Abstract: To investigate the protective effect and mechanism of theaflavin-3,3'-O-digallate (TFDG) on vascular endothelial injury and inflammation in rats with diabetes mellitus, diabetic rats were made by high fat feed and streptozotocin injection and then divided into model group (CON), 5 mg·kg^-1 and 10 mg·kg^-1 TFDG intervention group (TFDG5 and TFDG10). The normal rats were taken as control group (NC). After 8 weeks of treatment, the pathological changes of abdominal aorta were observed. Plasma IL-6, IL-1β and TNF-α were detected by ELISA. The protein expression was detected by Western blot. Compared with CON, TFDG administration has no significant effects on body weight and fasting blood glucose. Pathological sections show that the injury of aorta tissue in TFDG group was improved compared with that in CON group. At the same time, the level of plasma inflammatory factors was significantly decreased, the level of plasma NO was significantly increased, and the level of MDA in aorta tissue was decreased in TFDG group. Further studies show that TFDG could down-regulate NLRP3, caspase-1 and IL-1β expressions in the aorta of diabetic rats. TFDG effectively protected vascular endothelial injury and inhibit inflammatory response in diabetic rats, and its mechanism might be through down-regulation of NLRP3 inflammatory pathway.

Key words: theaflavin, diabetes mellitus, vascular endothelial injury, inflammatory response