Search resultsThe prenylflavonoid isoxanthohumol from hops (Humulus lupulus L.) is activated into the potent phytoestrogen 8-prenylnaringenin in vitro and in the human intestine
Title
The prenylflavonoid isoxanthohumol from hops (Humulus lupulus L.) is activated into the potent phytoestrogen 8-prenylnaringenin in vitro and in the human intestine
Publication type
Journal Article
Year of Publication
2006
Authors
Journal
Journal of Nutrition
Volume
136
Issue
7
Pagination
1862 - 1867
Date published
2006
ISBN
00223166 (ISSN)
Keywords
8 prenylnaringenin, 8-Prenylnaringenin, Adult, article, beer, bioavailability, biotransformation, Chromatography, High Pressure Liquid, colon, controlled study, demethylation, diet, digestion, estrogen, feces microflora, Female, Flavanones, food intake, Hops, human, Humans, Humulus, Humulus lupulus, Humulus lupulus extract, Intestinal bacteria, Intestine, intestine flora, Intestines, Isomerism, microbial immunity, nonhuman, normal human, phytoestrogen, Phytoestrogens, prenylflavonoid isoxanthohumol, Propiophenones, SHIME, stomach, unclassified drug, xanthohumol
Abstract
Hops, an essential beer ingredient, are a source of prenylflavonoids, including 8-prenylnaringenin (8-PN), one of the most potent phytoestrogens. Because 8-PN concentrations in beers are generally low, its health effects after moderate beer consumption were considered negligible. However, human intestinal microbiota may activate up to 4 mg/L isoxanthohumol (IX) in beer into 8-PN. Depending on interindividual differences in the intestinal transformation potential, this conversion could easily increase the 8-PN exposure 10-fold upon beer consumption. Here, we present a further investigation of the process both in vitro and in vivo. In vitro experiments with the dynamic SHIME model showed that hop prenylflavonoids pass unaltered through the stomach and small intestine and that activation of IX into 8-PN (up to 80% conversion) occurs only in the distal colon. In vitro incubations of 51 fecal samples from female volunteers with IX enabled us to separate the fecal microbiota into high (8 of 51), moderate (11 of 51) and slow (32 of 51) 8-PN producers, clearly illustrating an interindividual variability. Three women, selected from the respective groups, received a daily dose of 5.59 mg IX for 4 d. Intestinal IX activation and urinary 8-PN excretion were correlated (R2 = 0.6417, P < 0.01). These data show that intestinal conversion of IX upon moderate beer consumption can lead to 8-PN exposure values that might fall within the range of human biological activity.