Chemical structures of anthraquinone derivatives (a). The intrinsic fluorescence characterization of effects of the anthraquinones (at 100 µM) on the formation of HSA AGEs with different inducers including fructose (b), methylglyoxal (MGO) (c), and glyoxal (GO) (d). The inhibitory effects of the anthraquinones (at 100 µM) on HSA side chain modification induced by fructose (e). All data points represent the average of triplicate measurements with the bars at each point representing the respective standard derivation. *Aminoguanidine, AG (100 µM), served as a positive control.

Protective effects of the anthraquinones (at 100 µM) on the secondary structures of HSA against glycation-induced structural changes as characterized by circular dichroism (CD) experiments. Aminoguanidine, AG, (at 100 µM) served as the positive control.

Thermodynamic binding capacity of rhein and HSA obtained by isothermal titration calorimetry (ITC). Raw data plot of heat flow against time for the titration of rhein into HSA.

The UV-visible absorption spectra of HSA (0.25 mg/mL) with rhein at concentrations ranging from 25 to 100 µM (a) and rhein (25 µM) with HSA at concentrations ranging from 0.125 to 0.5 mg/mL (b).

Computational docking of HSA and rhein. The binding site of rhein on HSA (a). The binding mode of rhein and HSA in a zoomed view (b), and illustrations of types of interactions between rhein and HSA (c).