Design, Synthesis and Anticonvulsant Activity of Cinnamoyl Derivatives of 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1-(2H)-one Oxime

BACKGROUND

Epilepsy continues to be a significant global health problem and the search for new drugs for its treatment remains an urgent task. 5-HT2 and GABAA-receptors are among promising biotargets for the search for new anticonvulsants.

METHODS

New potential 5-HT2 and GABAA ligands in the series of substituted cinnamoyl derivatives of 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1-(2H)-one oxime were designed using pharmacophore model and molecular docking analysis. The synthesis of new compounds was carried out from 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1(2H)-one oxime and substituted cinnamoyl chlorides. The anticonvulsant activity of new substances has been established using the maximal electroshock seizure test.

RESULTS

Several synthesized substituted cinnamoyl derivatives of 3,4,6,7,8,9-hexahydrodibenzo [b,d]furan-1-(2H)-one oxime significantly reduced the severity of convulsive manifestations and completely prevented the death of animals after MES. The structure-activity relationship was investigated. The most effective compound was found to be GIZH-348 (1g) (3,4,6,7,8,9-hexahydrodibenzo[ b,d]furan-1(2Н)-one О-(4-chlorophenyl)acryloyl)oxime) at the doses of 10-20 mg/kg.

CONCLUSION

Molecular and pharmacophore modelling methods allowed us to create a new group of substituted cinnamoyl derivatives of 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1-(2H)-one oxime with anticonvulsant activity.

Multitargeting in cardioprotection: An example of biaromatic compounds

A multitarget drug design approach is actively developing in modern medicinal chemistry and pharmacology, especially with regard to multifactorial diseases such as cardiovascular diseases, cancer, and neurodegenerative diseases. A detailed study of many well-known drugs developed within the single-target approach also often reveals additional mechanisms of their real pharmacological action. One of the multitarget drug design approaches can be the identification of the basic pharmacophore models corresponding to a wide range of the required target ligands. Among such models in the group of cardioprotectors is the linked biaromatic system. This review develops the concept of a "basic pharmacophore" using the biaromatic pharmacophore of cardioprotectors as an example. It presents an analysis of possible biological targets for compounds corresponding to the biaromatic pharmacophore and an analysis of the spectrum of biological targets for the five most known and most studied cardioprotective drugs corresponding to this model, and their involvement in the biological effects of these drugs.

To the Mechanism of the Antiarrhythmic Action of Compound ALM-802: the Role of Ryanodine Receptors

The effect of the compound N¹-(2,3,4-trimethoxy)-N²-{2-[(2,3,4-trimethoxybenzyl)amino]ethyl}-1,2-ethane-diamine (code ALM-802) on the amplitude of the Ca²⁺ response in the cell was studied in in vitro experiments. The concentration of intracellular calcium was assessed using a Fura-2 two-wave probe. The experiments were performed on a culture of isolated rat hippocampal neurons. The effect of compound ALM-802 on the activity of ryanodine receptors (RyR2) was studied on an isolated strip of rat myocardium. The compound ALM-802 (69.8 μM) in hippocampal neurons causes a significant decrease in the amplitude of the Ca²⁺ response induced by addition of KCl to the medium. Experiments performed on an isolated myocardial strip showed that compound ALM-802 (10^-5 M) almost completely blocked the positive inotropic reaction of the strip to the RyR2 agonist caffeine (5×10^-5 M). The data obtained indicate that the decrease in the concentration of Ca²⁺ ions in the cell caused by ALM-802 is due to its ability to block RyR2 located on the membrane of the sarcoplasmic reticulum, which can be associated with the antiarrhythmic activity of the compound.

Mechanisms Underlying the Antiarrhythmic Action of Compound ALM-802

The mechanisms underlying the antiarrhythmic action of compound trihydrochloride N¹-(2,3,4-trimethoxy)-N²-{2-[(2,3,4-trimethoxybenzyl)amino]ethyl}-1,2-ethane-diamine (code ALM-802) were studied in vitro. The experiments were performed on a culture of rat hippocampal neurons. The electrical activity of neurons was recorded by the patch-clamp method in the whole cell configuration. It is shown that the compound ALM-802 effectively blocks potential-dependent Na⁺ and K⁺ channels and does not affect the activity of potential-dependent Ca²⁺ channels. The inhibition of currents through these channels is dose-dependent; the IC₅₀ of Na⁺ and K⁺ channels were 94±4 and 67±3 μM, respectively. These findings indicate that compound ALM-802 combines the properties of class I and class III antiarrhythmic agents according to the Vaughan-Williams classification.

