Phloretin attenuation of hepatic steatosis via an improvement of mitochondrial dysfunction by activating AMPK-dependent signaling pathways in C57BL/6J mice and HepG2 cells

Phloretin, a dihydrochalcone, widely exists in the fruits of apple trees and crabapple trees (Malus prunifolia) with multiple biological activities. Presently, we studied the function of phloretin on the attenuation of hepatic steatosis and further explored the underlying mechanisms both in vitro and in vivo. Male C57BL/6J mice were fed a normal diet or high fat diet (HFD) with or without phloretin (100 mg kg^-1) for 12 weeks. HepG2 cells were induced by 200 μM palmitic acid (PA) and co-incubated with phloretin (50 μM) for 24 h. The results showed that phloretin treatment significantly decreased the accumulation of lipids in the liver of the HFD-fed C57BL/6J mice and PA-induced HepG2 cells. Also, phloretin effectively ameliorated hepatic steatosis via promoting fatty acid β-oxidation (FAO). This biological activity of phloretin was closely related to its capacity to improve mitochondrial dysfunction, including the promotion of mitochondrial biosynthesis and inhibition of mitochondrial swelling through the AMPK-dependent SIRT1/PGC-1α and SIRT3/CypD signaling pathways, respectively. These results demonstrate that phloretin effectively improves mitochondrial function and ameliorates HFD-induced hepatic steatosis through an AMPK-dependent signaling pathway.