Synthesis and antimicrobial evaluation of some new substituted purine derivatives

A series of 8,9-disubstituted adenines (4, 5, 8), 6-substituted aminopurines (10–13) and 9-(p-fluorobenzyl/cyclopentyl)-6-substituted aminopurines (16, 17, 19–30) have been prepared and the antimicrobial activities of these compounds against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA, standard and clinical isolate), Bacillus subtilis, Escherichia coli and Candida albicans were evaluated. 6-[(N-phenylaminoethyl)amino]-9H-purine (12) which has no substitution at N-9 position and 9-cyclopentyl-6-[(4-fluorobenzyl)amino]-9H-purine (24) exhibited excellent activity against C. albicans with MIC 3.12 μg/mL. These compounds displayed better antifungal activity than that of standard oxiconazole. Furthermore, compound 22 carrying 4-chlorobenzylamino group at the 6-position of the purine moiety exhibited comparable antibacterial activity with that of the standard ciprofloxacin against both of the drug-resistant bacteria (MRSA, standard and clinical isolate).