Multinuclear non-heme iron complexes for double-strand DNA cleavage

Area of Science:

• Bioinorganic Chemistry
• Medicinal Chemistry
• Molecular Biology

Background:

• Bleomycin (BLM) anti-tumor drug activity is linked to its iron complex (Fe-BLM) inducing oxidative DNA damage.
• Mononuclear iron complexes like Fe-N4Py model Fe-BLM but only achieve single-strand DNA cleavage.
• Double-strand DNA cleavage requires two oxidizing equivalents, suggesting multinuclear complexes may be more effective.

Purpose of the Study:

• To synthesize and evaluate multinuclear iron complexes for enhanced oxidative double-strand DNA cleavage.
• To investigate the structure-activity relationship of ditopic and tritopic iron complexes in DNA cleavage.
• To compare the efficacy of multinuclear complexes against mononuclear models.

Main Methods:

• Synthesis of ditopic and tritopic N4Py-derived ligands.
• Formation and characterization of corresponding mononuclear, dinuclear, and trinuclear iron complexes.
• Evaluation of DNA cleavage activity using supercoiled pUC18 plasmid DNA assays.

Main Results:

• Dinuclear iron complexes exhibited significantly enhanced double-strand DNA cleavage compared to mononuclear Fe-N4Py.
• The structure of the linking moiety in dinuclear complexes did not substantially affect cleavage activity.
• Covalent attachment of a 9-aminoacridine intercalator did not improve double-strand DNA cleavage.
• Trinuclear iron complexes demonstrated the highest efficiency in oxidative double-strand DNA cleavage.

Conclusions:

• Multinuclear iron complexes, particularly trinuclear ones, are superior agents for oxidative double-strand DNA cleavage.
• The enhanced activity of trinuclear complexes is attributed to the increased probability of simultaneous delivery of two oxidizing equivalents to DNA.
• These findings offer a promising strategy for developing more effective DNA-cleaving agents for therapeutic applications.