Investigation of charge transfer complexes between luteolin and DNA nucleotides using experimental and computational methods

Luteolin, a flavonoid with antioxidant, anti-inflammatory, and anti-cancer properties, interacts with DNA through non-covalent mechanisms. Charge transfer complexes, critical in biochemical systems, were studied between luteolin and DNA mononucleotides (dAMP, dCMP, dGMP, and dTMP) using experimental and computational approaches. UV-Vis absorption, fluorescence spectroscopy, and cyclic voltammetry were conducted to explore intermolecular interactions and donor-acceptor properties. Geometry optimizations at omega B97XD/6-31+G(d,p) level and time-dependent density functional theory (TD-DFT) calculations using the same functionals with the 6-311++G(d,p) basis set revealed that complexation primarily occurred through hydrogen bonding, following the order dCMP > dAMP > dTMP > dGMP. Distinct spectral behaviors revealed a blue shift in the dAMP-Lt complex and a red shift in the dCMP-Lt complex, with charge transfer dominating most complexes except for local excitation in the dTMP-Lt. This finding highlights the significant role of hydrogen bonding in stabilizing the dCMP-Lt complex and distinguishes it from the other nucleotide-Lt complexes. Understanding the interaction between luteolin and DNA mononucleotides suggests promising applications in the design of donoracceptor systems.