Interaction of acridines and tetrahydroacridines with DNA at low DNA/dye ratios.

This study examines certain aspects of the interaction of acridines with DNA. A comparative study of the methods available for the determination of the association constants (Kap) for compounds which interact with DNA has been pursued. A new equation which permits the spectrophotomeric determination of Kap has been derived. This equation can be applied to compounds which upon interaction with a polymer exhibit discrete absorption changes. Application of this equation to substituted acridines and tetrahydroacridines yields some preliminary information on the effect of ring substituents on the interaction of acridines with DNA. Low levels of DNA/dye ratios have been used in the studies reported herein.