Synergistic antioxidant effects of phenolic acids and carotenes on H2O2-induced H9c2 cells: Role of cell membrane transporters

Phenolic acids (caffeic acid, p-coumaric acid,) and carotenes (beta-carotene, lycopene) were mixed in different ratios to investigate antioxidant interactions on H2O2-induced H9c2 cells with ezetimibe (inhibitor of carotenes membrane transporters). Cellular uptake of carotenes, expression of membrane transporters, reactive oxygen species (ROS), nuclear factor erythroid 2-related factor 2 (Nrf2), NAD(P)H dehydrogenase quinone1 (NQO1), heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC) were analyzed. Results revealed that phenolic acids increased cellular uptake of carotenes and expression of their membrane transporters. Combination groups contained more phenolic acids showed synergistic effects. For example, beta-carotene: caffeic acid = 1:2 significantly suppressed the intracellular ROS (+EZT, 66.34 +/- 51.53%) and enhanced the accumulation of nucleus-Nrf2 (+EZT, 30.23 +/- 5.30) compared to the groups contained more beta-carotene (+EZT, ROS: 75.48 +/- 2.55%, nucleus-Nrf2: 19.48 +/- 4.22). This study provided an implication of functional foods formulation and demonstrated that antioxidant synergism may due to the up-regulation of carotenes membrane transporters by phenolic acids.