目的 探讨桂花Osmanthus fragrans及其活性成分红景天苷改善高脂血症的作用机制。方法 采用油酸诱导法建立HepG2细胞脂质沉积模型，通过MTT实验及细胞内三酰甘油（triglyceride，TG）水平评价桂花醇提物及其成分毛蕊花糖苷、红景天苷、异类叶升麻苷、松果菊苷的调脂活性，并结合油红O染色法观察脂滴生成情况。采用高脂饲料喂养法建立高脂血症大鼠模型，设置对照组、模型组、桂花醇提物（810 mg/kg）组及红景天苷低、高剂量（40、80 mg/kg）组和辛伐他汀（2.1 mg/kg）组，每组8只，连续给药5周。检测各组大鼠血清脂质水平、肝脏指数及肝脏总胆固醇（total cholesterol，TC）、TG水平；油红O染色法观察各组肝脏脂质沉积情况；苏木素-伊红（hematoxylin-eosin，HE）染色法观察附睾脂肪组织病理形态；肝组织转录组测序法分析桂花醇提物改善高脂血症的潜在分子机制，并采用分子对接技术预测其主要活性成分红景天苷与细胞焦亡相关蛋白NOD样受体热蛋白结构域3（NOD like receptor family pyrin domain containing 3，NLRP3）、半胱氨酸天冬氨酸蛋白酶-1（cystein-asparate protease-1，Caspase-1）、消皮素D的N端片段（N-terminal fragment of gasdermin D，GSDMD-N）、白细胞介素-1β（interleukin-1β，IL-1β）、IL-18、IL-6的亲和力，进一步采用Western blotting验证红景天苷对肝组织中焦亡相关蛋白表达的影响。结果 桂花醇提物和红景天苷能显著降低油酸诱导的HepG2细胞内TG水平（P＜0.05、0.01、0.001），并减少脂滴积累；同时能显著降低模型大鼠血清TC、TG、低密度脂蛋白胆固醇（low density lipoprotein cholesterol，LDL-C）水平（P＜0.01、0.001），升高高密度脂蛋白胆固醇（high density lipoprotein cholesterol，HDL-C）水平（P＜0.001），并显著降低肝脏TC、TG水平（P＜0.01、0.001），减轻肝脏脂质沉积，改善脂肪组织病理形态。转录组学的基因本体（gene ontology，GO）及京都基因与基因组百科全书（Kyoto encyclopedia of genes and genomes，KEGG）富集分析结果提示桂花醇提物的调脂机制可能与调控脂质代谢和炎症反应有关。分子对接结果显示，红景天苷与NLRP3、Caspase-1、IL-1β等调控炎症反应的相关蛋白具有较高亲和力；Western blotting结果显示，与模型组比较，除红景天苷低剂量组肝组织中的剪切型Caspase-1（cleaved Caspase-1）外，其余各给药组焦亡相关蛋白表达水平均显著降低（P＜0.05、0.01、0.001）。结论 红景天苷可能是桂花改善高脂血症的主要活性成分之一，且其调脂机制与抑制NLRP3/Caspase-1/IL-1β信号通路抗细胞焦亡有关。

Objective To investigate the mechanism by which Osmanthus fragrans and its active component salidroside improve hyperlipidemia. Methods An oleic acid-induced lipid deposition model was established in HepG2 cells. Lipid-regulating activities of O. fragrans ethanol extract and its components (acteoside, salidroside, isoacteoside, echinacoside) were evaluated using MTT assay and intracellular triglyceride (TG) level, supplemented by oil red O staining to visualize lipid droplet formation. A hyperlipidemic rat model was established via high-fat diet feeding. Control group, model group, O. fragrans ethanol extract group (810 mg/kg), salidroside low-, high-dose (40, 80 mg/kg) groups and simvastatin (2.1 mg/kg) group were set up, with eight rats per group, drugs were continuously administration for five weeks. Serum lipid levels, hepatic index, hepatic total cholesterol (TC) and TG levels in rats of each group were measured. Oil red O staining was used to observe hepatic lipid deposition in each group. Hematoxylin-eosin (HE) staining was used to examine the pathological morphology of epididymal adipose tissue. Transcriptome sequencing of liver tissue was performed to analyze the potential molecular mechanisms by which O. fragrans ethanol extract ameliorates hyperlipidemia. Molecular docking technology was employed to predict the affinity of salidroside, the primary active component, with pyroptosis-related proteins NOD like receptor family pyrin domain containing 3 (NLRP3), cystein-asparate protease-1 (Caspase-1), N-terminal fragment of gasdermin D (GSDMD-N), interleukin-1β (IL-1β), IL-18 and IL-6. Western blotting was used to further validate the effect of salidroside on expressions of pyroptosis-related proteins in liver tissue. Results O. fragrans ethanol extract and salidroside significantly reduced TG levels (P < 0.05, 0.01, 0.001), and diminished lipid droplet accumulation in oleic acid-induced HepG2 cells. Concurrently, they markedly lowered TC, TG and low density lipoprotein cholesterol (LDL-C) levels in serum (P < 0.01, 0.001), increased high density lipoprotein cholesterol (HDL-C) level (P < 0.001), reduced hepatic TC and TG levels (P < 0.01, 0.001), alleviated liver lipid deposition, and improved adipose tissue pathology in model rats. Transcriptomic gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses suggested that the lipid-regulating mechanism of O. fragrans ethanol extract may be related to regulating lipid metabolism and inflammatory responses. Molecular docking results indicated that salidroside exhibits high affinity for proteins involved in regulating inflammatory responses, such as NLRP3, Caspase-1 and IL-1β. Western blotting results showed that compared with model group, except for the cleaved Caspase-1 in liver tissues of salidroside low-dose group, the expression levels of pyroptosis-related proteins were significantly reduced in all other treatment groups (P < 0.05, 0.01, 0.001). Conclusion Salidroside may be one of the primary active components in O. fragrans for improving hyperlipidemia, and its lipid-regulating mechanism is associated with inhibiting NLRP3/Caspase-1/IL-1β signaling pathway to counteract hepatic pyroptosis.

R285.5

四川省中医药管理局（2024MS538）；四川省科技计划项目苗子工程项目（2021JDRC0156）