Antihyperglycemic Effect of Aqueous Extract of Tetraclinis articulata in Streptozotocin-Induced Diabetic Rats and Acute Toxicity Analysis

Aims: The study aimed to evaluate the glucose-lowering effect of Tetraclinis articulata. Background: Tetraclinis articulata is commonly used for the treatment of diabetes characterized by chronic hyperglycemia. Objective: This work aimed to evaluate the effect of Tetraclinis articulata (T. articulata) Aqueous Extract (TAAE) on glycemia and lipid profile in normal and Streptozotocin (STZ)-induced diabetic rats. Additionally, its acute toxicity, phytochemical composition, and antioxidant capacity were assessed. Methods: To highlight the effect of TAAE on plasma glucose levels and lipid metabolism, blood glucose levels were measured at 1, 2, 4, and 6 hours of treatment for the acute test and on days 2, 4 and 7 over the daily oral administration for the subchronic test at two selected doses (10 mg/kg and 20 mg/kg). Furthermore, Triglycerides (TGs), Total Cholesterol (TC), and High-Density Lipoprotein cholesterol (HDL-c) were measured after the treatment. The rats' liver, extensor digitorum longus (EDL), and soleus muscle were isolated from diabetic rats treated with TAAE at a dose of 20 mg/kg at the end of the experiment to measure glycogen content using a standard method. The acute toxicity of TAAE was examined according to the OECD guideline. In addition, body weight, signs of toxicity, and/or mortality were observed for 14 days. Besides, a preliminary phytochemical screening, quantification of phenolic, flavonoid, and tannin contents as well as the antioxidant activity, were evaluated. Results: The results showed that TAAE at the doses of 10 and 20 mg/kg possesses a potent antihyperglycemic effect in STZ-treated diabetic rats and an acute hypoglycemic effect in normal rats, as well as the extract provoked a decrease of blood glucose levels after glucose loading in the glucose tolerance test in a dose-dependent manner. TAAE at a dose of 20 mg/kg revealed a significant improvement in the lipid profile. However, treatment with TAAE at a dose of 20 mg/kg did not significantly modify the glycogen content. In the same way, the acute toxicity analysis revealed no death or signs of toxicity in rats, and the LD50 value was more than 2 g/kg. In addition, preliminary phytochemical screening revealed that TAAE revealed the presence of polyphenols, flavonoids, tannins, carbohydrates, saponins, quinones, sterols and terpenoids. Furthermore, TAAE exhibited a potent antioxidant activity, which may be due to the richness in polyphenol content (756.21 ± 6.72 mg GAE/1 g of extract). Conclusion: The current study demonstrates for the first time that aqueous Tetraclinis articulata extract has a potent glucose-lowering effect.