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1.  A β-Fluoroamine Inhibitor of Purine Nucleoside Phosphorylase 
Journal of medicinal chemistry  2008;51(18):5880-5884.
The potent immucillin purine nucleoside phosphorylase (PNP) inhibitors F-DADMe-ImmH [(3S,4S)−3], and [(3R,4R)−3] are synthesized in seven steps. Cycloaddition to a fluoroalkene and an enzymic resolution are the key features of the construction of the fluoropyrrolidines 11, from which the immucillins are assembled by use of a three-component Mannich reaction. Slow-onset binding constants (Ki∗) for [(3S,4S)−3] and [(3R,4R)−3] with human PNP are 0.032 and 1.82 nM, respectively. F-DADMe-ImmH [(3S,4S)−3] exhibits oral availability in mice at doses as low as 0.2 mg/kg.
PMCID: PMC4508846  PMID: 18800772
2.  In Vitro and In Vivo Evaluation of Bifunctional Bisthiosemicarbazone 64Cu-Complexes for the Positron Emission Tomography Imaging of Hypoxia 
Journal of medicinal chemistry  2008;51(10):2985-2991.
The copper(II) bisthiosemicarbazonato complex, copper-diacetyl-bis(N4-methylthiosemicarbazonate) (Cu-ATSM), has been used clinically as a positron emission tomography (PET) tracer for the delineation of hypoxia. Six novel, asymmetric bis(thiosemicarbazones) derived from diacetyl-2-(4-N-methyl-3-thiosemicarbazone)-3-(4-N-amino-3-thiosemicarbazone) (H2ATSM/A), one of which contained a nitroimidazole functionality, were radiolabeled with 64Cu (t½ = 12.7 h, β+ = 19.3%). In vitro studies were performed on three of the compounds using EMT6 mammary carcinoma cells under hypoxic and normoxic conditions. All compounds displayed rapid cellular association and appreciable hypoxic selectivity with increased uptake under normoxic and hypoxic conditions when compared to 64Cu-ATSM. Biodistribution and small animal PET imaging studies were then carried out in vivo using two compounds in EMT6 tumor-bearing mice. The compounds showed high tumor uptake, but also substantial accumulation in the liver. These complexes demonstrate that H2ATSM/A represents a novel and versatile synthetic platform that can be utilized to provide hypoxic cell selectivity through functionalization of the bisthiosemicarbazonate group.
PMCID: PMC4404635  PMID: 18416544
3.  Indoleamine 2,3-Dioxygenase Is the Anticancer Target for a Novel Series of Potent Naphthoquinone-Based Inhibitors 
Journal of medicinal chemistry  2008;51(6):1706-1718.
Indoleamine 2,3-dioxygenase (IDO) is emerging as an important new therapeutic target for the treatment of cancer, chronic viral infections, and other diseases characterized by pathological immune suppression. While small molecule inhibitors of IDO exist, there remains a dearth of high-potency compounds offering in vivo efficacy and clinical translational potential. In this study, we address this gap by defining a new class of naphthoquinone-based IDO inhibitors exemplified by the natural product menadione, which is shown in mouse tumor models to have similar antitumor activity to previously characterized IDO inhibitors. Genetic validation that IDO is the critical in vivo target is demonstrated using IDO-null mice. Elaboration of menadione to a pyranonaphthoquinone has yielded low nanomolar potency inhibitors, including new compounds which are the most potent reported to date (Ki = 61–70 nM). Synthetic accessibility of this class will facilitate preclinical chemical–genetic studies as well as further optimization of pharmacological parameters for clinical translation.
PMCID: PMC4384695  PMID: 18318466
4.  Discovery and Labeling of High Affinity 3,4-Diarylpyrazolines as Candidate Radioligands for In Vivo Imaging of Cannabinoid Subtype-1 (CB1) Receptors 
Journal of medicinal chemistry  2008;51(18):5608-5616.
