Effect of Mulberry (Morus Alba Linn.) Leaves Extracts on Plasma Glucose Level in Streptozotocin-Induced Diabetic Rats

Abstract

Many medical plants have been used for treatment of diabetes mellitus but only a small number of these have received scientific and medical evaluation to assess their efficacy. Morus alba L. (family Moraceae), commonly known as mulberry (Thai name: Mon), is widely cultivated in the north and northeast regions of Thailand. In the present study three extract of mulberry leaves were prepared: ethanol (EM), freeze-dried water (WM) and tea (TM). The anti-hyperglycemic effect of mulberry leaves extracts were evaluated in diabetic rats (fasting plasma glucose (FPG) level of 250-400 mg/dl) induced by a single dose of streptozotocin (60 mg/kg, iv). Prolonged administration (4 weeks) of the extracts was performed in diabetic rats to investigate hypoglycemic and other effects including effects on body weight, food and fluid

intakes. Non treatment control and positive control (glibenclaminde 10 mg/kg) groups were included. FPG levels were recorded at week 0, 1, 2 and 4.

Oral administration of 150, 300 and 600 mg/kg of the EM once daily for 4 weeks resulted in reduction in plasma glucose, especially at the dose of 600 mg/kg (p<0.05) at week 1. Moreover, hypoglycemic activity of the EM was dose-dependent. It also induced weight gain. In the other experiment, 150, 300 and 600 mg/kg of the WM was orally administered once daily for 4 weeks. The dose of 300 mg/kg significantly decreased plasma glucose level (p <0.05) at week 1. The WM 150 mg/kg significantly decreased FPG level (p <0.05) in a longer treatment period. Consequently, polydipsia and polyphagia were also improved in the WM treated groups. The TM (2.34 g dried powder/kg), provided as a substitute for water ad Iibitum at 180 ml/rat/day in a concentration of 2.5 g/L, significantly decreased plasma glucose level (p <0.05) at week 1 and 2. However, the plasma glucose reduction of TM was nearly the same as that of WM 300 mg/kg.

The findings indicated that EM, WM and TM had hypoglycemic activity in streptozotocin-included diabetic rats. The degree of reduction was in the same range as with glibenclamide and significantly different from the non-treatment control rats. Therefore, the mulberry leave extracts should be useful in the treatment of diabetes. Its mechanism of hypoglycemic effect and isolation of active principles responsible for such activity should be elucidated in further studies.