Tert-butyl 4-((1-phenyl-1H-pyrazol-4-yl) methyl) piperazine-1-carboxylate (LQFM104)– New piperazine derivative with antianxiety and antidepressant-like effects: Putative role of serotonergic system

Nitrogen-containing heterocyclic compounds: A ray of hope in depression?

Depression is not similar to daily mood fluctuations and temporary emotional responses to day-to-day activities. Depression is not a passing problem; it is an ongoing problem. It deals with different episodes consisting of several symptoms that last for at least 2 weeks. It can be seen for several weeks, months, or years. At its final stage, or can say, in its worst condition, it can lead to suicide. Antidepressants are used to inhibit the reuptake of the neurotransmitters by some selective receptors, which increase the concentration of specific neurotransmitters around the nerves in the brain. Drugs that are currently being used for the management of various types of depression include selective serotonin reuptake inhibitors, tricyclic antidepressants, atypical antidepressants, serotonin, noradrenaline reuptake inhibitors, etc. In this review, we have outlined different symptoms, causes, and recent advancements in nitrogen-containing heterocyclic drug candidates for the management of depression. This article highlights the various structural features along with the structure-activity relationship (SAR) of nitrogen-containing heterocyclics that play a key role in binding at target sites for potential antidepressant action. The in silico studies were carried out to determine the binding interactions of the target ligands with the receptor site to determine the potential role of substitution patterns at core pharmacophoric features. This article will help medicinal chemists, biochemists, and other interested researchers in identifying the potential pharmacophores as lead compounds for further development of new potent antidepressants.

A Profound Insight into the Structure-activity Relationship of Ubiquitous Scaffold Piperazine: An Explicative Review

Despite extensive research in the field of drug discovery and development, still there is a need to develop novel molecular entities. Literature reveals a substantial heterocyclic nucleus named, piperazine, which shows an immense therapeutic voyage. For several decades, molecules having the piperazine nucleus have entered the market as a drug exhibiting biological potential. It was known to possess antipsychotic, antihistamine, antianginal, antidepressant, anticancer, antiviral, cardioprotective, and anti-inflammatory activity with a specific basis for structural activity relationship. Thus, it is regarded as a key structural feature in most of the already available therapeutic drugs in the market. Reports also suggest that the extensive utilization of these currently available drugs having a piperazine nucleus shows increasing tolerance significantly day by day. In addition to this, various other factors like solubility, low bioavailability, cost-effectiveness, and imbalance between pharmacokinetics and pharmacodynamics profile limit their utilization. Focusing on that issues, various structural modification studies were performed on the piperazine moiety to develop new derivatives/analogs to overcome the problems associated with available marketed drugs. Thus, this review article aims to gain insight into the number of structural modifications at the N-1 and N-4 positions of the piperazine scaffold. This SAR approach may prove to be the best way to overcome the above-discussed drawbacks and lead to the design of drug molecules with better efficacy and affinity. Hence, there is an urgent need to focus on the structural features of this scaffold which paves further work for deeper exploration and may help medicinal chemists as well as pharmaceutical industries.

Novel Multimodal Salicylamide Derivative with Antidepressant-like, Anxiolytic-like, Antipsychotic-like, and Anti-Amnesic Activity in Mice

Depression, anxiety, and schizophrenia may coexist in psychiatric patients. Moreover, these disorders are very often associated with cognitive impairments. However, pharmacotherapy of these conditions remains challenging due to limited drug effectiveness or numerous side effects. Therefore, there is an urgent need to develop novel multimodal compounds that can be used to treat depression, anxiety, and schizophrenia, as well as memory deficits. Thus, this study aimed to evaluate the potential antidepressant-like, anxiolytic-like, antipsychotic-like effects, and anti-amnesic properties, of the novel arylpiperazine derivative of salicylamide, JJGW07, with an affinity towards serotonin 5-HT1A, 5-HT2A, and 5-HT7 and dopamine D2 receptors. Firstly, we investigated the compound's affinity for 5-HT6 receptors and its functional activity by using in vitro assays. JJGW07 did not bind to 5-HT6 receptors and showed antagonistic properties for 5-HT1A, 5-HT2A, 5-HT7, and D2 receptors. Based on the receptor profile, we performed behavioral studies in mice to evaluate the antidepressant-like, anxiolytic-like, and antipsychotic-like activity of the tested compound using forced swim and tail suspension tests; four-plate, marble-burying, and elevated plus maze tests; and MK-801- and amphetamine-induced hyperlocomotion tests, respectively. JJGW07 revealed antidepressant-like properties in the tail suspension test, anxiolytic-like effects in the four-plate and marble-burying tests, and antipsychotic-like activity in the MK-801-induced hyperlocomotion test. Importantly, the tested compound did not induce catalepsy and motor impairments or influence locomotor activity in rodents. Finally, to assess the potential procognitive and anti-amnesic properties of JJGW07, we used passive avoidance and object recognition tests in mice. JJGW07 demonstrated positive effects on long-term emotional memory and also ameliorated MK-801-induced emotional memory impairments in mice, but showed no procognitive properties in the case of recognition memory. Our results encourage the search for new compounds among salicylamide derivatives, which could be model structures with multitarget mechanisms of action that could be used in psychiatric disorder therapy.

