DNA groove binding of an asymmetric cationic porphyrin and its Cu(II) complex: Resolved by spectroscopic, viscometric and molecular docking studies

In the present study, the interaction between water-soluble cationic asymmetric porphyrin, 5-(1-Hexadecyl pyridinium-4-yl)-10, 15, 20-tris (1-Butyl pyridinium-4-yl) Porphyrin Chloride, and its copper (II) derivative with calf thymus DNA (CT-DNA) were studied by means of spectroscopic techniques, viscosity measurements and molecular docking. The monitoring of the changes in visible absorbance spectra showed a small red shift and a little hypochromicity in the Soret band. Also, insignificant changes were appeared in the viscosity of DNA with increasing of the porphyrins. These results suggested that these porphyrins bound to DNA through the groove binding mode. Then, multivariate curve resolution-alternating least squares (MCR-ALS) method was employed on UV–visible spectral data matrix to resolve the spectral and concentration profiles of the components involved in the interaction and the binding constant was estimated by the combination of bard equation and MCR-ALS approach. Furthermore, molecular docking studies confirmed experimental results obtained by spectral techniques and provide deeper insight into the porphyrin-DNA interaction.