GABAA receptor
Loreclezole targets the GABAA receptor, where it acts as a positive allosteric modulator. It binds to a site distinct from benzodiazepines, enhancing chloride ion influx upon GABA binding. Loreclezole selectively modulates receptors containing β2 or β3 subunits. This modulation potentiates the inhibitory effects of GABA in the central nervous system, leading to anticonvulsant and sedative effects.

Loreclezole, an anticonvulsant and antiepileptic compound, potentiates gamma-aminobutyric acid (GABA) type A receptor function, by interacting with a specific allosteric modulatory site on receptor beta-subunits. A similar selectivity for GABAA receptor beta-subunits is apparent for the direct activation of receptor-operated Cl- channels, by the general anesthetics propofol and pentobarbital. The ability of loreclezole to activate GABAA receptors directly has now been compared, biochemically and electrophysiologically, with that of propofol. In well-washed rat cortical membranes (devoid of endogenous GABA), loreclezole and propofol increased t-[35S]butylbicyclophosphorothionate ([35S]TBPS) binding by up to 28% (at 5 microM) and 80% (at 10 microM), respectively. Higher concentrations (50-100 microM) of both compounds inhibited [35S]TBPS binding with great efficacy, an effect mimicked by GABA. In contrast, the benzodiazepine diazepam increased [35S]TBPS binding, but failed to inhibit this parameter, even at high concentrations. At concentrations of 50-100 microM, loreclezole induced inward Cl- currents in the absence of GABA, in Xenopus oocytes expressing human recombinant GABAA receptors, comprised of alpha 1-, beta 2- and gamma 2S-subunits. At 100 microM, the current evoked by loreclezole was 26% of that induced by 5 microM GABA. The current evoked by 100 microM propofol was 98% of that induced by 5 microM GABA. Currents induced by loreclezole, like those evoked by propofol, were potentiated by diazepam in a flumazenil-sensitive manner and blocked by either bicuculline or picrotoxin. These data suggest that loreclezole shares, with propofol, an agonistic action at GABAA receptors containing the beta 2-subunit and that the different efficacies of the two compounds in this regard, may underlie the difference in their pharmacological profiles. The failure of loreclezole to activate GABAA receptors containing the beta 1-subunit may be responsible for its lack of hypnotic effect[2].
In vitro, Loreclezole has been shown to potentiate GABA-induced chloride currents in a concentration-dependent manner. It selectively modulates GABAA receptors containing β2 or β3 subunits. The compound has been shown to directly activate GABAA receptors at higher concentrations. Loreclezole's binding site is distinct from that of benzodiazepines, barbiturates, and neurosteroids.

Loreclezole (10, 25, 50, or 75 mg/kg, administered intraperitoneally 60 minutes before epileptic threshold measurement) induced a dose-dependent rise in epileptic threshold, as determined by the dose of pentylenetetrazole necessary to trigger convulsion 60 minutes later. Loreclezole also has negligible effects on loss of muscle tone, as evaluated by the "Pull-Up" test [3].
In vivo, Loreclezole has been shown to be effective in various animal models of epilepsy and seizures. It has demonstrated efficacy in maximal electroshock (MES) and pentylenetetrazol (PTZ)-induced seizure models. The compound has also been studied in clinical trials for its anticonvulsant properties. Loreclezole has a sedative effect in addition to its anticonvulsant activity.

