Synthesis and antimicrobial activity of some new pyrazolo[3,4-d] pyrimidines and thiazolo[4,5-d]pyrimidines

The desired fused ring system 3-isopropyl-4-aryl-1,4,5,7-tetra hydropyrazolo[3,4-d] pyrimidin-6-ones 4a-d have been synthesized by the reaction of 5-isopropyl-2,4-dihydro-3-pyrazolone 1, urea and different aromatic aldehydes, while 7-aryl-6,7-dihydro-3H,4H-thiazolo[4,5-d]pyrmidine-2,5-diones 7a-d have been synthesized by using 2,4-thiazolidine 5 instead of 5-isopropyl-2,4-dihydro-3-pyrazolone 1. The structures of the compounds have been characterized by elemental analysis, IR, H-1 NMR, and mass spectroscopy. The antibacterial activity of the newly synthesized compounds have been tested against Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 1539; antifungal activity against Candida albicans ATCC 10231 have been tested using the disk diffusion method. Compounds 4b, 4c, 4d, 7c and 7d are found to be active against S. aureus ATCC 6538 (MIC: 185, 78, 156, 72 and 102 mu g/mL, respectively) and compounds 4d and 7d against C albicans ATCC 10231 (MIC: 312.5 mu g/mL). The minimum inhibitory concentrations of these compounds have been determined using the micro dilution method.