Nootkatone, a Characteristic Constituent of Grapefruit, Stimulates Energy Metabolism and Prevents Diet-Induced Obesity by Activating AMPK

Am J Physiol Endocrinol Metab. 2010 Aug;299(2):E266-75. doi: 10.1152/ajpendo.00774.2009. Epub 2010 May 25.

Abstract

AMP-activated protein kinase (AMPK) is a serine/threonine kinase that is implicated in the control of energy metabolism and is considered to be a molecular target for the suppression of obesity and the treatment of metabolic syndrome. Here, we identified and characterized nootkatone, a constituent of grapefruit, as a naturally occurring AMPK activator. Nootkatone induced an increase in AMPKalpha1 and -alpha2 activity along with an increase in the AMP/ATP ratio and an increase the phosphorylation of AMPKalpha and the downstream target acetyl-CoA carboxylase (ACC), in C(2)C(12) cells. Nootkatone-induced activation of AMPK was possibly mediated both by LKB1 and Ca(2+)/calmodulin-dependent protein kinase kinase. Nootkatone also upregulated PPARgamma coactivator-1alpha in C(2)C(12) cells and C57BL/6J mouse muscle. In addition, administration of nootkatone (200 mg/kg body wt) significantly enhanced AMPK activity, accompanied by LKB1, AMPK, and ACC phosphorylation in the liver and muscle of mice. Whole body energy expenditure evaluated by indirect calorimetry was also increased by nootkatone administration. Long-term intake of diets containing 0.1% to 0.3% (wt/wt) nootkatone significantly reduced high-fat and high-sucrose diet-induced body weight gain, abdominal fat accumulation, and the development of hyperglycemia, hyperinsulinemia, and hyperleptinemia in C57BL/6J mice. Furthermore, endurance capacity, evaluated as swimming time to exhaustion in BALB/c mice, was 21% longer in mice fed 0.2% nootkatone than in control mice. These findings indicate that long-term intake of nootkatone is beneficial toward preventing obesity and improving physical performance and that these effects are due, at least in part, to enhanced energy metabolism through AMPK activation in skeletal muscle and liver.

MeSH terms

  • Adenine Nucleotides / metabolism
  • Animals
  • Anti-Obesity Agents*
  • Blotting, Western
  • Calorimetry, Indirect
  • Cells, Cultured
  • Citrus paradisi / chemistry*
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Diet*
  • Energy Metabolism / drug effects*
  • Enzyme Activation / drug effects
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Obesity / drug therapy*
  • Obesity / enzymology*
  • Oxidation-Reduction
  • Peroxisome Proliferator-Activated Receptors / metabolism
  • Physical Endurance / physiology
  • Polycyclic Sesquiterpenes
  • Reactive Oxygen Species / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sesquiterpenes / pharmacology*
  • Stimulation, Chemical
  • Swimming / physiology

Substances

  • Adenine Nucleotides
  • Anti-Obesity Agents
  • Peroxisome Proliferator-Activated Receptors
  • Polycyclic Sesquiterpenes
  • Reactive Oxygen Species
  • Sesquiterpenes
  • Cyclic AMP-Dependent Protein Kinases
  • nootkatone