Interactions of Anionic Carboranylated Porphyrins with DNA.

In this study, the authors have characterized the acid-base equil. of meso-tetrakis[4-(nido-carboranyl)phenyl]porphyrin (p-H2TCP4-) and meso-tetrakis[3-(nido-carboranyl)phenyl]porphyrin (m-H2TCP4-) and investigated their interactions with DNA. The authors present evidence that these tetraanionic mols. do indeed interact with DNA under physiol. conditions (pH 7.4, and ionic strength I = 0.15 M NaCl). Furthermore, the authors show that the counterintuitive binding of these tetraanionic porphyrins to a 2-fold array of neg. charges is driven by mol. recognition processes that can be deeply affected by the spatial distribution of the anionic substituents. The authors have shown that neg. charged porphyrins bearing peripheric bulky nido-carborane groups can indeed interact with DNA. In addn., the authors have shown that the complexation between anionic porphyrins and DNA can be induced by either porphyrin inner core protonation or other noncovalent interactions. A more complete study of these systems is currently underway since a deeper understanding of these processes might lead to the design of new anticancer drugs with improved biol. activity and treatment effectiveness.