3-(7-Azaindolyl)-4-arylmaleimides as potent, selective inhibitors of glycogen synthase kinase-3

A novel series of acyclic 3-(7-azaindolyl)-4-(aryl/heteroaryl)maleimides was synthesized and evaluated for activity against GSK-3beta and selectivity versus PKC-betaII, as well as a broad panel of protein kinases. Compounds 14 and 17c potently inhibited GSK-3beta (IC(50)=7 and 26 nM, respectively) and exhibited excellent selectivity over PKC-betaII (325 and >385-fold, respectively). Compound 17c was also highly selective against 68 other protein kinases. In a cell-based functional assay, both 14 and 17c effectively increased glycogen synthase activity by inhibiting GSK-3beta.     

Synthesis of pyrazoles and isoxazoles as potent alpha(v)beta3 receptor antagonists

We describe a series of pyrazole and isoxazole analogs as antagonists of the alpha(v)beta3 receptor. Compounds showed low to sub-nanomolar potency against alpha(v)beta3, as well as good selectivity against alpha(IIb)beta3. In HT29 cells, most analogs also demonstrated significant selectivity against alpha(v)beta6. Several compounds showed good pharmacokinetic properties in rats, in addition to anti-angiogenic activity in a mouse corneal micropocket model. Compounds were synthesized in a straightforward manner from readily available glutarate precursors.     

Discovery of potent and orally bioavailable heterocycle-based beta3-adrenergic receptor agonists, potential therapeutics for the treatment of obesity

A novel series of heterocycle-based analogs were prepared and evaluated for their in vitro and in vivo biological activity as human beta(3)-adrenergic receptor (AR) agonists. Several analogs demonstrated potent agonist activity at the beta(3)-AR, functional selectivity against beta(1)- and beta(2)-ARs, and favorable pharmacokinetic profiles in vivo. Compound 17 increased oxygen consumption in rats, a measure of energy expenditure, with an ED(20%) of 2mg/kg.     

Novel (4-piperidin-1-yl)-phenyl sulfonamides as potent and selective human beta(3) agonists

A series of novel (4-piperidin-1-yl)-phenyl sulfonamides was prepared and evaluated for their biological activity on the human beta(3)-adrenergic receptor (AR). Replacement of the 3,4-dihydroxyl group of the catechol moiety with 4-hydroxyl-3-methyl sulfonamide on the left-hand side of the compounds resulted in a number of potent full agonists at the beta(3) receptor. Modification of the right-hand side of the compounds by incorporation of a free carboxylic acid resulted in a few potent human beta(3) agonists with low affinities for beta(1)- and beta(2)-ARs. N-Alkyl substitution on the 4-piperidin-1-yl-phenylamine further increased the beta(3) potency while maintaining the selectivity. For example, sulfonamide 48 is a potent full beta(3) agonist (EC(50)=0.004 microM, IA=1.0) with > 500-fold selectivity over beta(1)- and beta(2)-ARs.     

Tryptamine-based human beta3-adrenergic receptor agonists. Part 1: SAR studies of the 7-position of the indole ring

A series of tryptamine-based 2-thiophenesulfonamide derivatives were prepared and their agonistic activity for the beta-adrenergic receptors (ARs) was evaluated. Compound 54, containing 7-methanesulfonyloxy tryptamine, was found to be a highly potent beta3-AR agonist (EC50=0.21 nM, IA=97%) with excellent selectivity for the beta3-AR over the beta1- and beta2-ARs (210- and 86-fold, respectively).     

Synthesis and biological evaluation of novel macrocyclic bis-7-azaindolylmaleimides as potent and highly selective glycogen synthase kinase-3 beta (GSK-3 beta) inhibitors

Palladium catalyzed cross-coupling reactions were used to synthesize two key intermediates 3 and 5 that resulted in the synthesis of novel series of macrocyclic bis-7-azaindolylmaleimides. Among the three series of macrocycles, the oxygen atom and thiophene containing linkers yielded molecules with higher inhibitory potency at GSK-3 beta (K(i)=0.011-0.079 microM) while the nitrogen atom containing linkers yielded molecules with lower potency (K(i)=0.150->1 microM). Compound 33 and 36 displayed 1-2 orders of magnitude selectivity at GSK-3 beta against CDK2, PKC beta II, Rsk3 and little or no inhibitions to the other 62 protein kinases. Compound 46 was at least 100-fold more selective towards GSK-3 beta than PKC beta II, and it had little or no activity against a panel of 65 protein kinases, almost behaved as a GSK-3 beta 'specific inhibitor'. All three compounds showed good potency in GS assay. Molecular docking studies were conducted in an attempt to rationalize the GSK-3 beta selectivity of azaindolylmaleimides. The high selectivity, inhibitory potency and cellular activities of these non-crown-ether typed molecules may provide them as a valuable pharmacological tools in elucidating the complex roles of GSK-3 beta in cell signaling pathways and the potential usage for the treatment of elevated level of GSK-3 beta involved diseases.     

