Synthesis and pharmacological evaluation of piperidine (piperazine)-amide substituted derivatives as multi-target antipsychotics

Advances in drug design and therapeutic potential of selective or multitarget 5-HT1A receptor ligands

5-HT1A receptor (5-HT1A-R) is a serotoninergic G-protein coupled receptor subtype which contributes to several physiological processes in both central nervous system and periphery. Despite being the first 5-HT-R identified, cloned and studied, it still represents a very attractive target in drug discovery and continues to be the focus of a myriad of drug discovery campaigns due to its involvement in numerous neuropsychiatric disorders. The structure-activity relationship studies (SAR) performed over the last years have been devoted to three main goals: (i) design and synthesis of 5-HT1A-R selective/preferential ligands; (ii) identification of 5-HT1A-R biased agonists, differentiating pre- versus post-synaptic agonism and signaling cellular mechanisms; (iii) development of multitarget compounds endowed with well-defined poly-pharmacological profiles targeting 5-HT1A-R along with other serotonin receptors, serotonin transporter (SERT), D2-like receptors and/or enzymes, such as acetylcholinesterase and phosphodiesterase, as a promising strategy for the management of complex psychiatric and neurodegenerative disorders. In this review, medicinal chemistry aspects of ligands acting as selective/preferential or multitarget 5-HT1A-R agonists and antagonists belonging to different chemotypes and developed in the last 7 years (2017-2023) have been discussed. The development of chemical and pharmacological 5-HT1A-R tools for molecular imaging have also been described. Finally, the pharmacological interest of 5-HT1A-R and the therapeutic potential of ligands targeting this receptor have been considered.

Multi-target potential of newly designed tacrine-derived cholinesterase inhibitors: Synthesis, computational and pharmacological study

Simple and scalable synthetic approach was used for the preparation of thirteen novel tacrine derivatives consisting of tacrine and N-aryl-piperidine-4-carboxamide moiety connected by a five-methylene group linker. An anti-Alzheimer disease (AD) potential of newly designed tacrine derivatives was evaluated against two important AD targets, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). In vitro pharmacological evaluation showed strong ChE inhibitory activity of all compounds, with IC50 values ranging from 117.5 to 455 nM for AChE and 34 to 324 nM for BuChE. As a representative of the series with the best cytotoxicity / ChE inhibitory activity ratio, expressed as the selectivity index (SI), 2-chlorobenzoyl derivative demonstrated mixed-type inhibition on AChE and BuChE, suggesting binding to both CAS and PAS of the enzymes. It also exhibited antioxidant capacity and neuroprotective potential against amyloid-β (Aβ) toxicity in the culture of neuron-like cells. In-depth computational analysis corroborated well with in vitro ChE inhibition, illuminating that all compounds exhibit significant potential in targeting both enzymes. Molecular dynamics (MD) simulations revealed that 2-chlorobenzoyl derivative, created complexes with AChE and BuChE that demonstrated sufficient stability throughout the observed MD simulation. Computationally predicted ADME properties indicated that these compounds should have good blood-brain barrier (BBB) permeability, an important factor for CNS-targeting drugs. Overall, all tested compounds showed promising pharmacological behavior, highlighting the multi-target potential of 2-chlorobenzoyl derivative which should be further investigated as a new lead in the drug development process.

Design, synthesis, and fungicidal activity of novel N-substituted piperazine-containing phenylpyridines against cucumber downy mildew

BACKGROUND

Cucumber downy mildew (CDM) is a severe plant disease and affects the yield of cucumber production worldwide. As the resistance toward conventional fungicides is emerging as a ubiquitous issue, it is urgent to discover efficient fungicides with unique structures.

RESULTS

In this study, a series of novel phenylpyridine derivatives were designed and synthesized. Bioassays revealed that most of these compounds possessed excellent fungicidal activities against CDM. Among the phenylpyridine compounds, 2-(4-(4-(tert-butyl)benzyl)piperazin-1-yl)-6-phenylnicotinonitrile (C8) [half-maximal effective concentration (EC₅₀ ) = 4.40 mg L^-1 ] displayed the highest activity, which was better than those of the commercial fungicides, such as azoxystrobin (EC₅₀  = 42.77 mg L^-1 ) and flumorph (EC₅₀  = 41.94 mg L^-1 ). Furthermore, the molecular electrostatic potential of high-activity compound C8 indicated that nitrogen atom of the cyano group on the pyridine ring was in the negative region and may easily form hydrogen bonds and allow for electrostatic interactions with potential receptors.

CONCLUSIONS

This study demonstrated that the novel N-substituted piperazine-containing phenylpyridine derivatives could be further developed as a candidate compound to control CDM.

Synthesis and Biological Evaluation of a Series of Novel 1-(3-((6-Fluoropyridin-3-yl)oxy)propyl)piperazines as Dopamine/Serotonin Receptor Agonists

Evidence suggested that the use of partial dopamine D2/D3 receptor agonists may be a better choice for the treatment of Parkinson's disease (PD), and the stimulation of 5-HT1A receptors (mainly via nondopaminergic mechanisms) alleviates motor and nonmotor disorders of PD, implying that the multitarget approach may provide a double bonus for the treatment of the disease. In this study, 20 novel 1-(3-((6-fluoropyridin-3-yl)oxy)propyl)piperazine derivatives were designed and synthesized using a bioisosterism approach, and their activities for D2/D3/5-HT1A receptors were further tested. The results showed that several compounds exhibited a multitarget combination of D2/5-HT1A agonism. Compounds 7b and 34c showed agonistic activities on D2/D3/5-HT1A receptor. The EC50 value of 7b for D2/D3/5-HT1A receptor were 0.9/19/2.3 nmol/L, respectively; and the EC50 value of 34c for D2/D3/5-HT1A receptor were 3.3/10/1.4 nmol/L, respectively. In addition, 34c exhibited good metabolic stability (the half-life T 1/2 = 159.7 minutes) in vitro, which is of great significance for the further exploration of multitarget anti-PD drugs.

Design, synthesis, and evaluation of phenylpiperazine-phenylacetate derivatives as rapid recovery hypnotic agents

In this paper, we designed and synthesized a series of novel phenylpiperazine-phenylacetate derivatives as rapid recovery hypnotic agents. The best compound 10 had relatively high affinity for the GABAA receptor and low affinity for thirteen other off-target receptors. In three animal models (mice, rats, and rabbits), compound 10 exerted potent hypnotic effects (HD50 = 5.2 mg/kg in rabbits), comparable duration of the loss of righting reflex (LORR), and significant shorter recovery time (time to walk) than propanidid. Furthermore, compound 10 (TI = 18.1) showed higher safety profile than propanidid (TI = 14.7) in rabbits. Above results suggested that compound 10 may have predictable and rapid recovery profile in anesthesia.