Development of Novel Alaninamide Derivatives with Anticonvulsant Activity and Favorable Safety Profiles in Animal Models.

In our current study, we developed a focused series of original ((benzyloxy)benzyl)propanamide derivatives that demonstrated potent activity across in vivo mouse seizure models, specifically, maximal electroshock (MES) and 6 Hz (32 mA) seizures. Among these derivatives, compound 5 emerged as a lead molecule, exhibiting robust protection following intraperitoneal (i.p.) injection, as follows: ED50 = 48.0 mg/kg in the MES test, ED50 = 45.2 mg/kg in the 6 Hz (32 mA) test, and ED50 = 201.3 mg/kg in the 6 Hz (44 mA) model. Additionally, compound 5 displayed low potential for inducing motor impairment in the rotarod test (TD50 > 300 mg/kg), indicating a potentially favorable therapeutic window. In vitro toxicity assays further supported its promising safety profile. We also attempted to identify a plausible mechanism of action of compound 5 by applying both binding and functional in vitro studies. Overall, the data obtained for this lead molecule justifies the more comprehensive preclinical development of compound 5 as a candidate for a potentially broad-spectrum and safe anticonvulsant.

In Vivo and In Vitro Characterization of Close Analogs of Compound KA-11, a New Antiseizure Drug Candidate.

Epilepsy is a neurological disorder involving a number of disease syndromes with a complex etiology. A properly matched antiseizure drug (ASD) gives remission in up to 70% of patients. Nevertheless, there is still a group of about 30% of patients suffering from drug-resistant epilepsy. Consequently, the development of new more effective and/or safer ASDs is still an unmet clinical need. Thus, our current studies were focused on the structural optimization/modifications of one of the leading compounds, KA-11, aiming at the improvement of its antiseizure activity. As a result, we designed and synthesized two close analogs with highly pronounced drug-like physicochemical properties according to in silico predictions, namely KA-228 and KA-232, which were subsequently tested in a panel of animal seizure models, i.e., MES, 6 Hz (32 mA), scPTZ and ivPTZ. Among these compounds, KA-232, which was designed as a water-soluble salt, was distinctly more effective than KA-228 and assured similar antiseizure protection as its chemical prototype KA-11. With the aim of a more detailed characterization of both new molecules, in vitro binding tests were performed to evaluate the potential mechanisms of action. Furthermore, KA-232 was also evaluated in several ADME-Tox studies, and the results obtained strongly supported its drug-like potential. The proposed chemical modification of KA-11 enabled the identification of new pharmacologically active chemotypes, particularly water-soluble KA-232, which, despite the lack of better efficacy than the leading compound, may be used as a chemical prototype for the development of new ASDs, as well as substances potentially active in other neurological or neurodegenerative conditions.

Antinociceptive and Antiallodynic Activity of Some 3-(3-Methylthiophen-2-yl)pyrrolidine-2,5-dione Derivatives in Mouse Models of Tonic and Neuropathic Pain.

Antiseizure drugs (ASDs) are commonly used to treat a wide range of nonepileptic conditions, including pain. In this context, the analgesic effect of four pyrrolidine-2,5-dione derivatives (compounds 3, 4, 6, and 9), with previously confirmed anticonvulsant and preliminary antinociceptive activity, was assessed in established pain models. Consequently, antinociceptive activity was examined in a mouse model of tonic pain (the formalin test). In turn, antiallodynic and antihyperalgesic activity were examined in the oxaliplatin-induced model of peripheral neuropathy as well as in the streptozotocin-induced model of painful diabetic neuropathy in mice. In order to assess potential sedative properties (drug safety evaluation), the influence on locomotor activity was also investigated. As a result, three compounds, namely 3, 6, and 9, demonstrated a significant antinociceptive effect in the formalin-induced model of tonic pain. Furthermore, these substances also revealed antiallodynic properties in the model of oxaliplatin-induced peripheral neuropathy, while compound 3 attenuated tactile allodynia in the model of diabetic streptozotocin-induced peripheral neuropathy. Apart from favorable analgesic properties, the most active compound 3 did not induce any sedative effects at the active dose of 30 mg/kg after intraperitoneal (i.p.) injection.

