In vitro effect of fenugreek extracts on intestinal sodium-dependent glucose uptake and hepatic glycogen phosphorylase A.
Fenugreek (Trigonella foenum-graecum L. seed) is a food with traditional medicinal use in diabetes. Beneficial effects have been demonstrated in diabetic animals and both insulin-dependent and non-insulin-dependent diabetic subjects. Effects of a lipid extract A, crude ethanolic extract B, further sub-fractions of B (saponin-free C, saponin D and sapogenin E) and a gum fibre fraction F on intestinal sodium-dependent glucose uptake were investigated in vitro using rabbit intestinal brush border membrane vesicles. All fractions except A inhibited glucose-uptake at 0.33 and/or 3.3 mg/mL (p < 0.001). Greatest inhibition was observed with fractions D and E. Diosgenin and trigonelline (compounds reported in fenugreek) also inhibited glucose-uptake (IC50 values approximately 3 mg/ml, equivalent to 8 mM and 19 mM respectively) but did not account for the activity of the crude extracts. Fenugreek extracts had no effect on basal levels of glycogen phosphorylase a (HGPa) activity in rat hepatocyte suspensions. However fractions C and E caused a marginal but statistically significant inhibition (18.9 and 15.1% respectively, p < 0.05) of glucagon induction of this enzyme suggesting a glucagon-antagonist effect. Diosgenin (1.65 mg/ml; 4 mM) inhibited glucagon-induced HGPa activity by 20% (p < 0.05), and was more effective than trigonelline (non significant inhibition of 9.4% at 1.65 mg/ml, 10 mM).
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D022781:Hepatocytes / Q000201:enzymology*; D008099:Liver / Q000201:enzymology*; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D010762:Phosphorylase a / Q000187:drug effects / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D012503:Saponins; D012639:Seeds; D029910:Trigonella
D009004:Monosaccharide Transport Proteins; D010936:Plant Extracts; D012503:Saponins; D010762:Phosphorylase a; D005947:Glucose