Synthesis and Antibacterial Evaluation of Novel Small-Molecule Antibacterials of a Reduced Acridine Structure in S. aureus Strains Including MRSA.

The increasing antibacterial drug resistance remains a threat to global health with increasing mortality and morbidity. There is an urgent need to find novel antibacterials and develop alternative strategies to combat the increasing antibacterial drug resistance. <P> </P> Objective: We aimed to synthesize novel small-molecule antibacterials to evaluate the structuredependent antibacterial compound activities against S. aureus and MRSA. <P> </P> Method: Compounds were synthesized by primary N-alkylation to form alkyl acridinium salts that were further functionalized with substituted phenyl residues and finally purified by column chromatography. The antibacterial growth inhibition activity was determined as MIC value. <P> </P> Results: The substituent effects on the determined antibacterial growth inhibitory properties have been discussed. <P> </P> Conclusion: The best activities have been found for compounds with methoxy functions, exceeding the activities of reported novel antibacterial peptides. The compounds have also shown antibacterial drug-enhancing effects, which have been manifested as a reduction in the MIC values of the used antibiotics.