Electronic interaction of carcinogenic and noncarcinogenic benz(c)acridines and DNA.

Electronic interaction of DNA with nine benzacridine derivatives was studied. The interaction system of these benzacridines and DNA was found to show a marked hypochromism in the ultraviolet region. The orderly double helical structure of DNA was found to play an essential role in this spectroscopic change. A high concentration of the interactant, low environmental ionic strength, low pH, and low temperature were beneficial in this interaction. The degree of hypochromism expressed by the integrated and pKa of the benzacridines were found to be in parallel. The hypochromism of the interaction system, in which the carcinogenic benz[c]acridine derivatives took part, was larger than that of the system in which the noncarcinogenic derivatives were involved.