Predominant Binding Mode of Palmatine to DNA.

Palmatine is a protoberberine alkaloid, which may produce singlet oxygen under visible light irradiation and binds to DNA. The fact that singlet oxygen activation in palmatine may be triggered by environmental conditions, and in particular its interaction with nucleic acids, makes it a most suitable candidate for photodynamic therapy and DNA-targeted noninvasive anticancer strategies. Despite these remarkable properties, the actual binding mode between palmatine and DNA has not been resolved, yet. Its elucidation has indeed led to contrasting hypotheses. In this contribution, by using long-range molecular dynamic simulations and enhanced sampling approaches, we unequivocally identify that intercalation is the dominant binding mode of palmatine with DNA, from both a thermodynamic and kinetic point of view.