Asymmetric synthesis and in vivo/in vitro characterization of new hybrid anticonvulsants derived from (2,5-dioxopyrrolidin-1-yl)phenylacetamides.

In the current studies we carried out an optimized multistep asymmetric synthesis of R-enantiomers (eutomers) for a previously identified series of racemic hybrid anticonvulsants. The spatial structure of selected enantiomers was solved by the use of crystallographic methods. The compound (R)-16 was identified as a lead, which revealed broad-spectrum protective activity in a range of epilepsy models with the following ED50 values: the maximal electroshock (MES) test (36.0 mg/kg), the 6 Hz (32 mA) seizure model (39.2 mg/kg), and the pentylenetetrazole-induced seizure model (scPTZ) (54.8 mg/kg). Furthermore, (R)-16 displayed a low potency for the induction of motor impairment in the rotarod test (TD50 = 468.5 mg/kg), resulting in potentially very beneficial therapeutic window. Finally, (R)-16 showed satisfying ADME-Tox properties in the in vitro assays. Therefore, the data obtained in the current studies justify the further preclinical development of (R)-16 as candidate for potentially broad-spectrum and safe anticonvulsant.

Synthesis, anticonvulsant, and antinociceptive activity of new 3-(3-methyl-2,5-dioxo-3-phenylpyrrolidin-1-yl)propanamides and 3-phenyl-butanamides.

A focused library of new 3-(3-methyl-2,5-dioxo-3-phenylpyrrolidin-1-yl)propanamides and their nonimide analogs were synthesized and tested for anticonvulsant activity. These compounds were obtained through the coupling reaction of the starting carboxylic acids with appropriate amines. The initial anticonvulsant screening was performed in mice (intraperitoneal administration) using the maximal electroshock seizure (MES) and the subcutaneous pentylenetetrazole (scPTZ) seizure models. The most promising compound 6 showed more potent protection in the MES and scPTZ tests than valproic acid, which is still recognized as one of the most relevant first-line anticonvulsants. The structure-activity relationship analysis revealed that the presence of the pyrrolidine-2,5-dione ring is important but not indispensable to retain anticonvulsant activity. Additionally, compound 6 showed potent antinociceptive properties in the oxaliplatin-induced neuropathic pain model in mice. The most plausible mechanism of action for compound 6 may result from its influence on the neuronal sodium channel (Site 2) and the high-voltage-activated L-type calcium channel.

Preclinical Assessment of a New Hybrid Compound C11 Efficacy on Neurogenesis and Cognitive Functions after Pilocarpine Induced Status Epilepticus in Mice.

Status epilepticus (SE) is a frequent medical emergency that can lead to a variety of neurological disorders, including cognitive impairment and abnormal neurogenesis. The aim of the presented study was the in vitro evaluation of potential neuroprotective properties of a new pyrrolidine-2,5-dione derivatives compound C11, as well as the in vivo assessment of the impact on the neurogenesis and cognitive functions of C11 and levetiracetam (LEV) after pilocarpine (PILO)-induced SE in mice. The in vitro results indicated a protective effect of C11 (500, 1000, and 2500 ng/mL) on astrocytes under trophic stress conditions in the MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) test. The results obtained from the in vivo studies, where mice 72 h after PILO SE were treated with C11 (20 mg/kg) and LEV (10 mg/kg), indicated markedly beneficial effects of C11 on the improvement of the neurogenesis compared to the PILO control and PILO LEV mice. Moreover, this beneficial effect was reflected in the Morris Water Maze test evaluating the cognitive functions in mice. The in vitro confirmed protective effect of C11 on astrocytes, as well as the in vivo demonstrated beneficial impact on neurogenesis and cognitive functions, strongly indicate the need for further advanced molecular research on this compound to determine the exact neuroprotective mechanism of action of C11.

