S(+)-(2E)-N-(2-Hydroxypropyl)-3-Phenylprop-2-Enamide (KM-568): A Novel Cinnamamide Derivative with Anticonvulsant Activity in Animal Models of Seizures and Epilepsy

Epilepsy is one of the most frequent neurological disorders affecting about 1% of the world’s human population. Despite availability of multiple treatment options including antiseizure drugs, it is estimated that about 30% of seizures still remain resistant to pharmacotherapy. Searching for new antiseizure and antiepileptic agents constitutes an important issue within modern medicinal chemistry. Cinnamamide derivatives were identified in preclinical as well as clinical studies as important drug candidates for the treatment of epilepsy. The cinnamamide derivative presented here: S(+)-(2E)-N-(2-hydroxypropyl)-3-phenylprop-2-enamide (S(+)-N-(2-hydroxypropyl)cinnamamide, compound KM-568) showed anticonvulsant activity in several models of epilepsy and seizures in mice and rats. It was active in a genetic animal model of epilepsy (Frings audiogenic seizure-susceptible mouse model, ED(50) = 13.21 mg/kg, i.p.), acute seizures induced electrically (maximal electroshock test ED(50) = 44.46 mg/kg mice i.p., ED(50) = 86.6 mg/kg mice p.o., ED(50) = 27.58 mg/kg rats i.p., ED(50) = 30.81 mg/kg rats p.o., 6-Hz psychomotor seizure model 32 mA ED(50) = 71.55 mg/kg mice i.p., 44 mA ED(50) = 114.4 mg/kg mice i.p.), chronic seizures induced electrically (corneal kindled mouse model ED(50) = 79.17 mg/kg i.p., hippocampal kindled rat model ED(50) = 24.21 mg/kg i.p., lamotrigine-resistant amygdala kindled seizure model in rats ED(50) = 58.59 mg/kg i.p.), acute seizures induced chemically (subcutaneous metrazol seizure threshold test ED(50) = 104.29 mg/kg mice i.p., ED(50) = 107.27 mg/kg mice p.o., ED(50) = 41.72 mg/kg rats i.p., seizures induced by picrotoxin in mice ED(50) = 94.11 mg/kg i.p.) and the pilocarpine-induced status epilepticus model in rats (ED(50) = 279.45 mg/kg i.p., ED(97) = 498.2 mg/kg i.p.). The chemical structure of the compound including configuration of the chiral center was confirmed by NMR spectroscopy, LC/MS spectroscopy, elemental analysis, and crystallography. Compound KM-568 was identified as a moderately stable derivative in an in vitro mouse liver microsome system. According to the Ames microplate format mutagenicity assay performed, KM-568 was not a base substitution or frameshift mutagen. Cytotoxicity evaluation in two cell lines (HepG2 and H9c2) proved the safety of the compound in concentrations up to 100 µM. Based on the results of anticonvulsant activity and safety profile, S(+)-(2E)-N-(2-hydroxypropyl)-3-phenylprop-2-enamide could be proposed as a new lead compound for further preclinical studies on novel treatment options for epilepsy.