Imaging of cannabinoid subtype-1 (CB1) receptors in vivo with positron emission tomography (PET) is likely to be important for understanding their role in neuropsychiatric disorders and for drug development. Radioligands for imaging with PET are required for this purpose. We synthesized new ligands from a 3,4-diarylpyrazoline platform of which (-)-12a ((-)-3-(4-chlorophenyl)-N’-[(4-cyanophenyl)sulfonyl]-4-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamidine) was found to have high-affinity and selectivity for binding to CB1 receptors. (-)-12a and its lower affinity enantiomer ((+)-12a) were labeled with carbon-11 (t1/2 = 20.4 min) using [11C]cyanide ion as labeling agent and evaluated as PET radioligands in cynomolgus monkey. After injection of [11C](-)-12a there was high uptake and retention of radioactivity across brain according to the rank order of CB1 receptor densities. The distomer, [11C](+)-12a, failed to give a sustained CB1 receptor-specific distribution. Polar radiometabolites of [11C](-)-12a appeared moderately slowly in plasma. Radioligand [11C](-)-12a is promising for the study of brain CB1 receptors and merits further investigation in human subjects.
PMCID: PMC4182912  PMID: 18754613
5.  Synthesis and In Vitro Evaluation of 5-[18F]Fluoroalkyl Pyrimidine Nucleosides for Molecular Imaging of Herpes Simplex Virus Type-1 Thymidine Kinase Reporter Gene Expression 
Journal of medicinal chemistry  2008;51(18):5690-5701.
Two novel series of 5-fluoroalkyl-2′-deoxyuridines (FPrDU, FBuDU, FPeDU) and 2′-fluoro-2′-deoxy-5-fluoroalkylarabinouridines (FFPrAU, FFBuAU, FFPeAU), having three, four or five methylene units (propyl, butyl, or pentyl) at C-5, were prepared and tested as reporter probes for imaging HSV1-tk gene expression. The Negishi coupling methodology was employed to efficiently synthesize the radiolabeling precursors. All six 5-[18F]fluoroalkyl pyrimidines were prepared readily from 3-N-benzoyl-3′,5′-di-O-benzoyl-protected 5-O-mesylate precursors in 17–35% radiochemical yield (decay-corrected). In vitro studies highlighted that all six [18F]labeled nucleosides selectively accumulated in cells expressing the HSV1-TK protein, with negligible uptake in control cells. [18F]FPrDU, [18F]FBuDU, [18F]FPeDU, and [18F]FFBuAU had the best uptake profiles. Despite selective accumulation in HSV1-tk expressing cells, all 5-fluoroalkyl pyrimidine nucleosides had low to negligible cytotoxic activity (CC50>1000–209 μM). Ultimately, results demonstrated that 5-[18F]fluoropropyl, [18F]fluorobutyl, and [18F]fluoropentyl pyrimidine nucleosides have potential as in vivo HSV1-TK PET reporter probes over a dynamic range of reporter gene expression levels.
PMCID: PMC4122542  PMID: 18800764
6.  Adamantyl-Substituted Retinoid-Derived Molecules That Interact with the Orphan Nuclear Receptor Small Heterodimer Partner: Effects of Replacing the 1-Adamantyl or Hydroxyl Group on Inhibition of Cancer Cell Growth, Induction of Cancer Cell Apoptosis, and Inhibition of Src Homology 2 Domain-Containing Protein Tyrosine Phosphatase-2 Activity 
Journal of medicinal chemistry  2008;51(18):5650-5662.
(E)-4-[3-(1-Adamantyl)-4′-hydroxyphenyl]-3-chlorocinnamic acid (3-Cl-AHPC) induces the cell-cycle arrest and apoptosis of leukemia and cancer cells. Studies demonstrated that 3-Cl-AHPC bound to the atypical orphan nuclear receptor small heterodimer partner (SHP). Although missing a DNA-binding domain, SHP heterodimerizes with the ligand-binding domains of other nuclear receptors to repress their abilities to induce or inhibit gene expression. 3-Cl-AHPC analogues having the 1-adamantyl and phenolic hydroxyl pharmacophoric elements replaced with isosteric groups were designed, synthesized, and evaluated for their inhibition of proliferation and induction of human cancer cell apoptosis. Structure–anticancer activity relationship studies indicated the importance of both groups to apoptotic activity. Docking of 3-Cl-AHPC and its analogues to an SHP computational model that was based on the crystal structure of ultraspiracle complexed with 1-stearoyl-2-palmitoylglycero-3-phosphoethanolamine suggested why these 3-Cl-AHPC groups could influence SHP activity. Inhibitory activity against Src homology 2 domain-containing protein tyrosine phosphatase 2 (Shp-2) was also assessed. The most active Shp-2 inhibitor was found to be the 3′-(3,3-dimethylbutynyl) analogue of 3-Cl-AHPC.