Identification of New Compounds with Anticonvulsant and Antinociceptive Properties in a Group of 3-substituted (2,5-dioxo-pyrrolidin-1-yl)(phenyl)-Acetamides.

We report herein a series of water-soluble analogues of previously described anticonvulsants and their detailed in vivo and in vitro characterization. The majority of these compounds demonstrated broad-spectrum anticonvulsant properties in animal seizure models, including the maximal electroshock (MES) test, the pentylenetetrazole-induced seizure model (scPTZ), and the psychomotor 6 Hz (32 mA) seizure model in mice. Compound 14 showed the most robust anticonvulsant activity (ED50 MES = 49.6 mg/kg, ED50 6 Hz (32 mA) = 31.3 mg/kg, ED50scPTZ = 67.4 mg/kg). Notably, it was also effective in the 6 Hz (44 mA) model of drug-resistant epilepsy (ED50 = 63.2 mg/kg). Apart from favorable anticonvulsant properties, compound 14 revealed a high efficacy against pain responses in the formalin-induced tonic pain, the capsaicin-induced neurogenic pain, as well as in the oxaliplatin-induced neuropathic pain in mice. Moreover, compound 14 showed distinct anti-inflammatory activity in the model of carrageenan-induced aseptic inflammation. The mechanism of action of compound 14 is likely complex and may result from the inhibition of peripheral and central sodium and calcium currents, as well as the TRPV1 receptor antagonism as observed in the in vitro studies. This lead compound also revealed beneficial in vitro ADME-Tox properties and an in vivo pharmacokinetic profile, making it a potential candidate for future preclinical development. Interestingly, the in vitro studies also showed a favorable induction effect of compound 14 on the viability of neuroblastoma SH-SY5Y cells.

Synthesis, Anticonvulsant, and Antinociceptive Activity of New 3-(2-Chlorophenyl)- and 3-(3-Chlorophenyl)-2,5-dioxo-pyrrolidin-1-yl-acetamides.

The new series of 3-(2-chlorophenyl)- and 3-(3-chlorophenyl)-pyrrolidine-2,5-dione-acetamide derivatives as potential anticonvulsant and analgesic agents was synthesized. The compounds obtained were evaluated in the following acute models of epilepsy: maximal electroshock (MES), psychomotor (6 Hz, 32 mA), and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The most active substance-3-(2-chlorophenyl)-1-{2-[4-(4-fluorophenyl)piperazin-1-yl]-2-oxoethyl}-pyrrolidine-2,5-dione (6) showed more beneficial ED50 and protective index values than the reference drug-valproic acid (68.30 mg/kg vs. 252.74 mg/kg in the MES test and 28.20 mg/kg vs. 130.64 mg/kg in the 6 Hz (32 mA) test, respectively). Since anticonvulsant drugs are often effective in neuropathic pain management, the antinociceptive activity for two the promising compounds-namely, 6 and 19-was also investigated in the formalin model of tonic pain. Additionally, for the aforementioned compounds, the affinity for the voltage-gated sodium and calcium channels, as well as GABAA and TRPV1 receptors, was determined. As a result, the most probable molecular mechanism of action for the most active compound 6 relies on interaction with neuronal voltage-sensitive sodium (site 2) and L-type calcium channels. Compounds 6 and 19 were also tested for their neurotoxic and hepatotoxic properties and showed no significant cytotoxic effect.

C-11, a New Antiepileptic Drug Candidate: Evaluation of the Physicochemical Properties and Impact on the Protective Action of Selected Antiepileptic Drugs in the Mouse Maximal Electroshock-Induced Seizure Model.

