Antibacterial activity of substituted 5-methylbenzo[c]phenanthridinium derivatives

X1 and X12=H, phenyl, 4-bipheny R2,R3=OCH3 or –OCH2O– R7,R8=OCH3 or O–CH2O– and X1=C2H3, C3H5, C6H9, C6H11, 4-N(CH3)2phenyl, 3,4,5-trimethoxyphenyl, 3-furanyl, or 3-pyridyl R2,R3,R7,R8=OCH3. Antibiotic resistance has prompted efforts to discover antibiotics with novel mechanisms of action. FtsZ is an essential protein for bacterial cell division, and has been viewed as an attractive target for the development of new antibiotics. Sanguinarine is a benzophenanthridine alkaloid that prevents cytokinesis in bacteria by inhibiting FtsZ self-assembly. In this study, a series of 5-methylbenzo[c]phenanthridinium derivatives were synthesized and evaluated for antibacterial activity against Staphylococcus aureus and Enterococcus faecalis. The data indicate that the presence of a 1- or 12-phenyl substituent on 2,3,8,9-tetramethoxy-5-methylbenzo[c]phenanthridinium chloride significantly enhances antibacterial activity relative to the parent compound or sanguinarine.