Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts

Figure 11

Insulin-mimetic and antioxidant activities of steviol glycoside mixtures. Steviol glycosides are able to act as ligands of the insulin receptor (IR or IGF-1R), triggering the PI3K/Akt pathway. The insulin receptor antagonist, S961, blocks the signal induced by both insulin and steviol glycosides. Upon the receptor activation, steviol glycoside signal leads to Glut4 translocation from intracellular pool to the plasma membrane, allowing glucose entry into the cell and thus mimicking the insulin action. Steviol glycosides are also able to increase the activity and the expression of the antioxidant enzymes SOD and CAT, probably through the activation of the same pathway (dashed blue lines). Moreover, cytosolic GSH levels are significantly increased in rat cardiac fibroblasts treated with steviol glycoside mixtures.