Synthesis and antimicrobial evaluation of guanylsulfonamides

A series of guanylsulfonamides, 2-amino-9-[2-substituted-4-(4-substituted piperidin-1-sulfonyl)phenyl]-1,9-dihydropurin-6-ones, was synthesized by adopting reductive aminoformylation of 2-amino-5-nitro-6-[4-(piperidin-1-sulfonyl)phenylamino]-3H-pyrimidin- 4-one and subsequent intramolecular ring condensation as key steps. All the guanylsulfonamides were assayed for their in vitro antibacterial activities against Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, and Streptococcus faecalis, and their antifungal activities against Aspergillus flavus, Aspergillus niger, and Candida albicans. Of the guanylsulfonamides, 13e and 13f displayed better antibacterial activities than that of Norfloxacin against the bacterial strains S. aureus and S. faecalis except 13f against S. faecalis, which exhibited the activity similar to that of Norfloxacin. Against the fungal strains A. flavus and A. niger, 13g and 13h showed similar activities to that of Griseoflavin-16 except 13h against A. niger, which displayed a profound drop in the activity compared to that of Griseoflavin-16. The remarkable inhibition of the growth of the bacterial and fungal strains makes these substances promising microbial agents.