Synthesis and characterization of novel ligands and metal complexes and investigation of their cytotoxic effects on different cell lines

In this study, synthesis and characterization data for the L1 (LH) ligand and its metal complexes were presented, and the cytotoxic effects of free ligands and metal complexes from the L1 and L2 series were evaluated in HT-29 human colon adenocarcinoma cells. The investigation of these compounds was motivated by the need for novel anticancer agents to address the limitations of existing therapies. Cells were treated with different concentrations of the test compounds, and cell viability and IC₅₀ values were determined using the MTT assay after 24 hours. Cell death profiles of the L1 (LH) ligand and its Cu(L)₂, Ni(L)₂, and Zn(L)₂ complexes after 24 hours were evaluated using the Annexin V-FITC/PI assay. All four treatment groups showed a significant decrease in the viable cell population and a significant increase in the early apoptotic cell population compared with the control. The most pronounced early apoptotic profiles were observed in the Zn(L)₂ and Ni(L)₂ treatment groups. MTT results revealed varying cytotoxic activities among the compounds, with L2-Cd and L2-Hg exhibiting the lowest IC₅₀ values. Some metal complexes showed greater cytotoxic activity than their corresponding free ligands. Overall, the findings demonstrate compound-dependent cytotoxic effects in HT-29 cells. Further studies involving normal cell models and molecular analyses are required to assess selectivity and clarify the mechanisms underlying these effects.