Lead optimization of 2-(piperidin-3-yl)-1H-benzimidazoles: identification of 2-morpholin- and 2-thiomorpholin-2-yl-1H-benzimidazoles as selective and CNS penetrating H1-antihistamines for insomnia.

The structure-activity relationships of 2-(piperidin-3-yl)-1H-benzimidazoles, 2-morpholine and 2-thiomorpholin-2-yl-1H-benzimidazoles are described. In the lead optimization process, the pK(a) and/or logP of benzimidazole analogs were reduced either by attachment of polar substituents to the piperidine nitrogen or incorporation of heteroatoms into the piperidine heterocycle. Compounds 9a and 9b in the morpholine series and 10g in the thiomorpholine series demonstrated improved selectivity and CNS profiles compared to lead compound 2 and these are potential candidates for evaluation as sedative hypnotics.

Syntheses of tetrahydrothiophenes and tetrahydrofurans and studies of their derivatives as melanocortin-4 receptor ligands.

Piperazinebenzylamine derivatives from trans-4-(4-chlorophenyl)tetrahydrothiophene-3-carboxylic acid 6 and its S-oxide 7 and sulfone 8, and the tetrahydrofuran 9 and its two regioisomers 11 and 13 were synthesized and studied for their binding affinities at the human melanocortin-4 receptor. These five-membered ring constrained compounds possessed similar or lower potency compared to the acyclic analogs.

Structure-activity relationship studies on a series of piperazinebenzylalcohols and their ketone and amine analogs as melanocortin-4 receptor ligands.

A series of piperazinebenzylalcohols were prepared and studied to compare with their ketone and amine analogs as MC4R antagonists. Several benzylalcohols such as 14a and 14g displayed low nanomolar binding affinities (K(i)<10 nM), and high selectivities over other melanocortin receptor subtypes.

Design and synthesis of 3-arylpyrrolidine-2-carboxamide derivatives as melanocortin-4 receptor ligands.

Based on 3-phenylpropionamides, a series of 3-arylpyrrolidine-2-carboxamide derivatives was designed and synthesized to study the effect of cyclizations as melanocortin-4 receptor ligands. It was found that the 2R,3R-pyrrolidine isomer possessed the most potent affinity among the four stereoisomers.

Studies on the structure-activity relationship of bicifadine analogs as monoamine transporter inhibitors.

Compounds with various activities and selectivities were discovered through structure-activity relationship studies of bicifadine analogs as monoamine transporter inhibitors. The norepinephrine-selective 2-thienyl compound S-6j was efficacious in a rodent pain model.

Identification of 1S,2R-milnacipran analogs as potent norepinephrine and serotonin transporter inhibitors.

A series of milnacipran analogs were synthesized and studied as monoamine transporter inhibitors, and several potent compounds with moderate lipophilicity were identified from the 1S,2R-isomers. Thus, 15l exhibited IC(50) values of 1.7nM at NET and 25nM at SERT, which were, respectively, 20- and 13-fold more potent than 1S,2R-milnacipran 1-II.

Identification and characterization of pyrrolidine diastereoisomers as potent functional agonists and antagonists of the human melanocortin-4 receptor.

A series of trans-4-phenylpyrrolidine-3-carboxamides were synthesized and characterized as potent ligands of the human melanocortin-4 receptor. Interestingly, a pair of diastereoisomers 13b displayed potent functional agonist and antagonist activity, respectively. Thus, the 3S,4R-pyrrolidine 13b-1 possessed a Ki of 1.0 nM and an EC50 of 3.8 nM, while its 3R,4S-isomer 13b-2 exhibited a Ki of 4.7 and an IC50 of 64 nM. Both compounds were highly selective over other melanocortin receptor subtypes. The MC4R agonist 13b-1 also demonstrated efficacy in a diet-induced obesity model in rats.

Pharmacological and pharmacokinetic characterization of 2-piperazine-alpha-isopropyl benzylamine derivatives as melanocortin-4 receptor antagonists.

A series of 2-piperazine-alpha-isopropylbenzylamine derivatives were synthesized and characterized as melanocortin-4 receptor (MC4R) antagonists. Attaching an amino acid to benzylamines 7 significantly increased their binding affinity, and the resulting compounds 8-12 bound selectively to MC4R over other melanocortin receptor subtypes and behaved as functional antagonists. These compounds were also studied for their permeability using Caco-2 cell monolayers and metabolic stability in human liver microsomes. Most compounds exhibited low permeability and high efflux ratio possibly due to their high molecular weights. They also showed moderate metabolic stability which might be associated with their moderate to high lipophilicity. Pharmacokinetic properties of these MC4R antagonists, including brain penetration, were studied in mice after oral and intravenous administrations. Two compounds identified to possess high binding affinity and selectivity, 10d and 11d, were studied in a murine cachexia model. After intraperitoneal (ip) administration of 1mg/kg dose, mice treated with 10d had significantly more food intake and weight gain than the control animals, demonstrating efficacy by blocking the MC4 receptor. Similar in vivo effects were also observed when 11d was dosed orally at 20mg/kg. These results provide further evidence that a potent and selective MC4R antagonist has potential in the treatment of cancer cachexia.

Studies on the structure-activity relationship of the basic amine of phenylpiperazines as melanocortin-4 receptor antagonists.

A series of piperazinephenethylamines were synthesized to study the contribution of a basic amine to binding affinity at the melanocortin-4 receptor. Several potent compounds from this series possessed subnanomolar K(i) values in a competition binding assay.

Discovery of 1-[2-[(1S)-(3-dimethylaminopropionyl)amino-2-methylpropyl]-4-methylphenyl]-4-[(2R)-methyl-3-(4-chlorophenyl)-propionyl]piperazine as an orally active antagonist of the melanocortin-4 receptor for the potential treatment of cachexia.