C-11 is a hybrid compound derived from 2-(2,5-dioxopyrrolidin-1-yl) propanamide, with a wide spectrum of anticonvulsant activity and low neurotoxicity. The aim of this study was to determine the effects of C-11 on the protective action of various antiepileptic drugs (i.e., carbamazepine CBZ, lacosamide LCM, lamotrigine LTG, and valproate VPA) against maximal electroshock-induced seizures (MES) in mice, as well as its neuroprotective and physicochemical/pharmacokinetic properties. Results indicate that C-11 (30 mg/kg, i.p.) significantly enhanced the anticonvulsant action of LCM (p < 0.001) and VPA (p < 0.05) but not that of CBZ and LTG in the MES test. Neither C-11 (30 mg/kg) alone nor its combination with other anticonvulsant drugs (at their ED50 values from the MES test) affected motor coordination; skeletal muscular strength and long-term memory, as determined in the chimney; grip strength and passive avoidance tests, respectively. Pharmacokinetic characterization revealed that C-11 had no impact on total brain concentrations of LCM or VPA in mice. Qualitative analysis of neuroprotective properties of C-11, after a single administration of pilocarpine, revealed no protective effect of this substance in the tested animals. Determination of physicochemical descriptors showed that C-11 meets the drug-likeness requirements resulting from Lipinski and Veber's rules and prediction of gastrointestinal absorption and brain penetration, which is extremely important for the CNS-active compounds.

KA-104, a new multitargeted anticonvulsant with potent antinociceptive activity in preclinical models.

OBJECTIVE: The main objective of the present work was to assess the utility of KA-104 as potential therapy for drug-resistant seizures and neuropathic pain, and to characterize its druglike properties in a series of absorption, distribution, metabolism, excretion and toxicity (ADME-Tox) studies. We also aimed to establish its mechanism of action in electrophysiological studies. METHODS: The activity of KA-104 against drug-resistant seizures was tested in the mouse 6-Hz (44-mA) model, whereas the antinociceptive activity was assessed with the capsaicin- and oxaliplatin-induced pain models in mice. The patch-clamp technique was used to study the influence of KA-104 on fast voltage-gated sodium currents in rat prefrontal cortex pyramidal neurons. The pharmacokinetic profile was determined after intraperitoneal (ip) injection in mice. The in vitro ADME-Tox properties were studied by applying routine testing procedures. RESULTS: KA-104 was effective in the 6-Hz (44-mA) model (median effective dose [ED50 ] = 73.2 mg/kg) and revealed high efficacy in capsaicin-induced neurogenic pain as well as in oxaliplatin-induced neuropathic pain in mice. Patch-clamp technique showed that KA-104 reversibly inhibits voltage-gated sodium currents. KA-104 was rapidly absorbed after the ip injection and showed relatively good penetration through the blood-brain barrier. This molecule was also characterized by high passive permeability, moderate influence on CYP2C9, and negligible hepatotoxicity on HepG2 cells. SIGNIFICANCE: The results reported herein indicate that KA-104 is a new wide-spectrum multitargeted anticonvulsant with favorable in vitro ADME-Tox properties. Importantly, this compound may also prove to become an interesting and hopefully more effective therapeutic option for treatment of neuropathic pain.

The Search for New Anticonvulsants in a Group of (2,5-Dioxopyrrolidin-1-yl)(phenyl)Acetamides with Hybrid Structure-Synthesis and In Vivo/In Vitro Studies.

Epilepsy belongs to the most common and debilitating neurological disorders with multifactorial pathophysiology and a high level of drug resistance. Therefore, with the aim of searching for new, more effective, and/or safer therapeutics, we discovered a focused series of original hybrid pyrrolidine-2,5-dione derivatives with potent anticonvulsant properties. We applied an optimized coupling reaction yielding several hybrid compounds that showed broad-spectrum activity in widely accepted animal seizure models, namely, the maximal electroshock (MES) test and the psychomotor 6 Hz (32 mA) seizure model in mice. The most potent anticonvulsant activity and favorable safety profile was demonstrated for compound 30 (median effective dose (ED50) MES = 45.6 mg/kg, ED50 6 Hz (32 mA) = 39.5 mg/kg, median toxic dose (TD50) (rotarod test) = 162.4 mg/kg). Anticonvulsant drugs often show activity in pain models, and compound 30 was also proven effective in the formalin test of tonic pain, the capsaicin-induced pain model, and the oxaliplatin (OXPT)-induced neuropathic pain model in mice. Our studies showed that the most plausible mechanism of action of 30 involves inhibition of calcium currents mediated by Cav1.2 (L-type) channels. Importantly, 30 revealed high metabolic stability on human liver microsomes, negligible hepatotoxicity, and relatively weak inhibition of CYP3A4, CYP2D6, and CYP2C9 isoforms of cytochrome P450, compared to reference compounds. The promising in vivo activity profile and drug-like properties of compound 30 make it an interesting candidate for further preclinical development.