PMCID: PMC4097887  PMID: 18759424
7.  Identification of BRAF inhibitors through in silico screening 
Journal of medicinal chemistry  2008;51(19):6121-6127.
The BRAF protein kinase, a molecule in the RAS-RAF-MEK-ERK signaling pathway, is mutated to harbor elevated kinase activity in about 7% of human cancers, making it an important therapeutic target for inhibition. Several BRAF protein kinase inhibitors have been developed through high-throughout-screening in vitro, however many of these compounds suffer from a lack of suitable kinase specificity and other chemotherapeutic properties. In silico screening has evolved as a powerful complimentary approach to protein kinase inhibitor identification. Here we describe an in silico screen for BRAF inhibitors leading to the identification of a series of purine-2,6-dione analogues with IC50 values in the single digit micromolar range and with significant selectivity for BRAF over other representative protein kinases. The binding modes of these inhibitors to BRAF are analyzed through molecular docking to derive structure-activity relationships and to assist in the future development of more potent and specific BRAF inhibitors.
PMCID: PMC4010122  PMID: 18783202
8.  Rational design of substituted diarylureas: a scaffold for binding to G-quadruplex motifs 
Journal of medicinal chemistry  2008;51(24):7751-7767.
The design and synthesis of a series of urea-based non-polycyclic aromatic ligands with alkylaminoanilino side chains as telomeric and genomic G-quadruplex DNA interacting agents is described. Their interactions with quadruplexes have been examined by means of Fluorescent Resonance Energy Transfer melting, circular dichroism and surface plasmon resonance-based assays. These validate the design concept for such urea-based ligands and also show that they have significant selectivity for compared to duplex DNA, as well as for particular G-quadruplexes. The ligand-quadruplex complexes were investigated by computational molecular modeling, providing further information on structure activity relationships. Preliminary biological studies using short-term cell growth inhibition assays show that some of the ligands have cancer cell selectivity, although they appear to have low potency for intracellular telomeric G-quadruplex structures, suggesting that their cellular targets may be other, possibly oncogene-related quadruplexes.
PMCID: PMC3967098  PMID: 19053833
rational design; diarylureas; quadruplex DNA
9.  Use of the Nitrile Oxide Cycloaddition (NOC) Reaction for Molecular Probe Generation: A New Class of Enzyme Selective Histone Deacetylase Inhibitors (HDACIs) Showing Picomolar Activity at HDAC6 
Journal of medicinal chemistry  2008;51(15):4370-4373.
A series of hydroxamate based HDAC inhibitors containing a phenylisoxazole as the CAP group has been synthesized using nitrile oxide cycloaddition chemistry. An HDAC6 selective inhibitor having a potency of ∼2 picomolar was identified. Some of the compounds were examined for their ability to block pancreatic cancer cell growth and found to be about 10-fold more potent than SAHA. This research provides valuable, new molecular probes for use in exploring HDAC biology.
PMCID: PMC3913184  PMID: 18642892
10.  The Micelle-Associated 3D Structures of Boc-Y(SO3)-Nle-G-W-Nle-D-2-phenylethylester (JMV-180) and CCK-8(s) Share Conformational Elements of a Calculated CCK1 Receptor-Bound Model 
Journal of medicinal chemistry  2008;51(13):3742-3754.
JMV-180 (1) and CCK-8(s) are high affinity ligands at the CCK1 receptor that have similar and different actions via this receptor. Here we calculate the tertiary structure of 1 or CCK-8(s) in the presence of dodecylphosphocholine micelles at pH 5.0 and 35 °C from 2D 1H NMR data recorded at 600 MHz. The NMR derived 3D structures of 1 and CCK-8(s) share a common type I β-turn around residues Nle3/M3 and G4 and diverge from each other structurally at the N- and C-termini. The fluorescence and circular dichroism spectral properties of these peptides are consistent with their NMR derived structures. The structures determined in the presence of DPC micelles are compared to available models of 1 or CCK-8(s) bound to the CCK1 receptor. For CCK and 1, these comparisons show that DPC micelle associated structures duplicate some important aspects of the models calculated from cross-linking derived constraints at the CCK1 receptor.
