleosides as TcGAPDH inhibitors with trypanocidal activity
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The 1,4-dihydro-4-oxoquinoline ribonucleoside, Neq135, is the first low micromolar trypanosomatidae inhibitor to show good ligand efficiency (0.28 kcal mol-1 atom-1) and good ligand lipophilicity efficiency (0.37 kcal mol-1/sup
- Soares, Fabyana A.,Sesti-Costa, Renata,Da Silva, Jo?o Santana,De Souza, Maria Cecília B.V.,Ferreira, Vitor F.,Da C. Santos, Fernanda,Monteiro, Patricia A.U.,Leit?o, Andrei,Montanari, Carlos A.
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supporting information
p. 4597 - 4601
(2013/08/15)
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- Synthesis and study of 1-ethyl-3-carbohydrazide and 3-[1-oxo-2-hydrazino-3- {p-toluenesulfon}]quinolone derivatives against bacterial infections
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We have synthesized newer series of quinolone derivatives substituted with hydrazine group (6a-e) and sulfonamide group (7a-e). These compounds were screened for antibacterial activity. All these compounds were fully characterized by spectroscopic means and elemental analysis. From minimum inhibitory concentration (MIC) data, it has been observed that all the synthesized compounds exhibited good antibacterial activity in vitro.
- Srivastava, Nivedita,Kumar, Anil
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p. 464 - 468
(2013/10/01)
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- Synthesis of substituted-4-oxo-1, 4-dihydro-3-[1-oxo-2-hydrazino-3-{p- toluenesulfon}]quinoline derivatives and their biological activity against bacterial infections
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We have synthesized a series of quinolone and fluoroquinolones derivatives substituted with p-tosyl group. All these compounds were screened as antibacterial and datas were compared with reference marketed drug viz.; Ciprofloxacin & Norfloxacin.
- Srivatava,Kumar
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p. 507 - 511
(2013/11/06)
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- Oxoquinoline acyclonucleoside phosphonate analogues as a new class of specific inhibitors of human immunodeficiency virus type 1
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The emergence of a multidrug-resistant HIV-1 strain and the toxicity of anti-HIV-1 compounds approved for clinical use are the most significant problems facing antiretroviral therapies. Therefore, it is crucial to find new agents to overcome these issues. In this study, we synthesized a series of new oxoquinoline acyclonucleoside phosphonate analogues (ethyl 1- [(diisopropoxyphosphoryl)methyl]-4-oxo-1,4-dihydroquinoline-3-carboxylates 3a-3k), which contained different substituents at the C6 or C7 positions of the oxoquinoline nucleus and an N1-bonded phosphonate group. We subsequently investigated these compounds' in vitro inhibitory effects against HIV-1-infected peripheral blood mononuclear cells (PBMCs). The most active compounds were the fluoro-substituted derivatives 3f and 3g, which presented excellent EC 50 values of 0.4 ± 0.2 μM (3f) and 0.2 ± 0.005 μM (3g) and selectivity index values (SI) of 6240 and 14675, respectively.
- Faro, Leticia V.,De Almeida, Jessica M.,Cirne-Santos, Claudio C.,Giongo, Viveca A.,Castello-Branco, Luis R.,Oliveira, Ingrid De B.,Barbosa, Juliana E.F.,Cunha, Anna C.,Ferreira, Vitor F.,De Souza, Marcos C.,Paixao, Izabel C.N.P.,De Souza, Maria Cecilia B.V.
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scheme or table
p. 5055 - 5058
(2012/08/28)
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- Synthesis and anticancer activities of some novel 2-(benzo[d]thiazol-2-yl)- 8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones
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A series of 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c] quinolin-3(5H)-ones (3a-g) have been synthesized and evaluated for their in vitro antiproliferative activities against four human cancer cell lines: MDA-MB-435 (breast), HL-60 (leukemia), HCT-8 (colon) and SF-295 (central nervous system). The results showed that the compounds 3b (2-(benzo[d]thiazol-2-yl)-8- methyl-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) and 3c (2-(benzo[d]thiazol-2-yl)-8- bromo-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) exhibited good cytotoxicity for three cell lines with IC50 values lower than 5 μg/mL. Analysis of theoretical toxicity risks have shown medium tumorigenic and irritant risks related to 3b and 3c in contrast to doxorubicin, the positive control.
