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.

Analgesic and antiallodynic activity of novel anticonvulsant agents derived from 3-benzhydryl-pyrrolidine-2,5-dione in mouse models of nociceptive and neuropathic pain.

The objective of this study was to evaluate analgesic and antiallodynic activity of four new 3-benzhydryl-pyrrolidine-2,5-dione derivatives, which demonstrated previously anticonvulsant activity in the seizure tests in mice. Analgesic activity was examined in acute (the hot plate test), tonic (the formalin test), as well as neuropathic (the oxaliplatin-induced peripheral neuropathy) pain models in mice. Moreover, potential sedative properties and hepatotoxicity were evaluated. To establish the plausible mechanism of action, in vitro assays were carried out. All tested compounds RS 34, RS 37, RS 48, and RS 49, similarly to pregabalin, were active in the second phase of formalin test, a model of tonic pain. The most promising effect was observed for compounds RS 34, RS 48, and RS 49, which in a statistically significant way attenuated the nocifensive response at all tested doses 1, 10, and 30 mg/kg. Furthermore, all compounds at a dose of 30 mg/kg revealed antiallodynic activity in neuropathic pain related to chemotherapy-induced peripheral neuropathy in mice. In experimental tests on three compounds RS 34, RS 37 and RS 48 at active doses no sedative properties were registered. In the in vitro assay the selected molecule RS 34 did not induce cytotoxic effect on hepatoma cells. The binding and functional studies did not provide firm evidence on possible mechanism of action of these derivatives. In conclusion, the tested pyrrolidine-2,5-dione derivatives with antiseizure activity exerted also analgesic and antiallodynic effects in mouse models of pain.

Antiallodynic and antihyperalgesic activity of new 3,3-diphenyl-propionamides with anticonvulsant activity in models of pain in mice.

Anticonvulsant drugs are used to treat a wide range of non-epileptic conditions, including chronic pain. The aim of the present experiments was to examine analgesic activity of three new 3,3-diphenyl-propionamides, which had previously demonstrated anticonvulsant activity in the MES (maximal electroshock seizure), scPTZ (subcutaneous pentylenetetrazole) and/or 6Hz (psychomotor seizure) tests in mice. Antinociceptive activity was examined in mouse models of acute pain (the hot plate test) and tonic pain (the formalin test) in mice. Antiallodynic and antihyperalgesic activity was estimated in the oxaliplatin-induced neuropathic pain model of chemotherapy-induced peripheral neuropathy and in the streptozotocin-induced model of painful diabetic neuropathy in mice. Considering the drug safety evaluation, the influence on locomotor activity was checked. Moreover, using in vitro methods, selected compound was tested for potential hepatotoxicity on human hepatocellular carcinoma cell line and for metabolic stability. To determine the plausible mechanism of anticonvulsant and antinociceptive action, in vitro binding and functional assays were carried out. Among tested molecules two of them JOA 122 (3p) and JOA 123 (3q) revealed significant antinociceptive activity in the model of tonic pain - the formalin test and neuropathic pain models - the oxaliplatin and streptozotocin-induced peripheral neuropathy. In the binding studies JOA 122 (3p) revealed the high affinity to voltage-gated sodium channels (Nav1.2), as well as for 5-HT1A receptors. Metabolism studies in mouse liver microsomes showed a low metabolic stability of this compound.

Synthesis and Determination of Lipophilicity, Anticonvulsant Activity, and Preliminary Safety of 3-Substituted and 3-Unsubstituted N-[(4-Arylpiperazin-1-yl)alkyl]pyrrolidine-2,5-dione Derivatives.

A new series of 1,3-substituted pyrrolidine-2,5-dione derivatives as potential anticonvulsant agents are described. Initial pharmacological screening of these compounds was performed by using acute models of seizures (MES and scPTZ tests) in mice after intraperitoneal administration. Quantitative pharmacological research revealed that the most promising compounds were N-[{4-(3-trifluoromethylphenyl)piperazin-1-yl}propyl]-3-benzhydrylpyrrolidine-2,5-dione monohydrochloride (11) with a ED50 value of 75.9 mg kg-1 (MES test) and N-[{4-(3,4-dichlorophenyl)piperazin-1-yl}ethyl]-3-methylpyrrolidine-2,5-dione monohydrochloride (18) with ED50 =88.2 mg kg-1 (MES test) and ED50 =65.7 kg mg-1 (scPTZ test). These compounds displayed a more beneficial protective index than well-known antiepileptic drugs. A plausible mechanism of action of compounds 11 and 18 [molecule 11 blocked the sodium channel (site 2) and 18 blocked both the sodium (site 2) and L-type calcium channels] and their preliminary safety in vitro were evaluated. Besides, the lipophilicity of all synthesized compounds was determined by using UPLC-MS.

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.

Synthesis and evaluation of anticonvulsant properties of new N-Mannich bases derived from pyrrolidine-2,5-dione and its 3-methyl-, 3-isopropyl, and 3-benzhydryl analogs.

