A Study of Interaction between Flavonoids and the Parallel Quadruplex Structure [d(TGGGGT)] 4 by Electrospray Ionization Mass Spectrometry

In this study, electrospray ionization mass spectrometry (ESI‐MS) was used to investigate interaction of 21 flavonoids (10 aglycones and 11 glycosides) with the parallel quadruplex structure [d(TGGGGT)] 4 . Relative binding affinities of flavonoids toward [d(TGGGGT)] 4 were estimated based on the fraction of bound DNA. It was found that [d(TGGGGT)] 4 showed a binding preference to the flavonoid glycosides over flavonoid aglycones. It was deduced that glycosylation played a key role for the [d(TGGGGT)] 4 ‐binding properties of flavonoid glycosides. Upon collision‐induced dissociation, complexes of flavonoid/[d(TGGGGT)] 4 underwent the loss of flavonoids, suggesting an end‐stacking binding mode. The current work demonstrates that ESI‐MS is a powerful tool in the study of interaction between drugs and nucleic acids.