Schiff bases are versatile ligands capable of forming stable coordination compounds with transition metals, often enhancing biological activity through chelation. In this study, two quinoline-based Schiff base ligands derived from isoniazid were synthesized and used to prepare their Cu(II) and Zn(II) complexes. The ligands and their complexes were characterized using infrared, ultraviolet-visible, and nuclear magnetic resonance spectroscopy. Spectroscopic data confirmed bidentate coordination through azomethine nitrogen and carbonyl oxygen atoms, with Cu(II) complexes exhibiting distorted octahedral and square planar geometries, while Zn(II) complexes showed octahedral geometry. The compounds were evaluated for in vitro antimalarial activity against Plasmodium falciparum (3D7 strain) using the SYBR Green I fluorescence assay. All compounds demonstrated more than 50% inhibition at 10 μM, with the Cu(II) complex of ligand L1 showing the highest activity (69.0%), close to the values of chloroquine (74.3%) and artemisinin (74.4%) under the same screening conditions. These findings highlight the potential of isoniazid-derived Schiff base metal complexes as promising candidates for the development of new antimalarial agents.
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