Effect of Mulberry Leaf and Its Active Component, 1-Deoxynojirimycin, on Palmitic Acid-Induced Lipid Accumulation in HepG2 Cells

<b>Objectives:</b> Aqueous mulberry leaf extract (MLE) contains 1-deoxynojirimycin (DNJ) and L-leucine (LL). This study investigated the effects of MLE, DNJ, and LL on lipid accumulation caused by palmitic acid (PA) in human hepatoma HepG2 cells, pro-inflammatory cytokine levels, and regulation of lipogenesis. <b>Methods:</b> PA was applied to HepG2 cells to generate a fatty liver in vitro model. Then, the cells were treated with MLE, DNJ, or LL for 24 h. Western blot analysis was performed to determine the protein expression levels of peroxisome proliferator-activated receptor gamma (PPAR-γ) and fatty acid synthase (FAS) in HepG2 cells. <b>Results:</b> Staining with Oil Red O (ORO) indicated that MLE, DNJ, and LL significantly decreased excessive lipid accumulation in HepG2 cells. Cytokine ELISA assay indicated that MLE, DNJ, and LL significantly decreased excessive pro-inflammatory cytokine levels in HepG2 cells. In addition, MLE, DNJ, and LL decreased the protein expression levels of PPAR-γ and FAS, suggesting a potential suppression of lipogenesis. <b>Conclusions:</b> Our results suggest that MLE, DNJ, and LL reduce lipid accumulation, pro-inflammatory cytokine levels, and the protein expressions of FAS and PPAR-γ in PA-induced fatty liver cells.