Synthesis, Characterization and Antibacterial Studies of Some Isoniazid-derived Schiff Bases

Aims: To synthesize some isoniazid-derived imines by the condensation of isoniazid (INH) with some substituted benzaldehydes as well as pyridine carboxaldehydes and to determine their structures by spectroscopic methods.

Methodology: Isoniazid was mixed with equimolar amounts of some substituted benzaldehyes as well as pyridine carboxaldehydes and refluxed for 4-7 hours. The solid products were filtered by gravity and dried over anhydrous CaCl2 in a desiccator. The ligands were screened for the biological activities against Salmonella typhi, Staphylococcus aureus, Escherichia coli, Shiegella flexneri, and Salmonella enterica by paper disc diffusion method.

Results: Nine Schiff bases were synthesized and characterized by elemental analyses, 1H NMR, and13C NMR. Their melting temperatures were determined and their purity ascertained by HPLC.

Conclusion: Nine isoniazid-derivedimines were synthesized and characterized. The antibacterial activities of some of the imines were comparable to the activity of isoniazid against E. coli, whereas the other Schiff bases were more active than isoniazid against the other tested pathogens. Compound 7 showed good antibacterial activity compared to isoniazid against all the tested pathogens and compound 4 was inactive against all pathogens.