Synthesis, characterization, in vitro and computational assessment of new xanthene hydrazone derivatives as promising vasorelaxant agents

Abstract

Functionalized xanthene hydrazone derivatives were synthesized using two distinct pathways. Two routes of synthesis, involving condensation and O-alkylation reactions, were adopted to synthesize the target compounds. The structures of the synthetised intermediates and xanthene hydrazone derivatives were confirmed through high-resolution mass spectrometry (HRMS), ¹H-nuclear magnetic resonance (NMR), and ¹³C-NMR. Vasorelaxation assays indicated that derivatives modified solely by alkylation or condensation remained inactive. It was observed that compounds became active only when both functional groups were present simultaneously, highlighting the importance of the complementarity of the ester and hydrazone in the mechanism of action. Among the derivatives examined, compounds F3 and F4 exhibited the greatest potency as vasorelaxants, with EC₅₀ values of 38.204 and 41.300 µg mL⁻¹ and E_max values of 80.61% and 83.13%, respectively. While F3 and F4 displayed somewhat lower potency than verapamil (EC₅₀ = 18.000 ± 1.00 µg mL⁻¹; E_max = 61.67 ± 4.10%), they demonstrated significantly greater maximal effectiveness. These findings highlighted the great potential of compounds F3 and F4 as new vasorelaxant agents. Results of the in vitro tests on rat aortic rings that were pre-contracted using epinephrine revealed a clear correlation between both the chemical structure and biological activity. The results of molecular docking and molecular dynamics simulations show that F3 and F4 formed stable and robust binding modes with the human L-type calcium channel (CaV1.2). Furthermore, the in silico findings suggest that F3 and F4 possess acceptable ADMET properties, supporting their potential as promising drug candidates. Overall, the results indicate that these functionalized xanthene-hydrazone derivatives represent a promising foundation for the development of novel vasorelaxant agents.