Katarzyna Kulig

Synthesis, antiarrhythmic, and antihypertensive effects of novel 1-substituted pyrrolidin-2-one and pyrrolidine derivatives with adrenolytic activity

A series of 1-substituted pyrrolidin-2-one and pyrrolidine derivatives were synthesised and tested for electrocardiographic, antiarrhythmic, and antihypertensive activity as well as for alpha(1)- and alpha(2)-adrenoceptors binding affinities. Among the newly synthesised derivatives several compounds with 3-(4-arylpiperazin-1-yl)propyl moiety displayed strong antiarrhythmic (7a-12a) and antihypertensive (7a-11a) activities. Compound 11a, 1-[2-acetoxy-3-[4-(2-methoxyphenyl)piperazin-1-yl]propyl]pyrrolidin-2-one, was the most potent in this series. The pharmacological results and binding studies suggest that their antiarrhythmic and hypotensive effects may be related to their alpha-adrenolytic properties, and that those properties depend on the presence of the 1-phenylpiperazine moiety with a methoxy- or chloro- substituent in the ortho position in the phenyl ring.

New investigational drugs for the treatment of neuropathic pain.

Introduction: Neuropathic pain (NP) is a chronic condition that arises from a lesion or dysfunction of the somatosensory nervous system. However, there are several new targets and novel technologies in the pipeline to address this unmet medical need. Areas covered: In this review, the authors briefly discuss a direction of the development of agents that could be potentially used in NP treatment. Special attention is paid to 1.7-selective voltage-gated sodium channels, N-type voltage-gated calcium channels, angiotensin II (Ang II) AT2 receptors and nerve growth factor (NGF) as promising targets for new drugs. Furthermore, the article also presents and discusses, in detail, the results of Phase II clinical studies with the AT2 receptor antagonist − EMA401 in NP (the results of Phase II clinical trials of other described compounds are not available, yet). Expert opinion: There is a real hope that new drugs for NP may be available soon. This hope is based on advancing methods of genomics, developing new targets and more efficient drug screening. Some forms of direct influence on voltage-gated ion channels have a place in the treatment of NP, while the development of entirely novel Ang II AT2 receptor antagonists or NGF inhibitors may be available for many chronic pain sufferers in the foreseeable future.

Stereocontrolled synthesis of the enantiomers of 1-[2-hydroxy-3-(4-phenyl-1-piperazinyl)-propyl]-pyrrolidin-2-one

Abstract The asymmetric synthesis of 1-[2-hydroxy-3-(4-phenyl-1-piperazinyl)-propyl]-pyrrolidin-2-one 1 is described. Enantiomers of compound 1 were obtained using the Sharpless asymmetric dihydroxylation (AD) or hydrolytic kinetic resolution (HKR) methods. The enantiomers of compound 1, which were obtained by HKR had higher enantiomeric excesses than those which were synthesized by AD and epoxidation. The enantiomeric purity of the synthesized compounds was determinated by capillary electrophoresis.

Cebranopadol: a first-in-class potent analgesic agent with agonistic activity at nociceptin/orphanin FQ and opioid receptors

Introduction: Pain is a syndrome of various clinical disorders, which arises from various pathological conditions and which presents significant challenges in both its diagnosis and treatment. There is currently a strong medical demand to develop new therapies with a higher efficacy and a better tolerability profile. Areas covered: In this review, the authors report on the available data for the pharmacological properties of cebranopadol (GRT6005), a first in-class, potent analgesic compound which acts as an agonist of nociceptin/orphanin FQ peptide (NOP) and opioid receptors. They highlight the in vitro receptor binding studies, as well as the in vivo preclinical results on the analgesic efficacy of cebranopadol obtained in several rodent pain models. The authors also briefly summarize the available data from clinical trials with cebranopadol. Expert opinion: Cebranopadol displays analgesic, antiallodynic and antihyperalgesic properties in several rat models of acute nociceptive, inflammatory, cancer and neuropathic pain. In contrast to classical opioids, it has a higher analgesic potency in models of neuropathic pain than in acute nociceptive pain. Even at higher analgesic doses, cebranopadol does not induce motor coordination deficits or respiratory depression in rats. Hence, it seems to possess a broader therapeutic window than classical opioids. While it is particularly interesting as a novel, potent bifunctional agonist of NOP/opioid receptors, the outcome of its ongoing and planned clinical trials will be crucial for its future development and potential application in humans.

