Dietary secoisolariciresinol diglucoside and its oligomers with 3-hydroxy-3-methyl glutaric acid decrease vitamin E levels in rats.
Secoisolariciresinol diglucoside (SDG) is an important dietary lignan that is found at very high levels in flaxseed (1-4 %, w/w). Flaxseed lignans have received much research interest in recent years because of reported phyto-oestrogenic, anticarcinogenic, and anti-atherogenic effects. Previously, flaxseed feeding has been shown to decrease vitamin E concentrations in rats despite the antioxidant potential of SDG in vitro. Sesamin, a sesame lignan, on the other hand has been shown to increase vitamin E concentrations in rats. The aim of the present study was to investigate the effect of dietary SDG and its oligomers on vitamin E and cholesterol concentrations in rats. SDG was extracted from defatted flaxseed flour with a dioxane-ethanol mixture and purified by silica column chromatography. The major oligomers with 3-hydroxy-3-methyl glutaric acid, containing a high ratio of SDG to p-coumaric and ferulic acid glucosides, were purified from the extracts by reversed-phase liquid chromatography. When fed to rats at 0.1 % in the diet for 27 d, both SDG and its oligomers had no effect on animal performance but caused an increase in liver cholesterol and a 2-fold reduction in the levels of alpha- and gamma-tocopherols in rat plasma and liver. It is notable that a phenolic antioxidant, such as SDG, causes a vitamin E-lowering effect in rats. This cannot be explained at present, but warrants further investigations with respect to the magnitude, mechanism, and significance of the observed effect for human nutrition.
Frank
Jan
J
Department of Food Science, Swedish University of Agricultural Sciences (SLU), Box 7051, S-750 07 Uppsala, Sweden. Jan.Frank@lmv.slu.se
Eliasson
Christina
C
Leroy-Nivard
Diane
D
Budek
Alicja
A
Lundh
Torbjörn
T
Vessby
Bengt
B
Aman
Per
P
Kamal-Eldin
Afaf
A
D000818:Animals; D000924:Anticholesteremic Agents / Q000008:administration & dosage*; D000975:Antioxidants / Q000008:administration & dosage / Q000737:chemistry; D002072:Butylene Glycols / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D002784:Cholesterol / Q000032:analysis* / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003373:Coumaric Acids / Q000008:administration & dosage / Q000737:chemistry; D004032:Diet; D019597:Flax / Q000737:chemistry; D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000737:chemistry; D005960:Glucosides / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D008099:Liver / Q000737:chemistry; D015093:Meglutol / Q000008:administration & dosage*; D011422:Propionates; D051381:Rats; D017207:Rats, Sprague-Dawley; D012639:Seeds / Q000737:chemistry; D024505:Tocopherols / Q000032:analysis / Q000097:blood; D014810:Vitamin E / Q000097:blood*
D000924:Anticholesteremic Agents; D000975:Antioxidants; D002072:Butylene Glycols; D003373:Coumaric Acids; D016166:Free Radical Scavengers; D005960:Glucosides; D011422:Propionates; D014810:Vitamin E; D002784:Cholesterol; C004999:ferulic acid; D015093:Meglutol; C495469:p-coumaric acid; D024505:Tocopherols; C090142:secoisolariciresinol diglucoside