Discovery of a potent and selective alpha v beta 3 integrin antagonist with strong inhibitory activity against neointima formation in rat balloon injury model

A new series of phenylpiperazine-based derivatives with strong antagonistic activity for alpha v beta 3 integrin were synthesized. Of these derivatives, the fluorine-substituted compound 8 showed strong inhibitory activity and high selectivity for alpha v beta 3 integrin receptor (IC(50) = 0.055 nM). In vivo evaluation of the antistenotic effects of 8 indicated that this compound significantly inhibits neointima formation in rat balloon injury model.     

Novel and potent human and rat beta3-adrenergic receptor agonists containing substituted 3-indolylalkylamines

A novel series of 2-(3-indolyl)alkylamino-1-(3-chlorophenyl)ethanols was prepared and evaluated for in vitro ability to stimulate cAMP production in Chinese hamster ovary cells expressing cloned human beta(3)-AR. The optically active 30a was found to be the most potent and selective human beta(3)-AR agonist in this series with an EC(50) value of 0.062nM. In addition, 30a selectivity for human beta(3)-AR was 210-fold and 103-fold that for human beta(2)-AR and beta(1)-AR, respectively. Furthermore, 30a showed potent agonistic activity at rat beta(3)-AR.     

New oxadiazolidinedione derivatives as potent and selective human beta3 agonists

As part of our investigation into the development of potent and selective human beta3 agonists, a series of thiazolidinedione analogues was prepared and evaluated for their biological activity on the human beta3-adrenergic receptor. The oxadiazolidinedione derivative 17 was found to be the most potent and selective compound in this study, with an EC50 value of 0.02 microM at the beta3 receptor, 259-fold selectivity over the beta1 receptor, and 745-fold selectivity over the beta2 receptor.     

Convergent, parallel synthesis of a series of beta-substituted 1,2,4-oxadiazole butanoic acids as potent and selective alpha(v)beta3 receptor antagonists

We describe a series of 1,2,4-oxadiazoles, which are potent antagonists of the integrin alpha(v)beta3 and, in addition, show selectivity relative to the other beta3 integrin alpha(IIb)beta3. In whole cells, the majority of these analogs also demonstrated modest selectivity against other alpha(v) integrins such as alpha(v)beta1 and alpha(v)beta6.     

Discovery of novel series of benzoic acid derivatives containing biphenyl ether moiety as potent and selective human beta(3)-adrenergic receptor agonists: Part IV

Identification and SAR study of novel series of beta(3)-AR agonists with benzoic acid are described. Conversion of ether linkage position of phenoxybenzoic acid derivative 2b led to compound 7b with moderate beta(3)-AR activity. Further modification in right, center and left parts of compound 7b was investigated to improve the beta(3)-AR potency and selectivity. Compounds 7g and 7k, with the bulky aliphatic-substituted group at 2-position of benzoic acid moiety, were identified as potent and selective beta(3)-AR agonists. In addition, in vivo efficacy of compounds 7g and 7k was exhibited on dog OAB model.     

Potent, elective human beta3 adrenergic receptor agonists containing a substituted indoline-5-sulfonamide pharmacophore.

A series of compounds possessing an N-substituted indoline-5-sulfonamide pharmacophore was prepared and evaluated for their human beta3 adrenergic receptor agonist activity. The SAR of a wide range of urea and heterocyclic substituents is discussed. 4-Octyl thiazole compound 8c was the most potent and selective compound in the series, with 2800-fold selectivity over beta1 binding and 1400-fold selectivity over beta2 binding.     

