Opposite Effects of F1 and F5 Fractions of Total Methanol Leaf-extract of Dialium guineense (Cesalpiniaceae) on Blood Glucose in Rat

Abstract

The purpose of this study is to investigate the effects of total methanol leaf-extract of Dialium guineense (Cesalpiniaceae) and its fractions on blood glucose in rat. The fractions of methanol extract were obtained by chromatography Sephadex LH 20 gel, numbered F1 to F5. Experiments were performed in normoglycemic, glucose tolerance test, and type 2 diabetic rats. The total methanol leaf-extract (300 mg/kg, per os), induced a significant increase of blood glucose level in normoglycemic rats (2.27±0.12 vs 0.94±0.03 g/L) (p<0.05, n=5). F1 and F2 fractions (100 mg/kg, per os) increased the blood glucose level. Glycaemia respectively varied from 0.90 ± 0.03 to 2. 28 ± 0.22 g/L and 0.91 ± 0.03 to 1.43 ± 0.04 g /L (p<0.05, n=5). However, F5 fraction (300 mg/kg, per os), induced hypoglycemia (0.61 ± 0.01 vs 0. 80 ± 0.03 g/L) (p<0.05, n=5). F5 fraction prevented the pic of hyperglycemia caused by glucose (4 g/kg, per os). In type 2 diabetic rats, the daily oral administration of F5 fraction (300 mg/kg) induced an anti-hyperglycemic effect (1.28 ± 0.15 vs 4.48 ± 0.08 g/L). Fractionation by gel permeation chromatography allowed to highlight the presence of compounds both hyper-and hypoglycemic in total methanol leaf-extract of D. guineense. The lack of hypoglycemic effect in normoglycemic rats of total methanol leaf-extract, could respectively be related to the presence of both hyper- and hypoglycemic compounds in F1 and F5 fractions, which induced opposite effects.