Chemical profile and beneficial effect of standardized extract of Stevia rebaudiana Bertoni leaves on metabolic syndrome in high fat diet streptozotocin-induced diabetic rats

Stevia (Stevia rebaudiana Bertoni) is a natural zero calorie sweetener with significant economic and medicinal values due to its high contents of steviosides (SVGs) in the leaves. The aqueous extract of Stevia leaves (TAqE) was standardized to contain 8.5% w/w of SVGs (HPLC), total phenolics (164.63 +/- 1.39 mu g Gallic acid/mg extract) and total flavonoids of 100.5 +/- 0.79 mu g QE/mg extract. Twenty-one compounds were tentatively identified in the leaves via UPLC-Orbitrap HRMS and stevioside, rebaudioside A, and quercetrin were isolated from TAqE by repeated column chromatography. Stevioside showed significant inhibition of pancreatic lipase, alpha-amylase, and alpha-glucosidase enzymes. The effect of a standardized TAqE on high fat diet (HFD)-streptozotocin (STZ)-induced diabetic rats was investigated. Thirty-six animals were divided into 6 groups (each of 6). Rats in group I (control) and group II (control/HFD-STZ) received distilled water, and rats in groups III and IV received TAqE for 4 weeks in two doses; 300 mg/kg b.wt., and 500 mg/kg b.wt., respectively. Rats in group V received metformin (200 mg/kg), while those in group VI received statin (1 mg/kg). Body weight, fasting blood glucose, lipid profile (total cholesterol and triglycerides), liver enzymes (alanine transaminase and aspartic transaminase), and serum kidney parameters (urea and creatinine) were decreased in rats treated with TAqE (300 mg/kg b.wt.), while insulin sensitivity was enhanced, when compared to that in group II. These findings could justify the use of Stevia as a complementary medicine for the prevention and treatment of metabolic changes associated with diabetes mellitus type 2.