title: Aryl hydrocarbon receptor ligand activity of commercial health foods.
abstract: The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates toxicological effects by binding to agonists such as dioxins. We previously reported the presence of natural dioxin-like ligands in foods. To further characterise natural ligands with dioxin-like activity, we examined the influence of 50 kinds of commercial supplement and health food on the AhR, using a reporter gene assay. Some samples, prepared using soybean, sesame, or propolis as an ingredient, were revealed to show AhR-binding activity, similar to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), at high concentrations. To characterise the AhR-activating substances in eight active samples, the respective extracts were subjected to fractionation with n-hexane, ethyl acetate, and water, followed by estimating their AhR activities. The n-hexane fraction of the propolis extract sample, and the ethyl acetate fractions of the other samples, showed AhR activity similar to that of TCDD, at a high concentration range. HPLC analysis of the active fractions identified isoflavones, such as daidzein and glycitein, and flavones, such as tectochrysin and chrysin, in the samples. Among these compounds, tectochrysin exhibited marked AhR activation. Flavonoids, which are characterised as natural AhR ligands, are known to have representative beneficial effects on human health. The natural AhR ligands identified in this study are known to be useful for human health. Therefore, it is considered that AhR may play a beneficial regulatory role in humans.
authors.affiliation: Division of Pharmacognosy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan. Electronic address: amakura@cc.matsuyama-u.ac.jp.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Amakura
authors.affiliation: Division of Foods, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Tsutsumi
authors.affiliation: Hiyoshi Corporation, 908 Kitanosho-cho, Omihachiman, Shiga 523-8555, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Hiyoshi Corporation, 908 Kitanosho-cho, Omihachiman, Shiga 523-8555, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Handa
authors.affiliation: Division of Pharmacognosy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Yoshimura
authors.affiliation: Division of Foods, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Rieko
authors.initials: R
authors.lastname: Matsuda
authors.affiliation: Division of Pharmacognosy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshida
keywords: Aryl hydrocarbon receptor; Dioxin; Health food; Plant material; Reporter gene assay