Spectroscopic studies on the interaction of alpha-eleostearic acid with calf thymus DNA

Interaction between alpha-eleostearic acid (alpha-ESA) and calf thymus DNA in Tris-HCl buffer (pH = 7.4) using neutral red (NR) dye as a spectral probe was investigated using UV-Vis absorption and fluorescence spectroscopy. Spectral data matrix of the complexed reaction between alpha-ESA and NR with DNA was processed with an alternative least-squares (ALS) algorithm, the obtained concentration profiles and the corresponding pure spectra for species (NR, DNA-NR, and DNA-NR-ESA) demonstrated three kinds of reactions might occur in the system. The major groove binding between alpha-ESA and DNA was further validated using circular dichroism, viscosity, DNA melting, and ionic strength effect measurements. Moreover, the calculated values of thermodynamic parameters, such as enthalpy (Delta H-theta, -22.04 kJ/mol) and entropy change (Delta S-theta, 91.52 J K-1 mol(-1)), suggested binding between alpha-ESA and DNA was mainly driven by hydrophobic interactions and hydrogen bonds without electrostatic force.