Synthesis and Anticonvulsant Properties of New 3,3-Diphenyl-2,5-dioxo-pyrrolidin-1-yl-acetamides and 3,3-Diphenyl-propionamides.

The focused library of new amides derived from 3,3-diphenyl-2,5-dioxo-pyrrolidin-1-yl-acetic acid (2a-t) and 3,3-diphenyl-propionic acid (3a-t) as potential anticonvulsant agents was synthesized. The final products were obtained in the amidation reaction of the given carboxylic acid (2, 3) with appropriate secondary amines in the presence of carbonyldiimidazole (CDI) as a coupling reagent. The initial anticonvulsant screening was performed in mice intraperitoneally (i.p.) using the "classical" maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure models, whereas the acute neurological toxicity was determined applying the rotarod test. Additionally, several compounds were studied also in the 6-Hz seizures recognized as the animal model of human pharmacoresistant epilepsy. In this series, compound 3q displayed a broad spectrum of activity across the preclinical seizure models (ED50 MES = 31.64 mg/kg; ED50 scPTZ = 75.41 mg/kg, ED50 6-Hz (32 mA) = 38.15 mg/kg). Consequently, compound 3q revealed a wider spectrum of protection, higher activity or/and a better safety profile than the commonly used antiepileptic drugs such as phenytoin, ethosuximide, valproic acid, or/and levetiracetam. Notably, the in vitro studies showed that the most possible mechanism of action of 3q may be connected to the interaction with neuronal voltage-sensitive sodium channels (site 2). Other substances were active predominantly in the chemically induced seizures. The results of the current studies indicate that the presence of the pyrrolidine-2,5-dione ring is important but not indispensable for anticonvulsant activity.

Design, synthesis and anticonvulsant activity of new hybrid compounds derived from N-phenyl-2-(2,5-dioxopyrrolidin-1-yl)-propanamides and -butanamides.

The focused library of 21 new N-phenyl-2-(2,5-dioxopyrrolidin-1-yl)propanamide, 2-(3-methyl-2,5-dioxopyrrolidin-1-yl)propanamide, and 2-(2,5-dioxopyrrolidin-1-yl)butanamide derivatives as potential new hybrid anticonvulsant agents was synthesized. These hybrid molecules were obtained as close analogs of previously described N-benzyl derivatives and fuse the chemical fragments of clinically relevant antiepileptic drugs such as ethosuximide, levetiracetam, and lacosamide. The initial anticonvulsant screening was performed in mice (ip) using the 'classical' maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) tests, as well as in the six-Hertz (6Hz) model of pharmacoresistant limbic seizures. Applying the rotarod test, the acute neurological toxicity was determined. The broad spectra of activity across the preclinical seizure models in mice (ip) displayed compounds 4, 5, 11, and 19. The most favorable anticonvulsant properties demonstrated 4 (ED50 MES=96.9mg/kg, ED50scPTZ=75.4mg/kg, ED50 6Hz=44.3mg/kg) which showed TD50=335.8mg/kg in the rotarod test that yielded satisfying protective indexes (PI MES=3.5, PI scPTZ=4.4, PI 6Hz=7.6). Consequently, compound 4 revealed comparable or better safety profile than model antiepileptic drugs (AEDs): ethosuximide, lacosamide, and valproic acid. In the in vitro assays, compound 4 was observed as relatively effective binder to the neuronal voltage-sensitive sodium and diltiazem site of L-type calcium channels.

