Identification of equol producers in a Japanese population by high-performance liquid chromatography with coulometric array for determining serum isoflavones

Zhao, J.H.; Sun, S.J.; Arao, Y.; Oguma, E.; Yamada, K.; Horiguchi, H.; Kayama, F.

doi:10.1016/j.phymed.2005.09.013

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Volume 13, Issue 5 , Pages 304-309, 9 May 2006

Identification of equol producers in a Japanese population by high-performance liquid chromatography with coulometric array for determining serum isoflavones☆

J.H. Zhao
- Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan
- Second Hospital, Hebei Medical University, Shijiazhuang, China
- CREST-JST, Kawaguchi, Saitama, Japan
S.J. Sun
- Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan
- CREST-JST, Kawaguchi, Saitama, Japan
- College of Public Health, Hebei Medical University, Shijiazhang, China
Y. Arao
- Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan
- CREST-JST, Kawaguchi, Saitama, Japan
E. Oguma
- Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan
- CREST-JST, Kawaguchi, Saitama, Japan
K. Yamada
- CREST-JST, Kawaguchi, Saitama, Japan
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Japan
H. Horiguchi
- Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan
- CREST-JST, Kawaguchi, Saitama, Japan
F. Kayama
- Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan
- CREST-JST, Kawaguchi, Saitama, Japan
- Corresponding author. Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan. Tel.: +81285587336; fax: +81285448465.

Abstract

Using a method of high-performance liquid chromatography (HPLC) with coulometric array, we measured isoflavone levels in sera from seven volunteers before and after three days of ingesting Soyaflavone E (an isoflavones powder) and from 129 female farmers (Japanese Multiple Environmental Toxicants Study; JMETS). Results showed that the serum isoflavone concentrations rose dramatically after three days of ingesting Soyaflavone E in all subjects except for the serum equol concentrations in two subjects. The geometric mean concentrations of daidzein, genistein, and equol in the serum of 129 Japanese women were 25.0ng/ml of daidzein, 94.1ng/ml of genistein, and 9.6ng/ml of equol. Interestingly, there existed two dominant groups in terms of serum equol concentrations in an independent manner of soy-derived product intake among the study participants.

Keywords: Isoflavone, HPLC coulometric array, Human serum, Equol producer, JMETS project