Synthesis and anticonvulsant and neurotoxic properties of substituted N- phenyl derivatives of the phthalimide pharmacophore

Article abstract of DOI:10.1021/jm990068t

A series of compounds including 4-amino (1), 3-amino (2), 4-nitro (3), 2-methyl-3-amino (4), 2-methyl-3-nitro (5), 2-methyl-4-amino (6), 2-methyl-4- nitro (7), 2-methyl-5-amino (8), 2-methyl-5-nitro (9), 2-methyl-6-amino (10), 2-methyl-6-mitro (11), 2,6-dimethyl (12), 2-methyl-3-carboxy (13), 2- methoxycarbonyl (14), 2-methyl-4-methoxy (15), 2,4-dimethoxy (16), 2-chloro- 4-amino (17), and 2-chloro-4-nitro (18) N-phenyl substituents of phthalimide were evaluated along with N-[3-methyl-(2-pyridinyl)]phthalimide (19), N-(3- amino-2-methylphenyl)succinimide (20), and phenytoin for anticonvulsant and neurotoxic properties. Initial screening in the intraperitoneal (ip) maximal electroshock-induced seizure (MES) test and the subcutaneous pentylenetetrazol-induced seizure (scPtz) test in mice led to the selection of 1, 2, 4, 10, 12, 17, and 19 for oral MES evaluation in rats. The resultant ED₅₀ values for 4, 10, 17, and phenytoin were 8.0, 28.3, 5.7 and 29.8 mg/kg, respectively. In the batrachotoxin affinity assay, IC₅₀ values for 17 and phenytoin were 0.15 and 0.93 μM, respectively, and in the recently validated magnesium deficiency-dependent audiogenic seizure test, ED₅₀ values of 5.2 and 23 mg/kg were obtained for 17 and phenytoin, respectively. Electrophysiology studies on compound 17 point out its ability to (i) potentiate GABA-evoked current responses with a failure to directly activate the GABAA receptor and (ii) to affect, at 100 μM excitatory non NMDA, but not NMDA, receptors with a 25% block of kainate-evoked response. Electrophysiology measurements on voltagegated sodium channels in N1E-115 neuroblastoma cells confirm voltage-dependent block of these channels by compound 17. In view of its interaction with multiple ion channels, one would predict that compound 17 might be active in a wide range of seizure models.