Studies to explore the UVA photosensitizing action of 9-phenylacridine in cells by interaction with DNA

Abstract

Acridine and its derivatives are well known for their DNA binding properties. In this report, we present our findings on evaluating different binding parameters of the interaction of 9-phenylacridine (ACPH) with DNA. Absorption spectroscopic studies including standard and reverse titration, the effects of ionic strength and temperature on titration, and Job plot analysis were done to calculate the binding constant and determine the different thermodynamic parameters and stoichiometry of the binding. Spectrofluorimetry and circular dichroism (CD) spectral titration were also utilized to confirm these findings. The results indicated that ACPH binds to DNA reversibly through non-electrostatic interactions by hydrogen bonding and van der Waals interactions. The binding constant and the number of binding sites were of the order 10³ M^–1 and ≈2, respectively with a binding stoichiometry of 1:4. The binding of ACPH with DNA was spontaneous, exothermic and enthalpy-driven. The extent of uptake of ACPH in B16 melanoma cells was estimated. As this compound absorbs in the UVA region, the effect of treatment with ACPH prior to UVA exposure was assessed to evaluate its phototoxicity in these cells. Our results indicated that the binding to DNA enhanced damage to sensitize cells to killing through apoptosis. Our findings indicated its potential to act as a photosensitizer.

Keywords:

• 9-Phenylacridine
• DNA binding parameters
• UVA
• DNA damage
• apoptosis
• phototosensitization

Acknowledgments

The authors also acknowledge the infrastructural support from University of Kalyani and other facilities at the Department of Biochemistry & Biophysics, K.U. DST-FIST and DST-PURSE of Department of Science & Technology, Govt. of India, as well as, UGC-SAP and spectrofluorimetric facility at Department of Environmental Science, University of Kalyani.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

The authors, S. Hansda and A. Mitra acknowledge a fellowship from UGC-RGNF, Govt. of India and a DST-INSPIRE fellowship, Govt. of India, respectively.