Antihyperglycemic,Antioxidant and Antiglycation Activities of Mulberry Leaf Extract in Streptozotocin-Induced Chronic Diabetic Rats

In Thailand, beverages containing mulberry leaf (Morus alba L.) are believed to promote good health, especially in people with diabetes. We examined the effects of long-term administration of an ethanolic extract of mulberry leaf (MA) on blood glucose, oxidative damage, and glycation in streptozotocin-induced diabetic rats. Daily administration of 1 g/kg MA for six weeks decreased blood glucose by 22%, which was comparable to the effect of 4 U/kg insulin. Lipid peroxidation, measured as malondialdehyde and lipid hydroperoxide concentrations (3.50 ± 0.33 and 3.76 ± 0.18 μM, respectively) decreased significantly (P < 0.05) compared to nontreated control diabetic rats (8.19 ± 0.45 and 7.50 ± 0.46 μM, respectively). Hemoglobin A_1C, a biomarker for chronic exposure to high concentration of glucose, was also significantly decreased in the MA-treated group (6.78 ± 0.30%) in comparison to untreated group (9.02 ± 0.30%). The IC₅₀ of in vitro antiglycation and free radical scavenging activities of MA were 16.4 ± 5.6 μg/ml and 61.7 ± 2.1 μg/ml, respectively. These findings support that long-term administration of MA has antihyperglycemic, antioxidant and antiglycation effects in chronic diabetic rats, which may be beneficial as food supplement for diabetics.