Isorhapontigenin is a natural bioactive stilbene isolated from various plants and fruits. It has been reported to exhibit several physiological activities including anticancer and anti-inflammation activity in vitro and in experimental animal models. This study aimed to investigate whether isorhapontigenin exerts antidiabetic effects in vivo. To this end, diabetic db/db mice were treated with either 25 mg kg^–1 of isorhapontigenin or vehicle intraperitoneally for a period of 5 weeks. The results show that isorhapontigenin treatment significantly reduced postprandial levels of glucose, insulin, as well as free fatty acid, three markers of diabetes. Further studies show that isorhapontigenin treatment markedly improves insulin sensitivity and glucose tolerance of db/db mice as shown by ITT and GTT. Together, these physiological results show that isorhapontigenin possesses antidiabetic properties in vivo. Mechanistically, the isorhapontigenin-mediated antidiabetic effect is caused by favorable changes in adipose tissue, including reductions in adipocyte diameter and improved adipose insulin sensitivity. Further studies with 3T3-L1 cells show that isorhapontigenin treatment promotes preadipocyte differentiation by upregulation of the activity of the master adipogenic regulator PPARγ and deceleration of its proteasomal degradation. Together, our results establish for the first time an important role of isorhapontigenin as a potential nutraceutical agent for diabetes treatment.

中文翻译：

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异皂甙元通过调节脂肪细胞中PPARγ的活性和稳定性改善小鼠糖尿病

异皂甙元是从各种植物和水果中分离出来的天然生物活性二苯乙烯。据报道在体外和实验动物模型中表现出几种生理活性，包括抗癌和抗炎活性。这项研究旨在调查异皂甙元是否在体内发挥抗糖尿病作用。为此，糖尿病性db / db小鼠腹膜内用25 mg kg ^–1的异皂甙元或载体腹膜内治疗5周。结果表明，异源皂苷元治疗可显着降低餐后葡萄糖，胰岛素以及游离脂肪酸（糖尿病的三个标志物）的水平。进一步的研究表明，异皂甙元治疗显着改善了db / db的胰岛素敏感性和葡萄糖耐量如ITT和GTT所示。这些生理结果共同表明，异皂甙元在体内具有抗糖尿病的作用。从机理上讲，异源皂苷元介导的抗糖尿病作用是由脂肪组织的有利变化引起的，包括脂肪细胞直径的减小和脂肪胰岛素敏感性的提高。对3T3-L1细胞的进一步研究表明，异皂甙元处理可通过上调主成脂调节剂PPARγ的活性和减缓其蛋白酶体降解来促进前脂肪细胞分化。在一起，我们的研究结果首次确立了异皂甙元作为糖尿病治疗的潜在营养剂的重要作用。