17 September 2018

Quercetin - creating an estrogenic response

Natural toxin

Quercetin is found in large range of plant species, however most often in one of its conjugated forms

Quercetin has the ability, like genistein, to interact agonistically with estrogen receptors in the human and mammalian body, thereby creating an estrogenic response. That is, the response of showing feminizing effects. These effects are of great concern, and have received considerable attention, in relation to anthropogenic compounds such as bisphenol A. However compounds with a similar effect are widespread in nature. It occurs in among other the plant species kale (Brassica oleracea), Red onion (Allium cepa) and Canadian goldenrod (Solidago canadensis).

In the plants, quercetin is however often present as a glucoside, e.g. the monosaccharides quercetrin (quercetin-3-O-13-D-rhamnosid) or isoquercetrin (quercetin-3-O-13-D-glucoside), or the disaccharide rutin (quercetin-3-O-13-Drutinoside) (Fig. 1). These have only low affinity to the estrogenic receptors, thus little effect. In a study by Apati et al. (2002) on Solidago canadensis, quercetin was found in only trace amounts, while rutin, quercetrin and isoquercetrin in 27.3 g·kg-1, 5.7 g·kg-1 and 4.0 g·kg-1, respectively. In the stomach, nature and water cleaning processes, quercetin may however be released by hydrolysis of the conjugates. The stability and effects of quercetin is under continual investigation.

Fig. 1. Chemical structure. Click image for interactive 3D model of quercetin

Smiles: O=C1c3c(O/C(=C1/O)c2ccc(O)c(O)c2)cc(O)cc3O

References and further reading

Apati, P., Szentmihályi, K., Balázs, A., Baumann, D., Hamburger, M., Kristó, T. Sz., Szőke, É., Kéry, Á. (2002): HPLC Analysis of the Flavonoids in Pharmaceutical Preparations from Canadian Goldenrod (Solidago canadensis), Chromatographia, 55(1), 65-68.

Beck, V., Rohr. U., Jungbauer, A. (2005): Phytoestrogens derived from red clover: An alternative to estrogen replacement therapy? Journal of Steroid Biochemistry & Molecular Biology (94) 499-518.

Biesaga, M. & Pyrzynska, K. (2009): Analytical Procedures for Determination of Quercetin and its Glycosides in Plant Material. Critical Reviews in Analytical Chemistry, 39, 95-107

Picture attributions