The aim of this paper was to describe the synthesis of a library of 28 new 1,3-substituted pyrrolidine-2,5-dione as potential anticonvulsant agents. The anticonvulsant activity was evaluated using three acute models of seizures in mice (MES-maximal electroshock, scPTZ-subcutaneous pentylenetetrazole, and 6Hz-psychomotor seizure tests). The neurotoxicity was determined by rotarod test. The most promising compound was found to be N-[{morpholin-1-yl}-methyl]-3-benzhydryl-pyrrolidine-2,5-dione (15), as it was active in the MES (ED50=41.0mg/kg), scPTZ (ED50=101.6kg/mg), and 6Hz (ED50=45.42mg/kg) tests. This compound displayed more beneficial protection index (PI) than antiepileptic drugs such as ethosuximide, lacosamide and valproic acid. In vitro studies for compound 15 were conducted and provided information that its possible mechanism of action is related to blocking of the neuronal voltage-sensitive sodium (site 2) and L-type calcium channels.

Synthesis and evaluation of anticonvulsant properties of new N-Mannich bases derived from 3-(1-phenylethyl)- and 3-benzyl-pyrrolidine-2,5-dione.

Two series of new derivatives of pyrrolidine-2,5-dione were synthesized and evaluated for their anticonvulsant properties. Initial screening for their anticonvulsant properties was performed in mice after intraperitoneal administration, using the maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and 6-Hz seizure tests. Quantitative pharmacological research revealed that the highest level of protection was demonstrated by compound N-[{4-methylpiperazin-1-yl}-methyl]-3-(1-phenylethyl)-pyrrolidine-2,5-dione monohydrochloride (22) which was effective both in the scPTZ test (ED50=39 mg/kg) and in the 6-Hz test (ED50=36 mg/kg). This molecule showed higher potency than reference antiepileptic drugs such as ethosuximide, lacosamide and valproic acid. With the aim of explaining the possible mechanism of action of the selected molecule, its influence on sodium and calcium channels as well as NMDA and GABAA receptors binding properties were evaluated in vitro.

Anticonvulsant and antinociceptive activity of new amides derived from 3-phenyl-2,5-dioxo-pyrrolidine-1-yl-acetic acid in mice.

The aim of the present experiments was to examine the anticonvulsant and antinociceptive activity of five new amides derived from 3-phenyl-2,5-dioxo-pyrrolidine-1-yl-acetic acid in animal models of seizures and pain. The antiseizure activity was investigated in three acute models of seizures, namely, the maximal electroshock (MES), the subcutaneous pentylenetetrazole (scPTZ), and 6Hz psychomotor seizure tests in mice. The antinociceptive properties were estimated in the formalin model of tonic pain, and in the oxaliplatin-induced neuropathic pain model in mice. Considering drug safety evaluation, acute neurological toxicity was determined in the rotarod test. Three tested compounds (3, 4, and 7) displayed a broad spectrum of anticonvulsant activity and showed better protective indices than those obtained for MES/scPTZ/6Hz active reference drug - valproic acid. Furthermore, three compounds (3, 4, and 6) demonstrated a significant antinociceptive effect in the formalin test, as well as antiallodynic activity in the oxaliplatin-induced neuropathic pain model. Among the tested agents, compounds 3 and 4 displayed not only antiseizure properties, but also collateral prominent analgesic properties. The in vitro binding study indicated that the plausible mechanism of action of chosen compound (4) was the influence on neuronal voltage-sensitive sodium (site 2) and L-type calcium channels.

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.

Synthesis and anticonvulsant activity of new N-mannich bases derived from benzhydryl- and isopropyl-pyrrolidine-2,5-dione.

Synthesis and anticonvulsant properties of 26 new N-Mannich bases of 3-benzhydryl-(5-17) and 3-isopropyl-pyrrolidine-2,5-diones (18-30) have been described. Initial anticonvulsant screening for these compounds was evaluated in mice after intraperitoneal administration in the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. The acute neurological toxicity was determined by applying the rotorod test. The in vivo results in mice showed that the majority of 3-benzhydryl-pyrrolidine-2,5-dione derivatives revealed effectiveness, while 3-isopropyl-pyrrolidine-2,5-dione derivatives were practically devoid of activity. The quantitative evaluation in both tests revealed that the most active were N-[{4-(3-chlorophenyl)-piperazin-1-yl}-methyl]-3-benzhydryl-pyrrolidine-2,5-dione (9) with ED5 0 value =42.71 mg/kg (MES), ED5 0 value >150 mg/kg (scPTZ), and N-[{4-(3-trifluoromethylphenyl)-piperazin-1-yl}-methyl]-3-benzhydryl-pyrrolidine-2,5-dione (13) with ED5 0 value =101.46 mg/kg (MES) and ED5 0 value =72.59 mg/kg (scPTZ). These molecules showed higher potency and lower neurotoxicity than the reference antiepileptic drugs (ethosuximide and valproic acid). To explain the probable mechanism of action of selected active derivatives (9 and 13), their influence on Nav1.2 and l-type calcium channel was evaluated in vitro.

