Diacridines, bifunctional intercalators--IV. Effect on nucleolar RNA synthesis;

Design of a new DNA-polyintercalating drug, a bisacridinyl peptidic analogue of Triostin A

The synthesis of a new bifunctional compound in which two aminoacridine chromophores are linked by the bicyclic depsipeptidic backbone of des-N-tetramethylTriostin A is described. The molecule, bis-[(9-acridinyl)-D-seryl-L-alanyl-L-cysteinyl-L-valine] dilactone disulphide, structurally analogous to the antibiotic anti-tumour drug Triostin A, is shown to possess a high affinity to DNA and to act as a bis-intercalator on the basis of spectroscopic, viscosimetric and thermal-denaturation studies. This model constitutes the first attempt of a synergic association between a peptidic moiety that mimics a naturally occurring drug and aminoacridine, the two parts themselves each exhibiting a high affinity for the DNA target.

Bifunctional intercalators: relationship of antitumor activity of diacridines to the cell membrane

The in vivo antitumor effectiveness [as measured by the percentage increase in life-span (ILS%)] of 28 diacridine bis-intercalators of nucleic acids shows a highly significant correlation with their effect on phenomena associated with plasma membrane as well as a high degree of structural specificity. In contrast, the ILS% does not correlate with the uptake of these diacridines by cells, nor with the inhibition of RNA synthesis or of DNA synthesis or with the inhibition of growth of cells in culture. The possibility that the antitumor effectiveness of actinomycin D, another DNA intercalator, is associated with sites of action other than the hibition of RNA synthesis is discussed.