Design and synthesis of novel heterofused pyrimidine analogues as effective antimicrobial agents

A total of 66 novel heterofused pyrimidine analogues (pyrazolo[3,4-d]pyrimidine (7-43) and pyrido[2,3-d]pyrimidine (51a-l & 52a-h)) were synthesized by employing suitable methods. The desired structures of all the synthesized compounds were confirmed based on FT-IR, 1H NMR, 13C NMR and HRMS experimental data. Further, 19F NMR and 1H-15N HMBC of the representative compound were presented. All the final compounds were screened for their in vitro antitubercular (Mycobacterium tuberculosis; H37 Rv), antibacterial (S. aureus, B. subtilis, E. coli and P. aeruginosa) and antifungal (C. neoformans, C. albicans and A. niger) activities. Compounds 51d, 51j, 51k, 51l, and 51g displayed good antibacterial and antifungal activity (MIC = 12.5 μg/ml) against bacterial and fungal strains, while moderate inhibition (MIC = 59 μM) was observed for 51l against H37 Rv strain.