INTERACTION OF SANGUINARINE IMINIUM AND ALKANOLAMINE FORM WITH CALF THYMUS DNA

The interaction of sanguinarine iminium form (structure I) and sanguin arine alkanolamine form (structure II) with calf thymus DNA has been s tudied in buffer of pH 5.2 and pH 10.5, respectively, where the physic ochemical properties of DNA remain unchanged. The binding of sanguinar ine Iminium form to DNA is characterized by hypochromism and bathochro mism in the absorption band, quenching of fluorescence intensity, incr ease in fluorescence polarization anisotropy, increase in positive and negative ellipticity of DNA, sign and magnitude of the thermodynamic parameters and increase in contour length of sonicated rodlike duplex DNA indicating that it binds to DNA by a mechanism of intercalation. I n contrast, sanguinarine alkanolamine form does not show (i) any signi ficant change in fluorescence polarization anisotropy, (ii) alteration of B form structure of DNA and (iii) increase in contour length of DN A indicating that it does not bind to DNA. But at a very high concentr ation of DNA, the alkanolamine form is influenced to form an iminium-D NA complex.