苦瓜皂苷对秀丽隐杆线虫寿命的影响及其机制研究

目的：研究苦瓜皂苷对秀丽隐杆线虫寿命的影响及其与降脂作用的相关性。方法：结合油红O染色与甘油三酯生化试剂盒分析苦瓜皂苷（50、100、200 μg/mL）对线虫脂肪沉积的作用；通过测定线虫体长、体宽、运动能力以及寿命评估苦瓜皂苷对线虫基础生理指标的影响；采用实时荧光定量聚合酶链式反应技术检测脂代谢相关基因的mRNA表达水平；利用脂代谢相关基因缺失的线虫突变株，通过系统寿命评估，考察苦瓜皂苷调控线虫寿命与脂代谢的相关性。结果：100、200 μg/mL苦瓜皂苷在不改变虫体大小、运动能力等基础生理指标条件下，能够显著降低线虫甘油三酯相对含量（P＜0.05），并延长线虫自然寿命（P＜0.000 1）。经100 μg/mL苦瓜皂苷处理后，脂肪合成相关基因nhr-80、fat-5、fat-6和fat-7 mRNA表达水平显著降低（P＜0.05），而对脂肪酸氧化或脂肪分解相关的基因无明显作用。经苦瓜皂苷处理后，fat-6、fat-7单突变体和fat-6/fat-7双突变体的寿命均无显著延长（P＞0.05）。结论：苦瓜皂苷延长线虫自然寿命的作用与其降低脂肪沉积的功效密切相关，其机制主要是抑制了脂肪酸合成途径中脱饱和酶fat-6和fat-7的基因表达。

Effect of Saponin from Bitter Melon (Momordica charantia) on the Lifespan of Caenorhabditis elegans and Its Mechanism

Objective: The aim of this study was to determine the effect of bitter melon saponin (BMS) on the lifespan of Caenorhabditis elegans and its correlation with the lipid-lowering effect of BMS. Methods: The effect of BMS (50, 100 and 200 μg/mL) on fat deposition in C. elegans was analyzed by oil red O staining and triglyceride (TG) assay. The impacts of BMS on the basic physiological activities of C. elegans were evaluated by measuring body length, body width, locomotive activity and lifespan. The mRNA expression levels of lipid metabolism-related genes were detected by quantitative real-time polymerase chain reaction (qPCR). By using C. elegans mutants deficient in lipid metabolism-related genes, the relationship between the regulatory effect of BMS on the lifespan of C. elegans and its lipid metabolism was established. Results: 100 and 200 μg/mL BMS treatment could significantly reduce the TG level (P < 0.05), prolong the natural lifespan of C. elegans (P < 0.000 1) without changing basic physiological activities such as body size and locomotive ability. The mRNA expression levels of nhr-80, fat-5, fat-6 and fat-7 were significantly decreased by treatment with 100 μg/mL BMS (P < 0.05), while the mRNA expression levels of genes related to fatty acid oxidation or lipolysis were not affected. BMS treatment did not significantly extend the lifespan of the single or double mutants deficient in the fat-6 or/and fat-7 genes (P > 0.05). Conclusion: The effect of BMS on prolonging the natural lifespan of C. elegans is closely related to its efficacy in reducing fat deposition, and the mechanism is mainly inhibiting the expression of the two genes encoding desaturases, fat-6 and fat-7.