In Vitro Assay for The Anti-Diabetic Effect Of Ocimum Canum and Other Medicinal Plants

Abstract

The major objective of this work was to establish an in vitro assay system for evaluating Ocimum canum, an antidiabetic plants, using insulin release from isolated pancreatic p-islet cells of rats. An in vivo assay was carried out to confirm the previous work by Hogarh (1996) indicating the anti-diabetic activity of 0. canum. The effect of the aqueous extract of fresh leaves of 0. canum on lipid profile of genetically diabetic mice and their lean littermates was also evaluated. In vivo, the aqueous extract of fresh leaves of 0. canum reduced fasting blood glucose levels and body weight of genetically diabetic mice and their non-diabetic lean littermates confirming Hogarh’s result. The extract lowered serum total cholesterol and LDL-cholesterol levels and raised HDL-cholesterol levels of the experimental animals, but did not affect their triacylglycerol levels. However, aqueous extract from dried leaves lowered, fasting blood glucose levels but not body weight. The anti-diabetic property of "mirabetic" a plant preparation used for the management of diabetes mellitus was also evaluated in vivo using STZ-induced diabetic mice and their non-diabetic lean littermates. The "mirabetic" extract did not prevent the rise in plasma glucose levels in STZ-induced diabetic mice. In addition, the extract did not lower plasma glucose concentrations of the littermates at the end of the period, and did not affect the body weight of the littermates either. From In vitro experiments, the freeze dried extracts of fresh leaves of 0. canum significantly, enhanced insulin release from pancreatic p-islet cells. The effect was concentration-dependent up to a concentration of 0.03 mg/ml and thereafter decreased. The in vitro system established with 0. canum was used to evaluate "mirabetic" and Desmodium adscendens, a non anti-diabetic medicinal plant. "Mirabetic" signifi-cantly enhanced insulin release while D. adscendens decreased insulin release, with higher concentrations completely inhibiting insulin release. The results indicate that glucose-induced insulin release which is the mode of action of 0. canum, could be used effectively as an in vitro assay system to evaluate other anti-diabetic plants.