New hybrid molecules with anticonvulsant and antinociceptive activity derived from 3-methyl- or 3,3-dimethyl-1-[1-oxo-1-(4-phenylpiperazin-1-yl)propan-2-yl]pyrrolidine-2,5-diones.

The purpose of this study was to synthetize the focused library of 34 new piperazinamides of 3-methyl- and 3,3-dimethyl-(2,5-dioxopyrrolidin-1-yl)propanoic or butanoic acids as potential new hybrid anticonvulsants. These hybrid molecules join the chemical fragments of well-known antiepileptic drugs (AEDs) such as ethosuximide, levetiracetam, and lacosamide. Compounds 5-38 were prepared in a coupling reaction of the 3-methyl- or 3,3-dimethyl-2-(2,5-dioxopyrrolidin-1-yl)propanoic (1, 2) or butanoic acids (3, 4) with the appropriately substituted secondary amines in the presence of the N,N-carbonyldiimidazole reagent. The initial anticonvulsant screening was performed in mice (ip) using the 'classical' maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) tests as well as in the six-Hertz (6Hz) model of pharmacoresistant limbic seizures. The acute neurological toxicity was determined applying the chimney test. The broad spectra of activity across the preclinical seizure models in mice ip displayed compounds 7, 15, and 36. The most favorable anticonvulsant properties demonstrated 15 (ED50 MES=74.8mg/kg, ED50scPTZ=51.6mg/kg, ED50 6Hz=16.8mg/kg) which showed TD50=213.3mg/kg in the chimney test that yielded satisfying protective indexes (PI MES=2.85, PI scPTZ=4.13, PI 6Hz=12.70) at time point of 0.5h. As a result, compound 15 displayed comparable or better safety profile than clinically relevant AEDs: ethosuximide, lacosamide or valproic acid. In the in vitro assays compound 15 was observed as relatively effective binder to the neuronal voltage-sensitive sodium and L-type calcium channels. Beyond the anticonvulsant properties, 6 compounds diminished the pain responses in the formalin model of tonic pain in mice.

Synthesis, and anticonvulsant activity of new amides derived from 3-methyl- or 3-ethyl-3-methyl-2,5-dioxo-pyrrolidin-1-yl-acetic acids.

This paper describes the synthesis of the library of 22 new 3-methyl- and 3-ethyl-3-methyl-2,5-dioxo-pyrrolidin-1-yl-acetamides as potential anticonvulsant agents. The maximal electroshock (MES) and the subcutaneous pentylenetetrazole (scPTZ) seizure models were used for screening all the compounds. The 6 Hz model of pharmacoresistant limbic seizures was applied for studying selected derivatives. Six amides were chosen for pharmacological characterization of their antinociceptive activity in the formalin model of tonic pain as well as local anesthetic activity was assessed in mice. The pharmacological data indicate on the broad spectra of activity across the preclinical seizure models. Compounds 10 (ED50=32.08 mg/kg, MES test) and 9 (ED50=40.34 mg/kg, scPTZ test) demonstrated the highest potency. These compounds displayed considerably better safety profiles than clinically relevant antiepileptic drugs phenytoin, ethosuximide, or valproic acid. Several molecules showed antinociceptive and local anesthetic properties. The in vitro radioligand binding studies demonstrated that the influence on the sodium and calcium channels may be one of the essential mechanisms of action.

Design, synthesis and biological evaluation of new hybrid anticonvulsants derived from N-benzyl-2-(2,5-dioxopyrrolidin-1-yl)propanamide and 2-(2,5-dioxopyrrolidin-1-yl)butanamide derivatives.

