Actividad antidiabética de un extracto de hexane de Prosthechea michuacana en ratas diabéticas inducidas por estreptozotocina

In this study we investigated the antihyperglycaemic, antihyperlipidaemic and antiglycation effects of some extracts of Prosthechea michuacana bulbs in normoglycemic and diabetic rats induced by streptozocin (STZ). Hexane, chloroform and methanol extracts of P. michuacana were screened for hypoglycemic activity, and biochemical parameters as serum triglycerides, total cholesterol, lipid peroxidation, liver glycogen, skeletal muscle glycogen levels, superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase activity in diabetic rats. Additionally we determined Glucose 6 Phosphatase and glucokinase activities in liver, inhibition of insulin and protein glycation. Glucose levels in blood plasma were determined by using GOD-POD method. Administration of chloroform and methanol extracts showed no effect on STZ induced diabetic rats (SD). On the other hand, treatment with hexane extract at 200 and 400 mg/kg doses, resulted in a reversal of diabetes and its complications. Both doses significantly brought down blood glucose concentration (35.75 and 47.78% in diabetic rats, 50.64 and 57.10% in nondiabetic rats), increased glycogenesis and decreased glyconeogenesis bringing the glucose metabolism toward normalcy. These doses also reversed the hyperlipidemia by reducing cholesterol (41.56%, 46.08%) and triglycerides (37.5%, 46.27%) and improved hepatic antioxidant enzyme activities. Its effect was compared with that of glibenclamide and tolbutamide, as reference antidiabetic drugs. The hexane extract decreased the hyperinsulinemia by 24% in SD and showed a significant change on AGEs formation in vitro with IC50 values of 48.3 μg/ml comparable to inhibitory effect of aminoguanidine with IC50 values of 27.2 μg/ml. It reduced HbA1C levels by 6.4% in chronic STZ-diabetic rats. It is concluded that hexane extract of Prosthechea michuacana bulbs possesses anti-hyperglycemic and antihyperlipemic activity, improves the hyperinsulinemia and produces a significant change on AGEs formation, which may prove to be of importance in the management of diabetes and its complications.