Molecular docked structure of 6MP complex with DNA.

<p>Dodecamer duplex sequence (CGCGAATTCGCG)₂ (PDB ID: 1BNA) was used in the docking studies. The binding energy of the complex system was found to be −116.97 kJ/mole.</p

Interaction of 6MP with CT-DNA.

<p>UV-visible absorption spectra of 6MP (25 μM) in presence of increasing concentrations of CT-DNA in Tris-HCl buffer (pH 7.2). Hyperchromism was observed with increasing concentration of CT-DNA confirming the interaction of 6MP and DNA. Structure of 6 Mercaptopurine is shown in the inset.</p

Interaction of 6MP with CT-DNA studied using fluorescence spectroscopy.

<p>Fluorescence emission spectra of 6MP (50 μM) in the presence of increasing concentrations of CT-DNA. Increase in the fluorescent intensity was observed with increasing DNA concentration. Excitation wavelength was 280 nm and emission was recorded as shown in figure.</p

Role of ionic strength.

<p>To study the role of electrostatic effect on 6MP-DNA binding, NaCl was used. Maximum emission intensity plot of 6MP-DNA was plotted with increasing concentration of NaCl (0–70mM). Excitation wavelength was 280 nm. Increase in fluorescence intensity suggests for a possible electrostatic interaction between 6MP and CT-DNA.</p

KI quenching experiment.

<p>Stern-Volmer plot for fluorescence quenching of 6MP (50 μM) by KI in absence and presence of CT-DNA (100 μM). Quenching of 6MP fluorescent intensity was done using KI in absence and presence of CT-DNA and quenching constant was calculated in both the case. Difference in Ksv value was further used to investigate the binding mode of 6MP and DNA.</p

6MP induced generation of superoxide anion.

<p>Concentration dependent photo generation of superoxide anion by 6MP. Indicated concentration of 6MP was exposed to white light for 1h at RT and absorbance was measured at 560±SEM of three independent experiments. *<i>p</i> value <0.01 when compared to control.</p

Stern-Volmer plot for interaction of 6MP with CT-DNA.

<p>The fluorescent intensity was found to be directly proportional to DNA concentration. Binding constant of 7.8×10³M⁻¹ was obtained from the slope.</p

Effect of increasing the concentration of 6MP on the viscosity of CT-DNA.

<p>The concentration of CT-DNA was kept constant (100 μM) with increasing amount of 6MP. Values reported are mean of three independent experiments.</p