Amodiaquine Nonspecifically Binds Double Stranded and Three-Way Junction DNA Structures

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Molecular Biology

Background:

• The 4-aminoquinoline class, including amodiaquine and chloroquine, are vital antimalarial drugs.
• Their precise mechanism of action, particularly DNA interaction, remains largely unknown.

Purpose of the Study:

• To investigate the DNA-binding affinities of amodiaquine, chloroquine, quinine, and mefloquine.
• To explore the range of nucleic acid structures these compounds interact with.

Main Methods:

• Isothermal titration calorimetry (ITC) for high-affinity binding (nM to tens of μM).
• Nuclear Magnetic Resonance (NMR) spectroscopy for low-affinity binding (hundreds of μM).
• Free energy binding simulations using the Dickerson-Drew dodecamer.

Main Results:

• Amodiaquine demonstrated tight binding across all tested double-stranded DNA structures.
• Mefloquine exhibited strong binding to DNA duplexes and weak binding to a three-way junction.
• Quinine and chloroquine showed only weak binding to DNA duplexes.

Conclusions:

• Differential DNA binding affinities among 4-aminoquinoline antimalarials revealed.
• Findings provide a basis for understanding antimalarial activity and developing novel therapeutics.