A potent and selective antagonist of the melanocortin-4 receptor, 1-[2-[(1S)-(3-dimethylaminopropionyl)amino-2-methylpropyl]-6-methylphenyl]-4-[(2R)-methyl-3-(4-chlorophenyl)propionyl]piperazine (10d), was identified from a series piperazinebenzylamine attached with a N,N-dimethyl-beta-alanine side chain. This compound possessed high water solubility and exhibited good metabolic profiles. In animals, 10d showed moderate to good oral bioavailability and promoted food intake in tumor-bearing mice after oral administration.

Design, synthesis, in vitro, and in vivo characterization of phenylpiperazines and pyridinylpiperazines as potent and selective antagonists of the melanocortin-4 receptor.

Benzylamine and pyridinemethylamine derivatives were synthesized and characterized as potent and selective antagonists of the melanocortin-4 receptor (MC4R). These compounds were also profiled in rodents for their pharmacokinetic properties. Two compounds with diversified profiles in chemical structure, pharmacological activities, and pharmacokinetics, 10 and 12b, showed efficacy in an established murine cachexia model. For example, 12b had a K(i) value of 3.4 nM at MC4R, was more than 200-fold selective over MC3R, and had a good pharmacokinetic profile in mice, including high brain penetration. Moreover, 12b was able to stimulate food intake in the tumor-bearing mice and reverse their lean body mass loss. Our results provided further evidence that a potent and selective MC4R antagonist with appropriate pharmacokinetic properties might potentially be useful for the treatment of cancer cachexia.

Synthesis and characterization of trans-4-(4-chlorophenyl)pyrrolidine-3-carboxamides of piperazinecyclohexanes as ligands for the melanocortin-4 receptor.

A series of trans-N-alkyl-4-(4-chlorophenyl)pyrrolidine-3-carboxamides of piperazinecyclohexanemethylamines was synthesized and characterized for binding and function at the melanocortin-4 receptor (MC4R), and several potent benzylamine derivatives were identified. Compound 18 v was found to bind MC4R with potent affinity (K(i)=0.5 nM) and high selectivity over the other melanocortin subtypes and behaved as a functional antagonist (IC(50)=48 nM).

Synthesis and characterization of pyrrolidine derivatives as potent agonists of the human melanocortin-4 receptor.

A series of trans-4-phenylpyrrolidine-3-carboxamides were synthesized and characterized as potent ligands of the human melanocortin-4 receptor. Interestingly, a pair of diastereoisomers 20f-1 and 20f-2 displayed potent functional agonist and antagonist activity, respectively. Thus, the 3S,4R-compound 20f-1 possessed a K(i) of 11nM and an EC(50) of 24nM, while its 3R,4S-isomer 20f-2 exhibited a K(i) of 8.6 and an IC(50) of 65nM. Both compounds were highly selective over other melanocortin receptor subtypes. The MC4R agonist 20f-1 also demonstrated efficacy in diet-induced obese rats.

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.

Discovery of CX-6258. A Potent, Selective, and Orally Efficacious pan-Pim Kinases Inhibitor.

Structure-activity relationship analysis in a series of 3-(5-((2-oxoindolin-3-ylidene)methyl)furan-2-yl)amides identified compound 13, a pan-Pim kinases inhibitor with excellent biochemical potency and kinase selectivity. Compound 13 exhibited in vitro synergy with chemotherapeutics and robust in vivo efficacy in two Pim kinases driven tumor models.

Characterization of thien-2-yl 1S,2R-milnacipran analogues as potent norepinephrine/serotonin transporter inhibitors for the treatment of neuropathic pain.

Thien-2-yl 1S,2R-milnacipran analogues were synthesized and characterized as norepinephrine/serotonin transporter inhibitors. These compounds possessed higher potencies than 1S,2R-milnacipran (2R-1) while maintaining low molecular weight and moderate lipophilicity, which are the important features for the pharmacological and pharmacokinetic characteristics of milnacipran (1). Thus, compound 5c exhibited IC50 values of 2.3 and 32 nM, respectively, at NET and SERT, which were more than 10-fold better than those of 1 (NET IC50 = 77 nM, SERT IC50 = 420 nM). Moreover, 5c achieved the same efficacy as 1, but with much lower doses, in a rodent spinal nerve ligation pain model. In addition, 5c displayed desirable pharmacokinetic properties in several species, including high oral availability and significant brain penetration.

Pyrrolidines as potent functional agonists of the human melanocortin-4 receptor.

A series of pyrrolidine derivatives were synthesized and characterized as potent agonists of the human melanocortin-4 receptor. For example, 28c had a K(i) of 13 nM in binding affinity and EC(50) of 6.9 nM in agonist potency with an intrinsic activity of 100% of the endogenous ligand alpha-MSH.

Pyrrolidinones as orally bioavailable antagonists of the human melanocortin-4 receptor with anti-cachectic activity.

A series of pyrrolidinones derived from phenylalanines were synthesized as potent antagonists of the human melanocortin-4 receptor. These compounds showed high potencies and selectivities, and several of them had good oral bioavailabilities. In addition, 12e demonstrated in vivo efficacy in a murine cachexia model.

Pyrrolidinones as potent functional antagonists of the human melanocortin-4 receptor.

A series of pyrrolidinones derived from phenylalaninepiperazines were synthesized and characterized as potent and selective antagonists of the melanocortin-4 receptor. In addition to their high binding affinities, these compounds displayed high functional potencies. 12a had a K(i) of 0.94 nM in binding and IC(50) of 21 nM in functional activity. 12a also demonstrated efficacy in a mouse cachexia model.