Grzegorz Kazek

Novel arylsulfonamide derivatives with 5‑HT6/5-HT7 receptor antagonism targeting behavioral and psychological symptoms of dementia

In order to target behavioral and psychological symptoms of dementia (BPSD), we used molecular modeling-assisted design to obtain novel multifunctional arylsulfonamide derivatives that potently antagonize 5-HT(6/7/2A) and D2 receptors, without interacting with M1 receptors and hERG channels. In vitro studies confirmed their antagonism of 5-HT(7/2A) and D2 receptors and weak interactions with key antitargets (M1R and hERG) associated with side effects. Marked 5-HT6 receptor affinities were also observed, notably for 6-fluoro-3-(piperidin-4-yl)-1,2-benzoxazole derivatives connected by a 3-4 unit alkyl linker with mono- or bicyclic, lipophilic arylsulfonamide moieties. N-[4-[4-(6-Fluoro-1,2-benzoxazol-3-yl)piperidin-1-yl]butyl]benzothiophene-2-sulfonamide (72) was characterized in vitro on 14 targets and antitargets. It displayed dual blockade of 5-HT6 and D2 receptors and negligible interactions at hERG and M1 receptors. Unlike reference antipsychotics, 72 displayed marked antipsychotic and antidepressant activity in rats after oral administration, in the absence of cognitive or motor impairment. This profile is particularly attractive when targeting a fragile, elderly BPSD patient population.

Antidepressant- and Anxiolytic-Like Effects of New Dual 5-HT1A and 5-HT7 Antagonists in Animal Models

The aim of this study was to further characterize pharmacological properties of two phenylpiperazine derivatives: 1-{2-[2-(2,6-dimethlphenoxy)ethoxy]ethyl}-4-(2-methoxyphenyl)piperazynine hydrochloride (HBK-14) and 2-[2-(2-chloro-6-methylphenoxy)ethoxy]ethyl-4-(2- methoxyphenyl)piperazynine dihydrochloride (HBK-15) in radioligand binding and functional in vitro assays as well as in vivo models. Antidepressant-like properties were investigated in the forced swim test (FST) in mice and rats. Anxiolytic-like activity was evaluated in the four-plate test in mice and elevated plus maze test (EPM) in rats. Imipramine and escitalopram were used as reference drugs in the FST, and diazepam was used as a standard anxiolytic drug in animal models of anxiety. Our results indicate that HBK-14 and HBK-15 possess high or moderate affinity for serotonergic 5-HT2, adrenergic α1, and dopaminergic D2 receptors as well as being full 5-HT1A and 5-HT7 receptor antagonists. We also present their potent antidepressant-like activity (HBK-14—FST mice: 2.5 and 5 mg/kg; FST rats: 5 mg/kg) and (HBK-15—FST mice: 1.25, 2.5 and 5 mg/kg; FST rats: 1.25 and 2.5 mg/kg). We show that HBK-14 (four-plate test: 2.5 and 5 mg/kg; EPM: 2.5 mg/kg) and HBK-15 (four-plate test: 2.5 and 5 mg/kg; EPM: 5 mg/kg) possess anxiolytic-like properties. Among the two, HBK-15 has stronger antidepressant-like properties, and HBK-14 displays greater anxiolytic-like activity. Lastly, we demonstrate the involvement of serotonergic system, particularly 5-HT1A receptor, in the antidepressant- and anxiolytic-like actions of investigated compounds.

