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author:("japan, R.")
1.  Structure-Activity Relationship (SAR) and Preliminary Mode of Action Studies of 3-Substituted Benzylthioquinolinium Iodide as Anti-opportunistic Infection Agents 
European journal of medicinal chemistry  2013;70:10.1016/j.ejmech.2013.09.044.
Opportunistic infections are devastating to immunocompromised patients. And in especially sub-Saharan Africa where the AIDS epidemic is still raging, the mortality rate was recently as high as 70%. The paucity of anti-opportunistic drugs, the decreasing efficacy and the development of resistance against the azoles and even amphotericin B have stimulated the search for new drugs with new mechanisms of action. In a previous work, we showed that a new chemotype derived from the natural product cryptolepine displayed selective toxicity against opportunistic pathogens with minimal cytotoxicity to normal cells. In this manuscript, we report the design and synthesis of substituted benzylthioquinolinium iodides, evaluated their anti-infective properties and formulated some initial structure-activity relationships around phenyl ring A from the original natural product. The sensitivity of the most potent analog 10l, to selected strains of C. cerevisiae was also evaluated leading to the observation that this scaffold may have a different mode of action from its predecessor, cryptolepine.
PMCID: PMC3870201  PMID: 24141203
Substituted Quinolinium salts; benzylthioquinolinium iodides; antifungal agents; anti-opportunistic infections; cryptolepine; Craig plot; structure-activity relationships
2.  CoMFA studies and in vitro evaluation of some 3-substituted benzylthio quinolinium salts as anticryptococcal agents 
Bioorganic & medicinal chemistry  2013;21(22):10.1016/j.bmc.2013.08.043.
The 3-Dimensional Quantitative Structure-Activity Relationship (3D-QSAR) molecular modeling technique or Comparative Molecular Field Analysis (CoMFA) has been used to design analogs of the natural product cryptolepine (1). Twenty-three compounds with their in vitro biological activities (IC50 values) against C. neoformans were used to generate the training set database of compounds for the CoMFA studies. The cross-validated q2, non-cross-validated r2, and partial least squares (PLS) analysis results were used to predict the biological activity of 11 newly designed test set compounds. The best CoMFA model produced a q2 of 0.815 and an r2 of 0.976 indicating high statistical significance as a predictive model. The steric and electrostatic contributions from the contour map were interpreted from the color-coded contour plots generated from the PLS model and the active structural components for potency against C. neoformans were determined and validated in the test set compounds. The 3-substituted benzylthio quinolinium salts (4) that make up the test set were synthesized and evaluated based on the predicted activity from the CoMFA model and the results produced a good correlation between the predicted and experimental activity (R = 0.82). Thus, CoMFA has served as an effective tool to aid the design of new analogs and in this case, it has aided the identification of compounds equipotent with amphotericin B, the gold standard in antifungal drug design.
PMCID: PMC3838926  PMID: 24080102
CoMFA; Antifungal Agents; Cryptolepine; Mycoses; Opportunistic infection; Substituted benzylthioquinolinium Salts
3.  Indolo[3,2-b]quinolines: Synthesis, Biological Evaluation and Structure Activity-Relationships 
The tetracyclic indolo[3,2-b]quinoline ring system constitutes an important structural moiety in natural products exhibiting numerous biological activities. In particular, indolo [3, 2-b]quinoline, commonly known as linear quindo-line is of particular interest, because of its rigid structure and scope of derivatization. Although the core linear quindoline skeleton shows little or no activity in several biological systems, introduction of a methyl group on the N-5 atom leading to cryptolepine induces remarkable activity against a broad spectrum of biological targets. A number of analogs of quindoline and cryptolepine have been synthesized, incorporating various functional groups on the core quindoline skeleton leading to improved biological activities. In this review, we describe various synthetic methodologies leading to the quindoline scaffold, the biological activities and the structure activity relationships (SAR) of quindoline derivatives toward different disease states to give a better picture of the importance of this moiety in medicinal chemistry.
PMCID: PMC3777419  PMID: 18537709
Cryptolepine; indoloquinolines; synthesis; structure-activity relationship (SAR) studies
4.  Benzothiazoles as probes for the 5HT1A receptor and the serotonin transporter (SERT): A search for new dual-acting agents as potential antidepressants 
The synthesis and evaluation of several benzothiazole based compounds are described in an attempt to identify novel dual-acting 5HT1A receptor and SERT inhibitors as new antidepressants. Binding affinities at the 5HT1A receptor and the serotonin transporter do not appear to be congruent and other areas of the binding sites would need to be explored in order to improve binding simultaneously at both sites. Compounds 20 and 23 show moderate binding affinity at the 5HT1A receptor and the SERT site and thus, have the potential to be further explored as dual-acting agents. In addition, compound 20 binds with low affinity to the dopamine transporter (DAT), the norepinephrine transporter (NET) and 5HT2C receptor, which are desirable properties as selectivity for SERT (and not DAT or NET) is associated with an absence of cardiovascular side-effects.
