Anti-diabetic potential of Plectranthus lanuginosus in streptozotocin-induced diabetic rats

Purpose: To determine the antidiabetic effect of methanol extract of Plectranthus lanuginosus leaves in streptozotocin-induced hyperglycemic (HGD) rats. Methods: P. lanuginosus leaves were collected from Saad Medhas, Al Baha, Kingdom of Saudi Arabia. After defatting with n-hexane, they were extracted in vacuo at 40 degrees C with 75 % methanol. Streptozotocin (50 mgkg(-1), i.p.) was used to induce hyperglycemia (diabetes) in the rats. The HGD rats received either standard drug (glibenclamide, 10 mgkg(-1), p.o.) or Plectranthus lanuginosus leaf methanol leaf extract (PLLM) at doses of 200 and 400 mgkg(-1)/day, p.o. for 21 consecutive days. Blood samples were taken from the rat tails 2 h after dosing, and at 7-day intervals (i.e., 0, 7th, 14th and 21st days). The blood samples were used for measurement of fasting blood glucose (FBS), using a glucometer. On the 21st day, the rats were sacrificed via cardiac puncture. The activities of liver marker enzymes (SGPT and SGOT), and serum lipid profile (cholesterol, triglycerides, HDL and LDL) were determined using a hemolyzer. Results: Streptozotocin treatment produced significant hyperglycemia in the rats (348.9 +/- 5.6) when compared to control (79.2 +/- 1.3). However, PLLM (200 and 400 mg kg 1 ) produced significant and dose-dependent anti-diabetic (166.4 +/- 5.6 and 123.86 +/- 6.8 respectively) and antihyperlipidemic effects in HGD rats, at levels similar to those produced by the standard drug, glibenclamide (120.6 +/- 6.4). Conclusion: P. lanuginosus leaf extract possesses pronounced anti-diabetic and anti-hyperlipidemic properties which may be due to the presence of phenolic and flavonoid constituents in the plant. Therefore, the plant extract can be further developed for the management of diabetes.