Type A gamma-aminobutyric acid (GABAA) receptors of the mammalian nervous system are a family of ligand-gated ion channels probably formed from the coassembly of different subunits (alpha 1-6, beta 1-3, gamma 1-3, delta) in the arrangement alpha beta gamma or alpha beta delta. The activation of these receptors by GABA can be modulated by a range of compounds acting at distinct allosteric sites. One such compound is the broad-spectrum anticonvulsant loreclezole, which we have recently shown to act via a specific modulatory site on the beta subunit of the GABAA receptor. The action of loreclezole depends on the type of beta subunit present in the receptor complex; receptors containing beta 2 or beta 3 subunits have > 300-fold higher affinity for loreclezole than receptors containing a beta 1 subunit. We have used this property to identify the amino acid residue in the beta subunit that determines the subunit selectivity of loreclezole. Chimeric beta 1/beta 2 human GABAA receptor subunits were constructed and coexpressed in Xenopus oocytes with human alpha 1 and gamma 2s subunits. The chimera beta 1/beta 2Lys237-Gly334 conferred sensitivity to 1 microM loreclezole. Within this region there are four amino acids that are conserved in beta 2 and beta 3 but differ in beta 1. By mutating single amino acids of the beta 1 subunit to the beta 2/beta 3 equivalent, only the beta 1 mutation of Ser-290-->Asn conferred potentiation by loreclezole. Similarly, mutation of the homologous residue in the beta 2 and beta 3 subunits to the beta 1 equivalent (Asn-->Ser) resulted in loss of sensitivity to loreclezole. The affinity for GABA and the potentiation by flunitrazepam were unchanged in receptors containing the mutated beta subunits. Thus, a single amino acid, beta 2 Asn-289 (beta 3 Asn-290), located at the carboxyl-terminal end of the putative channel-lining domain TM2, confers sensitivity to the modulatory effects of loreclezole[1].
In vitro receptor binding assays for Loreclezole typically involve measuring its affinity for the GABAA receptor using radioligand binding. The compound is incubated with membrane preparations from brain tissue or cells expressing recombinant GABAA receptors and a radiolabeled ligand such as [3H]flunitrazepam or [3H]muscimol. The concentration of Loreclezole required to displace the radioligand is determined. The selectivity of Loreclezole for β2/β3-containing receptors can be assessed using receptors with different subunit compositions.

In vitro cell-based studies with Loreclezole typically involve cultured neurons or cell lines expressing recombinant GABAA receptors. Cells are treated with Loreclezole at various concentrations in the presence or absence of GABA. Chloride influx is measured using patch-clamp electrophysiology or fluorescent indicators. The potentiation of GABA-induced currents by Loreclezole is quantified. The effect of Loreclezole on receptor desensitization and internalization can also be studied.

Animal/Disease Models: Adult male Lister Hooded rat[3].
Doses: 10, 25, 50 or 75 mg/kg.
Route of Administration: IP, 60 minutes before measuring seizure threshold.
Experimental Results: Produced a dose-dependent increase in epileptic threshold, as measured by the dose of pentylenetetrazole required to produce convulsion after 60 minutes.

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Loreclezole is an anticonvulsant and anxiolytic compound which has been reported to potentiate GABA via a novel allosteric site on the beta-subunit of the receptor. We have now studied in rats both the in vivo and in vitro pharmacology of the compound. The dose of loreclezole required to increase by 50% the dose of intravenous pentylenetetrazol eliciting a seizure was comparable to that of barbiturates and chlormethiazole (in mg/kg): diazepam, 1.3; pentobarbitone, 16; chlormethiazole, 22; loreclezole, 25; pentobarbitone, 36. Loreclezole dose-dependently decreased locomotion (dose to decrease locomotion by 50% (in mg/kg): chlormethiazole, 9; pentobarbitone, 16; loreclezole, 25). Loreclezole, chlormethiazole and pentobarbitone all failed to displace [3H]muscimol and [3H]flunitrazepam binding from a rat cortical membrane preparation. All three compounds fully displaced [35S]TBPS binding (IC50 values: loreclezole, 4.34 +/- 0.68 microM; pentobarbitone, 37.39 +/- 3.24 microM; chlormethiazole, 82.10 +/- 8.52 microM). Addition of bicuculline (10 microM) produced a major rightward shift in the loreclezole and pentobarbitone displacement curves, increasing IC50 values for [35S]TBPS binding by 25 times (loreclezole), 6 times (pentobarbitone) and 2.7 times (chlormethiazole), suggesting a greater involvement of GABA in the interaction of loreclezole with the chloride channel than in the case of chlormethiazole. Anticonvulsant activity of the compounds did not appear to relate to [35S]TBPS binding activity. Other binding data suggested that although the evidence of others indicates that loreclezole interacts with a specific allosteric site on the beta-subunit, it nevertheless also alters the binding characteristics of other modulatory sites.[3]
In vivo animal studies with Loreclezole are typically conducted in rodent models of seizures. The compound is administered orally or intraperitoneally. The anticonvulsant effect is assessed using the maximal electroshock (MES) test or the pentylenetetrazol (PTZ) test. The effective dose (ED50) for protection against seizures is determined. The sedative effect of Loreclezole is assessed using the rotarod test or by measuring spontaneous locomotor activity. Pharmacokinetic studies are performed to evaluate the absorption and distribution of the compound.

