Hibiscus noldea (Malvaceae) Aqueous Extract Prevents Insulin Resistance and Protects Pancreatic Islets From Dexamethasone Damages in Rat.

Hibiscus noldea leaves-stems aqueous extract is used in Cameroonian traditional medecine to manage diabetes. To investigate the preventive effect of Hibiscus noldea aqueous extract on dexamethasone-induced insulin resistance, the animals received one of the following treatments: distilled water (10 mL/kg), metformine (200 mg/kg), or H. noldea (100 or 200 mg/kg) concomitantly with dexamethasone (0.5 mg/kg, ip) for ten days. Body weight was evaluated daily and blood glucose levels were measured. At the end of experiment, insulin sensitivity test was performed and lipid profile, transaminases Aspartate amino transferase, Alanin amino transferase, malondialdehyde, superoxide dismutase, catalase, and reduced glutathione were evaluated. Histological analysis of the liver was investigated to estimate glycogen content using Periodic Acid Schiff coloration and histomorphometry of pancreatic islets area was performed. The administration of dexamethasone during ten days induced body weight loss, hyperglycaemia, insulinresistance, an imbalance in lipid profile, an increase in transaminases and oxidative stress. Dexamethasone treatment also induced an increase in the pancreatic islets area and depletion in the levels of hepatic glycogen. Concomitant administration of dexamethasone and the aqueous plant extract prevented the rise in blood glucose levels, reduced insulinresistance, improved lipid profile and oxidative status. The aqueous extract of H. noldea prevented the use of glycogen storage and the increase in pancreatic islet area in dose dependent manner. Conclusion: The stem leaves aqueous extract from Hibiscus noldea have the ability to reduce insulinresistance via its antihyperglycaemic, hypolipidemic and antioxidant activities. These results justify the use of this extract in the management of diabetic state.