Effect of complexes of cyanidin-3-diglucoside-5-glucoside with rutin and metal ions on their antioxidant activities.

Studies have enabled a molecular understanding of the anthocyanin copigmentation phenomenon over several decades. However, the effect of combinations of, or even supramolecular assemblies of, anthocyanins with other phenols and/or metal ions on their antioxidative activity was unclear. In this study, anthocyanin complexes of cyanidin-3-diglucoside-5-glucoside (CY3D5G), rutin and Mg(II)/Fe(III) were constructed, analyzed, and evaluated for their antioxidant effects. The CY3D5G-rutin-Fe(III) exhibited supramolecular properties via visible, CD and FTIR spectra among complexes. The interaction of CY3D5G-rutin, CY3D5G-rutin-Mg(II), or CY3D5G-rutin-Fe(III) was synergistic (P<0.05) in the ORAC assay. On cellular ROS levels, the median effective concentration of the CY3D5G-rutin-Mg(II) was 7.76μmol QE/L and exhibited a synergistic interaction (CI=0.67, P<0.05), whereas the CY3D5G-rutin-Fe(III) (CI=0.79, P=0.074) was additive. The results indicate that the antioxidant properties were affected by the molecular combination. Additionally, Fe(III) might exhibit a negative effect, since the CY3D5G-Fe(III) required a greater concentration than CY3D5G to achieve the same effect on cells.