The isoflavonoid aglycone‐rich fractions of Chungkookjang, fermented unsalted soybeans, enhance insulin signaling and peroxisome proliferator‐activated receptor‐γ activity in vitro

Abstract

We investigated anti-diabetic candidates and their mechanisms from the fractions of Chungkookjang (CKJ), a traditional fermented unsalted soybean, by investigating insulin signaling, peroxisome proliferator-activated receptor (PPAR)-gamma activity and glucose-stimulated insulin secretion, in vitro. Cooked soybeans (CSB) and CKJ, fermented predominantly with Bacillus subtilis, were extracted by 70% EtOH followed by an XAD-4 column chromatography with a serial mixture of solvents comprised of MeOH and water. During fermentation, the contents of isoflavonoid aglycones were elevated, and the fractions enriched with aglycones enhanced insulin-stimulated glucose uptake in 3T3-L1 adipocytes. This increase in glucose uptake resulted from stimulating a translocation of the glucose transporter (GLUT)-4 into the plasma membrane through the phosphorylation of insulin receptor substrate (IRS)-1 and Akt. Especially, daidzein enriched fractions elevated insulin-stimulated glucose uptake by acting as PPAR-gamma agonist up to levels exhibited when 10 nM insulin is administered. Fractions containing small peptides with low polarity in CKJ slightly increased glucose-stimulated insulin secretion. The data suggest that an increase in isoflavonoid aglycones in CKJ, in comparison to CSB, enhances glucose utilization via activating insulin signaling and stimulates PPAR-gamma activity in adipocytes. In addition, CKJ contains small peptides improving glucose-stimulated insulin secretion in insulinoma cells. Overall, CKJ is superior to CSB in anti-diabetic action.

Postprandial insulin and glucose levels are reduced in healthy subjects when a standardised breakfast meal is supplemented with a filtered sugarcane molasses concentrate

“…Numerous flavonoids and phenolic acids have been shown in in vitro studies to increase the uptake of glucose into peripheral tissue cells [37,38]. They have been shown to enhance or bypass insulin signalling via numerous mechanisms: activation of insulin-dependent and insulin-independent signalling pathways such as AMP kinase [38,39] and PI-3 kinase [39] as well as mimicking insulin and activating the insulin receptor [40][41][42].…”

Fermented Soypastes, Doenjang and Cheonggukjang, and Obesity

“…In addition, 1-1.5kDa peptide profiles of Cheonggukjang fermented with B. lichemiformis, but not with B. subtilis or B. amylofenices, appears to be associated with improved insulin sensitivity [50]. Kwon et al [65] previously showed that 3kDa peptides do not contribute to the antidiabetic activity of fermented soybeans. Thus, it is reasonable to conclude that B. lichemiformis may be one of the major microorganisms responsible for the functional benefits of Cheonggukjang fermented soybeans.…”

Aktivitas antidislipidemia Tepung tempe dan susu kedelai pada profil lipid tikus diabetes yang diinduksi streptozotocin

“…Penelitian Kwon et al (2006) menyatakan bahwa fermentasi pada proses pembuatan tempe meningkatkan daya cerna zat gizi yang terkandung didalamnya serta meningkatkan bioavabilitas isoflavon. Selama proses fermentasi berlangsung isofl avon mengalami perubahan struktur dari glikosida menjadi aglikon, sedangkan protein dipecah menjadi peptida dan asam amino (7).…”