Antioxidant effects of maslinic acid in livers, hearts and kidneys of streptozotocin-induced diabetic rats: effects on kidney function

Abstract

Studies indicate that hyperglycemia-induced oxidative stress triggers the development of microvascular and macrovascular complications in diabetes. Accordingly, we hypothesized that maslinic acid (MA) prevents these complications due to its antioxidant properties. We, therefore, investigated the effects of 5-week MA treatment of streptozotocin (STZ)-induced diabetic rats on anti-oxidative status of cardiac, hepatic and renal tissues as well as on kidney function. Proximal tubular effects of MA were studied in anesthetized rats challenged with hypotonic saline after a 3.5 h equilibration for 4 h of 1 h control, 1.5 h treatment and 1.5 h recovery periods using lithium clearance. MA was added to the infusate during the treatment period. Oral glucose tolerance responses to MA were monitored in rats given a glucose load after an 18 h fast. Compared with untreated diabetic rats, MA-treated diabetic animals exhibited significantly low malondialdehyde (MDA, a marker of lipid peroxidation) and increased the activity of antioxidant enzymes; superoxide dismutase and glutathione peroxidase in hepatic, cardiac and renal tissues. The expressions of gastrocnemius muscle GLUT4 and kidney GLUT1 and GLUT2 were assessed to elucidate the mechanism of the hypoglycemic effects of MA. MA-treatment diminished the expression of GLUT1 and GLUT2 in diabetic kidney and reduced glycemia values of diabetic rats. MA administration increased urinary Na þ outputs and additionally the FE Na indicating that at least part of the overall reduction in Na þ reabsorption occurred in the proximal tubules. These results suggest antioxidant effects of MA can ameliorate oxidative stress and improve kidney function in diabetes mellitus.

The Effects of Syzygium Aromaticum-Derived Triterpenes on Gastrointestinal Ghrelin Expression in Streptozotocin-Induced Diabetic Rats

“…Various medicinal plant extracts have been reported to significantly reduce food intake possibly through the reduction of plasma ghrelin levels (Bast et al, 2002;Fong, 2002). Studies conducted in our laboratory have shown that Syzygium aromaticum-derived oleanolic acid (OA) and maslinic acid (MA) reduce blood glucose concentrations in STZ-induced diabetic rats in sub-chronic studies through a variety of mechanisms (Khathi et al, 2013;Mkhwanazi et al, 2014;Musabayane et al, 2010;Ngubane et al, 2011). Furthermore, these triterpenes have previously been reported to reduce food intake through unknown mechanisms (Khathi et al, 2013;Mkhwanazi et al, 2014).…”

“…Studies conducted in our laboratory have shown that Syzygium aromaticum-derived oleanolic acid (OA) and maslinic acid (MA) reduce blood glucose concentrations in STZ-induced diabetic rats in sub-chronic studies through a variety of mechanisms (Khathi et al, 2013;Mkhwanazi et al, 2014;Musabayane et al, 2010;Ngubane et al, 2011). Furthermore, these triterpenes have previously been reported to reduce food intake through unknown mechanisms (Khathi et al, 2013;Mkhwanazi et al, 2014). This study was therefore designed to evaluate the effects of these triterpenes on plasma ghrelin concentrations as well as the gastrointestinal expression of this hormone.…”

The effects of transdermal insulin treatment of streptozotocin-induced diabetic rats on kidney function and renal expression of glucose transporters

“…8 Our study shows that transdermal PI matrix patches can reverse the previously reported inability of the kidney to excrete Na + in STZ-diabetes mellitus. [30][31][32] Hyperinsulinemic edema and hypertension associated with intensive insulin therapy have been attributed, at least in part, to Na + retaining action of insulin. 8 However, literature evidence on the effects of insulin on kidney function in diabetes is conflicting and remains unclear.…”

The Effects of Transdermally Delivered Oleanolic Acid on Malaria Parasites and Blood Glucose Homeostasis in P. berghei-Infected Male Sprague-Dawley Rats

“…Reports indicate that S . aromaticum -derived oleanolic acid (OA) and maslinic acid (MA) possesses anti-inflammatory, antibacterial, antioxidant, and hepatoprotective properties [16–19]. We, therefore, speculate that these plant extracts may exert antiplasmodial effects against P .…”