Chiang Mai Journal of Science

 The stoichiometric reaction of citronellal with anthranilic acid in methanol was conducted. The reaction was kept on for four hours and stirred at room temperature. Consequently a new product of Schiff base was obtained. The synthesized Schiff base was then allowed to react with chloride salts of different active transition metals, including nickel, cobalt, copper, and zinc, to prepare their complexes. The synthesized Schiff base and its transition metal complexes were characterized by spectroscopic techniques such as 1H-NMR, 13C-NMR, FT-IR. Employing Disc diffusion protocol, Schiff base, and its metal complexes were subjected to antimicrobial assay against two Gram-positive bacterial strains, six Gram-negative bacterial strains, and two fungal strains. Schiff base and its metal complexes exhibited remarkable antimicrobial activity against the tested pathogens. Schiff base is active against all the pathogenic bacteria and fungi. It showed the best inhibition activity against K. pneumonia (18.9mm). None of the complexes was active against S. typhi except the Schiff base (15.8 mm). Among the complexes, NiL2 showed the best inhibition performance. It showed the highest inhibition activity against P. aeruginosa (19.7 mm). All the synthesized compounds were also searched for their antioxidant potential applying DPPH assay. Schiff base and the complexes have significant antioxidant properties. Complex CuL2 has the highest anti-radical potential (73.40 %) followed by NiL2 (72.07%) and CoL2 (70.21%). Complex ZnL2 has exhibited 69.41 % anti-radical performance, while Schiff base has the lowest antioxidant potential (50.79%).