The antidepressant-like activity of 6-methoxy-2-[4-(2-methoxyphenyl)piperazin-1-yl]-9H-xanthen-9-one involves serotonergic 5-HT1A and 5-HT2A/C receptors activation

Xanthone derivatives have been shown to posses many biological properties. Some of them act within the central nervous system and show neuroprotective or antidepressant-like properties. Taking this into account we investigated antidepressant-like activity in mice and the possible mechanism of action of 6-methoxy-2-[4-(2-methoxyphenyl)piperazin-1-yl]-9H-xanthen-9-one (HBK-11) - a new xanthone derivative. We demonstrated that HBK-11 produced antidepressant-like effects in the forced swim test and tail suspension test, comparable to that of venlafaxine. The combined treatment with sub-effective doses of HBK-11 and fluoxetine (but not reboxetine or bupropion) significantly reduced the immobility in the forced swim test. Moreover, the antidepressant-like activity of HBK-11 in the aforementioned test was blocked by p-chlorophenylalanine, and significantly reduced by serotonergic 5HT1A receptor antagonist - WAY-1006335 and 5HT2A/C receptor antagonist - ritanserin. As none of the above treatments influenced the spontaneous locomotor activity, it can be concluded that HBK-11 mediates its activity through a serotonergic system, and its antidepressant-like effect involves 5HT1A and 5HT2A/C receptor activation. Furthermore, at antidepressant-like doses HBK-11 did not cause the mice to display locomotor deficits in rotarod or chimney tests. Considering the pharmacokinetic profile, HBK-11 demonstrated rapid absorption after i.p. administration, high clearance value, short terminal half-life, very high volume of distribution and incomplete bioavailability. The compound studied had good penetration into the brain tissue of mice. Since studied xanthone derivative seems to present interesting, untypical mechanism of antidepressant-like action i.e. 5HT2A/C receptor activation, it may have a potential in the treatment of depressive disorders, and surely requires further studies.

Partial agonist efficacy of EMD386088, a 5-HT6 receptor ligand, in functional in vitro assays

BACKGROUND Over recent years, the 5-hydroxytryptamine6 (5-HT6) receptor has emerged as a promising molecular target which interacts with several central nervous system acting drugs. In animal models, both agonists and antagonists of this receptor exhibit equivalent potency and efficacy as potential antidepressants, anxiolytics and anti-obesity or anti-dementia drugs. EMD386088 (5-chloro-2-methyl-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole hydrochloride) has been described as a high affinity 5-HT6 receptor ligand with a full agonist activity and with moderate affinity for 5-HT3 sites. METHODS We have extended these data by broadening its profile for other, not yet tested, monoaminergic, GABA(A), opioid μ receptors and serotonin transporter (SERT) and we have conducted functional in vitro assays; i.e., measurement of cAMP by homogeneous TR-FRET immunoassay and HTRF method made by CEREP as well as aequorin-based calcium flux assay. RESULTS In two in vitro models based on cAMP formation, maximal efficacy values for EMD386088 were 65 and 31%, for in house and CEREP experiments, respectively. In a model based on calcium response, the studied compound showed 46% of maximal serotonin (5-HT) signal. EMD386088 antagonizes 5-HT response in increasing concentrations from 10(-9) to 10(-6) M. CONCLUSIONS The present in vitro findings confirm that EMD386088 is a selective 5-HT6 receptor ligand with moderate affinity for 5-HT3 sites only and it behaves as a potent partial agonist of 5-HT6 receptor with varying levels of agonist intrinsic activity, depending on a method employed. In view of these results, caution is recommended in the interpretation of pharmacological in vivo studies with EMD386088.

HBK-7 - A new xanthone derivative and a 5-HT1A receptor antagonist with antidepressant-like properties.

