4-{(2R)-[3-Aminopropionylamido]-3-(2,4-dichlorophenyl)propionyl}-1-{2-[(2-thienyl)ethylaminomethyl]phenyl}piperazine as a potent and selective melanocortin-4 receptor antagonist--design, synthesis, and characterization

Recent studies have demonstrated that melanocortin-4 receptor (MC4R) antagonists can prevent weight loss in tumor-bearing mice, which indicates clinical usage for the treatment of cachexia. In our efforts to develop potent and selective antagonists of the human MC4R, we designed piperazinebenzylamines bearing a 2,4-dichlorophenylalanine, by utilizing information derived from structure--activity relationships of MC4R agonists and mutagenesis results of the MC4R and peptide ligands. On the basis of known MC4R agonists such 6, we successfully synthesized potent MC4R antagonists exemplified by 10, which possesses a K(i) value of 1.8 nM in binding affinity. 10 does not stimulate cAMP release in HEK 293 cells expressing the human MC4 receptor at 10 microM concentration. It was demonstrated by Schild analysis that 10 was a competitive functional antagonist with a pA(2) value of 7.9 in the inhibition of alpha-MSH-stimulated cAMP accumulation. 10 also penetrated into the brain when dosed intravenously in rats.     

Design, synthesis, and anti-allergic activities of novel (R)(-)-1-[(4-chlorophenyl)phenyl methyl]piperazine derivatives

A series of novel (R)(-)-1-[(4-chlorophenyl)phenylmethyl]piperazine derivatives were designed, synthesized, and tested for in vivo anti-allergic activities. Most of these derivatives exhibited significant effects on both allergic asthma and allergic itching. Three of the 19 piperazine derivatives (namely, 3d, 3i, and 3r) have stronger potency against allergic asthma than levocetirizine, the positive control drug. Meanwhile, in the test of allergic itching, five of the 19 compounds (namely, 3b, 3g, 3k, 3o, and 3s) have more potent activities than levocetirizine.     

Discovery of (+)-N-(3-aminopropyl)-N-[1-(5-benzyl-3-methyl-4-oxo-[1,2]thiazolo[5,4-d]pyrimidin-6-yl)-2-methylpropyl]-4-methylbenzamide (AZD4877), a kinesin spindle protein inhibitor and potential anticancer agent

Structure-activity relationship analysis identified (+)-N-(3-aminopropyl)-N-[1-(5-benzyl-3-methyl-4-oxo-[1,2]thiazolo[5,4-d]pyrimidin-6-yl)-2-methylpropyl]-4-methylbenzamide (AZD4877), from a series of novel kinesin spindle protein (KSP) inhibitors, as exhibiting both excellent biochemical potency and pharmaceutical properties suitable for clinical development. The selected compound arrested cells in mitosis leading to the formation of the monopolar spindle phenotype characteristic of KSP inhibition and induction of cellular death. A favorable pharmacokinetic profile and notable in vivo efficacy supported the selection of this compound as a clinical candidate for the treatment of cancer.     

Discovery of N-{(1S,2S)-2-(3-cyanophenyl)- 3-[4-(2-[18F]fluoroethoxy)phenyl]-1-methylpropyl}- 2-methyl-2-[(5-methylpyridin-2-yl)oxy]propanamide, a cannabinoid-1 receptor positron emission tomography tracer suitable for clinical use

The discovery of a structurally distinct cannabinoid-1 receptor (CB1R) positron emission tomography tracer is described. Starting from an acyclic amide CB1R inverse agonist (1) as the lead compound, an efficient route to introduce 18F to the molecule was developed. Further optimization focused on reducing the lipophilicity and increasing the CB1R affinity. These efforts led to the identification of [18F]-16 that exhibited good brain uptake and an excellent signal-to-noise ratio in rhesus monkeys.     

A selective human H(4)-receptor agonist: (-)-2-cyano-1-methyl-3-[(2R,5R)-5- [1H-imidazol-4(5)-yl]tetrahydrofuran-2-y] methylguanidine

A series of 16 compounds related to chiral 4(5)-(5-aminomethyltetrahydrofuran-2-yl)imidazoles (1) have been designed, synthesized, and examined in vitro by radioligand displacement studies and functional assays for both the human H(3)- and H(4)-receptors expressed in SK-N-MC cells. Among them, the (2S,5S)-isomer 1d of amino compounds showed approximately 300-fold higher selectivity at the H(3)-receptor than the H(4)-receptor. On the other hand, (2R,5S)- and (2R,5R)-cyanoguanidines 3b and 3c, in which the amino group of the compounds 1b and 1c was substituted by the cyanoguanidino moiety, bound to the H(4)-receptor with a pEC(50) value of 6.65 and 7.11, respectively, and had >40-fold selectivities over the H(3)-receptor. As such, 3b and 3c are the first selective H(4) receptor agonists.     