PMCID: PMC3361616  PMID: 22520153
Benzothiazoles; SERT inhibition; 5HT1A binding; dual-acting antidepressants; 5HT1A agents; potential SERT inhibitors
5.  Structure–activity relationship studies of SYA 013, a homopiperazine analog of haloperidol 
Bioorganic & medicinal chemistry  2012;20(5):1671-1678.
Structure–activity relationship studies on 4-(4-(4-chlorophenyl)-1,4-diazepan-1-yl)-1-(4-fluorophenyl) butan-1-one (SYA 013), a homopiperazine analog of haloperidol has resulted in an understanding of the effect of structural modifications on binding affinity at dopamine and serotonin receptor subtypes. Further exploration, using bioisosteric replacement strategies has led to the identification of several new agents including compounds 7, 8, 11 and 12 which satisfy the initial criteria for further exploration as new antipsychotic agents. In addition, compound 18, a D3 selective tropanol, has been identified as having the potential for further optimization into a useful drug which may combat neuropsychiatric diseases.
PMCID: PMC3356581  PMID: 22336245
Antipsychotics; Haloperidol analogs; Structure–activity relationship studies; Atypical antipsychotics; Homopiperazine; Benzothiazole
6.  δ-Carbolines and their ring-opened analogs: Synthesis and evaluation against fungal and bacterial opportunistic pathogens 
Previous studies have indicated that the δ-carboline (2) ring system derived from the natural product cryptolepine (1) may represent a pharmacophore for anti-infective activity. This paper describes the design and synthesis of a small library of substituted δ-carbolines and the evaluation of the antifungal and antibacterial activities. An evaluation of the anti-bacterial activity of a previously reported library of ring-opened analogs was also conducted to provide an opportunity to test the hypothesis that both group of compounds may have the same biological target. Results indicate that against a selected group of fungal pathogens, substituted δ-carbolinium analogs displayed higher potency and several fold lower cytotoxicity than cryptolepine the parent natural product. Both the δ-carbolinium compounds and their ring-opened analogs, exhibited equally high anti-bacterial activity against the selected pathogens and especially against the gram positive bacteria evaluated.
PMCID: PMC3130796  PMID: 21459492
δ-carboline; antifungal; antibacterial; opportunistic; synthesis; quaternary
7.  Cannabinoid receptor 2 positions and retains marginal zone B cells within the splenic marginal zone 
The Journal of Experimental Medicine  2011;208(10):1941-1948.
In addition to other receptors, including sphingosine-1-phosphate receptor 1, cannabinoid receptor 2 positions mouse marginal zone B cells within the marginal zone and also prevents their loss to the blood.
Specialized B cells residing in the splenic marginal zone (MZ) continuously survey the blood for antigens and are important for immunity to systemic infections. However, the cues that uniquely attract cells to the MZ have not been defined. Previous work demonstrated that mice deficient in cannabinoid receptor 2 (CB2) have decreased numbers of MZ B cells but it has been unclear whether CB2 regulates MZ B cell development or positioning. We show that MZ B cells are highly responsive to the CB2 ligand 2-arachidonylglycerol (2-AG) and that CB2 antagonism rapidly displaces small numbers of MZ B cells to the blood. Antagonism for longer durations depletes MZ B cells from the spleen. In mice deficient in sphingosine-1-phosphate receptor function, CB2 antagonism causes MZ B cell displacement into follicles. Moreover, CB2 overexpression is sufficient to position B cells to the splenic MZ. These findings establish a role for CB2 in guiding B cells to the MZ and in preventing their loss to the blood. As a consequence of their MZ B cell deficiency, CB2-deficient mice have reduced numbers of CD1d-high B cells. We show that CB2 deficiency results in diminished humoral responses to a CD1d-restricted systemic antigen.
PMCID: PMC3182059  PMID: 21875957
8.  Identification of 3-Phenylaminoquinolinium and 3-Phenylaminopyridinium salts as New Agents against Opportunistic Fungal Pathogens 
Bioorganic & medicinal chemistry  2010;19(1):524-533.
Previous studies on the indoloquinoline alkaloid, cryptolepine (2), revealed that it has antiinfective properties among other activities. Using Structure Activity Relationship (SAR) techniques, several ring-opened analogs of cryptolepine (3-phenylaminopyridinium and 3-phenylaminoquinolinium derivatives) were designed to improve the potency and lower the cytotoxicity shown by several of the precursor agents. Results indicate that these ring-opened analogs constitute new anti-infective agents with over a 100-fold potency and several fold lower cytotoxicity than cryptolepine from which they are derived.
