title: AMPK activation by isorhamnetin protects hepatocytes against oxidative stress and mitochondrial dysfunction.
abstract: Arachidonic acid (AA) is a ω-6 polyunsaturated fatty acid that is found in the phospholipids of membranes and released from the cellular membrane lipid bilayer by phospholipase A2. During this process, AA could produce excess reactive oxygen species and induce apoptosis and mitochondrial dysfunction by selectively inhibiting complexes I and III. Isorhamnetin, an O-methylated flavonol aglycone, has been shown to have cardio-protective, anti-adipogenic, anti-tumor, and anti-inflammatory effects. In the present study, we investigated the effects of isorhamnetin on hepatotoxicity and the underlying mechanisms involved. Our in vitro experiments showed that isorhamnetin dose-dependently blocked the hepatotoxicity induced by treatment with AA plus iron in HepG2 cells. Furthermore, isorhamnetin inhibited the AA+iron induced generation of reactive oxygen species and reduction of glutathione, and subsequently maintained mitochondria membrane potential in AA+iron treated HepG2 cells. In addition, isorhamnetin activated AMP-activated protein kinase (AMPK) by Thr-172 phosphorylation of AMPKα, and this was mediated with Ca2+/calmodulin-dependent protein kinase kinase-2 (CaMKK2), but not liver kinase B1. Experiments using CaMKK2 siRNA or its selective inhibitor, STO-609, revealed the role of CaMKK2 in the isorhamnetin-induced activation of AMPK in HepG2 cells. These results indicate isorhamnetin protects against the hepatotoxic effect of AA plus iron, and suggest that the AMPK pathway is involved in the mechanism underlying the beneficial effect of isorhamnetin in the liver.
authors: Medical research center for Globalization of Herbal Formulation, College of Oriental Medicine, Daegu Haany University, Daegu 706-828 Republic of Korea.
authors: Guang-Zhi
authors: GZ
authors: Dong
authors: Medical research center for Globalization of Herbal Formulation, College of Oriental Medicine, Daegu Haany University, Daegu 706-828 Republic of Korea.
authors: Ju-Hee
authors: JH
authors: Lee
authors: College of Pharmacy, Chosun University, Gwangju 501-759, Republic of Korea.
authors: Sung Hwan
authors: SH
authors: Ki
authors: College of Pharmacy, Chosun University, Gwangju 501-759, Republic of Korea.
authors: Ji Hye
authors: JH
authors: Yang
authors: Medical research center for Globalization of Herbal Formulation, College of Oriental Medicine, Daegu Haany University, Daegu 706-828 Republic of Korea.
authors: Il Je
authors: IJ
authors: Cho
authors: Medical research center for Globalization of Herbal Formulation, College of Oriental Medicine, Daegu Haany University, Daegu 706-828 Republic of Korea; Sunlin University, Pohang, Gyeongbuk, Republic of Korea.
authors: Seung Ho
authors: SH
authors: Kang
authors: Medical research center for Globalization of Herbal Formulation, College of Oriental Medicine, Daegu Haany University, Daegu 706-828 Republic of Korea; Department of Pharmacology, Mudanjiang Medical University, Heilongjiang, China. Electronic address: zhao_rongjie@yahoo.com.
authors: Rong Jie
authors: RJ
authors: Zhao
authors: Medical research center for Globalization of Herbal Formulation, College of Oriental Medicine, Daegu Haany University, Daegu 706-828 Republic of Korea. Electronic address: sckim@dhu.ac.kr.
authors: Sang Chan
authors: SC
authors: Kim
authors: Medical research center for Globalization of Herbal Formulation, College of Oriental Medicine, Daegu Haany University, Daegu 706-828 Republic of Korea; College of Oriental Medicine, Dongguk University, Gyeongju, Gyeongbuk, Republic of Korea. Electronic address: ywkim@dhu.ac.kr.
authors: Young Woo
authors: YW
authors: Kim
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects; D020011:Protective Agents / Q000494:pharmacology*; D011794:Quercetin / Q000031:analogs & derivatives* / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats
chemical_list: D020011:Protective Agents; D034741:RNA, Small Interfering; C047368:3-methylquercetin; D011794:Quercetin; D006861:Hydrogen Peroxide; C517698:CAMKK2 protein, human; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D055372:AMP-Activated Protein Kinases; D005978:Glutathione
keywords: AMPK; Isorhamnetin; Isorhamnetin (PubChem CID: 5281654); Mitochondria; Oxidative stress