Wanwei Yang1, Cuihua Jiang2, Zhiguo Wang1, Jian Zhang2, Xiaodong Mao3, Guofang Chen3, Xiaoming Yao1, Chao Liu3. 1. Clinical Laboratory, Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing, Jiangsu, PR China. 2. Laboratory of Translational Medicine, Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing, Jiangsu, PR China. 3. Research Center of Endocrine and Metabolic Diseases, Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing, Jiangsu, PR China.
Abstract
CONTEXT: Cyclocarya paliurus (CP) (Batal.) Iljinsk (Cyclocaryaceae), a plant native to China, is the sole species in the genus Cyclocarya. Its leaves have been widely used as a remedy for hyperlipidaemia in traditional folk medicine. However, the mechanism underlying CP-induced lipolysis, especially in the liver, has not been entirely elucidated. OBJECTIVE: This study investigates the effect of CP ethanol extract (CPE) on hepatic steatosis and the underlying molecular mechanisms involved. MATERIALS AND METHODS: The effect of CPE at concentrations of 0, 6.25, 12.5, 25, 50, and 100 μg/mL on the viability of HepG2 cells was examined using the cell counting kit-8 (CCK-8) assay after incubation for 24 h. CPE-induced changes in intracellular lipid content were assessed by measuring the absorbance of oil red O staining at 520 nm, and the possible underlying mechanisms were further studied using quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis, western blotting, immunofluorescence studies and transmission electron microscopy. RESULTS: The half-maximal inhibitory concentration (IC50) of CPE in HepG2 cells was 97.27 μg/mL. Treatment with 50 μg/mL CPE increased lipid clearance, which was associated with increased autophagy in HepG2 cells. CPE-induced autophagy involved downregulation of phosphorylation level of mammalian target of rapamycin (0.87 ± 0.08 vs. 1.31 ± 0.10). Fluorescent double staining and electron microscopy images showed lipid deposits within autolysosomes, thereby confirming the abovementioned findings. DISCUSSION AND CONCLUSIONS: CPE can induce hepatic fat clearance through the autophagy-lysosome pathway known as lipophagy. CPE has potential as a functional food.
CONTEXT: Cyclocarya paliurus (CP) (Batal.) Iljinsk (Cyclocaryaceae), a plant native to China, is the sole species in the genus Cyclocarya. Its leaves have been widely used as a remedy for hyperlipidaemia in traditional folk medicine. However, the mechanism underlying CP-induced lipolysis, especially in the liver, has not been entirely elucidated. OBJECTIVE: This study investigates the effect of CP ethanol extract (CPE) on hepatic steatosis and the underlying molecular mechanisms involved. MATERIALS AND METHODS: The effect of CPE at concentrations of 0, 6.25, 12.5, 25, 50, and 100 μg/mL on the viability of HepG2 cells was examined using the cell counting kit-8 (CCK-8) assay after incubation for 24 h. CPE-induced changes in intracellular lipid content were assessed by measuring the absorbance of oil red O staining at 520 nm, and the possible underlying mechanisms were further studied using quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis, western blotting, immunofluorescence studies and transmission electron microscopy. RESULTS: The half-maximal inhibitory concentration (IC50) of CPE in HepG2 cells was 97.27 μg/mL. Treatment with 50 μg/mL CPE increased lipid clearance, which was associated with increased autophagy in HepG2 cells. CPE-induced autophagy involved downregulation of phosphorylation level of mammalian target of rapamycin (0.87 ± 0.08 vs. 1.31 ± 0.10). Fluorescent double staining and electron microscopy images showed lipid deposits within autolysosomes, thereby confirming the abovementioned findings. DISCUSSION AND CONCLUSIONS: CPE can induce hepatic fat clearance through the autophagy-lysosome pathway known as lipophagy. CPE has potential as a functional food.