title: Isoflavonoids and peptides from meju, long-term fermented soybeans, increase insulin sensitivity and exert insulinotropic effects in vitro.
abstract: OBJECTIVE
  Although soybeans have been shown to alleviate metabolic syndromes, fermented soybeans may have even greater effects. We investigated the antidiabetic effects of meju, a soy food that is fermented up to 2 mo, and the mechanism by which it exerts its effects.
  
  
  METHODS
  Meju was prepared by a traditional fermentation process: soybeans were fermented outdoors for 20 or 60 d. Methanol (M-60) and water (W-60) extracts from meju that had fermented for 60 d contained mostly isoflavonoid aglycones and small peptides, respectively, as opposed to mostly glycosylated isoflavonoids and proteins in the original soybeans.
  
  
  RESULTS
  Daidzein, M-60, and W-60 had better insulin-sensitizing actions by activating peroxisome proliferator-activated receptor-γ in 3T3-L1 adipocytes than did unfermented soybeans. In addition, Min6 insulinoma cells treated with genistein, M-60, and W-60 had greater glucose-stimulated insulin secretion capacity and greater β-cell viability than those treated with unfermented soybeans. This improvement was associated with insulin/insulin-like growth factor-1 signaling that was activated by the tyrosine phosphorylation of insulin receptor substrate-2 and serine phosphorylation of Akt, and this in turn increased pancreatic and duodenal homeobox-1 expression. Furthermore, genistein, daidzein, and M-60 stimulated glucagon-like peptide-1 secretion in enteroendocrine NCI-H716 cells, which generated insulinotropic actions.
  
  
  CONCLUSIONS
  The compositional changes in isoflavonoids and peptides that occurred during a longer fermentation period, without the use of salt, enhanced the antidiabetic effect of soybeans.
authors.affiliation: Food Functional Research Division, Korean Food Research Institutes, Sungnam-Si, Korea.
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Kwon
authors.forename: Sang Mee
authors.initials: SM
authors.lastname: Hong
authors.forename: Il Sung
authors.initials: IS
authors.lastname: Ahn
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Hye Jeong
authors.initials: HJ
authors.lastname: Yang
authors.forename: Sunmin
authors.initials: S
authors.lastname: Park
mesh_terms: D041721:3T3-L1 Cells; D000704:Analysis of Variance; D000818:Animals; D005285:Fermentation; D019833:Genistein / Q000378:metabolism; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D007529:Isoflavones / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D045730:Soy Foods / Q000032:analysis*
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D007529:Isoflavones; D010455:Peptides; C004742:daidzein; D052216:Glucagon-Like Peptide 1; D019833:Genistein