Synthesis, characterization and biological evaluation of some new amlodipine derivatives

Background and objective: The Schiff base compound is formed by the condensation reaction of a primary amine with aldehydes or ketones to form the azomethine group RCH=N-R. This study aims to synthesize some new compounds as Schiff bases from amlodipine derivatives and study their biological activity. Methods: Ether derivatives of benzaldehyde were synthesized using the Williamson ether synthetic method to react with 3-O-ethyl 5-O-methyl 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-6-methyl-1,4-dihydropyridine-3,5-dicarboxylate (amlodipine). Another type of Schiff bases was synthesized from some derivatives of benzaldehyde without the ether group. Results: The series of Schiff base compounds (6a–k) were obtained from the reaction of benzaldehyde derivatives (5a–k) with amlodipine (4). IR, 1H-NMR, and 13C-NMR spectroscopy were used for the characterization of the synthesized compounds. The antibacterial activities of both types of Schiff base compounds against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were compared. Conclusion: All of the synthesized ether derivatives (6a–f) showed more antibacterial activity than the derivatives of benzaldehyde (6g–k), and all of the synthesized compounds were more active against Gram-negative bacteria (Escherichia coli) than Gram-positive Staphylococcus aureus.