Theaflavin-3,3′-digallate (TFDG) in black tea has a strong antioxidant capacity. However, its effect on diabetic liver and kidney injury and the underlying mechanisms remain unclear. In the present study, our findings indicated that TFDG administration effectively lowers the fasting blood glucose and serum lipid concentrations and enhances the functionality and cellular architecture of the liver and kidney in rats with diabetes. The data also showed that TFDG mitigates oxidative harm in the liver and kidney of rats afflicted with diabetes. Additionally, metformin combined with TFDG was significantly more effective in reducing blood glucose and oxidative stress. Further studies suggested that TFDG upregulates the Nrf2 signal pathway and circ-ITCH (hsa_circ_0001141) expression. Silencing of circ-ITCH by transfection of the interfering plasmid apparently reduces the effects of TFDG on the Nrf2 signal pathway and oxidative stress in high-glucose-treated hepatic and renal cells. In conclusion, the present study highlights the great potential of TFDG in ameliorating diabetic liver and kidney injury by up-regulating circ-ITCH to promote the Nrf2 signal pathway and provides a potential option for the prevention and treatment of diabetic complications.

中文翻译：

---

Theaflavin-3,3'-Digallate 通过上调 Circ-ITCH 和 Nrf2 信号通路保护糖尿病大鼠的肝肾功能

红茶中的茶黄素-3,3′-二没食子酸酯（TFDG）具有很强的抗氧化能力。然而，其对糖尿病肝肾损伤的影响及其潜在机制仍不清楚。在本研究中，我们的研究结果表明，TFDG 给药可有效降低糖尿病大鼠的空腹血糖和血脂浓度，并增强肝脏和肾脏的功能和细胞结构。数据还表明，TFDG 可以减轻糖尿病大鼠肝脏和肾脏的氧化损伤。此外，二甲双胍联合 TFDG 在降低血糖和氧化应激方面显着更有效。进一步的研究表明 TFDG 上调 Nrf2 信号通路和 circ-ITCH (hsa_circ_0001141) 表达。通过转染干扰质粒沉默 circ-ITCH 明显降低了 TFDG 对高糖处理的肝细胞和肾细胞中 Nrf2 信号通路和氧化应激的影响。总之，本研究强调了 TFDG 通过上调 circ-ITCH 促进 Nrf2 信号通路在改善糖尿病肝肾损伤方面的巨大潜力，为预防和治疗糖尿病并发症提供了潜在的选择。