Phthalazine-1,4-dione derivatives as non-competitive AMPA receptor antagonists: design, synthesis, anticonvulsant evaluation, ADMET profile and molecular docking

In view of the anticonvulsant activity reported for phthalazine derivatives as non-competitive AMPA receptor antagonists, a new series of phthalazine-1,4-diones (2-12) were designed and synthesized. The neurotoxicity was assessed using rotarod test. The molecular docking was performed for the synthesized compounds to assess their binding affinities toward AMPA receptor as non-competitive antagonists. The molecular modeling data were strongly interrelated to biological screening data. Compounds 8, 7(b), 7(a), 10 and 3(a) exhibited the highest binding affinities as non-competitive AMPA receptor antagonists and also showed the highest relative potencies of 1.78, 1.66, 1.60, 1.59 and 1.29, respectively, as anticonvulsants in comparison with diazepam. The most active compounds 8, 7(b), 7(a), 10 and 3(a) were further tested against maximal electroshock seizure (MES). Compounds 8 and 7(b) and 3(a) showed 100% protection at a dose level of 125 mu gm/kg, while compounds 7(a) and 10 exhibited 83.33% protection at the same dose level. These agents exerted low neurotoxicity and high safety margin in comparison with valproate as a reference drug. Most of our designed compounds exhibited good ADMET profile.