Persistent hyperglycemia and elevated levels of free fatty acids (FFA) contribute to oxidative stress, a proximate cause for the onset and progression of diabetes and its complications. The present study was hypothesized to evaluate the anti-diabetic potential of Rosmarinic acid (RA) during high-fat diet (HFD)-streptozotocin (STZ)-induced type 2 Diabetes (T2D) in wistar albino rats. Oral administration of RA (100 mg/kg b.w) significantly (p < 0.05) increased the insulin sensitivity index (ISI0,120), while the levels of blood glucose, HbA1c, advanced glycation end products (AGE), TNF-α, IL-1β, IL 6, NO, p-JNK, P38 MAPK and NF-κB were significantly reduced, with a concomitant elevation in the plasma insulin levels in diabetic rats. Furthermore, RA treatment significantly (p < 0.05) reduced the levels of triglycerides, FFA and cholesterol in serum, and reduced the levels of lipid peroxides, AOPP's and protein carbonyls in the plasma and pancreas of diabetic rats. The diminished activities of pancreatic superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) and the decreased levels of plasma ceruloplasmin, vitamin C, vitamin E and reduced glutathione (GSH) in diabetic rats were also significantly (p < 0.05) recovered upon RA treatment denoting its antioxidant potential which was confirmed by Nrf-2, hemeoxyenase (HO-1) levels. Histological, ultrastructural and immunohistochemical data demonstrate that oral administration of RA protects pancreatic β-cells from oxidative niche in HFD-STZ-induced experimental diabetes. Our findings suggest that the oral treatment with RA alleviates pancreatic β-cell dysfunction and glucolipotoxicity-mediated oxidative stress during HFD-STZ-induced T2DM, perhaps through its antioxidant potential.

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The seeds of Nelumbo nucifera (Lotus) have been used in the traditional system of medicine for various ailments including diabetes. The present study was aimed at analyzing the levels of biologically important trace elements in the lotus seeds by atomic absorption spectroscopy and evaluating the hypoglycemic properties of seed ash on streptozotocin-induced diabetes in rats. Diabetic rats treated with lotus seed ash at a concentration of 200 mg/kg body weight orally for 30 days exhibited significant hypoglycemic activity. The presence of trace elements in appreciable amounts in the seeds may play a direct or indirect role on insulin secretion or its action in a synergetic manner. The hypoglycemic activity of the ash was comparable with glyclazide. The role of trace elements in disorders related to diabetes is also discussed briefly.

The results of the present study indicate that gossypin has potent antidiabetic activity in STZ-induced experimental diabetes in rats.

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