Design, Synthesis and Pharmacological Evaluation of Novel C2,C3-Quinoxaline Derivatives as Promising Anxiolytic Agents

A new series of quinoxaline derivatives, 2a-4b, were synthesized and their anxiolytic potential was evaluated in vivo using elevated plus maze (EPM), open field (OF) and light-dark box (LDB) techniques. According to the results of the EPM, four active compounds were found in 2a, 2b, 2c, 4b. Their anxiolytic properties were confirmed in terms of LDB and the most active was compound 2b. In the OF, only 2c had an influence on the locomotor activity of the rodents. Thus, the most promising substance was determined; this was 2b, which has the structure of 2-(2-{[3-(4-tert-butylphenyl)quinoxaline-2-yl]methyl}-4,5-dimethoxyphenyl)-N-methylethan-1-amine hydrochloride. The obtained data were analyzed with the pharmacophore feature prediction approach, which made it possible to compare the structures of the studied compounds with the reference drug diazepam, and to determine the contribution of pharmacophores to the manifestation of the activity under study. ADMET analysis was carried out for compound 2b and the acute oral toxicity of this substance was also tested in vivo. As a result of the study, a promising compound with a high anxiolytic effect and low level of toxicity 2b was found, which is of interest for further preclinical study of its properties.

LQFM212, a piperazine derivative, exhibits potential antioxidant effect as well as ameliorates LPS-induced behavioral, inflammatory and oxidative changes

AIMS

Oxidative stress, impaired antioxidant defense and neuroinflammation are often associated with the onset and progression of neuropsychiatric diseases. Conversely, several piperazine compounds presents beneficial neuropharmacological effects as well as antioxidant activity, and some derivatives combine both activities. LQFM212 (2,6-di-tert-butyl-4-((4-(2-hydroxyethyl)piperazin-1-yl)methyl)phenol) was synthesized to produce effects on CNS and to have an additional antioxidant effect. Previous preclinical tests have been shown anxiolytic- and antidepressant-like effects of LQFM212 in mice. Herein, the main objective was to verify the possible antioxidant potential and the effects of LQFM212 against behavioral changes, inflammatory and oxidative markers induced by lipopolysaccharide (LPS).

MAIN METHODS

Initially, antioxidant potential of LQFM212 was evaluated by electrochemical assays. Afterwards, the effects of oral treatment with LQFM212 were evaluated in mice using LPS-induced models of systemic or local inflammation.

KEY FINDINGS

In LPS-induced neuroinflammation, LQFM212 treatment reverted changes caused by LPS, demonstrated by attenuated anxiogenic- and depressive-like behaviors, reduced pro-inflammatory cytokines (TNF-α and IL-1β) and increased anti-inflammatory cytokines (IL-4 and IL-10) on serum, and also improved oxidative stress-related changes (levels of nitrite, malondialdehyde, glutathione and carbonylated protein, and superoxide dismutase, catalase, myeloperoxidase and cholinesterase activities) on brain cortex and hippocampus. However, LQFM212 treatment did not attenuate the inflammatory changes in LPS-induced pleurisy model.

SIGNIFICANCE

LQFM212 presents antioxidant activity and ameliorates behavioral, inflammatory and oxidative changes after LPS-induced neuroinflammation model. These effects do not seem to be secondary to a peripheral anti-inflammatory action of LQFM212, since this compound failed to attenuate the inflammatory changes in LPS-induced pleurisy model.

