Keywords: Alkaloid; metal complex; antibacterial; antifungal; antioxidant; antitumour

Abstract

Alkaloids possess various pharmacological actions and hence are considered as active biological moieties. Metal ions are essential for the normal functioning of the human body and any deficiency may cause diseases. In biomedical sciences, alkaloid metal ion complex formation has become a significant research area. In this study, three alkaloid ligands (L1, L2 and L3) underwent metal complex formation to produce iron(III) and zinc(II) metal complexes. Later, the biological activities of these alkaloid ligands and their iron(III) and zinc(II) metal complexes were investigated. These ligands and their metal complexes were characterized using ultraviolet-visible spectroscopy (UV-Vis), fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). Pharmacological tests including antibacterial, antifungal, antioxidant and antitumor assays were performed. All compounds showed antibacterial and antifungal activity, but the metal complexes showed better activities than the original ligands, especially the zinc(II) complexes of all ligands. All compounds showed more significant antifungal activity against Candida albicans than Candida glabrata. Free ligands illustrated better antioxidant behaviour and antitumour activity compared to the metal complexes. Thus, both ligands and their metal complexes, being active agents, should be explored further particularly with reference to their mechanism of action