Effect of Black Soybean Koji Extract on Glucose Utilization and Adipocyte Differentiation in 3T3-L1 Cells

Abstract

Adipocyte differentiation and the extent of subsequent fat accumulation are closely related to the occurrence and progression of diseases such as insulin resistance and obesity. Black soybean koji (BSK) is produced by the fermentation of black soybean with Aspergilllus awamori. Previous study indicated that BSK extract has antioxidative and multifunctional bioactivities, however, the role of BSK in the regulation of energy metabolism is still unclear. We aimed to investigate the effect of glucose utilization on insulin-resistant 3T3-L1 preadipocytes and adipogenesis-related protein expression in differentiated adipocytes with BSK treatment. Cytoxicity assay revealed that BSK did not adversely affect cell viability at levels up to 200 μg/mL. The potential for glucose utilization was increased by increased glucose transporter 1 (GLUT1), GLUT4 and protein kinase B (AKT) protein expression in insulin-resistant 3T3-L1 cells in response to BSK treatment. Simultaneously, BSK inhibited lipid droplet accumulation in differentiated 3T3-L1 cells. The inhibitory effect of adipogenesis was associated with downregulated peroxisome proliferator-activated receptor γ (PPARγ) level and upregulated Acrp30 protein expression. Our results suggest that BSK extract could improve glucose uptake by modulating GLUT1 and GLUT4 expression in a 3T3-L1 insulin-resistance cell model. In addition, BSK suppressed differentiation and lipid accumulation in mature 3T3-L1 adipocytes, which may suggest its potential for food supplementation to prevent obesity and related metabolic abnormalities.

Inhibitory effect of anthocyanin-rich black soybean testa (Glycine max (L.) Merr.) on the inflammation-induced adipogenesis in a DIO mouse model

“…It has been reported that delipidated soybean or anthocyanin derived from purple sweet potato inhibits lipogenesis by suppressing the expression of ACC and FAS, which play major roles in lipogenesis (Hwang et al, 2011;Lee et al, 2011). Another study demonstrated that BBC ethanol extract showed inhibitory effects on PPARγ but not on SREBP in 3T3-L1 adipocytes (Huang, Huang, Hou, Chi, & Huang, 2014). On the other hand, there had been reports of the insulin-like effect of C3G by increasing the activity of PPARγ in human omental adipocytes, showing that there might be a conflict in the role of anthocyanin on PPARγ (Scazzocchio et al, 2011).…”

Rebelling against the (Insulin) Resistance: A Review of the Proposed Insulin-Sensitizing Actions of Soybeans, Chickpeas, and Their Bioactive Compounds

“…Bioactive compounds from soybeans and pulses have been investigated for their efficacy in improving glucose utilization and insulin sensitivity via increasing GLUT4 gene expression and/or plasma membrane levels. Huang et al [ 49 ] used black soybean koji (a fermented black soybean product) to prepare an extract for treating 3T3-L1 preadipocytes. Preadipocytes are commonly used in insulin resistance studies to determine effects on adipogenesis and related processes, such as glucose uptake [ 50 , 51 ].…”

“…Insulin resistance was induced in the preadipocytes by treating with dexamethasone and insulin for 60 h (eight days is required to obtain mature adipocytes under the culture conditions), a method shown to promote insulin resistance in this cell line [ 52 ]. The black soybean koji extract increased protein levels of GLUT4 in a dose-dependent manner from 25 to 200 μg/mL compared with the vehicle treatment in the preadipocytes [ 49 ]. Furthermore, the highest concentration of black soybean koji extract (200 μg/mL) significantly increased glucose utilization in the preadipoctyes compared with the vehicle treatment.…”

“…Furthermore, the highest concentration of black soybean koji extract (200 μg/mL) significantly increased glucose utilization in the preadipoctyes compared with the vehicle treatment. Huang et al [ 49 ] analyzed the black soybean extract for isoflavone content but not for other flavonoids, such as anythocyanins, which are responsible for the black seed coat colour of this soybean variety and have been shown in other studies to increase GLUT4 expression [ 38 ]. A study conducted by Inaguma et al [ 53 ] is in accordance with the supposition that it is the anthocyanins in black soybeans that are responsible for increased glucose uptake.…”

Anti-Oxidant and Anti-Adipogenic Effects of Ethanol Extracts from Wheat Germ and Wheat Germ Fermented with Aspergillus oryzae

“…NADPH derived from glucose-6-phosphate dehydrogenase, the limiting enzyme of HMP, is known to increase the levels of cellular ROS production by NADPH oxidase. Furthermore, excessive ROS generation is associated with increased lipid accumulation during adipocyte differentiation ( 33 , 34 ). Previous studies reported excessive differentiation of 3T3-L1 cells induced by transition metals (Cu 2+ or Fe 2+ ), due to increased expression of adipogenic transcriptional factors related to the NADPH-dependent H 2 O 2 -generating system ( 35 ).…”