Original anticonvulsant properties of two N-phenylphthalimide derivatives

Impact of N-Alkylamino Substituents on Serotonin Receptor (5-HTR) Affinity and Phosphodiesterase 10A (PDE10A) Inhibition of Isoindole-1,3-dione Derivatives

In this study, a series of compounds derived from 4-methoxy-1H-isoindole-1,3(2H)-dione, potential ligands of phosphodiesterase 10A and serotonin receptors, were investigated as potential antipsychotics. A library of 4-methoxy-1H-isoindole-1,3(2H)-dione derivatives with various amine moieties was synthesized and examined for their phosphodiesterase 10A (PDE10A)-inhibiting properties and their 5-HT_1A and 5-HT₇ receptor affinities. Based on in vitro studies, the most potent compound, 18 (2-[4-(1H-benzimidazol-2-yl)butyl]-4-methoxy-1H-isoindole-1,3(2H)-dione), was selected and its safety in vitro was evaluated. In order to explain the binding mode of compound 18 in the active site of the PDE10A enzyme and describe the molecular interactions responsible for its inhibition, computer-aided docking studies were performed. The potential antipsychotic properties of compound 18 in a behavioral model of schizophrenia were also investigated.

Synthesis and anticonvulsant evaluation ofN-substituted-isoindolinedione derivatives

A series of N-substituted-1,3-isoindolinedione derivatives (2-16) were synthesized for the purpose of defining the effect of N-substitution on the anticonvulsant activity of these derivatives. The target compounds (2-16) were obtained by condensation of phthalic anhydride with the corresponding amine derivative. The structures of the synthesized derivatives (2-16) were confirmed by means of IR, 1H-NMR, 13C-NMR, MS and elemental analyses. The anticonvulsant activity of all compounds (2-16) were evaluated by subcutaneous pentylenetetrazole seizure threshold test at doses of 0.2, 0.4 and 0.8 mmol/kg compared with sodium valproate as a positive control. Their neurotoxicity were determined by the rotorod test. Many of the present series of compounds showed good anticonvulsant activity at the tested doses, as compared to sodium valproate. Three of them (4, 6 and 11) exhibited 100% protection against convulsions, neurotoxicity and death at all tested doses. Out of the series, two compounds (12 and 13) were completely inactive with 100% mortality. 3-(p-chlorophenyl)-4-(1,3-dioxo-2,3-dihydro-1H-2-isoindolyl)butanoic acid derivative (11) has emerged as the most active compound which is 20 times more active than valproate with ED50 8.7, 169 mg/kg; TD50 413, 406 mg/kg and PI 47.5, 2.4. The results revealed the importance of the combination of baclofenic and phthalimide moieties (compound 11) as a promising anticonvulsant candidate.

Comparative anticonvulsant activity and neurotoxicity of 4-amino-N-(2,6-dimethylphenyl)phthalimide and prototype antiepileptic drugs in mice and rats

We compared the anticonvulsant activity and neurotoxicity of 4-amino-N-(2,6-dimethylphenyl)phthalimide (ADD 213063) with those of phenytoin (PHT), carbamazepine (CBZ), phenobarbital (PB), ethosuximide (ESM), valproate (VPA), and felbamate (FBM). Evaluation of anticonvulsant properties performed according to well-established procedures in rats and mice showed that ADD 213063 is most effective in protecting animals against maximal electroshock seizures (MES). This anti-MES activity is achieved with nontoxic doses, with the optimal effect recorded in rats dosed orally with anti-MES ED50 and protective index (PI) values of 25.2 mumol/kg and > 75, respectively. ADD 213063 protects to a lesser extent against seizures induced by subcutaneous (s.c.) picrotoxin and subcutaneous pentylenetetrazol (PTZ) in mice dosed intraperitoneally and orally, respectively. The profile of anticonvulsant action of ADD 213063 closely parallels that of CBZ.

Synthesis and anticonvulsant activity of two N-(2,6- dimethylphenyl)pyridinedicarboximides

Two N-(2,6-dimethylphenyl)pyridinedicarboximides were synthesized and evaluated for anticonvulsant properties and neurotoxicity. These compounds were mainly active against maximal electroshock (MES) induced seizures in animal models. In rats dosed orally, N-(2,6-dimethylphenyl-2,3-pyridinedicarboximide 1 exhibited an anti-MES ED50 of 54.2 mumol/kg and a protective index (PI = TD50/ED50) superior to 27.4. In mice dosed intraperitoneally, compound 1 is less active against MES induced seizure (ED50 = 160.9 mumol/kg) and more neurotoxic as evidenced by a low protective index (1.93). Comparison with published data on phenytoin reveals that compound 1 is, in rats dosed orally, two-fold more potent than this antiepileptic drug against MES induced seizures.

Anticonvulsant activity of some 4-amino-N-phenylphthalimides and N-(3-amino-2-methylphenyl)phthalimides

A series of fifteen N-phenylphthalimides including 12 4-amino-N-phenylphthalimides and three N-(3-amino-2-methylphenyl)phthalimides was prepared and evaluated for anticonvulsant properties. The compounds were tested against seizures induced by electroshock (MES) and pentylenetetrazol (scPTZ) in mice dosed intraperitoneally. Their neurologic toxicity was assessed using the rotorod assay procedure. The most potent 4-amino-N-phenylphthalimides against MES were those possessing small lipophilic groups in either 2 or 2 and 6 positions of the N-phenyl ring. They also exhibited some activity against scPTZ and were the most toxic of the series. By contrast, no activity against scPTZ or neurotoxicity could be observed up to 300 mg/kg for members of the N-(3-amino-2- methylphenyl)phthalimide series. In this series, the order of anti-MES activity appears to correspond to the phthalimide ring substitution pattern of 4-amino > H > 4-methyl. Quantitation of anticonvulsant properties and toxicity of 4-amino-N-(2,6-dimethylphenyl)phthalimide (ADD 213063) previously initiated in rats has been, here, extended to mice dosed intraperitoneally but also orally. The confrontation of the two modes of administration in mice suggests that ADD 213063 presents with a good bioavailability.