Structure-activity relationship of three new piperazine derivates with anxiolytic-like and antidepressant-like effects

Anxiety and depression are common mental disorders affecting millions of people worldwide. Unsatisfactory clinical outcomes with the use of the available pharmacological interventions among some patients demand newer drugs with proven efficacy, safety, and tolerability profile. In this study, the LQFM211, LQFM213, and LQFM214 were designed from the piperazine scaffold and administered orally in mice. These mice were later evaluated in the open field, elevated plus maze, and forced swimming tests to assess the exploratory, anxiolytic, and antidepressant-like activities, respectively. The mechanism of action of these new derivatives was evaluated using Flumazenil (benzodiazepine antagonist) and WAY100635 (5-HT1A receptor antagonist). Unlike LQFM214, the LQFM211 and LQFM213 elicited anxiolytic and antidepressant-like effects. The blockade of the effect of LQFM213 by WAY100635 suggests the involvement of the serotonergic pathway. Keywords: anxiety, behavioral pharmacology, depression, medicinal chemistry.

Anxiolytic- and antidepressant-like effects of new phenylpiperazine derivative LQFM005 and its hydroxylated metabolite in mice

The current treatments available for anxiety and depression are only palliative. Full remission has remained elusive, characterizing unmet medical needs. In the scope of an academic drug discovery program, we describe here the design, synthesis, in vitro metabolism prediction and pharmacological characterization of a new piperazine compound, 1-(4-methoxyphenyl)-4-((1-phenyl-1H-pyrazol-4-yl)methyl)piperazine (LQFM005), and of its main putative metabolite, 4-(4-((4-(4-methoxyphenyl)piperazin-1-yl)methyl)- 1H-pyrazol-1-yl)phenol (LQFM235). The production of the metabolite was initially performed by in vitro biotransformation of LQFM005 using Aspergillus candidus and then by chemical synthesis. Oral administration of either 12 or 24 µmol/kg LQFM005 to mice did not affect spontaneous locomotor activity but increased the time spent in the center of the open field. Both LQFM005 and LQFM235 (24 µmol/kg) increased the time spent by the mice in the open arms of the elevated plus maze (EPM), a good indication of anxiolytic-like effect, and decreased the immobility time in the forced swimming test (FST), suggesting an antidepressant-like effect. The previous administration of WAY-100635 (a 5-HT_1A antagonist) abolished the effects of LQFM005 in both EPM and FST. Binding experiments showed that LQFM005 and its metabolite bind to the 5-HT_1A receptor with a moderate affinity (K_i around 5-9 µM). The two compounds are relatively safe, as indicated by cytotoxic assessment using the 3T3 fibroblast cell line and estimated LD₅₀ around 600 mg/kg. In conclusion, oral administration of the newly synthesized phenylpiperazines produced anxiolytic- and antidepressant-like effects in behavioral tests, putatively in part through the activation of 5-HT_1A receptors.

Involvement of GABAA Receptors in the Anxiolytic-Like Effect of Hydroxycitronellal

Hydroxycitronellal (HC) is a monoterpene present in essential oils of aromatic plants of different species, obtained from semisynthesis of citronellal, and is widely used as a fragrance in cosmetics. The objective of this work was to evaluate the possible anxiolytic-like activity of HC and its possible mechanism of action using in vivo and in silico methodologies. Swiss male mice (Mus musculus) were treated with HC (12.5, 25, and 50 mg/kg, i.p.) and subjected to the rota rod, elevated plus maze, and open field tests. No significant impairments were observed in the rota rod tests for the motor activity of the animals treated with HC at 12.5, 25, and 50 mg/kg, i.p., indicating no myo-relaxing or sedative effects. In the elevated plus maze, HC (in the three doses) induced significant increases in the percentage of entries (respectively, 34.8%, 33.8%, and 38.6%) and in the length of stay (respectively, 49.9%, 56.1%, and 57.0%) in the open arms of the EPM, as well as the number of crossings in the open field tests. The mechanism of action of the compound's anxiolytic-like activity can be attributed to the involvement of GABA_A receptors, and this interaction was observed in in vivo and in silico studies. For HC, the results suggest anxiolytic-like effects, possibly via modulation of the GABAergic system. The use of natural products to treat anxiety can become an alternative to existing synthetic products.

