Synergistic and Antagonistic Activity of Selected Dietary Phytochemicals against Oxidative Stress-Induced Injury in Cardiac H9c2 Cells via the Nrf2 Signaling Pathway

Abstract

The antioxidant activities of lycopene (LY), lutein (LU), chlorogenic acid (CA), and delphinidin (DP) were tested in vitro on H9c2 cell-based models. Some indicators, such as the generation of reactive oxygen (ROS), the quantification of cell antioxidant activity (CAA), and the expressions of SOD, GSH-Px, and CAT, were calculated to examine their antioxidant interactions. From our results, the phytochemical mixtures (M1: CA-LU: F3/10, M2: DP-CA: F7/10, M3: DP-LY: F5/10) displayed strong synergistic effects based on the generation of ROS and the quantification of CAA. However, great antagonistic bioactivities were seen in the combinations of LY-LU: F5/10 (M4), CA-LU: F9/10 (M5), and DP-LY: F7/10 (M6). Western blotting analysis indicated that the possible mechanism underlying the synergistic antioxidant interactions among phytochemical combinations was to enhance the accumulation of Nrf2 in the nucleus and the expression of its downstream antioxidant enzymes, HO-1 and GCLC. The combinations (M1–M3 groups) showed significant protection against the loss of mitochondrial membrane potential than individual groups to avoid excessive ROS production. The M4–M6 groups exerted antagonistic protective effects compared with the individual groups. In addition, lutein and lycopene absorption was improved more because of the presence of chlorogenic acid and delphinidin in the M1 and M3 groups, respectively. However, delphinidin significantly reduced the cellular uptake of lycopene in the M6 group. It appeared that antioxidant interactions of phytochemical combinations may contribute to the restoration of cellular redox homeostasis and lead to an improvement in diet quality and collocation.