Evaluation of anticonvulsant and antinociceptive properties of new N-Mannich bases derived from pyrrolidine-2,5-dione and 3-methylpyrrolidine-2,5-dione.

The aim of the present experiments was to examine anticonvulsant activity of new pyrrolidine-2,5-dione and 3-methylpyrrolidine-2,5-dione derivatives in animal models of epilepsy. In addition, the possible collateral antinociceptive activity was assessed. Anticonvulsant activity was investigated in the electroconvulsive threshold (MEST) test and the pilocarpine-induced seizure models in mice. Antinociceptive activity was examined in the hot plate and the formalin tests in mice. Considering the drug safety evaluation, the Vibrio harveyi test was used to estimate anti/mutagenic activity. To determine the plausible mechanism of anticonvulsant action, for two chosen compounds (12 and 23), in vitro binding assays were carried out. All of the tested compounds revealed significant anticonvulsant activity in the MEST test. Compounds 12 and 23 displayed anticonvulsant effect also in pilocarpine-induced seizures. Four of the tested compounds (12, 13, 15, and 24) revealed analgesic activity in the hot plate test as well as in the first phase of the formalin test, and all of them were active in the second phase of the formalin test. The possible mechanism of action of compounds 12 and 23 is the influence on the neuronal voltage-sensitive sodium and L-type calcium channels. The obtained results indicate that in the group of pyrrolidine-2,5-diones, new anticonvulsants with collateral analgesic properties can be found.

Design, synthesis and biological activity of new amides derived from 3-methyl-3-phenyl-2,5-dioxo-pyrrolidin-1-yl-acetic acid.

A series of new 3-methyl-3-phenyl-2,5-dioxo-pyrrolidin-1-yl-acetamides (6-23) has been synthesized and evaluated for their anticonvulsant activity in the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests after intraperitoneal injection in mice. The acute neurological toxicity was determined using the rotarod test. The in vivo preliminary pharmacological results showed that in the whole series only two compounds (15, 21) were devoid of activity, whereas other molecules revealed protection in at least one animal model of epilepsy (MES or/and scPTZ). The in vivo quantitative studies in mice showed that in the MES test the most active were 1-{2-[4-(2-methoxyphenyl)-piperazin-1-yl]-2-oxo-ethyl}-3-methyl-3-phenyl-pyrrolidine-2,5-dione (17), 1-{2-[4-(4-fluorophenyl)-piperazin-1-yl]-2-oxo-ethyl}-3-methyl-3-phenyl-pyrrolidine-2,5-dione (8), and its 2-fluorophenyl analog (7) with ED50 values of 97.51 mg/kg (17), 104.11 mg/kg (8), and 114.68 mg/kg (7), respectively. In the scPTZ screen the most potent were compound 6 with an ED50 = 40.87 mg/kg, and 4-benzylpiperidine derivative 22 - ED50 = 60.00 mg/kg. Furthermore, selected compounds 8, 14, 17, and 23 were tested in the psychomotor seizure 6-Hz test. Compounds 7, 8, and 17 revealed significant analgesic activity in the formalin model of tonic pain in mice, without impairment of the motor coordination in the chimney test. The in vitro binding studies showed that the mechanism of anticonvulsant activity may be partially related with the influence on the voltage-gated sodium and calcium channels. The mutagenic and antimutagenic effects of 13, 17, and 22 were evaluated using the novel Vibrio harveyi assay.

Antinociceptive properties of N-Mannich bases derived from 3-substituted pyrrolidine-2,5-dione in the formalin model of persistent pain in mice.

BACKGROUND: Accumulated data indicate that anticonvulsants possess antinociceptive properties in rodent pain models. In view of the anticonvulsant activity demonstrated previously among N-Mannich bases derived from 3-mono- (1-6) and 3,3-disubstituted pyrrolidine-2,5-diones (7-14) their analgesic activity has been investigated in the formalin model of tonic pain in mice. METHODS: The compounds 1-14 were tested at doses equal to the respective ED50 values obtained earlier in the MES test. 0.5% formalin solution was given as intraplantar injections into the hind paw of the mouse and the duration of the nocifensive response was counted in drug-treated and vehicle-treated animals in the acute and the late phases of the test. RESULTS: A significant antinociceptive activity was observed for majority of the compounds. In the first phase of the test all the active compounds, except for 9-11, reduced the duration of the licking response up to 88% (compounds 2 and 6; p<0.001). In the late phase the 1-3, 5, 6, 9 and 14 were the most effective agents and their analgesic activities ranged from 92 to 100%. CONCLUSIONS: The results of the research indicate that some of the investigated compounds reduced effectively either both phases of the test or were able to attenuate pain during only the acute or late phase of the formalin test. These properties, which are particularly strong in case of the compounds 1-3, 5, 6, 9 and 14, might be relevant for the development of novel analgesic-active compounds and their possible use in neuropathic pain syndromes.

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.