Synthesis, Characterization and Antibacterial Activity of Novel 2‐Oxo‐1,2‐dihydro‐1′H‐spiro[indoline‐3,2′‐quinazoline]‐4′‐carbohydrazones

Abstract

AbstractTreatment of isatin with ammonia in methanol under reflux, followed by hydrazine substitution of the methoxy group afforded isamic hydrazide in up to 79 % yield. Subsequent condensation of isamic hydrazide with selected aromatic ketones and aldehydes gave access to novel 2‐oxo‐1,2‐dihydro‐1′H‐spiro[indoline‐3,2′‐quinazoline]‐4′‐carbohydrazones (4–11) in yields between 59 % and 74 %. Detailed structural analysis of synthesized compounds was done using spectroscopic techniques. Antibacterial screening of the hydrazone derivatives (4–11) demonstrated broad‐spectrum activity against evaluated bacterial strains, with inhibition zones ranging from 10 to 32 mm. Specifically, compound 9 exhibited superior activity compared to the standard streptomycin against various bacterial strains, including B. polymyxa (LIO), B. cereus (NCBI 6349), C. pyogenes (LIO), B. subtilis (NCBI 3610), S. aureus (NCBI 8588), E. coli (NCIB 86), P. aeruginosa (NCIB 950), and K. pneumoniae (NCIB 418). Moreover, the inhibitory concentrations of compound 9 were lower than those of streptomycin, underscoring its efficacy as a potential antibacterial agent. These findings suggest that the synthesized hydrazone derivatives possess significant potential as novel and effective antibacterial agents, warranting further exploration in the field of antibacterial drug development.