Enhancement of 1-deoxynojirimycin content and α-glucosidase inhibitory activity in mulberry leaf using various fermenting microorganisms isolated from Korean traditional fermented food

Abstract

Mulberry leaf is known to be effective in inhibiting increases in blood glucose levels in diabetic patients. 1-Deoxynojirimycin (DNJ), a α-glucosidase inhibitor, is the major effective component in mulberry leaf. The aim of this study was to evaluate the level of DNJ in mulberry leaves fermented by various microorganisms, including lactic acid bacteria, yeast, and the bacillus isolated from Korean traditional fermented soybean food, and to assess the inhibitory effect of fermented mulberry leaf powder extract (FMLE) on α-glucosidase activity. The DNJ content in unfermented mulberry leaf powder extract (UFMLE), the control, was determined to be 53.2 ± 1.5 mg/100 g (dry weight eq.). Lactobacillus plantarum, Zygosaccharomyces rouxii, Wickerhamomyces anomalus, and Bacillus subtilis remarkably increased the DNJ levels in mulberry leaves by 1.2, 1.5, 2.0, and 1.8-fold, respectively, compared to the control. The inhibitory effects of the FMLEs on α-glucosidase were also examined at various concentrations, and their α-glucosidase inhibitory effects tended to be higher than that in UFMLE. These findings suggest that Korean traditional fermenting microorganisms can be used as starter strains for the development of DNJenhanced food products, and that FMLEs have the potential to be used in various functional foods for the prevention of diabetes.

Qualitative and quantitative analysis of flavonoids from 12 species of Korean mulberry leaves

“…Mulberry ( Morus spp.) is a deciduous tree that belongs to the genus Morus from the Moraceae family that consists of 10–16 species and is widely distributed in tropical, subtropical, and temperate regions globally (Jeong et al 2014 ). Mulberry has been used in East Asia (Korea, China, and Japan) as an herbal medicine due to its various pharmacological effects, including antihyperglycemic (Singab et al 2005 ), antiallergic (Chai et al 2005 ), and immunomodulatory activities (Bharani et al 2010 ).…”

Development of Herbal Capsules Containing Mulberry Leaf and Black Tea Extracts Using the Modified Liquisolid Techniques

“…Mulberry (Morus alba L.), a plant in the genus Morus of the family Moraceae, has long been used as medicine and food in Asia (China, Japan, and Thailand). Mulberry leaves have potential as a functional food source due to their biologically active compounds, including flavonoids, steroids, amino acids and vitamin [4]. In particular, mulberry leaves contain a large number of iminosugar alkaloids including 1-deoxynojirimycin (1-DNJ), which has strong inhibitory effects on mammalian glucosidase enzymes [1][2][3][4].…”

1-Deoxynojirimycin: Occurrence, Extraction, Chemistry, Oral Pharmacokinetics, Biological Activities and In Silico Target Fishing

“…All the mulberry leave groups showed 1–2-fold increase in DNJ contents in comparison to unfermented mulberry leaf powder extract (UFMLE). Additionally, FMLE exhibited higher α-glucosidase activity compared to UFMLE [61]. Resultantly, DNJ-rich food products can be prepared by fermenting mulberry leaves using the above-mentioned fermenting agents.…”