Background : 1-Deoxynojirimycin (DNJ) is a representative compound of the antidiabetic constituent in mulberry leaves (Morus alba L.). The hot water extracts of mulberry leaves were fermented with lactic acid bacteria in order to analysis the changes of the DNJ contents and α-glucosidase inhibition. Methods and Results : The mulberry leaves were extracted with hot water (121℃, 3 hr). The extracts were fermented with nine strains of lactic acid bacteria such as Lactobacillus acidophilus, in order to increase the contents of DNJ and α-glucosidase inhibition. DNJ contents in the fermented extracts were determinated by HPLC analysis. The α-glucosidase inhibition was mesured by comparing dose-inhibition curves of α-glucosidase and IC50 value. The DNJ contents after fermentation have increased in the almost fermented extracts. Especially, DNJ of the extracts fermented with L. acidophilus was increased from 8.38 ㎍ ㎖ -1 to 21.77 ㎍ ㎖-1. IC50 values of the α-glucosidase inhibition were shown to be decreased in the fermented extracts. The extracts fermented with L. casei KCTC 3109 was determined at 290.04 ㎍ ㎖-1, resulting it is lower about 140 ㎍ ㎖-1 than 429.76 ㎍ ㎖-1 of the control. Conclusion : From the above results, we may suggest that the lactic acid fermentation of mulberry leaves extracts can more enhance the hypoglycemic activities such as DNJ contents.

Background : The hypoglycemic effects of mulberry leaves extract were evaluated by comparing the abilities on glucose uptake in C2C12 myotubes and 3T3-L1 adipocyte. Glucose uptake of the extracts were identified to be enhanced by bio-conversion using cellulolytic enzyme like Viscozyme. Methods and Results : The mulberry (Morus alba L) leaves were extracted with 30% ethanol or hot water. The hypoglycemic compounds such as Moracin C and, Quercetin and 1-Deoxynojirimycin were identified from the extracts of mulberry leaves. The extracts were fermented using kinds of celluolytic enzymes, which were vicozyme, pectinase, β-glucosidase and xylanase, in order to increase the contents of hypoglycemic constituents in the extracts. The hypoglycemic effects of the fermented extracts were evaluated by comparing the abilities on glucose uptake in C2C12 myotubes and 3T3-L1 adipocyte. The extracts of mulberry leaves fermented with only Viscozyme were identified to increase glucose uptake in C2C12 myotubes and 3T3-L1 adipocyte by supplement of the concentration of 10 μM extracts, compared to insulin as control. However, bio-conversion effects by other enzymes were not shown in the treatments, suggesting hypoglycemic constituents in the extracts of mulberry leaves can be conversed to more active compounds by cellulolytic enzyme treatment like viscozyme. Conclusion : From the above results, we may suggest that the hypoglycemic constituents in mulberry leaves extracts can be conversed to more active compounds by cellulolytic enzymes.