The isoflavonoid aglycone-rich fractions of Chungkookjang, fermented unsalted soybeans, enhance insulin signaling and peroxisome proliferator-activated receptor-gamma activity in vitro.
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.
Kwon
Dae Young
DY
Food Functional Research Division, Korean Food Research Institutes, Korea.
Jang
Jin Sun
JS
Lee
Ji Eun
JE
Kim
Yong-Suk
YS
Shin
Dong-Hwa
DH
Park
Sunmin
S
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000737:chemistry / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D007529:Isoflavones / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D047495:PPAR gamma / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013025:Glycine max / Q000737:chemistry*; D014280:Triglycerides / Q000378:metabolism; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000378:metabolism
D007004:Hypoglycemic Agents; D007328:Insulin; D007529:Isoflavones; D047495:PPAR gamma; D014280:Triglycerides; C065753:isoflavanone; C004742:daidzein; D000516:alpha-Amylases; D005947:Glucose