The pharmacokinetic properties of Loreclezole have been studied in preclinical and clinical settings. The compound is absorbed after oral administration. Loreclezole is metabolized in the liver, primarily by cytochrome P450 enzymes. The elimination half-life is relatively short. Loreclezole is excreted in the urine primarily as metabolites. Detailed PK parameters such as Cmax, Tmax, AUC, and half-life have been reported in the literature.

Loreclezole has been evaluated in preclinical and clinical studies for its safety and tolerability. The most common adverse effects are related to its sedative properties and include drowsiness, dizziness, and ataxia. Loreclezole is generally well-tolerated at therapeutic doses. The compound is for research use only and is not approved for human therapeutic use.

[1]. The modulatory action of loreclezole at the gamma-aminobutyric acid type A receptor is determined by a single amino acid in the beta 2 and beta 3 subunit. Proc Natl Acad Sci U S A. 1994 May 10;91(10):4569-73.

[2]. Direct activation of GABAA receptors by loreclezole, an anticonvulsant drug with selectivity for the beta-subunit. Neuropharmacology. 1996;35(12):1753-60.

[3]. A behavioural and neurochemical study in rats of the pharmacology of loreclezole, a novel allosteric modulator of the GABAA receptor. Neuropharmacology. 1996;35(9-10):1243-50.

1-[2-chloro-2-(2,4-dichlorophenyl)vinyl]-1,2,4-triazole is a dichlorobenzene.
Loreclezole is an anticonvulsant and antiepileptic compound that acts as a positive allosteric modulator of GABAA receptors. It is a research compound that has been studied for its potential therapeutic applications in epilepsy and other neurological disorders. Loreclezole is not an FDA-approved drug and is not commercially available as a pharmaceutical product. It is primarily used as a research tool to study GABAA receptor pharmacology and to investigate the role of β2/β3-containing receptors in neurological disorders.

C10H6CL3N3

274.52

272.963

C, 43.75; H, 2.20; Cl, 38.74; N, 15.31

117857-45-1

117857-45-1;2227372-56-5 (HCl);

3034012

White to off-white solid powder

1.48g/cm3

418.7ºC at 760mmHg

207ºC

3.23E-07mmHg at 25°C

1.65

3.779

0

2

2

16

272

0

C1=CC(=C(C=C1Cl)Cl)/C(=C/N2C=NC=N2)/Cl

XGLHZTBDUXXHOM-WMZJFQQLSA-N

InChI=1S/C10H6Cl3N3/c11-7-1-2-8(9(12)3-7)10(13)4-16-6-14-5-15-16/h1-6H/b10-4-

(Z)-1-(2-chloro-2-(2,4-dichlorophenyl)vinyl)-1H-1,2,4-triazole

R-72063; R 72063; Loreclezole; 117857-45-1; R 72063; R-72063; 6DJ32STZ5W; Loreclezol; (Z)-1-(beta,2,4-Trichlorostyryl)-1H-1,2,4-triazole; (Z)-1-(2-chloro-2-(2,4-dichlorophenyl)vinyl)-1H-1,2,4-triazole; R72063

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~110 mg/mL (~400.68 mM)
H2O : < 0.1 mg/mL

Solubility in Formulation 1: ≥ 2.08 mg/mL (7.58 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (7.58 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)