Synthesis and antibacterial activity of 3-(arylazo)indoles and related azoheterocycles

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospitalizations and mortality from bacterial infections and is considered a national priority for disease control. In this work we synthesized and evaluated twenty novel C-3 arylazo-coupled indoles and one 4-arylazo-benzo[d]imidazole. The substituents on the C3-aromatic moiety included alkyl, halogen, amino, alkoxy, alkylsulfonyl at positions ortho, meta and para. The indoles utilized were 4-bromo, 5,6-methylenedioxy, 7-aza. In this effort, several azo-indoles showed promising anti-MRSA activities with MIC values as low as 3 μM. Another important finding of this work that sets that stage for a further larger investigation is that 4-arylazo-benzo[d]imidazole is a previously unexplored scaffold with potent anti-MRSA activity.