Synthesis and evaluation of some novel derivatives of 2-propoxybenzylideneisonicotinohydrazide for their potential antimicrobial activity

A novel series of Mannich bases containing isoniazid were prepared. First, reaction of 2-propoxybenzaldehyde with isoniazid gave the corresponding hydrazone (2a). Subsequently, product 2a after the Mannich reaction of aminomethylation with formaldehyde and secondary amines gave 2b–k. The inhibitory potencies of the synthesized compounds were assayed in vitro against a panel of microorganisms and against the A549 human lung adenocarcinoma cell line. Compounds 2c and 2k displayed moderate to potent antimicrobial activity against all the tested strains and they also exhibited significant cytotoxicity in a dose-dependent manner with IC50 values ranging from 2.84 to 8.55 μg/mL and 0.007–0.030 mM. The structures of the newly synthesized compounds were evaluated by elemental and spectral (IR, 1H-NMR, 13C-NMR) methods. The results demonstrated the potential and importance of developing new Mannich bases which would be effective against resistant microbial strains and may be useful leads for anticancer drug development in the future.