Moriwaki Sayaka, Murakami Hiroki, Takahashi Nobuyuki, Uemura Taku, Taketani Keiko, Hoshino Shohei, Tsuge Nobuaki, Narukami Toshihiko, Goto Tsuyoshi, Kawada Teruo
a Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture , Kyoto University , Kyoto , Japan.
Biosci Biotechnol Biochem. 2014;78(7):1231-6. doi: 10.1080/09168451.2014.915736. Epub 2014 Jun 17.
Yamogenin is a diastereomer of diosgenin, which we have identified as the compound responsible for the anti-hyperlipidemic effect of fenugreek. Here, we examined the effects of yamogenin on the accumulation of triacylglyceride (TG) in hepatocytes, because yamogenin is also contained in fenugreek. It was demonstrated that yamogenin also inhibited TG accumulation in HepG2 hepatocytes and suppressed the mRNA expression of fatty acid synthesis-related genes such as fatty acid synthase and sterol response element-binding protein-1c. Indeed, yamogenin also antagonized the activation of the liver X receptor (LXR) in luciferase ligand assay similar to diosgenin. However, yamogenin could not exert such effects in the presence of T0901713, a potent agonist of LXR. These findings indicate that the effects of yamogenin on TG accumulation would be weaker than those of diosgenin, suggesting that the structural difference between yamogenin and diosgenin would be important for the inhibition of LXR activation.
薯蓣皂苷元是薯蓣皂苷的非对映异构体，我们已确定其为胡芦巴抗高脂血症作用的活性成分。在此，由于胡芦巴中也含有薯蓣皂苷元，我们研究了其对肝细胞中甘油三酯（TG）蓄积的影响。结果表明，薯蓣皂苷元同样能抑制HepG2肝细胞中TG的蓄积，并抑制脂肪酸合成相关基因如脂肪酸合酶和固醇调节元件结合蛋白-1c的mRNA表达。实际上，在荧光素酶配体检测中，薯蓣皂苷元与薯蓣皂苷一样，也能拮抗肝脏X受体（LXR）的激活。然而，在强效LXR激动剂T0901713存在的情况下，薯蓣皂苷元无法发挥此类作用。这些发现表明，薯蓣皂苷元对TG蓄积的作用弱于薯蓣皂苷，提示薯蓣皂苷元与薯蓣皂苷的结构差异对于抑制LXR激活具有重要意义。
