X-ray crystal structure of a Cu(II) complex with the antiparasitic drug tinidazole, interaction with calf thymus DNA and evidence for antibacterial activity

Interaction of metal ions with biologically active molecules like 5-nitroimidazoles modulates their electronic environment and therefore influences their biological function. In the present work, an antiparasitic drug tinidazole (tnz) was selected and a Cu(II) complex of tnz [Cu2(OAc)4(tnz)2] was prepared. A dinuclear paddle-wheel [Cu2(OAc)4(tnz)2] was obtained by single-crystal XRD and further characterized by spectroscopic techniques and cyclic voltammetry. To understand the biological implications of complex formation, interaction of tnz and its complex was studied with calf thymus DNA, bacterial and fungal cell lines. Results of calf thymus DNA interaction using cyclic voltammetry indicate the overall binding constant (K*) of Cu2(OAc)4(tnz)2 [(59 ± 6) × 104 M−1] is ~17 times greater than that of tnz [(3.3 ± 0.4) × 104 M−1]. Minimum inhibitory concentration values suggest that [Cu2(OAc)4(tnz)2] possesses better antibacterial activity than tnz on both bacterial strains, while the activity on a fungal st...