A series of (8-hydroxyquinoline) gallium(III) complexes
(CP-1–4) was synthesized and characterized
by single X-ray crystallography and density functional theory (DFT)
calculation. The cytotoxicity of the four gallium complexes toward
a human nonsmall cell lung cancer cell line (A549), human colon cancer
cell line (HCT116), and human normal hepatocyte cell line (LO2) was
evaluated using MTT assays. CP-4 exhibited excellent
cytotoxicity against HCT116 cancer cells (IC50 = 1.2 ±
0.3 μM) and lower toxicity than cisplatin and oxaliplatin. We
also evaluated the anticancer mechanism studies in cell uptake, reactive
oxygen species analysis, cell cycle, wound-healing, and Western blotting
assays. The results showed that CP-4 affected the expression
of DNA-related proteins, which led to the apoptosis of cancer cells.
Moreover, molecular docking tests of CP-4 were performed
to predict other binding sites and to confirm its higher binding force
to disulfide isomerase (PDI) proteins. The emissive properties of
CP-4 suggest that this complex can be used for colon
cancer diagnosis and treatment, as well as in vivo imaging. These results also provide a foundation for the development
of gallium complexes as potent anticancer agents.