- Reis, Raísa Da R.,Azevedo, Elisa C.,De Souza, Maria Cecília B.V.,Ferreira, Vitor Francisco,Montenegro, Raquel C.,Araújo, Ana Jérsia,Pessoa, Cláudia,Costa-Lotufo, Letícia V.,De Moraes, Manoel O.,Filho, José D.B.M.,De Souza, Alessandra M.T.,De Carvalho, Natasha C.,Castro, Helena C.,Rodrigues, Carlos R.,Vasconcelos, Thatyana R.A.
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experimental part
p. 1448 - 1452
(2011/04/24)
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- Design, synthesis, and biological evaluation of novel quinoline derivatives as HIV-1 Tat-TAR interaction inhibitors
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Thirty-two quinoline derivatives were designed and synthesized as HIV-1 Tat-TAR interaction inhibitors. All the compounds showed high antiviral activities in inhibiting the formation of SIV-induced syncytium in CEM174 cells. Nine of them with low cytotoxicities were evaluated by Tat dependent HIV-1 LTR-driven CAT gene expression colorimetric enzyme assay in human 293T cells, indicating effective inhibitory activities of blocking the Tat-TAR interaction. Molecular modeling experiments indicated that these compounds may inhibit Tat-TAR interaction by binding to Tat protein instead of TAR RNA.
- Chen, Shuguang,Chen, Ran,He, Meizi,Pang, Ruifang,Tan, Zhiwu,Yang, Ming
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experimental part
p. 1948 - 1956
(2009/05/26)
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- Pharmacomodulations around the 4-oxo-1,4-dihydroquinoline-3-carboxamides, a class of potent CB2-selective cannabinoid receptor ligands: Consequences in receptor affinity and functionality
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CB2 receptor selective ligands are becoming increasingly attractive drugs due to the potential role of this receptor in several physiopathological processes. Thus, the development of our previously described series of 4-oxo-1,4-dihydroquinoline-3-carboxamides was pursued with the aim to further characterize the structure-affinity and structure-functionality relationships of these derivatives. The influence of the side chain was investigated by synthesizing compounds bearing various carboxamido and keto substituents. On the other hand, the role of the quinoline central scaffold was studied by synthesizing several 6-, 7-, or 8-chloro-4-oxo-1,4-dihydroquinolines, as well as 4-oxo-1,4-dihydronaphthyridine and 4-oxo-1,4-dihydrocinnoline derivatives. The effect of these modifications on the affinity and functionality at the CB2 receptor was studied and allowed for the characterization of new selective CB2 receptor ligands.
- Stern, Eric,Muccioli, Giulio G.,Bosier, Barbara,Hamtiaux, Laurie,Millet, Régis,Poupaert, Jacques H.,Hénichart, Jean-Pierre,Depreux, Patrick,Goossens, Jean-Fran?ois,Lambert, Didier M.
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p. 5471 - 5484
(2008/03/17)
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- Evaluation of 3-carboxy-4(1H)-quinolones as inhibitors of human protein kinase CK2
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Due to the emerging role of protein kinase CK2 as a molecule that participates not only in the development of some cancers but also in viral infections and inflammatory failures, small organic inhibitors of CK2, besides application in scientific research, may have therapeutic significance. In this paper, we present a new class of CK2 inhibitors-3-carboxy-4(1H)-quinolones. This class of inhibitors has been selected via receptor-based virtual screening of the Otava compound library. It was revealed that the most active compounds, 5,6,8-trichloro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (7) (IC 50 = 0.3 μM) and 4-oxo-1,4-dihydrobenzo[h]quinoline-3-carboxylic acid (9) (IC50 = 1 μM), are ATP competitive (Ki values are 0.06 and 0.28 μM, respectively). Evaluation of the inhibitors on seven protein kinases shows considerable selectivity toward CK2. According to theoretical calculations and experimental data, a structural model describing the key features of 3-carboxy-4(1H)-quinolones responsible for tight binding to CK2 active site has been developed.