Xanthone derivatives possess many biological properties, including neuroprotective, antioxidant or antidepressant-like. In this study we aimed to investigate antidepressant- and anxiolytic-like properties of a new xanthone derivative - 6-methoxy-4-[4-(2-methoxyphenyl)piperazin-1-yl]-9H-xanthen-9-one (HBK-7), as well as its possible mechanism of action, and the influence on cognitive and motor function. HBK-7 in our earlier studies showed high affinity for serotonergic 5-HT1A receptor. We determined the affinity of HBK-7 for CNS receptors and transporters using radioligand assays and examined its intrinsic activity towards 5-HT1A receptor. We evaluated antidepressant- and anxiolytic-like activity of HBK-7 in the mouse forced swim test, and four-plate test, respectively. We examined the influence on locomotor activity in mice to determine if the effect observed in the forced swim test was specific. We used step-through passive avoidance and rotarod tests to evaluate the influence of HBK-7 on cognitive and motor function, respectively. HBK-7 showed moderate affinity for dopaminergic D2 receptor and very low for serotonergic 5-HT2A, adrenergic α2 receptors, as well as serotonin transporter. Functional studies revealed that HBK-7 was a 5-HT1A receptor antagonist. HBK-7 (10mg/kg) decreased immobility time in the forced swim test. Combined treatment with sub-effective doses of HBK-7 and fluoxetine reduced immobility of mice in the forced swim test. Pretreatment with p-chlorophenylalanine and WAY-100,635 antagonized the antidepressant-like effect of HBK-7. Neither of the treatments influenced locomotor activity of mice. HBK-7 at antidepressant-like dose did not impair memory or motor coordination in mice. We demonstrated that HBK-7 was a 5-HT1A receptor antagonist with potent, comparable to mianserin, antidepressant-like activity. HBK-7 mediated its effect through serotonergic system and its antidepressant-like action required the activation of 5-HT1A receptors. At active dose it did not influence cognitive and motor function. Since 5-HT1A receptor antagonists may accelerate the occurrence of antidepressant effect, our findings highlight their potential as future antidepressants.

Synthesis and Pharmacological Evaluation of Novel Tricyclic[2,1-f]theophylline Derivatives

The multireceptor strategy was implemented to obtain potential antipsychotics and/or antidepressants in a series of long‐chain arylpiperazines bearing a tricyclic theophylline fragment. Their binding profile toward monoaminergic receptors (α1, 5‐HT1A, 5‐HT2A, 5‐HT6, 5‐HT7, D2, D3) was determined as well. The selected compounds 7 and 9 were tested in functional in vivo models and showed, like atypical antipsychotic drugs, presynaptic 5‐HT1A receptor agonistic and postsynaptic 5‐HT1A, 5‐HT2A, and D2 receptor antagonistic activity.

Arylpiperazinylalkyl derivatives of 8-amino-1,3-dimethylpurine-2,6-dione as novel multitarget 5-HT/D receptor agents with potential antipsychotic activity.

Abstract A series of new 7-arylpiperazinylalkyl-1,3-dimethyl-purine-2,6-dione derivatives with diversified 8-amino substituent in 8 position was synthesized and their 5-HT1A, 5-HT2A, 5-HT6, 5-HT7, and D2 receptor affinities were determined. The binding study allowed identifying some potent 5-HT1A/5-HT2A/5-HT7/D2 ligands. The most interesting because of their multireceptor profile were 8-piperidine (30–35) and 8-dipropylamine (45–47) analogs with four and five carbon aliphatic linkers. The selected compounds 24, 31, 34, 39, 41, 43, 45, and 46 in the functional in vitro evaluation for all targeted receptors showed significant partial D2 agonist, partial 5-HT1A agonist, and 5-HT2A antagonist properties. The advantageous in vitro affinity of compound 34 for 5-HT1A and D2 receptors has been explained by means of molecular modeling, taking into consideration its partial agonist activity towards the latter one. In behavioral studies, compounds 32 and 34 revealed antipsychotic-like properties, significantly decreasing d-amphetamine-induced hyperactivity in mice.

Synthesis and biological evaluation of 2-fluoro and 3-trifluoromethyl-phenyl-piperazinylalkyl derivatives of 1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione as potential antidepressant agents

