title: The lignan-rich fractions of Fructus Schisandrae improve insulin sensitivity via the PPAR-γ pathways in in vitro and in vivo studies.
abstract: BACKGROUND
  Fructus Schisandrae, the fruit of Schisandra chinensis (Turcz.) Baillon, has been traditionally used as a hypoglycemic agent in Asia and its extracts have been shown to improve insulin-stimulated glucose uptake in cell-based assays in previous studies.
  
  
  OBJECTIVE
  We set out to determine which fractions of Fructus Schisandrae improved peroxisome proliferator-activated receptor (PPAR)-γ activity and glucose-stimulated insulin secretion in cell-based experiments. The fractions that enhance glucose homeostasis were then tested for their hypoglycemic effects and mechanism was examined.
  
  
  METHODS
  The fractions (FS-0, FS-20, FS-40, FS-60, FS-80, FS-100) were made by extracting Fructus Schisandrae with 70% ethanol followed by its fractionation with a XDA column with a different ratio of methanol and water. The insulin-stimulated glucose uptake and PPAR-γ agonistic actions of each fraction were investigated in 3T3-L1 adipocytes and glucose-stimulated insulin secretion was determined in Min6 cells. The fraction(s) that were efficacious (200mg/kg bw) were orally given to 90% pancreatectomized (Px) diabetic rats for 8 weeks to evaluate insulin sensitivity in euglycemic hyperinsulinemic clamp and insulin secretion at hyperglycemic clamp.
  
  
  RESULTS
  FS-60 contains schizandrin, gomisin A and angeloylgomisin H while FS-80 contains deoxyschizandrin, γ-schizandrin, and gomisin N. A PPAR-γ agonistic action was greater in the ascending order of the control, FS-80 and FS-60 in 3T3-L1 adipocytes. FS-60 increased the glucose disposal rates of Px rats as much as rosiglitazone during euglycemic hyperinsulinemic clamp while hepatic glucose output at hyperinsulinemic clamped states decreased in the descending order of the control, FS-80, FS-60 with potentiating insulin signaling. At hyperglycemic clamp only FS-60 potentiated first phase insulin secretion in diabetic animals; the second phase was not increased.
  
  
  CONCLUSIONS
  FS-60, a lignan-rich fraction, improves glucose homeostasis by increasing glucose disposal rates and enhancing hepatic insulin sensitivity by working as a PPAR-γ agonist in type-2 diabetic rats.
authors: Food Functional Research Division, Korean Food Research Institutes, Sungnam 463-746, Republic of Korea.
authors: Dae Young
authors: DY
authors: Kwon
authors: Da Sol
authors: DS
authors: Kim
authors: Hye Jeong
authors: HJ
authors: Yang
authors: Sunmin
authors: S
authors: Park
mesh_terms: D041721:3T3-L1 Cells; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood; D005951:Glucose Tolerance Test; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D017705:Lignans / Q000494:pharmacology*; D051379:Mice; D047495:PPAR gamma / Q000187:drug effects* / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D032141:Schisandra / Q000737:chemistry*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D007328:Insulin; D017705:Lignans; D047495:PPAR gamma; D010936:Plant Extracts; D014280:Triglycerides