The natural product prodigiosin binds G-quadruplex DNA

Prodigiosin, a metabolite isolated from Serratia bacteria, is a potent anti-cancer agent. The goal of this research was to determine if prodigiosin could bind to G-quadruplex DNA. We found by using UV–vis spectroscopy that the G-quadruplex K+√d[TG4T]4, but not the single-stranded Li+√d[TG4T], increased the water solubility of prodigiosin. In addition, we found that prodigiosinu0027s fluorescence was strongly enhanced in the presence of K+√d[TG4T]4, further evidence for quadruplex-ligand binding. Using 1H and 31P NMR experiments, we confirmed that prodigiosin binds at the 3′-end of K+√d[TG4T]4. Saturation transfer difference NMR experiments, done by irradiating the G5 H8 signal in K+√d[TG4T]4, indicated specific interactions between the G-quadruplex and prodigiosinu0027s A and B rings. This study raises the possibility that G-quadruplex DNA may well be a target for the anti-cancer agent prodigiosin.