PMCID: PMC3909998  PMID: 18540665
11.  Pharmacological Exploitation of the Peroxisome Proliferator-Activated Receptor γ Agonist Ciglitazone to Develop a Novel Class of Androgen Receptor-Ablative Agents 
Journal of medicinal chemistry  2008;51(7):2100-2107.
Based on our finding that the peroxisome proliferator-activated receptor (PPAR)γ agonist ciglitazone at high doses was able to mediate PPARγ-independent transcriptional repression of androgen receptor (AR) in a tumor cell-specific manner, we used Δ2CG, a PPARγ-inactive analogue of ciglitazone, to conduct lead optimization to develop a novel class of AR-ablative agents. Structure-activity analysis indicates a high degree of flexibility in realigning Δ2CG’s structural moieties without compromising potency in AR repression, as evidenced by the higher AR-ablative activity of the permuted isomer 9 [(Z)-5-(4-hydroxy-benzylidene)-3-(1-methyl-cyclohexylmethyl)-thiazolidine-2,4-dione]. Further modificiations of 9 gave rise to 12 [(Z)-5-(4-hydroxy-3-trifluoromethyl-benzylidene)-3-(1-methyl-cyclohexylmethyl)-thiazolidine-2,4-dione] which completely inhibited AR expression in LNCaP cells at low μM concentrations. This AR downregulation led to growth inhibition in LNCaP cells through apoptosis induction. Moreover, the role of AR repression in the antiproliferative effect of compound 12 was validated by the differential inhibition of cell viability between androgen-responsive and androgen-nonresponsive cells.
PMCID: PMC3901315  PMID: 18335975
12.  Potent Dual Thymidylate Synthase and Dihydrofolate Reductase Inhibitors: Classical and Nonclassical 2-Amino-4-oxo-5-arylthio-substituted-6-methylthieno[2,3-d]pyrimidine Antifolates 
Journal of medicinal chemistry  2008;51(18):5789-5797.
N-{4-[(2-Amino-6-methyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-5-yl)sulfanyl]benzoyl}-L-glutamic acid (4) and nine nonclassical analogues 5–13 were synthesized as potential dual thymidylate synthase (TS) and dihydrofolate reductase (DHFR) inhibitors. The key intermediate in the synthesis was 2-amino-6-methylthieno[2,3-d]pyrimidin-4(3H)-one (16), which was converted to the 5-bromo-substituted compound 17 followed by an Ullmann reaction to afford 5–13. The classical analogue 4 was synthesized by coupling the benzoic acid derivative 19 with diethyl l-glutamate and saponification. Compound 4 is the most potent dual inhibitor of human TS (IC50 = 40 nM) and human DHFR (IC50 = 20 nM) known to date. The nonclassical analogues 5–13 were moderately potent against human TS with IC50 values ranging from 0.11 to 4.6 µM. The 4-nitrophenyl analogue 7 was the most potent compound in the nonclassical series, demonstrating potent dual inhibitory activities against human TS and DHFR. This study indicated that the 5-substituted 2-amino-4-oxo-6-methylthieno[2,3-d]pyrimidine scaffold is highly conducive to dual human TS-DHFR inhibitory activity.
PMCID: PMC3892769  PMID: 18800768
13.  N9-Substituted 2,4-Diaminoquinazolines: Synthesis and Biological Evaluation of Lipophilic Inhibitors of Pneumocystis carinii and Toxoplasma gondii Dihydrofolate Reductase 
Journal of medicinal chemistry  2008;51(19):10.1021/jm800694g.
N9-substituted 2,4-diaminoquinazolines were synthesized and evaluated as inhibitors of Pneumocystis carinii (pc) and Toxoplasma gondii (tg) dihydrofolate reductase (DHFR). Reduction of commercially available 2,4-diamino-6-nitroquinazoline 14 with Raney nickel afforded 2,4,6-triaminoquinazoline 15. Reductive amination of 15 with the appropriate benzaldehydes or naphthaldehydes, followed by N9-alkylation, afforded the target compounds 5–13. In the 2,5-dimethoxybenzylamino substituted quinazoline analogues, replacement of the N9—CH3 group of 4 with the N9—C2H5 group of 8 resulted in a 9- and 8-fold increase in potency against pcDHFR and tgDHFR, respectively. The N9—C2H5 substituted compound 8 was highly potent, with IC50 values of 9.9 and 3.7 nM against pcDHFR and tgDHFR, respectively. N9-propyl and N9-cyclopropyl methyl substitutions did not afford further increases in potency. This study indicates that the N9-ethyl substitution is optimum for inhibitory activity against pcDHFR and tgDHFR for the 2,4-diaminoquinazolines. Selectivity was unaffected by N9 substitution.