Synthesis and pharmacological evaluation of pyrrolidin-2-one derivatives as antiarrhythmic, antihypertensive and α-adrenolytic agents

A series of novel arylpiperazines bearing a pyrrolidin-2-one fragment were synthesized and evaluated for their binding affinity for alpha1- and alpha2-adrenoceptors (ARs) as well as their antiarrhythmic and antihypertensive activities. The highest affinity for the alpha1-AR was displayed by 1-{3-[4-(2-chloro-phenyl)-piperazin-1-yl]-propyl}-pyrrolidin-2-one 7, which binds with a pKi = 7.13. The highest affinity for the alpha2-AR was shown by 1-{3-[4-(4-chloro-phenyl)-piperazin-1-yl]-propyl}-pyrrolidin-2-one 18, which binds with a pKi = 7.29. Among the compounds tested, 1-{3-[4-(2-ethoxy-phenyl)-piperazin-1-yl]-propyl}-pyrrolidin-2-one 13 had the highest prophylactic antiarrhythmic activity in epinephrine-induced arrhythmia in anesthetized rats. Its ED50 value was 1.0 mg/kg intravenously (iv). The compounds with a hydroxy group in the 4-position of the phenyl ring or two substituents such as fluorine atoms in the 2 and 4 positions of the phenyl ring significantly decreased systolic and diastolic pressure in normotensive anesthetized rats at a dose of 2.5 mg/ kg iv, and their hypotensive effects lasted for longer than an hour.

Zucapsaicin for the treatment of neuropathic pain

Introduction: Neuropathic pain (NP) is a chronic disease that stems from a primary lesion or dysfunction of the central or peripheral nervous system. Zucapsaicin is a synthetic cis isomer of natural capsaicin that has shown therapeutic efficacy in pain accompanying osteoarthritis of the knee. It is also currently under investigation for the relief of severe pain in adults suffering from NP. Areas covered: The authors provide an overview of the pharmacological properties of zucapsaicin based on available data from both preclinical and clinical trials. They also discuss its mechanism of action. Expert opinion: The mechanism of action and clinical indications of zucapsaicin are similar to that of its naturally occurring isomer, capsaicin. However, in contrast to capsaicin, zucapsaicin is better tolerated. In the future, zucapsaicin could become a valuable drug for treating pain relief. Indeed, it is possible, in addition to providing NP relief, that it may have a use in treating osteoarthritic pain, headaches and pain that accompany intestinal diseases.

Use of quantitative structure–enantioselective retention relationship for the liquid chromatography chiral separation prediction of the series of pyrrolidin-2-one compounds

In this work, the enantioseparation of 15 structurally similar chiral solutes is studied, and analysis of the retention factors is performed using a genetic algorithm and multiple linear regression analysis technique. The present quantitative structure-enantioselective retention relationship model generated for retention factors data has confirmed the importance of a number of descriptors altering the retention behavior and enantioselectivity of the studied compounds. Thus, fragment-based descriptor PSA, which encodes polar surface area, has confirmed the crucial role of heteroatoms in the retention behavior exhibited by pyrroliddin-2-ones. The presence of E(LUMO) descriptor, which represents a quantum-chemical property, has indicated the role of charge transfer interactions between the chiral stationary phase and enantiomers to retention factors, showing that lowest unoccupied molecular orbital energy is significantly different between enantiomers. The developed model exhibits a very good performance characterized by following statistical parameters: r(2) = 0.93 for training set and r(2) = 0.99 for the validation set. The selected three-variable model displays high predictive ability, catching the main factors affecting the enantioselectivity of studied chiral compounds, and therefore can be used for prediction of retention factors of other chiral compounds of similar structure to improve the separation process and so on.

