10th U6+ Consortium of African Universities International Conference

The cytotoxic, antimicrobial, and antioxidant properties of metal complexes can be systematically tuned through deliberate modulation of ligand denticity, donor atom composition, and electronic configuration. In this study, a series of novel mixed-ligand nickel(II) and zinc(II) complexes incorporating 6-mercaptopurine and ascorbic acid were prepared, and their structures were elucidated by a combination of spectroscopic and physicochemical characterization techniques. Antimicrobial and antioxidant activities were evaluated experimentally, while theoretical investigations were conducted using density functional theory (DFT) calculations. The interaction of the synthesized complexes with two target proteins, 1KZN and 3HJ6, was further examined through molecular docking studies. Spectroscopic data confirmed that both 6-mercaptopurine and ascorbic acid function as bidentate ligands, forming stable coordination environments consistent with the outcomes of the DFT analysis. Powder X-ray diffraction (PXRD) analysis revealed that compound (1) adopts a crystalline phase, whereas compound (2) is obtained as an amorphous powder. Both complexes demonstrated appreciable inhibitory activity against Candida albicans; however, compound (2) exhibited superior antioxidant performance with a half-maximal inhibitory concentration (IC₅₀) of 0.51 mg/mL. In the 1KZN protein docking system, the Zn(II) complex displayed the most favourable binding energetics, recording the most negative MolDock score (−124.226 kcal/mol) relative to the Ni(II) analogue (−116.864 kcal/mol) and the reference drug ciprofloxacin (−118.783 kcal/mol). Likewise, in the 3HJ6 protein docking system, the Zn(II) complex exhibited a higher binding affinity (MolDock score: −126.887 kcal/mol) than both the Ni(II) complex (−102.679 kcal/mol) and the standard antifungal agent fluconazole (−86.000 kcal/mol). These findings underscore the promising pharmacological potential of the synthesized metal complexes as candidate therapeutic agents.