Zn(II) and Co(II) derivatives anchored with scorpionate precursor: Antiproliferative evaluation in human cancer cell lines

Abstract

A ‘scorpionate’ type precursor [bdtbpza = bis(3,5-di-t-butylpyrazol-1-yl)acetate] has been employed to synthesize two mononuclear ZnII and CoII derivatives, namely [Zn(bdtbpza)2 (H2O)2]·2.5CH3OH·2[(CH3)3C-C3H2N2-C(CH3)3] (1) and [Co(bdtbpza)2(CH3OH)4] (2) in good yield. Single crystal X-ray diffraction analysis reveals that in 1, the ZnII atom is tetrahedrally surrounded by a pair of Oacetate atoms of two bis(pyrazol-1-yl)acetate units and two water molecules; while in 2, the CoII atom shows an octahedral environment coordinating a pair of Oacetate atoms of two bis(pyrazol-1-yl)acetate units along with four methanol molecules. The EPR spectra of 2 recorded at 77 and 298 K confirmed the tetragonal symmetry of the high spin Co(II). The DFT (Density functional theory) computation is in good agreement with the geometry proposed for compounds 1 and 2. Both the compounds display a high antiproliferative activity against HCT116 (colorectal carcinoma) and A2780 (ovarian carcinoma) cell lines compared to human normal dermal fibroblasts. In the case of A2780 cells, compounds 1 and 2 exhibit IC50 values that are similar to those described for cisplatin, a widely used chemotherapeutic drug. Exposure of A2780 cells to the IC50 concentration of each compound led to an increase of the number of apoptotic and autophagic cells. In the case of compound 1, the accumulation of intracellular ROS (Reactive oxygen species) is responsible for triggering A2780 cell death.