Munirat S. Butea, Grema A. Malaa, Hassan B. Yesufub, Hauwa A. Zarmac, Malik A. Yurarid, and Ibrahim Waziria*
aDepartment of Pure and Applied Chemistry, University of Maiduguri, Maiduguri, Nigeria
bDepartment of Pharmaceutical Chemistry, University of Maiduguri, P.M.B. 1069, Maiduguri, Nigeria
cDepartment of Nutrition and Dietetics, University of Maiduguri, P.M.B. 1069, Maiduguri, Nigeria.
Department of Chemistry, Yobe State University, Damaturu, Nigeria
*Corresponding author’s Email: waziriibrahim@unimaid.edu.ng, doi.org/10.55639/607.02010080
ABSTRACT
In this study, a benzohydroxamic acid ligand (HL) was synthesized via the reaction of methyl-4-amino-2-methoxybenzoate with hydroxylamine sulphate. The ligand was subsequently complexed with Mn(II), Co(II), Ni(II), and Cu(II) ions using their respective salts in a 1:2 metal-to-ligand molar ratio to afford the corresponding complexes (C1–C4), respectively. The ligand and its complexes were characterized using infrared spectroscopy, UV–Visible spectroscopy, and elemental analysis. IR spectral data confirmed that HL acts as a bidentate, monoanionic ligand, coordinating through the oxygen atoms of the hydroxyl (–OH) and carbonyl (C=O) groups to form a five-membered chelate ring around the metal centre. The antioxidant potential of the ligand and its metal complexes was assessed in vitro using the DPPH free radical scavenging assay at concentrations ranging from 100 to 500 μg/mL. All tested samples exhibited concentration-dependent radical scavenging activity; however, the free ligand (HL) demonstrated higher antioxidant activity than its metal complexes across all concentrations, except Co(II) complex (C2), which outperformed the ligand. The IC50 values for the ligand and the complexes (C1 C4) were found to be 155.3, 403.1, 75.7, 601.9, and 440.7 μg/mL. Nonetheless, neither the ligand nor the complexes outperformed the standard antioxidant, ascorbic acid, which showed consistently superior activity (IC50 = 66.2 μg/mL). In general, the results highlight the antioxidant properties of the synthesized benzohydroxamic acid ligand and its metal complexes, supporting the relevance of hydroxamic acid derivatives as bioactive agents and warranting further investigation into their pharmacological potential.
Keywords:
Benzohydroxamic acid,
Transition metals,
Oxidative stress,
DPPH
radical scavenging,

