Glucose lowering effect of lupin seed gamma- conglutin in hyperglycaemic rats upon chronic treatment

Aim of the study was to evaluate the effect of a chronic oral administration of conglutin γ, a lupin seed protein, in male Sprague Dawley rats in which the hyperglicemia was induced by drinking water containing 10% d-glucose. A dosage of 100 mg/kg b.w. of conglutin γ was administered daily to rats for 21 days. Conglutin γ administration induced a statistically significant reduction in plasma glucose (-25%) and triglyceride (-20%) levels as well as a reduction of glycemia after the oral glucose loading, comparable to that of metformin. In order to assess the mechanism underlining this biological effect, Hep G2 cells, grown in DMEM containing different glucose concentrations (5.5 mM, 11 mM and 17 mM) for 24, 48 and 72 h, were exposed, respectively to 0.5 mg/mL conglutin γ +/- 10 mM metformin or +/- 100nM insulin. Conglutin γ induced in Hep G2 cells, in all experimental conditions, an increased glucose consumption (from 1.5 to 2.5 fold ) which was more evident after 24h of incubation. Moreover, the addition of conglutin γ potentiated, in this in vitro model, the activity of insulin and metformin in cell glucose uptake. These findings represent the first molecular evidence of the possible use of a legume protein in the control of glycemia.