Journal of Ethnopharmacology 105 (2006) 223–228 Analysis of estrogenic compounds in Polygonum cuspidatum by bioassay and high performance liquid chromatography Caining Zhang, Xiaozhe Zhang, Yan Zhang, Qing Xu, Hongbin Xiao, Xinmiao Liang ∗ Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P.R. China Received 4 May 2005; received in revised form 25 October 2005; accepted 26 October 2005 Available online 27 December 2005 Abstract The estrogenic activity of traditional Chinese herb–Polygonum cuspidatum Sieb. et Zucc. was investigated by a recombinant yeast screening (YES) assay. Anthraquinones are the main components in the plant, of which emodin is the most abundant one. The ethyl acetate fraction of the ethanol extract of Polygonum cuspidatum was separated on a silica gel TLC plate and seven sub-fractions were collected. The results of bioassay demonstrated that Hzs1 and Hzs6 showed higher estrogenic activities than that of others and the potency of these two compounds were approximately 10 -4 g/L and 10 -3 g/L, respectively. HPLC analysis was performed to determine the activities and the active components. Combining the results of HPLC analysis and estrogenic activity test by YES led to the conclusion that an unknown bioactive compound might exist in the extraction of Polygonum cuspidatum. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Polygonum cuspidatum; Anthraquinone; Estrogenic activity; Emodin 1. Introduction Hormone replacement therapy could ease the menopausal symptoms and reduce the risk of osteoporosis, cardiovascular disease and certain types of cancers (Grodstein et al., 1977; Harris et al., 1990; Colditz et al., 1995; Wickelgren, 1997), but it also increases the risk of developing breast and endome- trial cancer when traditional estrogen replacement therapy was used (Henderson et al., 1988; Liehr, 1990; Stampfer et al., 1992; Colditz et al., 1995; Bolton et al., 1998). Scientists found that some steroid-like plant compounds that come from the botan- icals could mimic or act as the precursors to sex hormones (Brandi, 1999). These compounds represent a diverse body of substances capable of eliciting agonist or antagonist responses possibly via a mechanism of action comparable to that of estro- gen (Dornstauder et al., 2001; Glazier and Bowman, 2001; Liu et al., 2001; Setchell and Lydeking-Olsen, 2003). These reports have attracted much more attention in the last decades due to their beneficial effects to humans, especially to the ∗ Corresponding author. Tel.: +86 411 84379519; fax: +86 411 84379756. E-mail address: liangxm@dicp.ac.cn (X.M. Liang). menopausal women (Brosage, 1995; Kurzer and Xu, 1997; Liu et al., 2001). These compounds are generally called phytoestro- gens. Phytoestrogens are produced by a wide variety of plants and were encompassed by several classes of compounds, includ- ing flavonoids, isoflavonoids, coumestans and lignans (Mazur et al., 1998). In addition, anthraquinones have been verified to con- tain estrogenic activity recently (Matsuda et al., 2001). Some Chinese herbs have been traditionally used for preven- tion and palliation of menoxenia and postmenopausal disease, such as Polygonum cuspidatum, Rheum tanguticum, Rheum officinale and Rheum coreanum, etc. The reason, these herbs can heal these diseases is believed due to be their anthraquinone content. Recently, Polygonum cuspidatum Sieb. et Zucc. (Huzhang in Chinese) was found to possess potent estrogenic activities. The methanolic extract from the roots of Polygonum cuspidatum can enhance cell proliferation at 30 g/mL or 100 g/mL in MCF- 7, an estrogen-sensitive cell line (Matsuda et al., 2001). It was reported that the estrogenic active compounds in Polygonum cus- pidatum were emodin, emodin-8-O--d-glucopyranoside and resveratrol, etc. Emodin showed the highest estrogenic activity among these compounds. Our laboratory has also proved that the estrogenic relative potency (RP) of alcohol extraction of Poly- 0378-8741/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jep.2005.10.029