Standardization parameters for C. nurvala stem bark were determined and all the parameters were found to be within pharmacopoeial standards limit. Crude powder taken for extraction was of yellowish-brown color with a bitter taste. Loss on drying, total ash, acid insoluble ash, and water soluble ash were found to be 4.37, 9.76, 0.647, and 1.56% w/w, respectively. Thin layer chromatography of C. nurvala stem bark revealed bright brownish red spot (Rf= 0.30), Rf= 0.71 (magenta color), Rf= 0.15, 0.90 (light violet spots) which turn magenta on keeping.
Phytochemical screening of all the extract of C. nurvala showed the presence of various chemical constituents, mainly triterpenoids and flavonoids which may be responsible for its antilithic and antidiabetic properties, respectively. The results obtained were comparable and satisfied the standard literature. In acute toxicity study, all the extracts of C. nurvala stem bark did not show significant toxicity signs when observed for the parameters during the first 4 h and followed by daily observations for 14 days and no mortality was also observed; the drug was found to be safe at the tested dose level of 5000 mg/kg b. wt. To ascertain a scientific base for the usefulness of this plant in the treatment of diabetes, it was decided to evaluate experimental design of antidiabetic activity by following glucose tolerance test and the alloxan-induced model. As expected, in the diabetic control (DC), there was severe hyperglycemia when compared with the normal animals. Compared with the DC, all the four extracts, C. nurvala aqueous extract (CNAE), C. nurvala ethanolic extract (CNEE), C. nurvala chloroform extract (CNCE), and C. nurvala petroleum ether extract (CNPEE) , lowered the elevated blood glucose levels only in subacute treatment . It was observed that the standard drug glibenclamide lowered the blood glucose level significantly bringing it nearly back to normal, whereas CNPEE and CNEE significantly (P< 0.01) decreased fasting blood serum glucose in the diabetic rats on third, fifth, and seventh days compared with the initial (0 h) blood serum glucose levels .
Effect of C. nurvala extracts on blood glucose level of alloxan-induced diabetic albino rats after subacute treatment
Blood glucose level of alloxan-induced diabetic albino rats after treatment
The effects of different extracts on glucose tolerance test in normal rats are shown in . At 30 min after glucose administration, the peak of blood glucose level increased rapidly from the fasting value and then subsequently decreased. CNEE and CNPEE exhibited remarkable blood glucose lowering effect at 90 min.
Effect of C. nurvala extracts on OGTT in normal rats
In the present study, diabetic rats had lower body weights, high blood glucose level as compared to the normal rats. In spite of the increased food consumption, loss of body weight due to defect in glucose metabolism and excessive breakdown of tissue protein is a characteristic condition in diabetics. As shown in , treatment with CNEE and CNPEE improved the average body weights of rats which indicate control over polyphagia and muscle wasting resulted due to hyperglycemic condition.
Effect of various extracts on body weight after treatment in diabetic rats
Alloxan causes massive reduction in insulin release, through the destruction of β-cells of the islets of Langerhans. In our study, we have observed a significant increase in the plasma insulin level when alloxan diabetic rats were treated with CNAE and CNPEE. This could be due to potentiation of the insulin effect of plasma by increasing the pancreatic secretion of insulin from existing β-cells of islets of Langerhans or its release from bound insulin. The significant and consistent antidiabetic effect of CNEE and CNPEE in alloxan diabetic rats may also be due to enhanced glucose utilization by peripheral tissues.
Few researchers such as Alam et al
. have reported the antinociceptive effect of the crude ethanolic extract of C. nurvala
on mice and showed that its action was peripherally and centrally mediated. Bhaskar et al
. have reported the antifertility activity of stem bark of C. nurvala
and that their action was due to antizygotic and blasocytotoxicity.[13
] Neither the exact biological active constitutent(s) responsible for the above said effect nor the exact mode of action of the antidiabetic activity was reported earlier, with the lone observation that it is used in folklore diabetic treatments.