Cytoprotective effect of eckol against oxidative stress-induced mitochondrial dysfunction: involvement of the FoxO3a/AMPK pathway.

This study investigated the cytoprotective effect of Ecklonia cava-derived eckol against H2O2-induced mitochondrial dysfunction in Chang liver cells. While H2O2 augmented levels of mitochondrial reactive oxygen species (ROS), eckol decreased it. Eckol also attenuated high intracellular Ca(2+) levels stimulated by H2O2 and recovered H2O2-diminished ATP levels and succinate dehydrogenase activity. Eckol time-dependently increased the expression of manganese superoxide dismutase (Mn SOD), a mitochondrial antioxidant enzyme with cytoprotective effect against oxidative stress. Eckol recovered Mn SOD expression and activity that were decreased by H2O2. Finally, eckol induced Mn SOD through phosphorylated AMP-activated protein kinase (AMPK) and forkhead box O3a (FoxO3a). Specific silencing RNAs (siRNAs) against FoxO3a and AMPK reduced eckol-stimulated Mn SOD expression, and diethyldithiocarbamate (Mn SOD inhibitor) and siRNA against Mn SOD reduced the cytoprotective effect of eckol against H2O2-provoked cell death. These results demonstrate that eckol protects cells from mitochondrial oxidative stress by activating AMPK/FoxO3a-mediated induction of Mn SOD.