Evaluation of Antidiabetic Activity of Rosmarinus officinalis var. prostratus Growing in Syria in Alloxan Diabetic Rats

Abstract

Background: The genus of Rosmarinus officinalis (Rosemary) is found in many parts of the world. Traditionally, Rosemary has been used in traditional medicine due to its therapeutic virtues and its ability to treat some diseases. Rosmarinus officinalis var. prostrates grows in the Al Kalamoon region of Syria but only a limited amount of scientific research on the medicinal uses of this plant has been done. This study focused on the medicinally active substances found in ethanolic extract of the leaves and flowers of this plant and their antidiabetic effect in alloxan-induced diabetic rats. First, an acute toxicity study was carried out to detect the optimal dose of the Rosmarinus officinalis var. prostrates extract. Then, the effect of the optimal dose of 300mg/kg was measured over 36 days. Method: During the study, diabetic rats were treated with different doses of extract (100, 200, 300, 400, 500, and 600 mg/kg). The percentage of fasting blood glucose (FBG) was measured immediately after administration of the extract and at 2h, 4h and 8h after administration. The dose of 300mg/kg was then used in the second part of the study, which involved four groups of rats: a healthy group, a diabetic group without treatment (the control group), a diabetic group treated with 300mg/kg of extract, and a diabetic group treated by metformin (50mg/kg). The treatment continued for 36 days. Results: The results showed that the extract was rich with flavonoids, phenols and tannins. Levels of FBG and DPP-4 were significantly lower in the extract-treated group in comparison with the control group; however, the level of insulin was significantly elevated in the extract-treated group compared to the control group. This effect may be caused by two factors. First, the antioxidant effects of flavonoids which protect pancreatic beta cells from damage caused by alloxan, supports regeneration of pancreatic beta cells, and therefore insulin production. Second, the inhibition of DPP-4 activity, which in turn leads to increased secretion of insulin. Conclusion: The ethanolic extract of Rosmarinus officinalis var. prostrates has an antidiabetic effect.