title: Honokiol protects osteoblastic MC3T3-E1 cells against antimycin A-induced cytotoxicity.
abstract: OBJECTIVE
  Honokiol is a phenolic compound isolated from the bark of Magnolia officinalis, a plant widely used in traditional medicine. Antimycin A, which inhibits complex III of the electron transport system, has been used as a reactive oxygen species generator in biological systems. In the present study, we investigated the protective effects of honokiol on antimycin A-induced dysfunction in osteoblastic MC3T3-E1 cells.
  
  
  METHODS
  Osteoblastic MC3T3-E1 cells were pre-incubated with honokiol before treatment with antimycin A, and markers of mitochondrial function and oxidative damage were examined. In addition, the effects of honokiol on the activation of PI3K (phosphoinositide 3-kinase) and CREB (cAMP-responsive element-binding protein) were examined in MC3T3-E1 cells.
  
  
  RESULTS
  Honokiol significantly (P < 0.05) increased cell viability and calcium deposition and decreased the production of ROS in the presence of antimycin A. Moreover, pretreatment with honokiol prior to antimycin A exposure significantly reduced antimycin A-induced mitochondrial membrane potential (MMP) dissipation, complex IV inactivation, nitrotyrosine formation, and thioredoxin reductase inactivation. Honokiol also induced the activation of PI3K and CREB inhibited by antimycin A, which demonstrates that honokiol utilizes the PI3K and CREB pathway to augment metabolic activity inhibited by antimycin A.
  
  
  CONCLUSIONS
  Honokiol may reduce or prevent osteoblast degeneration in osteoporosis or other degenerative disorders.
authors.affiliation: Department of Food and Nutrition, Education Graduate School, Kyung Hee University, 1, Hoegi-dong, Dongdaemun-gu, Seoul, 130-701, Korea. cheunmi@hanmail.net
authors.forename: Eun Mi
authors.initials: EM
authors.lastname: Choi
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000009:adverse effects; D000968:Antimycin A / Q000009:adverse effects*; D000975:Antioxidants / Q000378:metabolism; D001713:Biphenyl Compounds / Q000494:pharmacology*; D002470:Cell Survival; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017705:Lignans / Q000494:pharmacology*; D031566:Magnolia / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017382:Reactive Oxygen Species; D013481:Superoxides / Q000378:metabolism; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D000900:Anti-Bacterial Agents; D000968:Antimycin A; D000975:Antioxidants; D001713:Biphenyl Compounds; D017362:Cyclic AMP Response Element-Binding Protein; D017705:Lignans; D010100:Oxygen; D019869:Phosphatidylinositol 3-Kinases; D017382:Reactive Oxygen Species; D013481:Superoxides; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols