Butein Interacts at the Minor Groove of DNA: Multi-Spectroscopic, Thermodynamic, and Bioinformatic Analyses

DNA is an important therapeutic target, and characterizing its interactions with small molecules can inform drug development. Butein is a chalcone with reported antioxidant, anti-inflammatory, and anticancer activities. This study investigated the interaction between butein and calf thymus DNA using spectroscopic and computational methods. UV-visible absorption and fluorescence quenching measurements supported complex formation. Fluorescence-derived binding constants ranged from 4.04 × 10³ to 5.62 × 10³ M^-1, indicating weak to moderate binding affinity. Thermodynamic analysis indicated spontaneous binding that was both enthalpically and entropically favourable. DNA melting, urea disruption, viscosity, and competitive displacement assays supported a predominantly minor-groove binding mode. Molecular docking identified hydrogen bonds and van der Waals contacts between butein and DNA. Molecular dynamics simulations suggested that the complex remained stable over 250 ns at 310 K, with limited changes in DNA structure and dynamic hydrogen bonding. These findings characterize the interaction between butein and DNA and provide a basis for further investigation of its biological significance.