Changes in Superhelical Density of Closed Circular Deoxyribonucleic Acid by Intercalation of Anti-R-Plasmid Drugs and Primaquine

Abstract
The following compounds, which possess anti-R-plasmid activity (Hahn and Ciak, 1976) in decreasing order, were shown by viscometric titration to change systematically the superhelical density of closed circular PM2 deoxyribonucleic acid in the manner of intercalators: ethidium bromide, quinacrine, acridine orange, quinine, chlorpromazine, chloroquine, and methylene blue. The same effect was caused by the antimalarial drug primaquine, which has not been tested for antiplasmid activity.