Abstract
Increased oxidative stress is a widely accepted factor in the development and progression of diabetes and its complications. In this study, we evaluated the antioxidative potential of Teucrium polium (Family Lamiaceae) aqueous extract for protecting rat pancreatic tissue against streptozotocin (STZ)-induced oxidative stress. Diabetes was induced in rats by intraperitoneal injections of at a single dose of STZ at 40 mg/kg. The crude extract (equivalent to 0.5 g of plant powder/kg of body weight) was administered orally (intragastrically) to a group of STZ diabetic rats for 30 consecutive days. Changes in antioxidant status were evaluated by determining catalase (CAT) and superoxide dismutase (SOD) activities and the level of reduced glutathione (GSH) in pancreatic tissue. In addition, serum nitric oxide (NO) concentration, pancreatic tissue malondialdehyde (MDA) (an index of lipid peroxidation) level, and reliable markers of protein oxidation such as protein carbonyl content (PCO) and advanced oxidation protein products (AOPP) were also determined. Under diabetic conditions, blood glucose level, serum NO concentration, and pancreatic MDA, PCO, and AOPP levels were all increased. The diabetic rats also exhibited pancreatic GSH depletion along with significant reductions in activities of CAT and SOD. Rats treated with T. polium extract had significantly higher GSH levels along with enhanced CAT and SOD activities in pancreatic tissue. In addition to suppressed blood glucose levels, serum NO, pancreatic MDA, PCO, and AOPP levels were all lower than in the diabetic group. Our results strongly support the proposal that antioxidative activity of T. polium occurs by quenching the extent of lipid and protein oxidation. Based on these observations, it is concluded that T. polium may have protective effect(s) on pancreatic tissue in STZ-induced oxidative stress due to its high antioxidative potential.