Biochemical activity of a fluorescent dye rhodamine 6G: Molecular modeling, electrochemical, spectroscopic and thermodynamic studies

Abdulla Al Masum; Maharudra Chakraborty; Soumen Ghosh; Dipranjan Laha; Parimal Karmakar; Md Maidul Islam; Subrata Mukhopadhyay

doi:10.1016/j.jphotobiol.2016.10.002

Biochemical activity of a fluorescent dye rhodamine 6G: Molecular modeling, electrochemical, spectroscopic and thermodynamic studies

J Photochem Photobiol B. 2016 Nov:164:369-379. doi: 10.1016/j.jphotobiol.2016.10.002. Epub 2016 Oct 6.

Authors

Abdulla Al Masum¹, Maharudra Chakraborty², Soumen Ghosh³, Dipranjan Laha⁴, Parimal Karmakar⁴, Md Maidul Islam⁵, Subrata Mukhopadhyay²

Affiliations

¹ Department of Chemistry, Aliah University, Action Area IIA/27, New Town, Kolkata 700156, India.
² Department of Chemistry, Jadavpur University, Kolkata 700032, India.
³ Department of Chemistry, University College of Science, University of Calcutta, Kolkata 700009, India.
⁴ Department of Life science and Biotechnology, Jadavpur University, Kolkata 700032, India.
⁵ Department of Chemistry, Aliah University, Action Area IIA/27, New Town, Kolkata 700156, India. Electronic address: maidulaliah@gmail.com.

PMID: 27741488
DOI: 10.1016/j.jphotobiol.2016.10.002

Abstract

Interaction of CT DNA with Rhodamine 6G (R6G) has been studied using molecular docking, electrochemical, spectroscopic and thermodynamic methods. From the study, it was illustrated that Rhodamine 6G binds to the minor groove of CT DNA. The binding was cooperative in nature. Circular voltametric study showed significant change in peak current and peak potential due to complexation. All the studies showed that the binding constant was in the order of 10⁶M^-1. Circular dichroic spectra showed significant conformational change on binding and DNA unwind during binding. Thermodynamic study showed that binding was favored by negative enthalpy and positive entropy change. From thermodynamic study it was also observed that several positive and negative free energies played significant role during binding and the unfavorable conformational free energy change was overcame by highly negative hydrophobic and salt dependent free energy changes. The experimental results were further validated using molecular docking study and the effect of structure on binding has been studied theoretically. From docking study it was found that the hydrophobic interaction and hydrogen bonds played a significant role during binding. The dye was absorbed by cell and this phenomenon was studied using fluorescent microscope. Cell survivability test showed that the dye active against Human Breast Cancer cells MDA-MB 468. ROS study showed that the activity is due to the production of reactive oxygen.

Keywords: CT DNA; Cell imaging; Cytotoxicity; Molecular modeling; Rhodamine 6G; Thermodynamic.

MeSH terms

Electrochemical Techniques
Fluorescent Dyes / chemistry*
Models, Molecular
Rhodamines / chemistry*
Spectrum Analysis
Thermodynamics

Substances

Fluorescent Dyes
Rhodamines
rhodamine 6G