- Golub, Andriy G.,Yakovenko, Olexander Ya.,Bdzhola, Volodymyr G.,Sapelkin, Vladislav M.,Zien, Piotr,Yarmoluk, Sergiy M.
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p. 6443 - 6450
(2007/10/03)
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- Synthesis and anti-HSV-1 activity of quinolonic acyclovir analogues
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Several 1-[(2-hydroxy-ethoxy)methyl]-3-carbethoxy-4(1H)quinolones (2a-l) and l-[(2-hydroxy-ethoxy)methyl]-4(1H)quinolone-3-carboxylic acids (3a-j and 3l) were synthesized and 2a-j, 2l and 3a-j, 3l were evaluated against herpes simplex virus type 1 (HSV-1), employing a one-pot reaction: silylation of the desired quinolone (BSTFA 1% TMCS) followed by equimolar amount addition of 1,3-dioxolane, chlorotrimethylsilane and KI, at room temperature. The acyclonucleosides 2a-l were obtained in 40-77% yields. The esters 2a-j and 2l were subsequently converted into the corresponding hydroxyacids 3 in 40-70% yields. Attempts of hydrolysis of 2k produced only a mixture of degradation products. Antiviral activity of 2 and 3 on HSV-1 virus infection was assessed by the virus yield assay. Except for compounds 2i and 3e, the acyclonucleosides were found to reduce the virus yield by 70-99% at the concentration of 50 μM, being the acids, in general, more effective inhibitors than their corresponding esters. Compounds 3j and 2d exhibited antiviral activity against HSV-1 virus with EC50 of 0.7 ± 0.04 and 0.8 ± 0.09 μM, respectively. Both compounds were not toxic towards the Vero cell line.
- Lucero, Bianca D'A.,Gomes, Claudia Regina B.,Frugulhetti, Izabel Christina De P.P.,Faro, Leticia V.,Alvarenga, Lise,De Souza, Maria Cecilia B.V.,De Souza, Thiago M.L.,Ferreira, Vitor F.
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p. 1010 - 1013
(2008/12/23)
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- Design, synthesis, and biological evaluation of novel 4-hydro-quinoline-3- carboxamide derivatives as an immunomodulator
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A series of novel quinoline-3-carboxamide derivatives were synthesized and evaluated for their immunomodulatory activity. The compounds were tested in vitro for effects on spleen lymphocyte proliferation and TNF-α production by macrophage. Three compounds showed immunomodulatory profiles similar to and more potent than those of linomide and FR137316 and were selected for further pharmacological studies in vivo.
- He, Jun-Feng,Yun, Liu-Hong,Yang, Ri-Fang,Xiao, Zhi-Yong,Cheng, Jun-Ping,Zhou, Wen-Xia,Zhang, Yong-Xiang
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p. 2980 - 2985
(2007/10/03)
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- Microwave assisted Gould-Jacob reaction: Synthesis of 4-quinolones under solvent free conditions
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A single step Gould-Jacob reaction between aromatic amines and diethyl ethoxymethylenemalonates (EMME) for the synthesis of 4-quinolones under solvent free microwave irradiation has been carried out and compared with classical heating.
- Dave, Chaitanya G.,Joshipura, Hardik M.
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p. 650 - 652
(2007/10/03)
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- A clay catalyzed method for diethyl 2,2,2- trichloroethylidenepropanedioate, an efficient intermediate for the synthesis of enamino esters
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An improved high yielding procedure for diethyl 2,2,2- trichloroethyledinepropanedioate (3) using montmorillonite K-10 catalyst has been described. Various diethyl (substituted aminomethylene)propanedioates (6a-j) have been synthesised in excellent yields starting from propanedioate (3) via addition products (5a-j).