Piperazine, a Key Substructure for Antidepressants: Its Role in Developments and Structure-Activity Relationships

Depression is the single largest contributor to global disability with a huge economic and social burden on the world. There are a number of antidepressant drugs on the market, but treatment-resistant depression and relapse of depression in a large number of patients have increased problems for clinicians. One peculiarity observed in most of the marketed antidepressants is the presence of a piperazine substructure. Although piperazine is also used in the optimization of other pharmacological agents, it is almost extensively used for the development of novel antidepressants. One common understanding is that this is due to its favorable CNS pharmacokinetic profile; however, in the case of antidepressants, piperazine plays a much bigger role and is involved in specific binding conformations of these agents. Therefore, in this review, a critical analysis of the significance of the piperazine moiety in the development of antidepressants has been performed. An overview of current developments in the designing and synthesis of piperazine-based antidepressants (2015 onwards) along with SAR studies is also provided. The various piperazine-based therapeutic agents in early- or late-phase human testing for depression are also discussed. The preclinical compounds discussed in this review will help researchers understand how piperazine actually influences the design and development of novel antidepressant compounds. The SAR studies discussed will provide crucial clues about the structural features and optimizations required to enhance the efficacy and potency of piperazine-based antidepressants.

Searching for new anxiolytic agents among derivatives of 11-dialkylaminoethyl-2,3,4,5-tetrahydrodiazepino[1,2-a]benzimidazole

A study on the anxiolytic activity of the new derivatives of 11-dialkylaminoethyl-2,3,4,5-tetrahydrodiazepino[1,2-a]benzimidazole, containing privileged scaffolds of benzodiazepine and benzimidazole in their structure, was conducted. The cytotoxic properties of low levels of six compounds were preliminary determined in vitro using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide test. The screening of these substances for anxiolytic activity was conducted using elevated plus maze (EPM) test in vivo, and DAB-21 was found to be the most active compound. The acute toxicity of DAB-21 was determined as less toxic than that of diazepam. The dose-dependent effect of the most active compound revealed a minimum dose of 1.26 mg/kg, which resulted in the maximum counterphobic effect. The effect of DAB-21 was superior in a number of tests compared with that of diazepam, which indicated a high level of tranquilizing activity for DAB-21. The results of in silico docking analysis suggest that DAB-21 should have a slightly lower anxiolytic activity than diazepam, but should exhibit greater specific affinity for the benzodiazepine site of the GABA_A receptor, in comparison with its GABA-binding site. The interaction between DAB-21 and flumazenil in terms of EPM verifies the GABAergic mechanism of action of DAB-21. Our results highlight the potential of 11-dialkylaminomethyl-2,3,4,5-tetrahydrodiazepino[1,2-a]benzimidazoles as promising compounds in the search for new highly effective anxiolytics.

Potential antidepressant-like effect of piperazine derivative LQFM212 in mice: Role of monoaminergic pathway and brain-derived neurotrophic factor

Major depression disorder (MDD) is one of the most widespread and debilitating psychiatric diseases and may be associated with other mental disorders such as anxiety. Despite advances in neurobiology studies, currently no established mechanism can explain all facets of MDD, and available drugs often show therapeutic delay for clinical effectiveness and response rates in patients are around 50 %. Previous activities of piperazine derivatives on CNS are indicators of its therapeutic potential for treating mental disorders. In this regard, we have previously shown that the piperazine derivative 2,6-di-tert-butyl-4-((4-(2-hydroxyethyl)piperazin-1-yl)methyl)phenol (LQFM212) has anxiolytic-like activity which involves serotonergic pathway, nicotinic receptors and BZD-site of GABA_A receptor, without cognitive impairments. Herein, was evaluated the potential antidepressant-like effect of LQFM212 on forced swimming test (FST) after a single dose of 54 μmol/kg and after repeated treatment for 15 days in mice. Pretreatment with WAY-100635, PCPA, prazosin, SCH-23390, sulpiride or AMPT reversed the antidepressant-like effect on FST, suggesting that monoaminergic pathway contributes for effects of LQFM212. Furthermore, repeated treatment with LQFM212 increased hippocampal BDNF levels dosed by ELISA kit. In assessment of possible adverse effects, repeated treatment with LQFM212 did not alter the body weight of the animals, glutathione levels in the liver, and serum levels of AST, ALT, urea, and creatinine. Taken together, the results showed that LQFM212 has an antidepressant-like effect that involves monoaminergic pathway and increased BDNF levels. This compound represents promising candidate for prototype of psychoactive drugs for treatment of anxiety and depression disorders since these pathological conditions may exist in comorbidities.

