Effects of dietary cyanidin-3-diglucoside-5-glucoside complexes with rutin/Mg(II) against H2O2-induced cellular oxidative stress

Anthocyanins exist likely as complexes with flavones/metal ions in some plants. However, few studies indicate the complexation effects on bioactivities, i.e. antioxidant activities. The aim of this study was to evaluate effects of complexes of cyanidin-3-diglucoside-5-glucoside (CY3D5G) with rutin/Mg(II) on intrinsic antioxidant enzymes and mRNA expressions. All complexes exhibited cellular antioxidant activity in RAW264.7 cells, whereas half maximal effective concentration (EC50) values of CY3D5G complexes were significantly lower than its alone. Combination indexes of CY3D5G-rutin, CY3D5G-Mg(II), and CY3D5G-rutin-Mg(II) complexes were < 1 (p < .05), indicating of synergistic effects. Additionally, CY3D5G-Mg(II) rather than others significantly enhanced total antioxidant capacity, superoxide dismutase activity, and glutathione peroxidase activity while reducing malonic dialdehyde contents in H2O2-induced RAW264.7 cell model (p < 0.05), which were further confirmed with the up-regulated mRNA expression of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO.1), and the down-regulated p21 (p < 0.05). Our results demonstrated that CY3D5G and its complexes might enhance cellular antioxidant activities via the Nrf2/HO-1 signaling pathway. Additionally, a synergistic antioxidant effect of CY3D5G in the present of rutin/ Mg(II) as regular food components was evident, suggesting anthocyanin might interact with dietary components such as Mg(II) or rutin in food matrix or biological systems and exhibit a stronger antioxidant activity than it alone. The Mg (II) that exhibited no antioxidant activities alone shows potential as a co-adjuvant for the anthocyanin antioxidant activity.