New biocidal hybrids bearing acridine and aminophosphonate Scaffolds against different bacterial pathogens

Abstract

New hybrids containing acridine and α-amino phosphonate scaffolds 6a-h were synthesized by three one-pot reactions via Kabachnik–Fields reaction of 9-aminoacridine derivatives 3a-d, aldehydes 4a,b and triphenyl phosphite 5 in equimolar ratio under stirring at room temperature. The installation of the afforded hybrids was affirmed by different spectroscopic methods as IR, 1HNMR, 13CNMR, 31P NMR, MS and elemental analysis. The antibacterial activities of hybrids 6a-h were screened against both Gram-positive and Gram-negative bacteria of four pathogenic strains, comparable to ampicillin and chloramphenicol drugs. Most hybrids showed higher activity compared to the reference drugs. Notably, the antibacterial performance of 6c was more substantial than other analogues with best minimum inhibitory concentration (MIC) and highest zone of inhibition (ZOI) of 31, 34, 35, 38 mm, against Serratia marcescens, Streptococcus mutans, MRSA and Klebsiella pneumoniae clinical isolates respectively. In addition, Transmission Electron Microscopes (TEM) was carried out to study the mode of action of 6c with MRSA, the results confirmed that the titled hybrid caused the disruption of bacterial cell wall. Moreover, the time-dependent kill study revealed that the investigated compounds were time and dose-effective bactericidal agents and could be used as potential leads for further development and optimization of novel antibacterial agents.