PMCID: PMC3885247  PMID: 18771252
14.  The Effect of 5-Alkyl Modification on the Biological Activity of Pyrrolo[2,3-d]pyrimidine Containing Classical and Nonclassical Antifolates as Inhibitors of Dihydrofolate Reductase and as Antitumor and/or Antiopportunistic Infection Agents1a-e 
Journal of medicinal chemistry  2008;51(15):10.1021/jm800244v.
Novel classical antifolates (3 and 4) and 17 nonclassical antifolates (11-27) were synthesized as antitumor and/or antiopportunistic infection agents. Intermediates for the synthesis of 3, 4, and 11-27 were 2,4-diamino-5-alkylsubstituted-7H-pyrrolo[2,3-d]pyrimidines, 31 and 38, prepared by a ring transformation/ring annulation sequence of 2-amino-3-cyano-4-alkyl furans to which various aryl thiols were attached at the 6-position via an oxidative addition reaction using I2. The condensation of α-hydroxy ketones with malonodinitrile afforded the furans. For the classical analogues 3 and 4, the ester precursors were deprotected, coupled with diethyl-l-glutamate, and saponified. Compounds 3 (IC50 = 60 nM) and 4 (IC50 = 90 nM) were potent inhibitors of human DHFR. Compound 3 inhibited tumor cells in culture with GI50 ≤ 10−7 M. Nonclassical 17 (IC50 = 58 nM) was a potent inhibitor of Toxoplasma gondii (T. gondii) DHFR with >500-fold selectivity over human DHFR. Analogue 17 was 50-fold more potent than trimethoprim and about twice as selective against T. gondii DHFR.
PMCID: PMC3858179  PMID: 18605720
15.  Synthesis and QSAR of Fatty Acid Amide Hydrolase Inhibitors: Modulation at the N-Portion of Biphenyl-3-yl Alkylcarbamates 
Journal of medicinal chemistry  2008;51(12):3487-3498.
Alkylcarbamic acid biphenyl-3-yl esters are a class of fatty acid amide hydrolase (FAAH) inhibitors that comprises cyclohexylcarbamic acid 3′-carbamoylbiphenyl-3-yl ester (URB597), a compound with analgesic, anxiolytic-like and antidepressant-like properties in rat and mouse models. Here, we extended the structure-activity relationships (SARs) for this class of compounds by replacing the cyclohexyl ring of the parent compound cyclohexylcarbamic acid biphenyl-3-yl ester (URB524) (IC50, for FAAH = 63 nM) with a selected set of substituents of different size, shape, flexibility and lipophilicity.
Docking experiments and Linear Interaction Energy (LIE) calculations indicated that the N-terminal group of O-arylcarbamates fits within the lipophilic region of the substrate-binding site, mimicking the arachidonoyl chain of anandamide. Significant potency improvements were observed for the β-naphthylmethyl derivative 4q (IC50 = 5.3 nM) and its 3′-carbamoylbiphenyl-3-yl ester 4z (URB880, IC50 = 0.63 nM), indicating that shape complementarity and hydrogen bonds are crucial to obtain highly potent inhibitors.
PMCID: PMC3744893  PMID: 18507372
16.  Discovery of novel agonists and antagonists of the free fatty acid receptor one (FFAR1) using virtual screening 
Journal of medicinal chemistry  2008;51(3):625-633.
The G protein-coupled receptor free fatty acid receptor 1 (FFAR1), previously named GPR40, is a possible novel target for the treatment of type 2 diabetes. In an attempt to identify new ligands for this receptor, we performed virtual screening (VS) based on 2D-similarity, 3D-pharmacophore searches and docking studies, using the structure of known agonists and our model of the ligand binding site, which was validated by mutagenesis. VS of a database of 2.6 million compounds followed by extraction of structural neighbors of functionally-confirmed hits resulted in identification of 15 compounds active at FFAR1 either as full agonists, partial agonists, or pure antagonists. Site-directed mutagenesis and docking studies revealed different patterns of ligand-receptor interactions, and provided important information on the role of specific amino acids in binding and activation of FFAR1.
