Synthesis, theoretical analysis, and biological properties of a novel tridentate Schiff base palladium (II) complex

Abstract

Schiff base complexes play a crucial role in bioinorganic chemistry. A novel curcumin/phenylalanine tridentate Schiff base ligand and its palladium (II) complex were synthesized in order that they were stable in aqueous buffer. The structure of the complex was investigated using a variety of methods, including DFT, NBO analysis, FMOs, and MESP. The interaction of the complex with plasmid (pUC19) and CT-DNA was studied. The anticancer, antibacterial, and antioxidant activities of the complex were examined. The statistical analysis of MTT assay was compared using the 1-way ANOVA and Tukey test. Results showed that the complexes were stable in aqueous buffer, pH 8. The extrinsic fluorescence emission of the plasmid and CT-DNA was quenched while interacting with the complex. The complex had an IC50 of 72.47 μM against MCF-7 cells. The ANOVA and Tukey analysis of MTT data demonstrated a statistically significant difference between groups (P<0.0001). The minimum inhibitory concentrations (MIC) of the complex for E. coli and S. aureus were 300 and 200 μg/mL, with 96.3 % and 95.2 % biofilm growth inhibition at 250 μg/mL, respectively. The sample concentrations contributing to 50% radical inhibition in the 1,1-diphenyl-2picrylhydrazyl (DPPH) test for curcumin, ligand, and palladium (II) complex were 33.62, 21.27, and 51.26 μM, respectively. The results suggest that the complex interaction with DNA is one of the potential mechanisms in the elimination of cancer cells and bacteria in the planktonic and biofilm. On the other hand, while stability in aqueous buffer at pH 8 increases, modified curcumin antioxidant effect decreases.