Figure 3.

(a) Aromatic protons region of the ¹H NMR titration spectra of c-kit21T12T21 with aloe emodin-8-glucoside (2). The numbers indicate the assignation to the corresponding imino protons, the dotted lines highlight the change in chemical shifts. The asterisks (*) mark the aromatic protons of 2. (b) Schematic representation of the G-quadruplex structure. (c,d) imino-aromatic and imino-imino regions of 2D NOESY spectra (τm = 350 ms) of c-kit21T12T21 with 2. Spectra were acquired at 25 °C in 90% H₂O and 10% D₂O, 20 mM KCl, and 5 mM K-phosphate buffer, pH 6.9, R = 2.0.