Abstract
Forsythiaside, one of the main bioactive components of Chinese medicine Lian Qiao, exerts antioxidant, anti-bacterial, and anti-inflammatory effects. To date, the mechanism of Forsythiaside in cardiomyocyte injury remains unclear. However, the antioxidant effects of Forsythiaside on cardiac cells are currently unknown. This study investigated the effect and mechanism of Forsythiaside on oxidative stress in H9c2 cardiomyocytes. H9c2 cells were treated with H2O2 and Forsythiaside and then transfected with small-interfering RNA against nuclear factor erythroid 2-related factor 2 (siNrf2). Cell viability, apoptosis, accumulation of reactive oxygen species (ROS), and mitochondrial membrane potential were measured using methyl thiazolyl tetrazolium (MTT), terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) assay, fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA), and rhodamine 123, respectively. The levels of oxidative stress-related markers were determined using their respective detection kits. Furthermore, the levels of apoptosis- and Nrf2 pathway-related molecules were determined via Western blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Forsythiaside had no obvious toxicity on H9c2 cells. H2O2 suppressed the viability, and reduced the levels of mitochondrial membrane potential, B-cell lymphoma-2 (Bcl-2), glutathione peroxidase (GSH-Px) and catalase (CAT) and superoxide dismutase (SOD), while promoted apoptosis, ROS accumulation, and elevated the levels of cleaved caspase 3, BCL2-Associated X (Bax) and malondialdehyde (MDA) in H9c2 cells. Contrarily, Forsythiaside reversed the aforementioned effects. H2O2 advanced the levels of cytoplasm Nrf2, heme oxygenase-1 (HO-1), and nucleus Nrf2 in H9c2 cells, whereas Forsythiaside enhanced these effects. SiNrf2 reversed the functions of H2O2 or Forsythiaside in cell viability, MDA, SOD, GSH-Px, CAT, Nrf2, and HO-1 in H9c2 cells, whereas Forsythiaside reversed the aforementioned effects of siNrf2. In sum, Forsythiaside protected H9c2 cells from oxidative stress and apoptosis induced by H2O2 by activating the Nrf2/HO-1 pathway.