Synthesis and biological evaluation of 1,4-diazepane derivatives as T-type calcium channel blockers

Discovery of a novel selective kappa-opioid receptor agonist using crystal structure-based virtual screening

Kappa-opioid (KOP) receptor agonists exhibit analgesic effects without activating reward pathways. In the search for nonaddictive opioid therapeutics and novel chemical tools to study physiological functions regulated by the KOP receptor, we screened in silico its recently released inactive crystal structure. A selective novel KOP receptor agonist emerged as a notable result and is proposed as a new chemotype for the study of the KOP receptor in the etiology of drug addiction, depression, and/or pain.

Synthesis and pharmacological evaluation of 1-alkyl-N-[(1R)-1-(4-fluorophenyl)-2-methylpropyl]piperidine-4-carboxamide derivatives as novel antihypertensive agents

We synthesized and evaluated inhibitory activity against T-type Ca(2+) channels for a series of 1-alkyl-N-[(1R)-1-(4-fluorophenyl)-2-methylpropyl]piperidine-4-carboxamide derivatives. Structure-activity relationship studies have revealed that the isopropyl substituent at the benzylic position plays an important role in exerting potent inhibitory activity, and the absolute configuration of the benzylic position was found to be opposite that of mibefradil, which was first launched as a new class of T-type Ca(2+) channel blocker. Oral administration of N-[(1R)-1-(4-fluorophenyl)-2-methylpropyl]-1-[2-(3-methoxyphenyl)ethyl]piperidine-4-carboxamide (17f) lowered blood pressure in spontaneously hypertensive rats without inducing reflex tachycardia, an adverse effect often caused by traditional L-type Ca(2+) channel blockers.

The Discovery and Characterization of ML218: A Novel, Centrally Active T-Type Calcium Channel Inhibitor with Robust Effects in STN Neurons and in a Rodent Model of Parkinson's Disease

T-type Ca(2+) channel inhibitors hold tremendous therapeutic potential for the treatment of pain, epilepsy, sleep disorders, essential tremor and other neurological disorders; however, a lack of truly selective tools has hindered basic research, and selective tools from the pharmaceutical industry are potentially burdened with intellectual property (IP) constraints. Thus, an MLPCN high-throughput screen (HTS) was conducted to identify novel T-type Ca(2+) channel inhibitors free from IP constraints, and freely available through the MLPCN, for use by the biomedical community to study T-type Ca(2+) channels. While the HTS provided numerous hits, these compounds could not be optimized to the required level of potency to be appropriate tool compounds. Therefore, a scaffold hopping approach, guided by SurflexSim, ultimately afforded ML218 (CID 45115620) a selective T-Type Ca(2+) (Ca(v)3.1, Ca(v)3.2, Ca(v)3.3) inhibitor (Ca(v)3.2, IC(50) = 150 nM in Ca(2+) flux; Ca(v)3.2 IC(50) = 310 nM and Ca(v)3.3 IC(50) = 270 nM, respectively in patch clamp electrophysiology) with good DMPK properties, acceptable in vivo rat PK and excellent brain levels. Electrophysiology studies in subthalamic nucleus (STN) neurons demonstrated robust effects of ML218 on the inhibition of T-Type calcium current, inhibition of low threshold spike and rebound burst activity. Based on the basal ganglia circuitry in Parkinson's disease (PD), the effects of ML218 in STN neurons suggest a therapeutic role for T-type Ca(2+) channel inhibitors, and ML218 was found to be orally efficacious in haloperidol-induced catalepsy, a preclinical PD model, with comparable efficacy to an A(2A) antagonist, a clinically validated PD target. ML218 proves to be a powerful new probe to study T-Type Ca(2+) function in vitro and in vivo, and freely available.

Pyridyl amides as potent inhibitors of T-type calcium channels

A novel series of amide T-type calcium channel antagonists were prepared and evaluated using in vitro and in vivo assays. Optimization of the screening hit 3 led to identification of the potent and selective T-type antagonist 37 that displayed in vivo efficacy in rodent models of epilepsy and sleep.

Facile synthesis and biological evaluation of 3,3-diphenylpropanoyl piperazines as T-type calcium channel blockers

We have developed a facile synthesis of 3,3-diphenylpropanamides using Meldrum's acid derivatives as amide coupling components. The in vitro biological evaluation of the title compounds led to the identification of compound 1h, which has good inhibitory activity against T-type calcium channel (IC(50) = 0.83 μM).