PMCID: PMC3014406  PMID: 21130660
9.  Benzothieno[3,2-b]quinolinium and 3-(Phenylthio)quinolinium Compounds: Synthesis and Evaluation against Opportunistic Fungal Pathogens 
Bioorganic & medicinal chemistry  2010;19(1):458-470.
Substitution around 5-methyl benzothieno[3,2-b]quinolinium (2) ring system was explored in order to identify positions of substitution that could improve its antifungal profile. The 3-methoxy (10b) was active against C. albicans, C. neoformans and A. fumigatus and the 4-chloro (10f) analog showed moderate increases in anti-cryptococcal and anti-aspergillus activities. The effectiveness of 10b and 10f were validated in murine models of candidiasis and cryptococcosis respectively. The efficacy of 10f in reducing brain cryptococcal infection and its observation in the brain of mice injected with this quaternary compound confirm the capacity of these compounds to cross the blood-brain barrier of mice. Overall, several of the chloro and methoxy substituted compounds showed significant improvements in activity against A. fumigatus, the fungal pathogen prevalent in patients receiving organ transplant. Opening the benzothiophene ring of 2 to form 1-(5-cyclohexylpentyl)-3-(phenylthio)quinolinium compound (3) resulted in the identification of several novel compounds with over 50-fold increases in potency (cf 2) while retaining low cytotoxicities. Thus, compound 3 constitutes a new scaffold for development of drugs against opportunistic infections.
PMCID: PMC3014419  PMID: 21134759
10.  Di­hydrogen phosphate mediated supra­molecular frameworks in 2- and 4-chloro­anilinium dihydrogen phosphate salts 
The title compounds, 2-chloro­anilinium dihydrogen phosphate (2CADHP) and 4-chloro­anilinium di­hydrogen phosphate (4CADHP), both C6H7NCl+·H2PO4 −, form two-dimensional supra­molecular organic–inorganic hybrid frameworks. In 2CADHP, the dihydrogen phosphate anions form a double-stranded anionic chain generated parallel to the [010] direction through O—H⋯O hydrogen bonds, whereas in 4CADHP they form a two-dimensional supra­molecular net extending parallel to the crystallographic (001) plane into which the cations are linked through strong N—H⋯O hydrogen bonds.
PMCID: PMC2855582  PMID: 20203405
11.  1,3-Dicyclo­hexyl-1-(4-nitro­benzo­yl)urea 
In the title compound, C20H27N3O4, both cyclo­hexane rings adopt chair conformations. The benzene ring and the amide group are oriented at a dihedral angle of 62.1 (2)°. In the crystal structure, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into chains propagating in [010], which contain R 2 2(12) ring motifs.
PMCID: PMC2979486  PMID: 21579388
12.  10-[2-(Dimethyl­amino)eth­yl]-9-(4-methoxy­phen­yl)-3,3,6,6-tetra­methyl-3,4,6,7,9,10-hexa­hydro­acridine-1,8(2H,5H)-dione 
In the title compound, C28H38N2O3, the central ring of the acridinedione system adopts a boat conformation, while one of the outer rings adopts a half-chair conformation and the conformation of the other outer ring is between a sofa and a half-chair. The acridinedione system is buckled, with an angle of 22.01 (3)°. The crystal packing comprises layers of mol­ecules laid parallel to the ac plane, being reinforced by an intermolecular C—H⋯O interaction.
PMCID: PMC2968240  PMID: 21581885
13.  SPOTS 
The Journal of Cell Biology  2004;167(4):735-744.
Fas (CD95, APO-1, TNFRSF6) is a TNF receptor superfamily member that directly triggers apoptosis and contributes to the maintenance of lymphocyte homeostasis and prevention of autoimmunity. Although FADD and caspase-8 have been identified as key intracellular mediators of Fas signaling, it is not clear how recruitment of these proteins to the Fas death domain leads to activation of caspase-8 in the receptor signaling complex. We have used high-resolution confocal microscopy and live cell imaging to study the sequelae of early events in Fas signaling. These studies have revealed a new stage of Fas signaling in which receptor ligation leads to the formation of surface receptor oligomers that we term signaling protein oligomerization transduction structures (SPOTS). Formation of SPOTS depends on the presence of an intact Fas death domain and FADD but is independent of caspase activity. Analysis of cells expressing Fas mutations from patients with the autoimmune lymphoproliferative syndrome (ALPS) reveals that formation of SPOTS can be disrupted by distinct mechanisms in ALPS.
PMCID: PMC2172594  PMID: 15557123

Results 1-13 (13)