PMCID: PMC3711565  PMID: 18193825
17.  Discovery of Substituted 4-(Pyrazol-4-yl)-phenylbenzodioxane-2-carboxamides as Potent and Highly Selective Rho Kinase (ROCK-II) Inhibitors 
Journal of medicinal chemistry  2008;51(21):6642-6645.
The identification of a new class of potent and selective ROCK-II inhibitors is presented. Compound 5 (SR-3677) had an IC50 of ~3 nM in enzyme and cell based assays and had an off-target hit rate of 1.4% against 353 kinases, and inhibited only 3 out of 70 nonkinase enzymes and receptors. Pharmacology studies showed that 5 was efficacious in both, increasing ex vivo aqueous humor outflow in porcine eyes and inhibiting myosin light chain phosphorylation.
PMCID: PMC3708311  PMID: 18834107
18.  Bornyl- and Isobornyl-Δ8-tetrahydrocannabinols: A Novel Class of Cannabinergic Ligands 
Journal of medicinal chemistry  2008;51(20):6393-6399.
Structure-activity relationship studies of classical cannabinoid analogs have established that the C3 aliphatic side chain plays a pivotal role in determining cannabinergic potency. In earlier work we provided evidence for the presence of subsites within the CB1 and CB2 cannabinoid receptor binding domains that can accommodate bulky conformationally defined substituents at the C3 alkyl side chain pharmacophore of classical cannabinoids. We have now extended this work with the synthesis of a series of Δ8-THC analogs in which bornyl substituents are introduced at the C3 position. Our results indicate that for optimal interactions with both CB1 and CB2 receptors, the bornyl substituents need to be within close proximity of the tricyclic core of Δ8-THC and that the conformational space occupied by the C3 substituents influences CB1/CB2 receptor subtype selectivity.
PMCID: PMC3700413  PMID: 18826296
19.  Magnetically Aligned Bicelles to Study the Orientation of Lipophilic Ligands in Membrane Bilayers 
Journal of medicinal chemistry  2008;51(21):6793-6799.
Magnetically aligned bicelles were used as a model membrane to study the orientation and dynamic properties of two cannabinoids (Δ8-THC and Me-Δ8-THC) using 31P- and 2H-NMR. The uniform alignment of the bicelles allowed us to obtain well resolved deuterium spectra from a solution NMR spectrometer. The preferred orientations of Δ8-THC and Me-Δ8-THC were calculated based on the measurements of individual quadrupolar splittings. Our results agree with previous experiments using multilamellar membranes as well as with molecular dynamics simulation data described here. In conjunction with our earlier report using small and fast tumbling bicelles, the present work of well aligned bicelles shows that bicelle preparations can provide either pseudo-isotropic or anisotropic NMR spectra to study the conformation, orientation and dynamic properties of ligands in membrane bilayers. Such data are of critical value for understanding the interactions of lipophilic drug molecules with membrane proteins.
PMCID: PMC3694723  PMID: 18834109
20.  An X-ray Snapshot of the Mechanism of Inactivation of Human Neutrophil Elastase by 1, 2, 5 –Thiadiazolidin-3-one 1, 1 Dioxide Derivatives‡ 
Journal of medicinal chemistry  2008;51(7):2003-2008.
The mechanism of action of a general class of mechanism-based inhibitors of serine proteases, including human neutrophil elastaseα (HNE), has been elucidated by determining the X-ray crystal structure of an enzyme-inhibitor complex. The captured intermediate indicates that processing of inhibitor (I) by the enzyme generates an N-sulfonyl imine functionality that is tethered to Ser195, in accordance with the postulated mechanism of action of this class of inhibitors. The identity of the HNE-N-sulfonyl imine species was further corroborated using electrospray ionization mass spectrometry.
PMCID: PMC3623276  PMID: 18318470
21.  Structure-Activity Relationships of Truncated D- and L-4′-Thioadenosine Derivatives as Species-Independent A3 Adenosine Receptor Antagonists1 
Journal of medicinal chemistry  2008;51(20):6609-6613.
