Eco-Friendly Synthesis and Molecular Modelling of 2-Phenylimidazo[1,2-b]pyridazine Derivatives: In Vitro and In Vivo Studies for Lead Optimization.

Abstract

7-methyl-2-phenylimidazo[1,2-b]pyridazin-3-carboxylic acid (DM1) and 6-methoxy-2-phenylimidazo[1,2-b]pyridazin-3-carboxylic acid (DM2) have been shown to act as human (h) Cav3.1 voltage-gated calcium channel blockers with promising in vivo anti-absence activity, positioning them as potential antiepileptic drugs. The primary aim of this work was to develop cost-effective and environmentally friendly synthetic procedures for preparing 2-phenylimidazo[1,2-b]pyridazine derivatives. After optimizing the synthesis of this compound class using efficient and green techniques such as microwaves and ultrasound irradiation, we further evaluated the antiepileptic effects of DM1 and DM2 in two animal models: CD-1 ICR mice after pentylenetetrazol administration and DBA/2 mice with seizures induced by audiogenic stimuli. Their neuroprotective effect against oxidative stress were assessed using C6 rat brain glioma cells. DM1 and DM2 exhibited potent anti-seizure effects in both animal models and demonstrated significant in vitro neuroprotective activity by reducing reactive oxygen species release. To lay the groundwork for the future rational optimization of this promising class of compounds, the molecular bases of DM1 and DM2 activity were investigated by modelling their interaction with hCav3.1 channels. The calculated binding modes of DM1 and DM2 to hCav3.1 channels partially mirrored that of the selective Cav3.1 blocker Z944, paving the way for future lead optimization.