Synthesis, 3D-QSAR, and docking studies of 1-phenyl-1H-1,2,3-triazoles as selective antagonists for beta3 over alpha1beta2gamma2 GABA receptors

A series of 16 1-phenyl-1H-1,2,3-triazoles with substituents at both the 4- and 5-positions of the triazole ring were synthesized, and a total of 49 compounds, including previously reported 4- or 5-monosubstituted analogues, were examined for their ability to inhibit the specific binding of [(3)H]4'-ethynyl-4-n-propylbicycloorthobenzoate (EBOB), a non-competitive antagonist, to human homo-oligomeric beta3 and hetero-oligomeric alpha1beta2gamma2 gamma-aminobutyric acid (GABA) receptors. Among all tested compounds, the 4-n-propyl-5-chloromethyl analogue of 1-(2,6-dichloro-4-trifluoromethylphenyl)-1H-1,2,3-triazole showed the highest level of affinity for both beta3 and alpha1beta2gamma2 receptors, with K(i) values of 659pM and 266nM, respectively. Most of the tested compounds showed selectivity for beta3 over alpha1beta2gamma2 receptors. Among all 1-phenyl-1H-1,2,3-triazoles, the 4-n-propyl-5-ethyl analogue exhibited the highest (>1133-fold) selectivity, followed by the 4-n-propyl-5-methyl analogue of 1-(2,6-dibromo-4-trifluoromethylphenyl)-1H-1,2,3-triazole with a >671-fold selectivity. The 2,6-dichloro plus 4-trifluoromethyl substitution pattern on the benzene ring was found to be important for the high affinity for both beta3 and alpha1beta2gamma2 receptors. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) provided similar contour maps, revealing that an electronegative substituent at the 4-position of the benzene ring, a compact, hydrophobic substituent at the 4-position of the triazole ring, and a small, electronegative substituent at the 5-position of the triazole ring play significant roles for the high potency in beta3 receptors. Molecular docking studies suggested that the putative binding sites for 1-phenyl-1H-1,2,3-triazole antagonists are located in the channel-lining 2'-6' region of the second transmembrane segment of beta3 and alpha1beta2gamma2 receptors. A difference in the hydrophobic environment at the 2' position might underlie the selectivity of 1-phenyl-1H-1,2,3-triazoles for beta3 over alpha1beta2gamma2 receptors. The compounds that had high affinity for beta3 receptors with homology to insect GABA receptors showed insecticidal activity against houseflies with LD(50) values in the pmol/fly range. The information obtained in the present study should prove helpful for the discovery of selective insect control chemicals.     

Macrocyclic bisindolylmaleimides as inhibitors of protein kinase C and glycogen synthase kinase-3

Efficient methods were developed to synthesize a novel series of macrocyclic bisindolylmaleimides containing linkers with multiple heteroatoms. Potent inhibitors (single digit nanomolar IC(50)) for PKC-beta and GSK-3beta were identified, and compounds showed good selectivity over PKC-alpha, -gamma, -delta, -epsilon, and -zeta. Representative compound 5a also had high selectivity in a screening panel of 10 other protein kinases. In cell-based functional assays, several compounds effectively blocked interleukin-8 release induced by PKC-betaII and increased glycogen synthase activity by inhibiting GSK-3beta.     

Isolation,structure, and activity of GID,a novel alpha 4/7-conotoxin with an extended N-terminal sequence

Using assay-directed fractionation of Conus geographus crude venom, we isolated alpha-conotoxin GID, which acts selectively at neuronal nicotinic acetylcholine receptors (nAChRs). Unlike other neuronally selective alpha-conotoxins, alpha-GID has a four amino acid N-terminal tail, gamma-carboxyglutamate (Gla), and hydroxyproline (O) residues, and lacks an amidated C terminus. GID inhibits alpha 7 and alpha 3 beta 2 nAChRs with IC(50) values of 5 and 3 nm, respectively and is at least 1000-fold less potent at the alpha 1 beta 1 gamma delta, alpha 3 beta 4, and alpha 4 beta 4 combinations. GID also potently inhibits the alpha 4 beta 2 subtype (IC(50) of 150 nm). Deletion of the N-terminal sequence (GID Delta 1-4) significantly decreased activity at the alpha 4 beta 2 nAChR but hardly affected potency at alpha 3 beta 2 and alpha 7 nAChRs, despite enhancing the off-rates at these receptors. In contrast, Arg(12) contributed to alpha 4 beta 2 and alpha 7 activity but not to alpha 3 beta 2 activity. The three-dimensional structure of GID is well defined over residues 4-19 with a similar motif to other alpha-conotoxins. However, despite its influence on activity, the tail appears to be disordered in solution. Comparison of GID with other alpha 4/7-conotoxins which possess an NN(P/O) motif in loop II, revealed a correlation between increasing length of the aliphatic side-chain in position 10 (equivalent to 13 in GID) and greater alpha 7 versus alpha 3 beta 2 selectivity.     

