Prunetin is an O-methylated isoflavone, which is a type of flavonoid. There are a limited number of reports detailing the biological activities of prunetin. Although an anti-inflammatory effect of prunetin has been reported in vitro, to our knowledge, there have been no reports on anti-adipogenic effects of prunetin in obese animals. The aims of this study were to determine whether prunetin suppresses high-fat diet (HFD)-induced adipogenesis in the liver and visceral adipose tissues of mice, and to explore the underlying mechanisms mediating the actions of prunetin. To this end, mice were fed a HFD for 10 weeks to induce obesity, and prunetin (10 μg/kg or 20 μg/kg) was administered in the last 3 weeks. Compared to saline-treated mice, mice treated with prunetin showed significantly reduced body weight gain, visceral fat pad weights, and plasma glucose levels. We found that prunetin significantly inhibited the HFD-induced upregulation of the expression of important adipogenic genes (PPARγ, C/EBPα, SREBP, aP2, LPL adiponectin, and leptin), and suppressed HFD-mediated increase in expression of lipid metabolism-related genes (SREBP, PPARγ, LXR, and HMG-CoA) in the liver tissues. Furthermore, prunetin induced expression of adiponectin receptors 1 and 2 (adipoR1, adipoR2), as well as that of AMP-activated protein kinase (AMPK) in the liver and adipose tissue. These results suggest that prunetin mediates anti-obesity/adipogenesis effects by suppressing obesity-related transcription through a feedback mechanism that regulates the expression of adiponectin, adipoR1, adipoR2, and AMPK.
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