Piperazine-based CCR5 antagonists as HIV-1 inhibitors. IV. Discovery of 1-[(4,6-dimethyl-5-pyrimidinyl)carbonyl]- 4-[4-[2-methoxy-1(R)-4-(trifluoromethyl)phenyl]ethyl-3(S)-methyl-1-piperazinyl]- 4-methylpiperidine (Sch-417690/Sch-D), a potent, highly selective, and orally bioavailable CCR5 antagonist

The nature and the size of the benzylic substituent are shown to be the key to controlling receptor selectivity (CCR5 vs M1, M2) and potency in the title compounds. Optimization of the lead benzylic methyl compound 3 led to the methoxymethyl analogue 30, which had excellent receptor selectivity and oral bioavailability in rats and monkeys. Compound 30 (Sch-417690/Sch-D), a potent inhibitor of HIV-1 entry into target cells, is currently in clinical trials.     

Synthesis and in-vitro antimycobacterial activity of amino-5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione

A series of amino-5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H- 1-pyrazolylmethanethione were synthesized by the reaction between thiosemicarbazide and chalcones and were tested for their antimycobacterial activity in vitro against Mycobacterium tuberculosis H37Rv and INH resistant Mycobacterium tuberculosis using bactec method. Among the synthesized compounds, compound (4b), amino-5-(4-chlorophenyl)-3-(4-hydroxy-3-methylphenyl)-4, 5-dihydro-H-1-pyrazolylmethanethione was found to be the most active agent against Mycobacterium tuberculosis H37Rv (MTB) and INH resistant Mycobacterium tuberculosis (INHR-MTB) with minimum inhibitory concentration of 0.43 microM . When compared to INH-compound (4b) was found to be 1.62 fold and 26.41 fold more active against MTB and INHR-MTB, respectively.     

Discovery of a potent, orally bioavailable beta(3) adrenergic receptor agonist, (R)-N-[4-[2-[[2-hydroxy-2-(3-pyridinyl)ethyl]amino]ethyl]phenyl]-4-[4 -[4-(trifluoromethyl)phenyl]thiazol-2-yl]benzenesulfonamide

As part of our investigation into the development of orally bioavailable beta(3) adrenergic receptor agonists, we have identified a series of pyridylethanolamine analogues possessing a substituted thiazole benzenesulfonamide pharmacophore that are potent human beta(3) agonists with excellent selectivity against other human beta receptor subtypes. Several of these compounds also exhibited an improved pharmacokinetic profile in dogs. For example, thiazole sulfonamide 2e (R = 4-F(3)C-C(6)H(4)) is a potent full beta(3) agonist (EC(50) = 3.6 nM, 94% activation) with >600-fold selectivity over the human beta(1) and beta(2) receptors, which also displays good oral bioavailability in several mammalian species, as well as an extended duration of action.     

Development of long-acting dopamine transporter ligands as potential cocaine-abuse therapeutic agents: chiral hydroxyl-containing derivatives of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine and 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine

In our search for long-acting agents for the treatment of cocaine abuse, a series of optically pure hydroxylated derivatives of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (1) and 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine (2) (GBR 12909 and GBR 12935, respectively) were synthesized and evaluated in vitro and in vivo. The enantiomers of the 2-hydroxylated analogues displayed substantial enantioselectivity. The S enantiomers displayed higher dopamine transporter (DAT) affinity and the R enantiomers were found to interact at the serotonin transporter (SERT) with higher affinity. The two-carbon spacer between the hydroxyl group and the piperazine ring was essential for enantioselectivity, and the length of the alkyl chain between the phenyl group and the piperazine ring influenced binding affinity and selectivity for the DAT and SERT. Phenylethyl analogues had a higher binding affinity for the SERT and a weaker affinity and selectivity for the DAT than the corresponding phenylpropyl analogues. Thus, (S)-(+)-1-[4-[2-[bis(4-fluorophenyl)methoxy]ethyl]piperazinyl]-3-phenylpropan-2-ol (6) displayed the highest affinity to the DAT, and (S)-(+)-1-[4-[2-(diphenylmethoxy)ethyl]piperazinyl]-3-phenylpropan-2-ol (8) had the highest selectivity. The latter (8) is one of the most DAT selective ligands known. In accord with the in vitro data, 6 showed greater potency than 7 in elevating extracellular dopamine levels in a microdialysis assay and in inhibiting cocaine-maintained responding in rhesus monkeys.     

6-(4-chlorophenyl)-3-substituted-thieno[3,2-d]pyrimidin-4(3H)-one-based melanin-concentrating hormone receptor 1 antagonist

Genetic manipulation studies in mice at both the MCH receptor 1 (MCHR1) as well as the MCH peptide levels have implicated MCHR1 as a key player in energy homeostasis. The phenotype exhibited by these studies, that is, increased metabolic rate, resistance to high fat diet, and subsequent weight loss, has spurred considerable efforts to develop antagonists of MCHR1. In continuation of efforts directed toward this goal, the present work capitalizes on the putative binding mode of an MCH antagonist, resulting in the identification of several novel chemotypes that are potent and selective MCHR1 antagonists. In addition, the favorable pharmacokinetics of representative examples has allowed for the evaluation of an MCHR1 antagonist in a high fat diet-induced obese rodent model of obesity. The tolerability of the right-hand side of the template for diverse chemotypes accompanied by favorable effects on weight loss enhances the attractiveness of this template in the pursuit toward development of effective anti-obesity agents.