- Deshmukh,Panse,Bhawal
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p. 1801 - 1809
(2007/10/03)
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- Structure-activity relationship investigations of the modulating effect of core substituents on the affinity of pyrazoloquinolinone congeners for the benzodiazepine receptor
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A series of 6- and 7-substituted-2-arylpyrazolo [4,3-c] quinolin-3-ones was synthesized and tested in vitro for binding with the benzodiazepine receptor in competition with [3H]flunitrazepam. Electronic parameters (molecular electrostatic potential (MEP), charge distribution on the nitrogen atoms, dipole moment μ, and ionization potential (IP) were calculated for the compounds by semi-empirical quantum chemistry methods. Lipophilicity of the compounds, expressed as logarithm of the octanol-water partition coefficient (log P), was calculated by the program Pallas. A quantitative correlation of the biological data with molecular parameters revealed a significant dependence (r = 0.95) of the activity on hydrophobic constants of the substituents, log P, and magnitude of the MEP minimum associated with the carbonyl oxygen atom.
- Karolak-Wojciechowska, Janina,Lange, Jerzy,Ksiazek, Waldemar,Gniewosz, Malgorzata,Rump, Slawomir
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p. 579 - 585
(2007/10/03)
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- Antimalarials: Synthesis of 4-aminoquinolines that circumvent drug resistance in malaria parasites
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The strategies described here have permitted the synthesis of a series of 4-aminoquinoline antimalarials. Substantive improvements over previous syntheses include nucleophilic substitution with neat amine rather than in phenol, regioselective reductive alkylation to convert the terminal primary amine (12a-20a) on the diaminoalkane side chain to a diethylamino group, and purification by column chromatography with basic alumina. The 1H nmr spectra obtained after regioselective reductive alkylation with sodium borodeuteride (in comparison with sodium borohydride) demonstrated that this reductive alkylation proceeds via formation and subsequent reduction of the corresponding diamides in situ.
- De,Byers,Krogstad
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p. 315 - 320
(2007/10/03)
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- An NMR study of halogenated 1,4-dihydro-1-ethyl-4-oxoquinoline-3-carboxylates
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Ethyl 1,4-dihydro-1-ethyl-4-oxoquinoline-3-carboxylate and 29 of its mono-, di-and tri-fluoro and/or -chloro derivatives were synthesized and their 1H, 13C and 19F NMR spectra were recorded. 1H, 13C and 19F chemical shifts, JHH, JFH, JCF and JFF coupling constants are reported. The 13C substituent chemical shift values of the chloro and fluoro substituents were calculated by linear multiple regression.
- Podanyi, Benjamin,Kereszturi, Geza,Vasvari-Debreczy, Lelle,Chinoin, Istvan Hermecz,Toth, Gabor
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p. 972 - 978
(2007/10/03)
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- Vibrational Spectroscopy and Conformations of 2-Alkoxycarbonyl-3-aminoacrylic Esters
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The i.r., Raman, and 1H n.m.r. spectra of 2-alkoxycarbonyl-3-aminoacrylic esters (IV; R1=H, alkyl, aryl) and those of their N-deuteriated derivatives show that these substances exist in the enamino-ester form with a strong intramolecular hydrogen bond between the cis-NH (or -ND) and CO2R2 groups.Some complexities in the i.r. and Raman bands, and their dependence on solvent polarity, temperature, and aggregation state, indicate the existence of rotational isomerism: conformers (IVa and b) predominate in non-polar media; an additional rotamer (IVd) is also probably present in polar solvents.Conformation (IVb) is preferred in the solid state.Some features of the ν(C=O) bands suggest a weak vibrational coupling between the carbonyls.The validity of the criteria established by Smith and Taylor to ascertain the planarity of these and related substances is discussed, and no significant difference in this respect is considered to exist between compounds (IV) with primary and secondary amino-groups.
- Gomez-Sanchez, Antonio,Sempere, Eugenia,Bellanato, Juana
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p. 561 - 570
(2007/10/02)
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