In Vitro Evaluation of Standardized White Mulberry Leaf Extract for Postprandial Glucose Control: Dual Mechanisms of Enzyme Inhibition and Insulin-Sensitizing Activity

This study systematically evaluated the antidiabetic potential of a standardized hydro-ethanolic extract of Morus alba L. leaves (White Mulberry Leaf Extract, WMLE). The extract was standardized to contain 1.82% 1-deoxynojirimycin (DNJ) and 3.05% rutin. WMLE exhibited potent, dose-dependent inhibition of α-glucosidase (IC₅₀ = 38.5 µg/mL) and α-amylase (IC₅₀ = 245.7 µg/mL), with preferential activity against α-glucosidase. The extract also significantly stimulated glucose uptake in L6 skeletal muscle cells, both independently and synergistically with insulin. Synergy analysis revealed enhanced efficacy of the whole extract compared to isolated fractions (Combination Index = 0.78). These findings suggest WMLE acts through dual mechanisms—slowing carbohydrate digestion and enhancing peripheral glucose disposal— making it a promising multi-target botanical for managing postprandial hyperglycemia and insulin resistance in type 2 diabetes.