Water-soluble genistin glycoside isoflavones up-regulate antioxidant metallothionein expression and scavenge free radicals.
Genistin has antioxidant activities; however, its insolubility in water often limits its biological availability in vivo. Using a novel transglycosylation process, the solubility of genistin glycosides was increased 1000 to 10000-fold, but it was not known whether these modified genistin glycosides maintained antioxidant activity. We found that both genistin and its glycosides similarly up-regulated the transcription of several metallothionein (MT) antioxidant genes (MT1A, MT2A, MT1E, and MT1X), as well as the glucose 6-phosphate dehydrogenase (G6PD) gene in HepG2 cells. This gene induction was mediated by the sequestration of zinc in the cytosol, which up-regulated the metal-responsive transcription factor-1 (MTF-1) that induced MT gene expression. Although not as effective as ascorbic acid, genistin glycosides possessed slightly greater reducing power than genistin. We concluded that genistin and genistin glycosides have a direct antioxidant effect and an indirect antioxidant effect, perhaps via induction of MT by activity of MTF-1.
Chung
Mi Ja
MJ
Division of Food Science, College of Life and Environmental Sciences, Institute of Biomedical Sciences and Food Safety, Korea University, Seoul 136-713, Korea.
Kang
Ah-Young
AY
Lee
Kyung Min
KM
Oh
Eunji
E
Jun
Hee-Jin
HJ
Kim
Sang-Yeon
SY
Auh
Joong Hyuck
JH
Moon
Tae-Wha
TW
Lee
Sung-Joon
SJ
Park
Kwan-Hwa
KH
D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D019833:Genistein / Q000494:pharmacology*; D006027:Glycosides / Q000494:pharmacology*; D008668:Metallothionein / Q000235:genetics*; D012995:Solubility; D015533:Transcriptional Activation; D014867:Water; D015032:Zinc / Q000378:metabolism
D000975:Antioxidants; D016166:Free Radical Scavengers; D006027:Glycosides; D014867:Water; D008668:Metallothionein; D019833:Genistein; D015032:Zinc; D001205:Ascorbic Acid