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 (EC 50 ) 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 H 2 O 2 -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.