Comparative Analysis of 1-Deoxynojirimycin (DNJ) Content in Different Mulberry Leaf Varieties and Its Potential Role in Diabetes Management

Abstract

Mulberry (Morus spp.) leaves are widely recognized for their antidiabetic properties, primarily attributed to the presence of 1-deoxynojirimycin (DNJ), a potent α-glucosidase inhibitor. This study aimed to evaluate the variation in DNJ content among different mulberry varieties and assess their potential efficacy in diabetes management. Five commonly cultivated mulberry varieties were analyzed under controlled conditions to quantify DNJ levels using High-Performance Liquid Chromatography (HPLC). Results indicated significant variation (p < 0.05) in DNJ concentration among the tested varieties, with values ranging from 0.25% to 0.68% (dry weight basis). Variety V3 exhibited the highest DNJ content, followed by V5 and V2, while V1 and V4 showed comparatively lower concentrations. Seasonal variation also influenced DNJ accumulation, with higher levels observed during early summer harvests. The study further evaluated the inhibitory activity of mulberry leaf extracts against α-glucosidase enzyme, revealing a strong positive correlation (r = 0.89) between DNJ content and enzyme inhibition. These findings confirm that mulberry varieties with higher DNJ content possess greater potential for controlling postprandial hyperglycemia. This research highlights the importance of varietal selection and harvest timing in maximizing DNJ yield for functional food and pharmaceutical applications. The results provide a scientific basis for promoting mulberry leaves as a natural therapeutic agent in diabetes management and support their inclusion in nutraceutical formulations.