Efficacy of sauchinone as a novel AMPK-activating lignan for preventing iron-induced oxidative stress and liver injury

Iron-overload disorders cause hepatocyte injury and inflammation by oxidative stress, possibly leading to liver fibrosis and hepatocellular carcinoma. This study investigated the efficacy of sauchinone, a bioactive lignan, in preventing iron-induced liver injury and explored the mechanism of sauchinone's activity. To create iron overload, mice were injected with phenylhydrazine, and the effects on hepatic iron and histopathology were assessed. Phenylhydrazine treatment promoted liver iron accumulation and ferritin expression, causing hepatocyte death and increased plasma arachidonic acid (AA). Sauchinone attenuated liver injury (EC50 = 10 mg/kg) and activated AMPK in mice. Treatment of hepatocytes with iron and AA simulated iron overload conditions: iron + AA synergistically amplified cytotoxicity, increasing H2O2 and the mitochondrial permeability transition. Sauchinone protected hepatocytes from iron + AA-induced cytotoxicity, preventing the induction of mitochondrial dysfunction and apoptosis (EC50 = 1 mu M), similar to the result using metformin. Sauchinone treatment activated LKB1, which led to AMPK activation: these events contributed to cell survival. Evidence of cytoprotection by LKB1 and AMPK activation was revealed in the reversal of sauchinone's restoration of the mitochondrial membrane potential by either dominant negative mutant AMPK alpha or chemical inhibitor. In conclusion, sauchinone protects the liver from toxicity induced by iron accumulation, and sauchinone's effects may be mediated by LKB1-dependent AMPK activation. (C) 2009 Elsevier Inc. All rights reserved.