Food-Grade Mulberry Powder Enriched with 1-Deoxynojirimycin Suppresses the Elevation of Postprandial Blood Glucose in Humans

Abstract

Mulberry 1-deoxynojirimycin (DNJ), a potent glucosidase inhibitor, has been hypothesized to be beneficial for the suppression of abnormally high blood glucose levels and thereby prevention of diabetes mellitus. However, DNJ contents in commercial mulberry products were as low as about 0.1% (100 mg/100 g of dry product), implying that the bioavailability of DNJ might not be expected. We carried out studies in two directions: (1) production of food-grade mulberry powder containing a maximally high DNJ content; (2) determination of the optimal dose of the DNJ-enriched powder for the suppression of the postprandial blood glucose through clinical trials. The following method was used: (1) DNJ concentrations in mulberry leaves from different cultivars, harvest seasons, and leaf locations were determined using hydrophilic interaction chromatography with evaporative light scattering detection. (2) Healthy volunteers received 0, 0.4, 0.8, and 1.2 g of DNJ-enriched powder (corresponding to 0, 6, 12, and 18 mg of DNJ, respectively), followed by 50 g of sucrose. Before and 30-180 min after the DNJ/sucrose administration, plasma glucose and insulin were determined. The following results were obtained: (1) Young mulberry leaves taken from the top part of the branches in summer contained the highest amount of DNJ. After optimization of the harvesting and drying processes for young mulberry leaves (Morus alba L. var. Shin ichinose), DNJ-enriched powder (1.5%) was produced. (2) A human study indicated that the single oral administration of 0.8 and 1.2 g of DNJ-enriched powder significantly suppressed the elevation of postprandial blood glucose and secretion of insulin, revealing the physiological impact of mulberry DNJ (effective dose and efficacy in humans). This study suggests that the newly developed DNJ-enriched powder can be used as a dietary supplement for preventing diabetes mellitus.

Effect of Environmental Conditions on the α-Glucosidase Inhibitory Activity of Mulberry Leaves

“…[8][9][10][11] Yatsunami et al have reported the relationship between the -glucosidase inhibitory activity and 1-DNJ concentration from a group of species, 10) but not enough is known about -glucosidase inhibitors other than 1-DNJ from each cultivar. Since the -glucosidase inhibitory activity was not consistent with the 1-DNJ concentration in several cultivars, it is thought that -glucosidase inhibitors besides 1-DNJ were involved in the effective defense by mulberry plants against insect herbivores.…”

“…The typical cultivars of mulberry plants are maintained and administered in Japan at the National Institute of Agrobiological Sciences (Tsukuba, Ibaraki, Japan) and the Experimental Farm of Textile Science and Technology of Shinshu University (Ueda, Nagano, Japan). It has been reported that the -glucosidase inhibitory activity and 1-DNJ concentration of mulberry leaves differ among various cultivars and seasons, [8][9][10][11] but it is unknown which environmental conditions influence the -glucosidase inhibitory activity. We therefore investigated in this study the relationship between the environmental conditions and -glucosidase inhibitory activity.…”

Formulation of Mulberry Leaf (Morus Alba L.) Extract Hydrogel Beads Using Cross-Linked Pectin

“…From the results obtained, all formulations had a swelling time of <1 minute. This result could be explained by the fact that the cross-linking time was not long (15 minutes), so it caused the beads to swell quickly [5,6]. Furthermore, pectin was used as the polymer, and it is a hydrophilic polymer, so it can absorb water.…”

“…A previous study showed that mulberry leaf extract had an anti-diabetic effect in diabetes-induced Wistar rats [4,5]. Mulberry leaves (Morus alba L.) contain 1-deoxynojirimycin and its derivatives, an intestinal glucosidase inhibitor that prevents the hydrolysis of carbohydrates to monosaccharide, and therefore, suppresses the blood glucose level [6]. Mulberry leaf extract has been formulated as an effervescent tablet, whitening cream, and capsule.…”

Optimisation of Ultrasonic-Microwave-Assisted Extraction Conditions for Polysaccharides from Mulberry（Morus atropurpurea Roxb) Leaves and Evaluation of Antioxidant Activities in vitro

“…The leaves of mulberry, as a folk medicine, has been traditionally used in Asian countries for purposes to treat fever, protect the liver, improve eyesight, strengthen joints, facilitate the discharge of urine, reduce blood glucose and lower blood pressure [1]. Mulberry leaves extracts have shown multi-direction biological activities, such as the antioxidant, antimicrobial, anti-inflammatory, anti-allergic, anti-atherosclerotic, and significant hypoglycemic effect [2][3][4][5][6][7]. A large amount of polysaccharides was contained in mulberry leaves, and their useful pharmacological effects, such as hypoglycemic and lipid-lowering activities, have been verified [8].…”