New quaternary ammonium pyridoxine derivatives: synthesis and antibacterial activity

Abstract

© 2017, Springer Science+Business Media, LLC. A diverse library of 34 new quaternary mono-ammonium and bis-ammonium pyridoxine derivatives was synthesized, and their antibacterial activity against several clinically relevant bacterial strains was evaluated in vitro. Several mono-ammonium compounds demonstrated high antibacterial activity against methicillin-resistant Staphylococcus strains with minimum inhibitory concentrations in the range of 0.5–8 µg/mL, which exceeded activity of miramistin and was comparable to that of benzalkonium chloride. SOS-chromotest in Salmonella typhimurium showed the lack of DNA-damage activity for all active compounds. A clear correlation has been observed between the lipophilicity of the obtained compounds and their activity against the studied Gram-positive bacterial strains. Cytotoxicity studies on HEK-293 cells demonstrated that some of the active compounds were less toxic than the reference drugs. Antibacterial activity studies in the presence of CaCl 2 suggested that the cell wall damage associated with the removal of Ca 2+ ions from the bacterial membrane is one of the possible mechanisms of antibacterial activity. The obtained results make the described active compounds a promising starting point for the development of new antibacterial therapies.