The requirement of intact double helical structure for primary binding in quinacrine-nucleic acid complexes

Effects of quinacrine on endothelial cell morphology and transcription factor-DNA interactions

Quinacrine has been used for decades and the beneficial effects of this drug are as numerous as its toxic effects. Since endothelial cells (EC) are in many cases the first cells coming in contact with drugs, the effect of quinacrine on certain aspects of EC biology were studied. The presented data demonstrate that quinacrine can have a marked impact on the integrity on EC monolayer without grossly interfering with cell viability. The described impact of quinacrine on EC might explain, at least in part, the toxic effects of this drug observed in the past. Furthermore, quinacrine profoundly effects gene regulation in EC. Quinacrine binds to DNA in a sequence-specific manner. While NF-kappa B-DNA interactions are not effected, AP-1-DNA binding is blocked by quinacrine. Such differential effects are presumably due to intercalation of quinacrine into the AP-1 consensus element. Preincubation of oligonucleotides resembling this sequence blocked the subsequent binding of nuclear extract containing AP-1 protein(s). Taken together, these data suggest that quinacrine interferes with EC physiology and alters the repertoire of EC to respond to stimuli. Furthermore, the differential effects of quinacrine might be exploited to study and gain additional insight in the involvement of AP-1 and NF-kappa B in gene regulation.

Intercalative and nonintercalative binding of large cationic porphyrin ligands to polynucleotides

The interactions of two positional isomers and one analogue of meso-tetra (4-N-methylpyridyl) porphine, with the synthetic polynucleotides poly[d(A-T)] . poly[d(A-T)] and poly[d(G-C)] . poly[d(G-C)] have been investigated by circular dichroism. All four porphyrins were found to bind to the polynucleotides as shown by the induction of circular dichroism in their Soret bands. Furthermore, the sign of the induced ellipticity reflects selective occupation of binding sites by the porphyrin ligands. The conformational lability of poly[d(A-T)] X poly[d(A-T)] was found to be appreciable as micromolar amounts of meso-substituted 4-N-methylpyridyl, 3-N-methylpyridyl, and p-N-trimethylanilinium porphines induced a CD spectrum similar but not identical to that of DNA in the Z-form, i.e. a negative band at 280 nm and a positive band at 259 nm. The effect of porphyrin binding to poly[d(G-C)] X poly[d(G-C)] was less pronounced and dissimilar to that seen in the AT polymer.

Genetic effects of acridine compounds

Acridines and a very large number of acridine derivatives are used in enormous quantities both in medicine and industry. The mutagenic action of these compounds has been demonstrated in a wide variety of organisms and is known to occur both in the dark as well as in the presence of light (photodynamic action). At the molecular level, acridines have been shown to cause frameshift mutations of both the addition and deletion types, a characteristic which has been of tremendous help in elucidating the nature of the genetic code. These and various other biological effects of acridines, such as inhibition of DNA repair, curing of plasmids and cell-growth inhibition, are examined in this review.