Polyphenol-rich extract of Syzygium cumini (L.) Skeels leaves improves the metabolic profile and redox status of dexamethasone-induced diabetic rats

Diabetes is an endemic disease that affects a large portion of the global population. As a result, the search for new antidiabetic drugs and supportive treatments is crucial to combat this widespread condition. Syzygium cumini (L.) Skeels (Myrtaceae), popularly known as "jambolão," reportedly has antioxidant, anti-inflammatory, and antidiabetic properties. This study aimed to evaluate the effects of the polyphenol-rich extract of Syzygium cumini leaves (PESc) on the metabolic profile and redox status of dexamethasone-induced diabetic rats. Male Wistar rats were randomly assigned to three groups: control group (CTRL), rats that received 0.9% saline solution (1 mL/kg/day, v.o., 10 days); dexamethasone group (DEX), rats that received dexamethasone (1 mg/kg/day, i.p., 5 days); and experimental group (PESc+DEX), rats that were pre-treated with PESc (500 mg/kg/day, v.o.), for 5 days prior to and during the dexamethasone regime. Fasting blood glucose and serum triglycerides increased in the DEX group compared to CTRL, which were reduced by the treatment with PESc. Similar effects were observed with serum insulin. We also observed that under hyperglycemic conditions, PESc-treated animals reversed the dexamethasone-induced insulin hypersecretion. However, the redox status was mildly affected by PESc treatment. Both superoxide dismutase and catalase activity increased in DEX group in comparison to CTRL, however PESc treatment attenuated only catalase activity. Moreover, serum hydroperoxides also increased in DEX, but was attenuated with PESc treatment. Our findings support the antidiabetic effects of PESc with a direct modulation on the insulin secretion, which appears to be partially related to redox-dependent mechanisms.