Synthesis and potent antimicrobial activity of some novel 2-phenyl or methyl-4H-1-benzopyran-4-ones carrying amidinobenzimidazoles

Series of flavones and methyl-4H-1-benzopyran-4-ones carrying mono or diamidinobenzimidazoles at different positions were synthesized and evaluated for antibacterial and antifungal activities against E. coli, S. aureus, MRSA (methicillin-resistant S. aureus), MRSE (methicillin-resistant S. epidermidis), S. faecalis and C. albicans, C. krusei. The results showed that while all diamidines are inactive, the compounds having monoamidinobenzimidazoles at the C-6 position of the 2-phenyl-4H-1-benzopyran-4-one have potent antibacterial activities, particularly, against Gram-positive bacteria. Compounds 23 and 22 exhibited the best inhibitory activity with MIC values of 1.56 microg/ml against S. aureus, MRSA, MRSE and 3.12 microg/ml against C. albicans, respectively.