Abstract:
Diabetes mellitus (DM) is a chronic metabolic disorder, characterised by constant elevated levels of glucose in the blood. Currently, type 2 diabetes mellitus (T2DM) emerged as global burden disease. Despite the significant progress in treating diabetes by hypoglycaemic drugs, search for new drugs continues as the present synthetic drugs have several limitations. The herbal drugs with antidiabetic activity are attracting scientists' attention. Commonly, the aims of using herbs are to enhance insulin sensitivity and secretion. Madecassoside (MAD) and catalpol (CAT) are antioxidant herbal compounds. This study aimed to investigate the effect of MAD and CAT on insulin sensitivity and release in INS-1E cells. INS-1E cells were cultured in high glucose medium for 48 h. Subsequently, the medium was removed then MAD and CAT were added for 24 h. Then glucose stimulated insulin secretion (GSIS) and insulin signalling proteins were investigated. Results showed that 30 μM MAD and 40 μM CAT significantly increased the insulin concentration 26.4 ± 0.1 (P<0.01) and 26.1 ± 0.2 μg/L (P <0.05), respectively. Furthermore, these compounds improved insulin resistance through a significant enhancement of Phospho- (Tyr608) insulin receptor substrate-1 (IRS1), Akt, phospho-Ser473 Akt and GLUT2 expressions. In conclusion, 30 μM MAD and 40 μM CAT markedly increased the sensitivity of the cells to glucose and insulin.
