6,8-Diprenylnaringenin

Determination of phytoestrogens in dietary supplements by LC-MS/MS.[Pubmed:18478479]

Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2008 May;25(5):534-47.

Labelling data quantifying the exact content of individual phytoestrogen analytes in dietary supplements are generally poor. As these products are commonly used in the management of menopause symptoms, any clinical benefits would be dependent on the exact dosage of isoflavones received. Well-established extraction procedures and updated isotope dilution mass spectrometry liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS) have been used to accurately quantify the concentrations of ten common isoflavones in 35 dietary supplement samples on sale in the UK, Canada and Italy. Concentration-specific ionization suppression is described for biochanin A and formononetin. All supplements contained phytoestrogens. The soya isoflavones (genistein, daidzein, glycitein) were present in all products and the majority also contained the red clover isoflavones (biochanin A, formononetin) and some the Kudzu isoflavones (daidzein, puerarin). The content of total isoflavones per dose ranged from <1 to 53 mg. Trace amounts of coumestrol were found in six products. Other less common analytes, the prenylnaringenins (6-prenylnaringenin, 8-prenylnaringenin, 6,8-Diprenylnaringenin) were not found in any of the products. Only 14 of 35 supplements were found to deliver more than or equal to 40 mg day(-1) of aglycone isoflavones, a consensus dose value recognized as delivering therapeutic benefit. Eleven did not match label claims. Six delivered less than 10 mg day (-1) of isoflavones. There has been little improvement in the overall quality of industry labelling in the five years since this was last investigated. Consequently, the public, retailers and healthcare professionals should consider using standardized isoflavone supplements, which are supported by analytical measurements.

Identification, quantitation and biological activity of phytoestrogens in a dietary supplement for breast enhancement.[Pubmed:11696395]

Food Chem Toxicol. 2001 Dec;39(12):1211-24.

A hop-based dietary supplement, marketed for natural breast enhancement, was analysed to determine the identity and biological activity of active constituents and potential biological effects in man. Extracts of the dietary supplement were analysed by LC-MS(n) and phytoestrogens identified and quantitated by reference to appropriate standards. Only hop-associated phytoestrogens were found in the dietary supplement at significant concentrations as follows (mean+/-1 S.D.); 8-prenylnaringenin 10.9+/-0.3, 6-prenylnaringenin 27.4+/-1.2, 6,8-Diprenylnaringenin 0.9+/-0.1, xanthohumol 321+/-17 and isoxanthohumol 81.1+/-1.6 microg/g of dietary supplement. The oestrogenic activity of extracts in an ERalpha reporter gene assay was equivalent to 48+/-6.3 ng 17beta-oestradiol/g supplement and consistent with the 8-prenylnaringenin content. The dietary supplement extract also inhibited reductive 17beta-hydroxysteroid oxidoreductase activity, but to a greater extent than a concentration matched reference mixture of hop phytoestrogens. However, the supplement was only weakly active in mouse uterotrophic assays following administration in feed or after subcutaneous injection of extract at doses of 8-PN up to 250 times higher than that recommended for women. These preliminary findings suggest that the dietary supplement is unlikely to produce oestrogenic effects in vivo at the level of the uterus; supporting evidence is still required to demonstrate efficacy.

The endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavonoids.[Pubmed:11134162]

J Clin Endocrinol Metab. 2000 Dec;85(12):4912-5.

The female flowers of the hop plant have long been used as a preservative and a flavoring agent in beer, but they are now being included in some herbal preparations for women for "breast enhancement." This study investigated the relative estrogenic, androgenic and progestogenic activities of the known phytoestrogen, 8-prenylnaringenin, and structurally related hop flavonoids. 6-Prenylnaringenin, 6,8-Diprenylnaringenin and 8-geranylnaringenin exhibited some estrogenicity, but their potency was less than 1% of that of 8-prenylnaringenin. 8-Prenylnaringenin alone competed strongly with 17ss-estradiol for binding to both the alpha- and ss-estrogen receptors. None of the compounds (xanthohumol, isoxanthohumol, 8-prenyl-naringenin, 6-prenylnaringenin, 3'-geranylchalconaringenin, 6-geranylnaringenin, 8-geranylnaringenin, 4'-O:-methyl-3'-prenylchalconaringenin and 6,8-Diprenylnaringenin) nor polyphenolic hop extracts showed progestogenic or androgenic bioactivity. These results indicate that the endocrine properties of hops and hop products are due to the very high estrogenic activity of 8-prenylnaringenin and concern must be expressed about the unrestricted use of hops in herbal preparations for women.