Gold(III) complex from pyrimidine and morpholine analogue Schiff base ligand: Synthesis, characterization, DFT, TDDFT, catalytic, anticancer, molecular modeling with DNA and BSA and DNA binding studies

Abstract

New gold(III) complex, [AuL2]Cl3 was synthesized from (2-(4-morpholinobenzylidene)-1-(4-(trifluoromethyl)pyrimidin-2-yl)hydrazine) and characterized by analytical and miscellaneous spectral methods. These results show that Au(III) complex has square planar geometry. Density functional theory (DFT) calculations have been done to understand the electronic structure of the Au(III) complexand free ligand while time dependent density functional theory (TDDFT) calculations have been employed to compute absorption spectra of ligand and Au(III) complex. Antimicrobial results suggest that ligand and complex have been inhibited the E. coli bacteria (13 mm) and C. albicans fungi (16 mm) than other microbes. Antioxidant results exhibit the ligand and complex has enhanced scavenging activities against several free radicals. In vitro anticancer activities of cisplatin, ligand and complex have been explored by MTT assay against various human cancer cell lines (breast-MCF-7, liver-HepG2, cervical-HeLa, lung-A549) and one normal cell line (NHDF- normal human dermal fibroblasts). The results show that complex has low IC50 values against cancer cell lines (20.6 ± 0.98 μg/mL, MCF-7; 22.68 ± 1.13 μg/mL, HepG2; 32.00 ± 1.60 μg/mL, HeLa; 33.19 ± 1.66 μg/mL, A549) than ligand. Moreover, complex has ten times least toxic activity (109.65 ± 5.48 μg/mL) on NHDF cell line as compared to cisplatin (10.28 ± 0.51 μg/mL). Based on the least toxic activity of complex has been further discovered by in vivo anticancer study using Ehrlich Ascites Carcinoma (EAC) tumor bearing Swiss albino mice. DNA interactions of ligand and complex have been studied by electronic absorption, fluorescence, viscometric and cyclic voltammetic methods. The results suggest that ligand and complex binds with CT-DNA through an intercalative interaction. Further confirm the nature of interaction between ligand and Au(III) complex towards DNA and BSA protein, molecular docking analysis has been carried out. These results reveal that Au(III) complex shows greater binding ability towards DNA and BSA than the ligand.