Design, synthesis and biological evaluation of phenylacridine based antibacterial agent

KWTRT de Silva, RP Perera, CM Nanayakkara


Objective: The rapid development of multidrug resistant pathogenic bacteria and shortage of new antimicrobial agents prompted us to develop a novel antimicrobial agent with less toxicity to humans.  Discovery of penicillin outrivaled acridine, a medicinally important heterocyclic nucleus, but extensive increase of bacterial drug resistance captures scientists’ consideration to acridine again. The present study is to develop an acridine based new antimicrobial agent.

Method: An organic synthesis was carried out to synthesize the novel acridine derivative of 9-phenyl-10-(2-phenylalkyl)acridinium bromide. The formation of the compound was confirmed using 1H-NMR analysis; (acetone, δ, ppm): 3.8 (s,2H), 5.0 (s,2H), 7.24-7.47 (m,8H), 7.8-7.4 (m,5H), 8.0-7.8 (m,5H). In vitro antimicrobial activities of 9-phenyl-10-(2-phenylalkyl)acridinium bromide was measured against Gram positive Staphylococcus aureus and against Gram negative Escherichia coli from disk diffusion method using gentamycin as the positive control.

Results: S.aureus showed a higher antibacterial activity (12 mm for 2 µl/ml) than activity (11 mm for 2 µl/ml) against E.coli for 9-phenyl-10-(2-phenylalkyl)acridinium bromide. For grntamycin (3000 µg/ml), inhibition for S.aureus was 24 mm and for E.coli it was 23 mm. The MIC for S.aureus was 3 x 10-4 µl/ml and the MIC for E.coli was 1 x 10-2 µl/ml. The density of the novel compound is apparently higher than that of water. Therefore these MIC values should be lesser than 0.3 µg/ml and 10 µg/ml respectively.

Conclusion: Strong antibacterial activity of 9-phenyl-10-(2-phenylalkyl)acridinium bromide against S.aureus and E.coli indicates that there is a possibility to use it as an effective antibacterial agent.


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Proceedings of Annual Scientific Sessions of Faculty of Medical Sciences, University of Sri Jayewardeneprua, Sri Lanka