Effect of Rubia cordifolia on blood glucose level and glucose utilization by isolated rat hemidiaphragm

The present study aims to investigate the effect of ethyl acetate fraction of roots of Rubia cordifolia (RCEAF) on blood glucose level and glucose utilization study to find out the mechanism of action of the extract. Recently we have reported hypoglycaemic effect of ethanolic extract of roots of R. cordifolia L. (RCAE). RCEAF was fractionated from RCAE by column chromatography. Single dose study of RCEAF (50,100 and 200mg/kg, p.o.) was carried out in i) normal fasted ii) oral glucose tolerance test (OGTT) iii) alloxan (120mg/kg, s.c.)- induced diabetic rats. Repeated dose study of RCEAF (100 and 200mg/kg, p.o.) was carried out for two weeks. The blood glucose levels were estimated by glucose oxidase- peroxidase reactive strips (One Touch, Johnson and Johnson, India). We found that, oral pre-treatment with RCEAF induced a significant (P<0.05) decrease in blood glucose level in i) normoglycaemic rats at 6h ii) OGTT at ½ h compared to control glucose fed rats iii) alloxan- induced diabetic rats at 6h. After two weeks daily administration of RCEAF, diabetic treated rats showed significant (P<0.05) reduction in blood glucose level as compared to diabetic control rats. In vitro experiment showed that insulin (0.05 IU/mL) increased glucose utilization by an isolated rat diaphragm. Alone RCEAF (25mg/mL) as well as combination of RCEAF (25mg/mL) and insulin (0.05 IU/mL) showed a marked increase (P<0.05) of glucose uptake. This exhibited the extra- pancreatic effect of the RCEAF. Further studies with estimation of insulin and insulin receptor may give more insight into the mechanism of the antidiabetic activity of the R. cordifolia.