Coordination-Accelerated Radical Formation from Acyclic Enediynes for Tumor Cell Suppression

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Materials Science

Background:

• Enediynes are a class of natural products and synthetic compounds known for their potent DNA-cleaving ability and anticancer properties.
• The development of synthetic enediynes with controlled activation and improved therapeutic profiles remains a significant challenge in medicinal chemistry.

Purpose of the Study:

• To synthesize and characterize a novel maleimide-based acyclic enediyne ligand and its metal complexes.
• To investigate the effect of metal ion coordination on the thermal stability and cycloaromatization of the enediyne.
• To evaluate the DNA cleavage ability, radical generation, and cytotoxicity of the metalloenediynes as potential anticancer agents.

Main Methods:

• Synthesis of a maleimide-based acyclic enediyne ligand with salicylaldiminato substituents.
• Chelation of the enediyne ligand with Cu(II), Zn(II), and Mg(II) ions to form metalloenediynes.
• Thermal analysis (onset temperature determination) of cycloaromatization.
• Assessment of DNA cleavage activity.
• Evaluation of cytotoxicity against HeLa cells using half-maximal inhibitory concentration (IC50) assays.

Main Results:

• The synthesized enediyne ligand formed stable metalloenediynes with Cu(II), Zn(II), and Mg(II).
• Metal coordination significantly accelerated the cycloaromatization of the enediyne ligand.
• The Cu(II)-metalloenediyne exhibited a very low onset temperature (55°C) and spontaneous cycloaromatization at ambient temperature, generating free radicals and reactive oxygen species.
• The metalloenediyne demonstrated potent DNA cleavage ability and high cytotoxicity towards HeLa cells, with IC50 values comparable to commercial antitumor drugs.

Conclusions:

• The combination of a maleimide moiety and metal coordination at the alkyne termini effectively enhances the activity of enediynes.
• These metalloenediynes represent a promising class of compounds for the development of novel and highly efficient anticancer agents.
• The facile activation and potent biological activity highlight the potential of this design strategy for future drug discovery efforts.