黑木耳多肽对棕榈酸诱导的脂肪肝细胞的降脂作用

目的：探究黑木耳多肽（Auricularia auricula polypeptides，AAP）对由棕榈酸（palmitic acid，PA）诱导的HepG2细胞脂肪肝模型的降脂作用。方法：本实验通过比较HepG2细胞内甘油三酯（triglyceride，TG）积累水平，筛选出分子质量低于3 kDa的多肽（AAP-3）降脂效果最好，并进一步探究其对细胞代谢及相关基因表达的影响。结果：在含200 μmol/L PA的培养基中生长24 h的HepG2细胞，胞内TG水平上升至阴性对照组的1.70 倍，而后与2.0 mg/mL AAP-3共培养24 h后可降低TG水平至正常细胞水平（P＞0.05）。此外，AAP-3还可降低总胆固醇（total cholesterol，TC）、低密度脂蛋白（low-density lipoprotein，LDL）、丙二醛（malondialdehyde，MDA）以及胞外谷草转氨酶（aspartate aminotransferase，AST）和谷丙转氨酶（alanine aminotransferase，ALT）水平，提升胞内高密度脂蛋白（high-density lipoprotein，HDL）和超氧化物歧化酶（superoxide dismutase，SOD）水平，表现出降脂、降胆固醇和抗氧化的活性。通过实时荧光定量聚合酶链式反应分析，发现AAP-3可降低脂肪酸合成基因FAS、SREBP-1c的转录水平，提高脂肪氧化分解相关基因AMPK、PPAR-α、PGC-1α、ATGL的转录水平。该研究结果为探索黑木耳功能性成分和植物功能性多肽提供了理论依据。

Lipid-Lowering Effect of Auricularia auricula Peptides on Palmitic Acid-Induced Liver Cells

This study explored the ameliorative effect of Auricularia auricula peptides (AAPs) on palmitic acid (PA)-induced non-alcoholic fatty liver in HepG2 cells. The effect of AAP with molecular mass less than 3 kDa (AAP-3), with the highest ability to reduce intracellular triglyceride (TG) accumulation, on cell metabolism and gene expression was investigated. The result showed that intracellular TG level was increased by 1.70 times in 200 μmol/L PA-treated HepG2 cells after 24 h of culture compared to the negative control group, and returned to normal after subsequent treatment with 2.0 mg/mL AAP-3 for 24 h (P > 0.05). Moreover, AAP-3 decreased total cholesterol (TC), low density lipoprotein (LDL) and malondialdehyde (MDA) level, as well as aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity, and increased high-density lipoprotein (HDL) level and superoxide dismutase (SOD) activity, thus exhibiting lipid-lowering, cholesterol-lowering and antioxidant activities. By real-time quantitative polymerase chain reaction (PCR) analysis, it was found that AAP-3 decreased the expression levels of the fatty-acid synthase (FAS) and sterol regulatory element-binding protein-1c (SREBP-1c) genes, and increased the expression levels of AMPK (AMP-activated protein kinase), PPAR-α (peroxisome proliferator-activated receptor alpha), PGC-1α (peroxisome?proliferator-activated receptor γ coactivator 1 alpha), and ATGL (adipose triglyceride lipase). The findings of this study may provide a theoretical basis for exploring the functional components of Auricularia auricula and plant-derived functional polypeptides.