Novel chiral Schiff base Palladium(II), Nickel(II), Copper(II) and Iron(II) complexes: Synthesis, characterization, anticancer activity and molecular docking studies.

In this study, two chiral Schiff base ligands (L1 and L2) were synthesized from the condensation reaction of (S)-2-amino-3-phenyl-1-propanol with 2-hydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde as metal precursors for the preparation of transition metal complexes with Pd(II), Fe(II), Ni(II) and Cu(II). The compounds were characterized by using X-ray (for L1-Pd(II)), NMR, FT-IR, UV-Vis, magnetic susceptibility, molar conductivity, and elemental analysis. The in vitro cytotoxic effects of ligands (L1 and L2) and their metal complexes on colon cancer cells (DLD-1), breast cancer cells (MDA-MB-231) and healthy lung human cell lines were investigated by using the 3-(4,5-dimethylthiazol-2-yl)-2,5‑diphenyl tetrazolium bromide (MTT) assay. Among the synthesized compounds, L1-Pd(II) was particularly found to be the most potent anticancer drug candidate in this series with IC50 values of 4.07, and 9.97 µM in DLD-1 and MDA-MB-231 cell lines, respectively. In addition, molecular docking results indicate that Glu122, Asn103, Ala104, Lys126, Phe114, Leu123, and Lys126 amino acids are the binding site of the colon cancer antigen protein, in which the most active complex, L1-Pd(II) can inhibit the current target.