Abstract A series of 2-fluoro and 3-trifluoromethylphenylpiperazinylalkyl derivatives of 1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione (4–21) were synthesized and evaluated for their serotonin (5-HT1A/5-HT7) receptor affinity and phosphodiesterase (PDE4B and PDE10A) inhibitor activity. The study enabled the identification of potent 5-HT1A, 5-HT7 and mixed 5-HT1A/5-HT7 receptor ligands with weak inhibitory potencies for PDE4B and PDE10A. The tests have been completed with the determination of lipophilicity and metabolic stability using micellar electrokinetic chromatography (MEKC) system and human liver microsomes (HLM) model. In preliminary pharmacological in vivo studies, selected compound 8-(5-(4-(2-fluorophenyl)piperazin-1-yl)pentyl)-1,3,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione (9) behaved as a potential antidepressant in forced swim test (FST) in mice. Moreover, potency of antianxiety effects evoked by 9 (2.5 mg/kg) is greater than that of the reference anxiolytic drug, diazepam. Molecular modeling revealed that fluorinated arylpiperazinylalkyl derivatives of 1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione have major significance for the provision of lead compounds for antidepressant and/or anxiolytic application.

Structure-5-HT receptor affinity relationship in a new group of 7-arylpiperazynylalkyl and 7-tetrahydroisoquinolinylalkyl derivatives of 8-amino-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione.

In our previous paper, we have reported that some 8‐alkoxy‐1,3‐dimethyl‐1H‐purine‐2,6(3H,7H)‐dione derivatives possessed high affinity and displayed agonistic activity for the serotonin 5‐HT1A receptor. In order to examine the influence of the substituent in the position 8 of the purine moiety on the affinity for the serotonin 5‐HT1A, 5‐HT2A, and 5‐HT7 receptors, a series of 7‐arylpiperazynylalkyl and 7‐tetrahydroisoquinolinylalkyl (THIQ) derivatives of 8‐amino‐1,3‐dimethyl‐1H‐purine‐2,6(3H,7H)‐dione were synthesized. All the final compounds were investigated in in vitro competition binding experiments for serotonin 5‐HT1A, 5‐HT2A, and 5‐HT7 receptors. The structure–affinity relationships for this group of compounds were discussed. For selected compounds, functional assays for the 5‐HT1A receptor were carried out. The results of the assays indicated that these groups of derivatives possessed antagonistic activity for this receptor.

Influence of analgesic active 3-[4-(3-trifluoromethyl-phenyl)-piperazin-1-yl]-dihydrofuran-2-one on the antioxidant status, glucose utilization and lipid accumulation in some in vitro and ex vivo assays

Abstract Purpose: Earlier we demonstrated that 3-[4-(3-trifluoromethyl-phenyl)-piperazin-1-yl]-dihydrofuran-2-one (LPP1) elevates nociceptive thresholds in the mouse model of diabetic neuropathic pain. Since drug-induced impairments of glucose and lipid metabolism and the oxidative stress might diminish benefits from analgesia achieved by analgesic drugs used in diabetic neuropathy, the effect of LPP1 on glucose utilization, lipid accumulation and its antioxidant and cytotoxic potential were assessed in some in vitro and ex vivo tests. Methods: Total antioxidant capacity was evaluated spectrophotometrically using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method, whereas the activities of glutathione (GSH) peroxidase and reductase were measured using methods based on the oxidation of NADPH to NADP. The spectrophotometric method for the evaluation of GSH level in mouse brain tissue homogenates involved the oxidation of GSH by the sulfhydryl reagent 5,5′-dithio-bis(2-nitrobenzoic acid) (DTNB) to form a yellow derivative, 5′-thio-2-nitrobenzoic acid (TNB), measurable at 412 nm. Cytotoxicity and glucose utilization were measured in hepatoma HepG2 cells and in 3T3-L1 adipocytes. Lipid accumulation was measured in 3T3-L1 cell lines. Results: LPP1 had dose-dependent antioxidant properties in DPPH radical assay (14–22% versus control; p < 0.001). Its single administration caused an increase in GSH concentration in brain tissue homogenates of mice by 34% (versus control group; p < 0.05). LPP1 was not cytotoxic and it did not increase glucose utilization or lipid accumulation in cell cultures. Conclusions: Previously demonstrated antinociceptive properties of LPP1 are accompanied by a lack of cytotoxicity. LPP1 does not impair glucose or lipid metabolism and is an antioxidant. All these properties might be advantageous for its use in diabetic neuropathy.