Icaritin Attenuates Lipid Accumulation by Increasing Energy Expenditure and Autophagy Regulated by Phosphorylating AMPK

BACKGROUND AND AIMS: Lipid accumulation is the major characteristic of non-alcoholic fatty liver disease, the prevalence of which continues to rise. We aimed to investigate the effects and mechanisms of icaritin on lipid accumulation. METHODS: Cells were treated with icaritin at 0.7, 2.2, 6.7, or 20 µM for 24 h. The effects on lipid accumulation in L02 and Huh-7 cells were detected by Bodipy and oil red O staining, respectively. Mitochondria biogenesis of L02 cells was detected by MitoTracker Orange staining. Glucose uptake and adenosine triphosphate content of 3T3-L1 adipocytes and C2C12 myotubes were detected. The expression levels of proteins in the adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling pathway, biomarkers of autophagy, and mitochondria biogenesis were measured by western blotting. LC3 puncta were detected by immunofluorescence. RESULTS: Icaritin significantly attenuated lipid accumulation in L02 and Huh-7 cells and boosted the mitochondria biogenesis of L02 cells. Icaritin enhanced glucose uptake, decreased adenosine triphosphate content, and activated the AMPK signaling pathway in 3T3-L1 adipocytes and C2C12 myotubes. Icaritin boosted autophagy and also enhanced the initiation of autophagic flux in 3T3-L1 preadipocytes and C2C12 myoblasts. However, icaritin decreased autophagy and promoted mitochondria biogenesis in 3T3-L1 adipocytes and C2C12 myotubes. CONCLUSIONS: Icaritin attenuates lipid accumulation by increasing energy expenditure and regulating autophagy by activating the AMPK pathway.