Synthesis and antimicrobial activity of newly synthesized 4-substituted-pyrazolo[3,4-d]pyrimidine derivatives

The purpose of this study was to explore the possibility of synthesizing pyrazolo[3,4-d]pyrimidine derivatives that have antimicrobial activities. A novel series of 4-substituted-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine derivatives including hydrazones (4a-i and 5), pyrazoles (6a, b) and (8), and oxadiazole-2-thiol (7), has been synthesized. Compounds 4g, 4b, 4h, 4d, 6a, 7, 8 have shown that some of the synthesized compounds have a moderate to outstanding antimicrobial activity against Gram Positive bacteria: Streptococcus pneumonia and Bacillis subtilis, gram negative bacteria: Pseudomonas aeruginosa and Escherichia coli, and fungi: Aspergillus fumigatus and Candida albicans strains. Interestingly, compound (7) "5-{[(1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-yl)amino]methyl}-1,3,4-oxadiazole-2-thiol" exhibited superior antimicrobial activity compared to ampicillin and gentamicin suggesting that it can be used as a lead compound for further investigations.