DIMERIZATION OF CORALYNE AND ITS PROPYL ANALOG AND THEIR ASSOCIATION WITH DNA

Dimerization of coralyne, la, and its propyl analogue Ic has been analyzed at neutral pH as a function of ionic strength. Even at low ionic strength (7 = 0.02) dimerization constants (molar units) for both compounds are 105 or greater, which is considerably larger than values obtained for similar intercalating molecules. Coralyne seems to undergo association to higher aggregates somewhat easier than Ic, which could be due to the fact that the propyl group on Ic provides some steric hinderance in forming higher aggregates. Both compounds readily associate with DNA. At high ratios of ligand to DNA, the spectra for la or Ic are similar to that of a highly aggregated complex. At low ratios of ligand to DNA, the spectra for both compounds approach a limit, which is relatively independent of ionic strength and concentration, and can be identified with the intercalated species. The slight differences between la and Ic in dimerization or in association with DNA do not seem capable of explaining the significant differences in antileukemic activity of these compounds. © 1979, American Chemical Society. All rights reserved.