QSAR studies on a number of pyrrolidin-2-one antiarrhythmic arylpiperazinyls

The activity of a number of 1-[3-(4-arylpiperazin-1-yl)propyl]pyrrolidin-2-one antiarrhythmic (AA) agents was described using the quantitative structure–activity relationship model by applying it to 33 compounds. The molecular descriptors of the AA activity were obtained by quantum chemical calculations combined with molecular modeling calculations. The resulting model explains up to 91% of the variance and it was successfully validated by four tests (LOO, LMO, external test, and Y-scrambling test). Statistical analysis shows that the AA activity of the studied compounds depends mainly on the PCR and JGI4 descriptors.

Antidepressant-like activity of the phenylpiperazine pyrrolidin-2-one derivatives in mice

The present study was designed to investigate the central nervous system activity of 23 novel phenylpiperazine pyrrolidin-2-one derivatives. These compounds had marked antiarrhythmic and hypotensive activities and revealed affinity for α1- and α2-adrenoceptors. These effects may be related to their α-adrenolytic properties. We assessed their antidepressant-like effect in the forced swimming test, influence of spontaneous locomotor activities and binding to 5-HT1A and 5-HT2 receptors. Our study demonstrated the strong antidepressant-like activity of compound EP-65 in the forced swimming test. The effect of EP-65 was stronger than results obtained with the classical antidepressants imipramine and mianserin. Other compounds, EP-41, EP-42, EP-44, EP-47, EP-48, EP-49, EP-50, EP-62, EP-66, EP-70, EP-75 and EP-76, showed significantly weaker activities in this test. Compound EP-42 showed the strongest affinity for 5-HT1A (Ki=24.5 nM), and compound EP-50 showed the strongest affinity for the 5-HT2 receptor (Ki=109.1 nM). All tested compounds significantly suppressed the spontaneous locomotor activity of mice. Currently, it is not possible to determine which mechanisms are involved in the witnessed antidepressant-like activity of novel phenylpiperazine pyrrolidin-2-one derivatives.

Synthesis, physicochemical properties, anticonvulsant activities, and GABA-ergic and voltage-sensitive calcium channel receptor affinities of α-substituted N-benzylamides of γ-hydroxybutyric acid. Part 4 : Search for new anticonvulsant compounds

In a search for new anticonvulsant compounds, two series of N‐benzylamides of α‐(benzylamino)‐γ‐hydroxybutyric acid (series A) and α‐(2‐phenylethylamino)‐γ‐hydroxybutyric acid (series B), were investigated in maximal electroshock (MES), subcutaneous metrazole, and rotorod toxicity assays. The most potent anticonvulsant compounds were α‐(benzylamino)‐γ‐hydroxybutyric acid N‐benzylamide (3) and N‐(2‐chlorobenzyl‐amide (4) with median effective (ED50) doses 63.0 mg/kg and 54.0 mg/kg, respectively. α‐(4‐Phenylpiperazinyl)‐γ‐hydroxy‐butyric acid N‐(4‐methylbenzyl)amide (17) and α‐(benzylpiperazinyl‐γ‐hydroxy‐ butyric acid N‐(4‐methylbenzyl)amide (18) were also tested for their ability to potentiate [3H]‐muscimol binding and to inhibit [35S]‐TBPS binding (as indices of GABA‐A receptor potentiation). Amide 17 exhibited activity at the GABA‐A complex which may be the mechanism by which the anticonvulsant effect of this compound is mediated. The N‐benzylamides of α‐(benzylamino)‐γ‐hydroxybutyric acid (3‐9) were also evaluated for their ability to displace [3H]‐nitrendipine from voltage‐sensitive calcium channel (VSCC) receptors isolated from rat cortex.