Synthesis, Structural Characterization, and Apoptosis Cell Death Facilitated Palladium(II) Schiff Base Complexes Derived From Salicylaldehyde and Aminoguanidine

ABSTRACT Schiff base ligands (L 1 – L 4 ) and their palladium(II) (Pd(II)) complexes (P1–P4) were derived from the derivatives of salicylaldehyde with aminoguanidine bicarbonate and diaminoguanidine, respectively. Ligands and complexes was characterized by various analytical and spectroscopic studies. From these results suggested that the ligands were coordinated to metal as a monobasic tridentate (ONN) manner. The protein binding activity of synthesized compounds was investigated, results revealed that the compound quenched BSA in a static manner. Moreover, the cytotoxic ability of ligands and Pd(II) complexes was screened against A549 and MDA‐MB‐231 cell lines. From IC 50 and IC 90 values, all the complexes exhibited better activity compared to the ligands. Among these complexes, complex P3 displays lower IC 50 (26.5 and 34.22 µM) value in A549 and MDA‐MB‐231 cell lines, respectively. Bright‐field microscopy, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), nuclear 4',6‐diamidino‐2‐phenylindole test, and caspase‐3 studies were used to evaluate the anticancer mechanism of complex P3 in A549 and MDA‐MB‐231 cell lines. By contrast with the control cell, the complex‐treated cell exhibits up‐regulated caspase‐3, and the ROS and MMP assay findings show that the activities are dosage dependent. These results revealed DNA damage and blebbing of the cellular membrane, which are morphological indicators of apoptosis.