Synthesis and Anticonvulsant Activity of Substituted-1,3-diazaspiro[4.5]decan-4-ones.

A series of novel spiroimidazolidinone derivatives 6a-d and 8a-x were synthesized and biologically evaluated for their anticonvulsant activity in the maximal electroshock seizure (MES) assay and the subcutaneous pentylenetetrazole (scPTZ) screening test. Compound 8w was the most active derivative in the scPTZ screening test with an ED50 value by about 5- and 83.6-fold lower than those of phenobarbital and ethosuximide as reference drugs, respectively. Most of the tested compounds exhibited moderate to weak activity in the MES screen test, except for 8a which displayed 100% protection at 0.09 mmol/kg. Moreover, all the test compounds did not show any minimal motor impairment in the neurotoxicity test.