Synthesis and nicotinic binding of novel phenyl derivatives of UB-165. Identifying factors associated with alpha7 selectivity

Four racemic phenyl-substituted analogues 3-6 of the potent nicotinic agonist UB-165 1 have been synthesised and evaluated against the alpha(4)beta(2), alpha(3)beta(4), and alpha(7) neuronal nicotinic receptors. The 2'-phenyl derivative 3 shows no activity at these major receptor subtypes, while the 4'-phenyl analogue 4 shows an enhanced level of alpha(7) selectivity as compared to UB-165 and deschloro UB-165 2. These results are discussed within the context of recent pharmacophore models.     

Kinetic rationale for selectivity toward N- and C-terminal oxygen-dependent degradation domain substrates mediated by a loop region of hypoxia-inducible factor prolyl hydroxylases

Hydroxylation of two conserved prolyl residues in the N- and C-terminal oxygen-dependent degradation domains (NODD and CODD) of the alpha-subunit of hypoxia-inducible factor (HIF) signals for its degradation via the ubiquitin-proteasome pathway. In human cells, three prolyl hydroxylases (PHDs 1-3) belonging to the Fe(II) and 2-oxoglutarate (2OG)-dependent oxygenase family catalyze prolyl hydroxylation with differing selectivity for CODD and NODD. Sequence analysis of the catalytic domains of the PHDs in the light of crystal structures for PHD2, and results for other 2OG oxygenases, suggested that either the C-terminal region or a loop linking two beta-strands (beta2 and beta3 in human PHD2) are important in determining substrate selectivity. Mutation analyses on PHD2 revealed that the beta2beta3 loop is a major determinant in conferring selectivity for CODD over NODD peptides. A chimeric PHD in which the beta2beta3 loop of PHD2 was replaced with that of PHD3 displayed an almost complete selectivity for CODD (in competition experiments), as observed for wild-type PHD3. CODD was observed to bind much more tightly to this chimeric protein than the wild type PHD2 catalytic domain.     

Trinorcucurbitane and cucurbitane triterpenoids from the roots of Momordica charantia

Five cucurbitacins, kuguacins A-E (1-5), together with three known analogues, 3beta,7beta,25-trihydroxycucurbita-5,(23E)-diene-19-al (6), 3beta,25-dihydroxy-5beta,19-epoxycucurbita-6,(23E)-diene (7), and momordicine I (8), were isolated from roots of Momordica charantia. Structures of 1-5 were elucidated by NMR and MS spectroscopic analysis. Among them, compounds 3-5 possess an unprecedented 25,26,27-trinorcucurbitane backbone. Compounds 3 and 5 showed moderate anti-HIV-1 activity with EC(50) values of 8.45 and 25.62 microg/ml, and exerted minimal cytotoxicity against C8166 cells (IC(50)>200 microg/ml), with a selectivity index more than 23.68 and 7.81, respectively.     

Synthesis, pharmacological evaluation, and structure-activity relationships of benzopyran derivatives with potent SERM activity

The synthesis, binding affinity for estrogen receptor subtypes (ER alpha and ER beta) and pharmacological activity on rat uterus of a new class of potent ligands, characterized by a 3-phenylbenzopyran scaffold with a basic side chain in position 4, are reported. Some of these compounds, endowed with very high receptor affinity, showed potent inhibition of agonist-stimulated uterine growth, with no or limited proliferative effect. Binding affinity mostly depended on the nature and position of substituents at the 3-phenyl ring, while the uterine activity seems to be affected by basic chain length. Compound 9c (CHF4227) showed excellent binding affinity and antagonist activity on the uterus. The docking of benzopyran derivatives explained the structure-affinity relationships observed for 3-phenyl substitution: a small, hydrophobic 4'-substituent could interact with a small accessory binding cavity, while di-substitution at 4' and 3' led to some ER alpha selectivity. This selectivity can be ascribed to differences in amino acid composition and side chain conformation in the region accommodating the 3-phenyl ring at human ER alpha and ER beta ligand-binding domain.     

Triazolo[1,5-a]pyrimidines as novel CDK2 inhibitors: protein structure-guided design and SAR

Crystallographic and modelling data, in conjunction with a medicinal chemistry template-hopping approach, led to the identification of a series of novel and potent inhibitors of human cyclin-dependent kinase 2 (CDK2), with selectivity over glycogen synthase kinase-3beta (GSK-3beta). One example had a CDK2 IC(50) of 120 nM and showed selectivity over GSK-3beta of 167-fold.