The purpose of this study was to synthesize the library of 33 new N-benzyl-2-(2,5-dioxopyrrolidin-1-yl)propanamides, 2-(3-methyl-2,5-dioxopyrrolidin-1-yl)propanamides, and 2-(2,5-dioxopyrrolidin-1-yl)butanamides as potential new hybrid anticonvulsant agents. These hybrid molecules join the chemical fragments of well-known antiepileptic drugs (AEDs) such as ethosuximide, levetiracetam, and lacosamide. The coupling reaction of the 2-(2,5-dioxopyrrolidin-1-yl)propanoic acid, 2-(3-methyl-2,5-dioxopyrrolidin-1-yl)propanoic acid, or 2-(2,5-dioxopyrrolidin-1-yl)butanoic acid with the appropriately substituted benzylamines in the presence of the coupling reagent, N,N-carbonyldiimidazole (CDI) generated the final compounds 4-36. Spectral data acquired via (1)H NMR, (13)C NMR, and LC-MS confirmed the chemical structures of the newly prepared compounds. The initial anticonvulsant screening was performed in mice intraperitoneally (ip), using the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The rotarod test determined the acute neurological toxicity (NT). The results of preliminary pharmacological screening revealed that 25 compounds showed protection in half or more of the animals tested in the MES and/or scPTZ seizure models at the fixed dose of 100mg/kg. The broad spectra of activity across the preclinical seizure models displayed compounds 4, 7, 8, 13, 15-18, 24, and 26. The quantitative pharmacological studies in mice demonstrated the highest protection for compounds 4 (ED50 MES=67.65 mg/kg, ED50scPTZ=42.83 mg/kg); 8 (ED50 MES=54.90 mg/kg, ED50scPTZ=50.29 mg/kg); and 20 (ED50scPTZ=47.39 mg/kg). These compounds were distinctly more potent and provided better safety profiles in the rotarod test compared to valproic acid or ethosuximide, which were used as model AEDs. Compound 8 underwent only a slight metabolic change by the human liver microsomes (HLMs), and also did not affect the activity of human cytochrome P450 isoform, CYP3A4, in the in vitro assays.

Synthesis and anticonvulsant activity of new N-phenyl-2-(4-phenylpiperazin-1-yl)acetamide derivatives.

Twenty-two new N-phenyl-2-(4-phenylpiperazin-1-yl)acetamide derivatives have been synthesized and evaluated for their anticonvulsant activity in animal models of epilepsy. These molecules have been designed as analogs of previously obtained anticonvulsant active pyrrolidine-2,5-diones in which heterocyclic imide ring has been changed into chain amide bound. The final compounds were synthesized in the alkylation reaction of the corresponding amines with the previously obtained alkylating reagents 2-chloro-1-(3-chlorophenyl)ethanone (1) or 2-chloro-1-[3-(trifluoromethyl)phenyl]ethanone (2). Initial anticonvulsant screening was performed using standard maximal electroshock (MES) and subcutaneous pentylenetetrazole screens in mice and/or rats. Several compounds were tested additionally in the psychomotor seizures (6-Hz model). The acute neurological toxicity was determined applying the rotarod test. The results of pharmacological studies showed activity exclusively in the MES seizures especially for 3-(trifluoromethyl)anilide derivatives, whereas majority of 3-chloroanilide analogs were inactive. It should be emphasize that several molecules showed also activity in the 6-Hz screen which is an animal model of human partial and therapy-resistant epilepsy. In the in vitro studies, the most potent derivative 20 was observed as moderate binder to the neuronal voltage-sensitive sodium channels (site 2). The SAR studies for anticonvulsant activity confirmed the crucial role of pyrrolidine-2,5-dione core fragment for anticonvulsant activity.

Synthesis, anticonvulsant properties, and SAR analysis of differently substituted pyrrolidine-2,5-diones and piperidine-2,6-diones.