Linked biaromatic compounds as cardioprotective agents

Cardiovascular diseases (CVDs) are widespread in the modern world, and their number is constantly growing. For a long time, CVDs have been the leading cause of morbidity and mortality worldwide. Drugs for the treatment of CVD have been developed almost since the beginning of the 20th century, and a large number of effective cardioprotective agents of various classes have been created. Nevertheless, the need for the design and development of new safe drugs for the treatment of CVD remains. Literature data indicate that a huge number of cardioprotective agents of various generations and mechanisms correspond to a single generalized pharmacophore model containing two aromatic nuclei linked by a linear linker. In this regard, we put forward a concept for the design of a new generation of cardioprotective agents with a multitarget mechanism of action within the indicated pharmacophore model. This review is devoted to a generalization of the currently known compounds with cardioprotective properties and corresponding to the pharmacophore model of biaromatic compounds linked by a linear linker. Particular attention is paid to the history of the creation of these drugs, approaches to their design, and analysis of the structure-action relationship within each class.

The Ligands of Translocator Protein: Design and Biological Properties

In 2020, it is already 43 years since Braestrup and Squires discovered 18 kDa translocator protein (TSPO), known until 2006 as "peripheral benzodiazepine receptor". During this time, the functions of this receptor, which is located on the outer membrane of mitochondria, were studied in detail. One of the key functions of TSPO is the transfer of cholesterol from the outer to the inner mitochondrial membrane, which is the limiting stage in the synthesis of neurosteroids. TSPO is also involved in the transport of porphyrins, mitochondrial respiration, the opening of mitochondrial pores, apoptosis and cell proliferation. This review presents current information on the structure of TSPO, the mechanism of its participation in neurosteroidogenesis, as well as endogenous and synthetic TSPO ligands. Particular emphasis is placed on the analysis of approaches to the design of synthetic ligands and their neuropsychotropic activity in vitro and in vivo. The presented review demonstrates the promise of constructing new neuropsychotropic drugs in the series of TSPO ligands.

Choice of Tactics for Experimental Therapy of Chronic Heart Failure with ALM-802 Compound

The cardioprotective activity of ALM-802 compound was demonstrated in model experiments simulating postinfarction chronic heart failure in rats forming in 90 days after anterior transmural myocardial infarction. ALM-802 decreased the left ventricle and improved its inotropic function (p=0.038). This effect was observed in case of systematic administration of ALM-802 over 28 days (starting from day 91 after infarction modeling). This is apparently the minimum time for the cardioprotective effect of ALM-802 to prevent or treat the resulting heart failure, because short-term systematic therapy (15 days) produced no positive effect.

Cardioprotective Effects of Metalloproteinase Inhibitor 1-({4-[(4-Chlorobenzoyl)amino]phenyl}sulfonyl-L-Proline in Modeled Acute Myocardial Infarction

Cardioprotective effect of 1-({4 [(4 chlorobenzoyl)amino]phenyl}sulfonyl-L-proline (compound AL-828) was studied in rats with modeled acute myocardial infarction. The test compound was administered intragastrically in a dose of 30 mg/kg/day for 3 days prior to infarction modeling. Metalloproteinase inhibitor antibiotic doxycycline served as the reference drug and was administered in a dose of 40 mg/kg/day by the same schedule. It was shown that AL-828 similar to doxycycline significantly reduced the intensity of myocardial remodeling and maintained the inotropic function of the myocardium in the acute phase of myocardial infarction. By the 20th minute of ischemia, the end-systolic dimension of the left ventricle in control animals increased from 1.98±0.12 to 3.84±0.16 mm, while in animals treated with AL-828, this increase was significantly (p=0.007) less pronounced (from 1.84±0.07 and 2.87±0.21 mm, respectively). The ejection fraction characterizing the inotropic status of the left ventricle in animals treated with AL-828 was significantly higher (p=0.02). By its cardioprotective activity, AL-828 was not inferior to the reference drug doxycycline. It can be assumed that the cardioprotective activity of compound AL-828 is related to suppression of MMP-9 expression and/or inhibition of its activity as was previously demonstrated by us.

Anti-Ischemic Activity of Triamine ALM-802 under Conditions of Endothelial Dysfunction

Anti-ischemic activity of N1-(2,3,4-trimethoxybenzyl)-N2-{2-[(2,3,4-trimethoxybenzyl)amino] ethyl}-1,2-ethanediamine (ALM-802) based on the structure of standard p-FOX inhibitors trimetazidine and ranolazine was studied on the model of endocardial ischemia in intact rats and animals with endothelial dysfunction. Acute endocardial myocardial ischemia was caused by infusion of isoproterenol (20 μg/kg/min intravenously). Endothelial dysfunction in rats was modeled by inducing hyperhomocysteinemia (3 g/kg methionine intragastrically one a day over 7 days). The reference drugs trimetazidine (30 mg/kg, intravenously) and ranolazine 10 mg/kg, intravenously) that were effective only in intact rats. In contrast, ALM-802 (2 mg/kg, intravenously) showed a pronounced anti-ischemic effect in animals with endothelial dysfunction, which suggests that the mechanisms of its cardioprotective action differ from those known for p-FOX inhibitors.