Neuropharmacological assessment in mice and molecular docking of piperazine derivative LQFM212

Piperazine derivatives are an attractive class of chemical compounds for the treatment of various mental illness. Herein, we demonstrated the synthesis of LQFM212, a piperazine derivative, behavioral evaluation in mice and computational studies. In neuropharmacological assessment, LQFM212 treatment at doses of 18, 54 or 162 μmol/kg increased the sleep duration in sodium pentobarbital-induced sleep test. LQFM212 at dose of 162 μmol/kg increased climbing time in the chimney test and decreased the number of squares crossed in the open field test, suggesting that LQFM212 in high doses reduces spontaneous movement. However, LQFM212 treatment at the doses of 18 or 54 μmol/kg increased the preference for the center of field which could be indicative of anxiolytic-like effects. In elevated plus maze and light-dark box tests, LQFM212 treatment altered all parameters observed that demonstrate anxiolytic-like activity. These effects were reversed by flumazenil, mecamylamine, WAY-100635 and PCPA, but not with ketanserin, showing that anxiolytic-like activity involve benzodiazepine site of GABA_A receptor, nicotinic and serotonergic pathways. Molecular docking of LQFM212 showed that the ligand has more interactions with GABA_A receptor than with 5-HT_1A receptor. Despite the involvement of benzodiazepine site on anxiolytic-like effect of LQFM212, treatment with this compound did not alter cognitive function in the step-down avoidance test. In this sense, this piperazine derivative is a good prototype for treating anxiety disorders with putative mechanism of action.

Influence of Diazepino[1,2-a]benzimidazole derivative (DAB-19) on behavioral aspects of animals

Introduction: Diazepino[1,2-a]benzimidazole derivatives showed anxiolytic (EPM, L/D box, Vogel test), antidepressant (Tail Suspension test, Porsolt test), anticonvulsant (Pentylenetetrazole-Induced seizures) and analgesic (Tail-Flick, Hot Plate) actions, which were described earlier (Spasov et al. 2020). 11-(4-tert-butylbenzyl)-2,3,4,5-tetrahydro[1,3]diazepino[1,2-a]benzimidazole hydrobromide (compound DAB-19) has evident anxiolytic, antidepressant and anticonvulsant effects. In the present study, compound DAB-19 was screened for its influence on animals` behavior patterns, such as aggression, obsessive-compulsive behavior, emotional lability, and unsociability.

Materials and methods: 112 outbred white animals (rats and mice) were used. Compound DAB-19 (2.34 mg/kg, p.o.) and diazepam (2 mg/kg, p.o.) were injected to the treatment groups. Using an Open Field (OF) test, we evaluated a spontaneous motor activity, a search activity of mice and a degree of their emotionality. During a Marble Burying (MB) test, we monitored anxiolytic and anticompulsive effects of DAB-19. Using a Resident-intruder (RI) test, we evaluated a degree of aggression in the experimental animals, properties of their social interaction, as well as defensive and individual behavior.

Results and discussion: Compound DAB-19 has positive influence on the search activity, mood stabilizing activity and antiaggressive actions. Administration of both DAB-19 (2.34 mg/kg, p.o.) and diazepam (2 mg/kg, p.o.) reduced anxiety-like behavior in OP, RI and MB tests, as indicated by a significantly increased number of entries to the center of OP; a decreased number of marbles buried in MB and reduced aggressive behavior in RI. It was stated that using DAB-19 leads to a decrease in affective reactions of the animals – aggression, obsessive-compulsive behavior, neurotic condition and emotional instability.

Conclusions: The compound (DAB-19) produces anxiolytic-like effects, compared with those of diazepam, in various anxiety paradigms.

An antibacterial and biocompatible piperazine polymer

Bacterial repellence by biomedical materials is a desirable property that can potentially improve the healing process. In this study, we described a simple and green method to prepare a novel piperazine polymer (PE), which was based on the raw materials piperazine (PA) and ethylenediaminetetraacetic dianhydride (EDTAD). The structure and thermal stability of the obtained material were characterized using Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance spectroscopy (NMR), elementary analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). To evaluate the antibacterial properties of PE, a strain of Gram-negative Escherichia coli (E. coli) bacteria and a strain of Gram-positive Staphylococcus aureus (S. aureus) bacteria were used. The results indicated that PE exhibited good antibacterial activity against both strains of bacteria in a short time frame. The initial cytotoxicity test of the obtained material was based on the changes in the morphology and proliferation of osteoblasts, and the results demonstrated that the cytotoxicity of PE was concentration-dependent. Combining the experimental results of these two parts, it was shown that bacteria could be inhibited by a certain concentration of PE, while its toxicity toward osteoblasts was very low. In summary, these results revealed the potential usefulness of PE in biomedical applications.