Twenty-two differently substituted 1H-isoindole-1,3(2H)-diones (30-39), 8-azaspiro[4.5]decane-7,9-diones (40-45), and 3-azaspiro[5.5]undecane-2,4-diones (46-51) were synthesized and tested for anticonvulsant activity. These molecules were designed as analogs of previously obtained azaspirosuccinimides (1-24). Initial anticonvulsant screening was performed in mice using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The acute neurological toxicity was determined applying the minimal motor impairment rotorod test. The preliminary pharmacological results showed that 15 new compounds were effective in at least one animal model of epilepsy, from which nine molecules showed protection against both MES and scPTZ seizures. The structure-activity relationship analysis revealed that anticonvulsant activity was connected closely with the structure of the imide fragment; the most favorable one was the hexahydro-1H-isoindole-1,3(2H)-dione core. 2-(2-Chlorophenyl)hexahydro-1H-isoindole-1,3(2H)-dione (31) showed activity in the 6-Hz psychomotor seizure model, which identifies substances effective in partial and therapy-resistant epilepsy. 3-[(4-Chlorophenyl)amino]-3-azaspiro[5.5]undecane-2,4-dione (47) was active in the in vitro hippocampal slice culture neuroprotection assay.

Synthesis, physicochemical, and anticonvulsant properties of new N-Mannich bases derived from pyrrolidine-2,5-dione and its 3-methyl analog.

A series of 22 new N-[(4-phenylpiperazin-1-yl)-methyl]-3-methyl-pyrrolidine-2,5-dione and pyrrolidine-2,5-dione derivatives were synthesized and evaluated for their anticonvulsant activities in the maximum electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests after intraperitoneal injection into mice. The neurotoxicity was determined applying the rotarod test. The in vivo results in mice showed that seven compounds were effective in the MES or/and scPTZ seizure tests. The quantitative evaluation in both tests after i.p. administration into mice revealed that the most active compounds were N-[{4-(3,4-dichlorophenyl)-piperazin-1-yl}-methyl]-3-methylpyrrolidine-2,5-dione (12) with ED50 = 16.13 mg/kg (MES), ED50 = 133.99 mg/kg (scPTZ) and N-[{4-(3,4-dichlorophenyl)-piperazin-1-yl}-methyl]-pyrrolidine-2,5-dione (23) with ED50 = 37.79 mg/kg (MES), ED50 = 128.82 mg/kg (scPTZ), whereas N-[{4-(3-trifluoromethylphenyl)-piperazin-1-yl}-methyl]-pyrrolidine-2,5-dione (24) was effective only in the MES test with ED50 = 16.37 mg/kg. These molecules showed higher potency and also lower neurotoxicity than the reference antiepileptic drugs such as ethosuximide and valproic acid.

A comprehensive assessment of palmatine as anticonvulsant agent - In vivo and in silico studies.

Previously, we demonstrated that palmatine (PALM) - an isoquinoline alkaloid from Berberis sibrica radix, exerted antiseizure activity in the pentylenetetrazole (PTZ)-induced seizure assay in larval zebrafish. The aim of the present study was to more precisely characterize PALM as a potential anticonvulsant drug candidate. A range of zebrafish and mouse seizure/epilepsy models were applied in the investigation. Immunostaining analysis was conducted to assess the changes in mouse brains, while in silico molecular modelling was performed to determine potential targets for PALM. Accordingly, PALM had anticonvulsant effect in ethyl 2-ketopent-4-enoate (EKP)-induced seizure assay in zebrafish larvae as well as in the 6 Hz-induced psychomotor seizure threshold and timed infusion PTZ tests in mice. The protective effect in the EKP-induced seizure assay was confirmed in the local field potential recordings. PALM did not affect seizures in the gabra1a knockout line of zebrafish larvae. In the scn1Lab-/- zebrafish line, pretreatment with PALM potentiated seizure-like behaviour of larvae. Repetitive treatment with PALM, however, did not reduce development of PTZ-induced seizure activity nor prevent the loss of parvalbumin-interneurons in the hippocampus of the PTZ kindled mice. In silico molecular modelling revealed that the noted anticonvulsant effect of PALM in EKP-induced seizure assay might result from its interactions with glutamic acid decarboxylase and/or via AMPA receptor non-competitive antagonism. Our study has demonstrated the anticonvulsant activity of PALM in some experimental models of seizures, including a model of pharmacoresistant seizures induced by EKP. These results indicate that PALM might be a suitable new drug candidate but the precise mechanism of its anticonvulsant activity has to be determined.