Syzygium cumini Ameliorates Insulin Resistance and ^|^beta;-Cell Dysfunction via Modulation of PPAR^|^gamma;, Dyslipidemia, Oxidative Stress, and TNF-^|^alpha; in Type 2 Diabetic Rats

Abstract

Abstract. Syzygium cumini (SC) is well known for its anti-diabetic potential, but the mechanism underlying its amelioration of type 2 diabetes is still elusive. Therefore, for the first time, we investigated whether SC aqueous seed extract (100, 200, or 400 mg/kg) exerts any beneficial effects on insulin resistance (IR), serum lipid profile, antioxidant status, and/or pancreatic β-cell damage in high-fat diet / streptozotocin-induced (HFD-STZ) diabetic rats. Wistar albino rats were fed with HFD (55% of calories as fat) during the experiment to induce IR and on the 10th day were injected with STZ (40 mg/kg, i.p.) to develop type 2 diabetes. Subsequently, after confirmation of hyperglycemia on the 14th day (fasting glucose level > 13.89 mM), diabetic rats were treated with SC for the next 21 days. Diabetic rats showed increased serum glucose, insulin, IR, TNF-α, dyslipidemia, and pancreatic thiobarbituric acid-reactive substances with a concomitant decrease in β-cell function and pancreatic superoxide dismutase, catalase, and glutathione peroxidase antioxidant enzyme activities. Microscopic examination of their pancreas revealed pathological changes in islets and β-cells. These alterations reverted to near-normal levels after treatment with SC at 400 mg/kg. Moreover, hepatic tissue demonstrated increased PPARγ and PPARα protein expressions. Thus, our study demonstrated the beneficial effect of SC seed extract on IR and β-cell dysfunction in HFD-STZ-induced type 2 diabetic rats.

Immunohistochemistry, histopathology, and biomarker studies of swertiamarin, a secoiridoid glycoside, prevents and protects streptozotocin-induced β-cell damage in Wistar rat pancreas

“…STZ-induced diabetic rats showed histological features in contrast to normal rats, such as reduction in pancreatic islets number and size, atrophy of islet cells, fatty infiltration, and degeneration of acini, karyolysis, and degranulation of β-cells. Treatment with swertiamarin of the diabetic rats restored these histopathological features with significant increase in the plasma insulin, which overlaid with the similar reports by other authors of other plant extracts [66][67][68][69]. Similar histological changes were found in glibenclamide-treated groups.…”

Phytochemical Composition and Pleotropic Pharmacological Properties of Jamun, Syzygium Cumini Skeels

“…97 Moreover, treatment of streptozotocin-induced type-II diabetic rats with 400 mg/kg aqueous seed extract of Jamun brought the glucose level to near normal and also increased the expression of PPARγ and PPARα proteins in the rat liver. 98 The aqueous and methanol extracts of root, stem bark, leaf and seed of Jamun have been reported to lower serum glucose levels in alloxan-induced diabetes in male Sprague-Dawley rats. 99 The aqueous extract of Jamun seeds has also been reported to reduce serum glucose levels in alloxan-induced diabetes in mice.…”

Syzygium cumini seed extract ameliorates adenosine deaminase activity and biochemical parameters but does not alter insulin sensitivity and pancreas architecture in a short-term model of diabetes

“…Nonetheless, ASc treatment did not affect insulin levels ( Table 2). In fact, one of the mechanisms through which ASc exerts its hypoglycemic effects in vivo is through the inhibition of carbohydrate hydrolyzing enzymes, preventing the hydrolysis of glycogen [28][29][30]. Therefore, the lack of effect on insulin levels and the maintenance of glycogen content in diabetic rats may indicate that the ASc, when used for a short period of time, can modulate the hyperglycemic state through the direct peripheral glucose uptake, preventing its accumulation in the blood.…”