Spectroscopic and electrochemical monitoring on the binding of idarubicin as a chemotherapy drug with ds-DNA

Abstract

<span style="font-size:9.0pt;mso-bidi-font-size:10.0pt;color:black" lang="EN-US">The interaction between idarubicin, a heterocyclic anticancer drug, and fish sperm DNA has been investigated in physiological buffer (<i style="mso-bidi-font-style: normal">p</i>H 7.4) using methylene blue dye as a spectral probe by UV–vis absorption, cyclic voltammetry, fluorescence spectroscopy, as well as viscosity measurements. The hypochromicity effect on the spectra of idarubicin in the presence of DNA with a partial red shift is observed. The results indicate that idarubicin molecule can bind to DNA and the major binding mode is intercalative binding in high ionic strength while the electrostatic binding is dominant in low ionic strength. The binding constants and the number of binding sites of idarubicin molecule with DNA are obtained by UV-vis spectrophotometry and fluorescence quenching methods. The thermodynamic parameters, <img src='/image/spc_char/delta.gif' border=0><i>H</i>, <img src='/image/spc_char/delta.gif' border=0><i>S</i> and <img src='/image/spc_char/delta.gif' border=0><i>G</i> are calculated as 1.95<img src='/image/spc_char/cross.gif' border=0>10⁴ J mol^-1, 1.52<img src='/image/spc_char/cross.gif' border=0>10²J mol^-1 K^-1 and -2.51<img src='/image/spc_char/cross.gif' border=0>10⁴J mol^-1 respectively, showing that the binding of idarubicin to DNA is driven mainly by hydrophobic interaction. The diffusion coefficient for the free drug is found to be 2.6×10^-3 cm² s^-1, whereas in the presence of DNA, it is 1.2×10^-3 cm² s^-1.

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