Design, Synthesis and Anxiolytic Activity Evaluation of N-Acyltryptophanyl- Containing Dipeptides, Potential TSPO Ligands#

Background:

The 18 kDa translocator protein (TSPO), previously known as the peripheral- type benzodiazepine receptor, plays a key role for the synthesis of neurosteroids by promoting transport of cholesterol from the outer to the inner mitochondrial membrane, which is the ratelimiting step in neurosteroid biosynthesis. Neurosteroids interact with nonbenzodiazepine site of GABAa receptor causing an anxiolytic effect without the side effects.

Methods:

Using the original peptide drug-based design strategy, the first putative dipeptide ligand of the TSPO N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide (GD-23) was obtained. Molecular docking of GD-23 in the active pocket of the TSPO receptor using Glide software was carried out. The lead compounds GD-23 and its analogues were synthesized using activated succinimide esters coupling method. The anxiolytic activity of GD-23 and its analogues was investigated in vivo, using two validated behavioral tests, illuminated open field and elevated plus-maze.

Results:

he in vivo studies revealed that the following parameters are necessary for the manifestation of anxiolytic activity of new compounds: the L-configuration of tryptophan, the presence of an amide group at the C-terminus, the specific size of the N-acyl substituent at the Nterminus. Compound GD-23 (N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide) demonstrated a high anxiolytic-like effect in the doses of 0.05–1.0 mg/kg i.p. comparable with that of diazepam. Compound GD-23 was also active in the open field test when was administered orally in the doses of 0.1-5.0 mg/kg. The involvement of TSPO receptor in the mechanism of anxiolytic-like activity of new compounds was proved by the antagonism of compound GD-23 with TSPO selective inhibitor PK11195 as well as with inhibitors of enzymes which are involved in the biosynthesis of neurosteroids, trilostane and finasteride.

Conclusion:

A series of N-acyl-tryptophanyl-containing dipeptides were designed and synthesized as 18 kDa translocator protein (TSPO) ligands. Using a drug-based peptide design method a series of the first dipeptide TSPO ligands have been designed and synthesized and their anxiolytic activity has been evaluated. In general, some of the compounds displayed a high level of anxiolytic efficacy comparable with that of diazepam. The involvement of TSPO receptor in the mechanism of anxiolytic activity of new compounds was proved using two methods. On this basis, the N-acyl-Ltryptophanyl- isoleucine amides could potentially be a novel class of TSPO ligands with anxiolytic activity.

[PHARMACOLOGICAL STUDY OF NEW COMPOUNDS ACTING AS REGULATORS OF 18-KDA TRANSLOCATOR PROTEIN LIGANDS]

The interaction of new original 1-arylpyrrolo[1,2-a]pyrazine-3-carboxamide derivatives with mitochondrial translocator protein (MTP) 18 kDa has been studied by radioligand binding assay. Compounds GML-1 (Ki = 5.2 x 10⁻⁸ M) and GML-3 (Ki = 5.3 x 10⁻⁷ M) exhibit high binding affinity for MTP. GML-1 and GML-3 in a dose range of 0.1-1 mg/kg (i.p.) demonstrated anxiolytic-like effects in the elevated plus-maze test in CD-1 mice, which were blocked by the MTP selective antagonist PK11195. The data obtained on the molecular target, anxiolytic-like effects and low toxicity GML-1 and GML-3 suggest that these compounds are promising for further investigation as anxiolytics.

[Comparative study of discriminative stimulus properties of antidepressants]

Interoceptive stimulus properties of amitriptyline (54 mg/kg body weight), fluoxetine (10 mg/kg), and pyrrolo[1,2-a][1,4]diazepine derivative GMAL-24 (10 mg/kg) were studied in a standard operant model with liquid reinforcement of drug discrimination (DD) in male Wistar rats. A new experimental schedule that includes subchronic (7-day) administration of a training drug was used to perform DD learning. For the first time, it was found that amitriptyline has a discriminative interoceptive stimulus properties. Neither fluoxetine nor GMAL-24 did exhibit interoceptive properties. Imipramine (15 mg/kg, i.p.) fully substitutes for amitriptyline stimulus in substitution test. Fluoxetine (5 - 20 mg/kg, i.p.) failed to substitute with amitriptyline. Thus, amitriptyline/saline drug discrimination should be used for a comparative analysis of the central mechanisms of action of psychotropic substances, rather than for screening specific antidepressant activity.

[Role of GABA-A receptors in mechanism of psychotropic action of pyrrol[1,2-a][1,4]diazepines studied using drug discrimination technique in Wistar rats]

The role of GABA-A receptors in psychotropic effects of pyrrolo[1,2-a][1,4]diazepine derivatives GMAL-24 and GMAL-27 has been studied on an operant method with liquid reinforcement of drug discrimination in male Wistar rats. It is established that, in substitution tests, GMAL-24 (2, 5, 10 mg/kg) and GMAL-27 (2, 5, 10 mg/kg) do not produce interoceptive effects of phenazepam (1 mg/kg) and fail to inhibit interoceptive effects of corasol (20 mg/kg). The obtained results indicate that pyrrolo[1,2-a][1,4]diazepine derivatives do not exhibit GABA-A receptor-positive modulator properties in vivo.