Momordica charantia is a popular vegetable associated with effective complementary and alternative diabetes management in some parts of the world. However, the molecular mechanism is less commonly investigated. In this study, we investigated the association between a major cucurbitane triterpenoid isolated from M. charantia, 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al (THCB) and peroxisome proliferator activated receptor gamma (PPARγ) activation and its related activities using cell culture and molecular biology techniques. In this study, we report on both M. charantia fruit crude extract and THCB in driving the luciferase activity of Peroxisome Proliferator Response Element, associated with PPARγ activation. Other than that, THCB also induced adipocyte differentiation at far less intensity as compared to the full agonist rosiglitazone. In conjunction, THCB treatment on adipocytes also resulted in upregulation of PPAR gamma target genes expression; AP2, adiponectin, LPL and CD34 at a lower magnitude compared to rosiglitazone’s induction. THCB also induced glucose uptake into muscle cells and the mechanism is via Glut4 translocation to the cell membrane. In conclusion, THCB acts as one of the many components in M. charantia to induce hypoglycaemic effect by acting as PPARγ ligand and inducing glucose uptake activity in the muscles by means of Glut4 translocation.

中文翻译：

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苦瓜天然化合物 3β,7β,25-triHydroxycucurbita-5,23(E)-dien-19-al 作为 PPARγ 配体

苦瓜是一种受欢迎的蔬菜，在世界某些地区与有效的补充和替代糖尿病管理有关。然而，其分子机制的研究较少。在这项研究中，我们研究了从苦瓜中分离出的一种主要葫芦烷三萜类化合物 3β,7β,25-三羟基葫芦-5,23(E)-dien-19-al (THCB) 与过氧化物酶体增殖物激活受体 γ (PPARγ) 之间的关联）利用细胞培养和分子生物学技术进行激活及其相关活动。在这项研究中，我们报告了苦瓜果实粗提物和 THCB 在驱动过氧化物酶体增殖物反应元件的荧光素酶活性方面的作用，该活性与 PPARγ 激活相关。除此之外，与完全激动剂罗格列酮相比，THCB 还以低得多的强度诱导脂肪细胞分化。同时，THCB 对脂肪细胞的治疗也导致 PPAR γ 靶基因表达上调；与罗格列酮的诱导相比，AP2、脂联素、LPL 和 CD34 的量级较低。THCB 还诱导肌肉细胞摄取葡萄糖，其机制是通过 Glut4 易位到细胞膜。总之，THCB 作为苦瓜中的众多成分之一，通过充当 PPARγ 配体并通过 Glut4 易位诱导肌肉中的葡萄糖摄取活性来诱导降血糖作用。