Degradation of Single Stranded Nucleic Acids by the Chemical Nuclease Activity of the Metal Complex [Cu(phen)(nal)]+

The chemical design of metal complexes of the type Cu(phen)(antib)]⁺ (where antib is a quinolone or a fluoroquinolone) has been carried out in an approach to better understand how the coordination of their components affect the activity of quinolones. The ability of Cu(phen)(nal)]⁺ to interact with DNA in vivo and its capacity to promote the degradation of plasmid and chromosomal DNA, under reductive conditions has been previously reported. However whether this compound utilizes other intracellular targets to promote bacterial killing was a question that deserved to be answered. In this paper, the studies of the chemical nuclease properties encoded by the metal complex Cu(phen)(nal)]⁺ were extended by using different types of single chain nucleic acids, i.e, ribosomal and tumor mosaic virus RNAs as well as poly-dA-dT. Our results showed that degradation of the nucleic acids occurred only under reductive conditions. Although MPA and 3-mercaptoethanol were the chemical reducers that best assisted the nuclease reaction, other biological compounds such as citric and succinic acid also were shown to act like reducers in that reaction. All.hough the nuclease activity of Cu(phen)(nal)]⁺ was comparable to that exhibited by bis copper phenanthroline Cu(phen)z]²⁺our results showed that none of the individual components of Cu(phen)(nal)]⁺ was able to promote the degradation of either the RNAs or poly(dA-dT). These results strongly support the hypothesis that the metal complex Cu(phen)(nal)] uses not only DNA but also RNA as targets to promote bacterial killing.