One-pot Synthesis and in Vitro Bioactivity of Novel 4-Aminopyrazolo[3,4-b]pyridine Derivatives As Potential Antimicrobial Compounds

The present paper describes an efficient synthesis of a series of 4-aminopyrazolo[3,4-b]pyridine derivatives 11a-i in 69-81% yields by one-pot three-component domino reaction of phenylhydrazine and two different beta-ketonitriles in DMSO. All the synthesized derivatives were screened in vitro for their antimicrobial potential against seven Gram-positive and Gram-negative clinical bacterial strains and one fungal strain. Most of the tested derivatives displayed promising antimicrobial potency and activity was found to be comparable to standard drugs (amoxicillin and fluconazole). Compounds 11a and 11d with the MIC value of 3.12 mu g/mL were identified as broad spectrum antibacterial agents. Compounds 11b, f, h and 11i exhibited equivalent antifungal activity (MIC 6.25 mu g/mL) against Candida albicans to fluconazole. Interestingly, all the compounds were found to be non-toxic to normal mammalian and plant cells at very high concentration of 1 mg/mL.