Quaternary Hexadeca-Substituted Manganese (III) Phthalocyanine as a DNA Interacting Agent; Binding Mode and Thermodynamic Parameters

Objective: Recently, phthalocyanines have been of interest in therapeutic applications owing to the discovery of their outstanding biological activities (especially efficient DNA interactions). Therefore, this study reports the preparation of a new hexadeca-substituted manganese (III) phthalocyanine (MnPc) and its water-soluble derivative (QMnPc).Materials and Methods: MnPc, bearing hexyloxy, aminated, and fluorinated groups, was synthesized via a one-step metal template mechanism and then converted into its water-soluble form by treating it with iodomethane. The phthalocyanines were characterized using Fourier-transform infrared (FT-IR) and ultraviolet visible (UV-vis) spectroscopies. Additionally, the interaction between the macromolecule QMnPc and the DNA molecule was studied using a UV-vis spectrophotometer at 310 and 338 Kelvin.Results: As DNA concentration increased, the absorbance decreased, accompanied by a bathochromic shift. This observation confirmed that the studied phthalocyanine interacted with the DNA molecule via non-bonding mechanisms (intercalation and electrostatic attraction). Moreover, the binding mode was examined by obtaining the thermodynamic parameters (entropy change (∆S)>0, enthalpy change (∆H)<0, and Gibbs free energy change (∆G)<0).Conclusion: The computed positive ΔS, as well as the negative values of ΔG and ΔH, confirmed that the DNA-QMnPc interaction was spontaneous and thermodynamically favored. Therefore, macromolecule QMnPc can be considered a promising agent for medical applications.