Formation of the aggregates of actinocin derivatives containing 4′-benzo-15-crown-5 radicals in amide groups and their interaction with a DNA molecule

Methods of spectrophotometry, spectropolarimetry, and viscometry are used to study the self-organization in the solution of crown-containing actinocin derivative (I) exhibiting antitumor activity and the interaction of the formed aggregates with a DNA molecule. The presence of the 4′-benzo-15-crown-5 radical in the structure of the studied compound determines the observed differences in its complexation with Na+ and K+ ions. The process of aggregation in the presence of K+ ions is accompanied by a shift of the long-wave band in the absorption spectrum to short-wave (the formation of H type aggregates) or long-wave (the formation of J type aggregates) regions depending on the K+ ion concentration in the solution. In the presence of Na+ ions, regardless of their concentration in the solution, J type aggregates form. A scheme of complex formation and their mutual transformations with changes in the ionic composition of the medium is proposed. A study of the interaction of this compound with DNA shows that in the presence of K+ ions it binds to the DNA molecule in the form of monomers and/or dimers without producing large supramolecular aggregates. The H and J structures formed in K+-containing solutions of compound I are broken in the interaction with DNA. If a solution of compound I is added to a DNA solution containing Na+ ions, the J type aggregates are formed directly on the surface of the DNA molecule. At the same type, the J structures originally formed in the Na+-containing solution of compound I practically do not interact with DNA. A study of this system shows that the introduction of the crown group in the compound molecule with a heterocyclic chromophore provides the opportunity to affect its affinity and binding to the DNA molecule by means of the ionic composition of the medium.