Novel D- and L-4′-thioadenosine derivatives lacking the 4′-hydroxymethyl moiety were synthesized, starting from D-mannose and D-gulonic γ-lactone, respectively, as potent and selective species-independent A3 adenosine receptor (AR) antagonists. Among the novel 4′-truncated 2-H nucleosides tested, a N6-(3-chlorobenzyl) derivative 7c was the most potent at the human A3 AR (Ki = 1.5 nM), but a N6-(3-bromobenzyl) derivative 7d showed the optimal species-independent binding affinity.
PMCID: PMC3616494  PMID: 18811138
22.  Polyaminohydroxamic Acids and Polyaminobenzamides as Isoform Selective Histone Deacetylase Inhibitors§ 
Journal of medicinal chemistry  2008;51(8):2447-2456.
A series of polyaminohydroxamic acids (PAHAs) and polyaminobenzamides (PABAs) were synthesized and evaluated as isoform-selective histone deacetylase (HDAC) inhibitors. These analogues contain a polyamine chain to increase affinity for chromatin and facilitate cellular import. Seven PAHAs inhibited HDAC >50% (1 µM), and two PABAs inhibited HDAC >50% (5 µM). Compound 17 increased acetylated α-tubulin in HCT116 colon tumor cells 253-fold but only modestly increased p21waf1 and acetylated histones 3 and 4, suggesting that 17 selectively inhibits HDAC 6. PABA 22 alone minimally increased p21waf1 and acetylated histones 3 and 4 but caused dose-dependent increases in p21waf1 in combination with 0.1 µM 5-azadeoxycytidine. Finally, 22 appeared to be a substrate for the polyamine transport system. None of these compounds were cytotoxic at 100 µM. PAHAs and PABAs exhibit strikingly different cellular effects from SAHA and have the potential for use in combination antitumor therapies with reduced toxicity.
PMCID: PMC3556737  PMID: 18348516
23.  Histone Deacetylase Inhibitors through Click Chemistry 
Journal of medicinal chemistry  2008;51(23):7417-7427.
Histone deacetylase inhibitors (HDACi) are a relatively new class of chemotherapy agents. Herein, we report a click-chemistry based approach to the synthesis of HDACi. Fourteen agents were synthesized from the combination of two alkyne and seven azido precursors. The inhibition of HDAC1 and HDAC8 was then determined by in vitro enzymatic assays, after which the cytotoxicity was evaluated in the NCI human cancer cell line screen. A lead compound 5g (NSC746457) was discovered that inhibited HDAC1 at an IC50 value of 104 ± 30 nM and proved quite potent in the cancer cell line screen with GI50 values ranging from 3.92 μM to 10 nM. Thus, this click HDACi design has provided a new chemical scaffold that has not only revealed a lead compound, but one which is easily amendable to further structural modifications given the modular nature of this approach.
PMCID: PMC3441833  PMID: 19007204
HDAC; histone; deacetylase; click chemistry; inhibitor; synthesis
24.  Trifluoromethoxyl Substituted Phenylethylene Diamines as High Affinity σ Receptor Ligands with Potent Anti-Cocaine Actions 
Journal of Medicinal Chemistry  2008;51(11):3322-3325.
The phenylethylene diamines are a class of σ receptor ligands with excellent selectivity over other biological systems and with anti-cocaine actions that involve antagonism of σ1 receptors. In order to increase the potency of the aromatic methoxyl substituted analogues, trifluoromethoxyl groups were introduced to prevent metabolic demethylation. The para-substituted trifluoromethoxyl substituted analogues were shown to have increased σ receptor affinity and represent the most potent anti-cocaine phenylethylene diamines yet described.
PMCID: PMC3401596  PMID: 18461921
25.  Opioids and Efflux Transporters. Part 2: P-Glycoprotein Substrate Activity of 3- and 6-Substituted Morphine Analogs 
Journal of Medicinal Chemistry  2008;51(7):2316-2320.
Continuing our studies investigating opioids with reduced P-glycoprotein (P-gp) substrate activity, a series of known 3- and 6-hydroxy, -methoxy, and -desoxymorphine analogs was synthesized and analyzed for P-gp substrate activity and opioid binding affinity. 6-Desoxymorphine (7) showed high affinity for opioid receptors and did not induce P-gp-mediated ATP hydrolysis. Additionally, 7 demonstrated morphine-like antinociceptive potency in mice, indicating this compound as an ideal lead to further evaluate the role of P-gp in opioid analgesic tolerance development.
PMCID: PMC3401598  PMID: 18311899

Results 1-25 (165)