Activation of pro-estrogens from hops by intestinal bacteria

Sam Possemiers, Selin Bolca, Veerle Maervoet, Tom Van de Wiele, Arne Heyerick, Denis De Keukeleire & Willy Verstraete

Production of the phytoestrogen 8-prenylnaringenin

Laboratory of Microbial Ecology & Technology (LabMET)http://labmet.ugent.be

“Plant constituents which structurally or functionally mimic the female estrogen 17β-estradiol”

Beneficial role in the prevention of osteoporosis, menopauzal complaints and cancers

Applications!

Phytoestrogens (1)

HO

CH3 OH

17β-estradiol

Phytoestrogens (2) 2 well known groups:

Isoflavones from soy: daidzein, genistein

Lignans from linseed, fruits, nuts…

O

OHO

OH

OH

genistein

HO

OH

OH

OH

OH

OH

O

O

Secoisolariciresinol(SECO)

Phytoestrogens (3) Common caracteristics:

Crucial activation by the intestinal microbiota Daidzein equol SECO enterodiol, enterolacton Strong influence on biological activity!

BUT: interindividual differences!!! E.g. only 1/3rd of population produces equol

Beneficial effects depend on microbial community composition

Phytoestrogens from hop (1)

Humulus lupulus L. (Hop)>Cannabaceae (+ Cannabis sativa L.)

Mainly used in beer industry But also source of the prenylflavonoid 8-prenylnaringenin (8-PN)

3rd group of phytoestrogens

Phytoestrogens from hop (2) Research topic:

Intestinal metabolism? Cfr other phytoestrogens: intestinal activation?

Hop prenylflavonoids: 8-prenylnaringenin (8-PN): very low concentrations

Isoxanthohumol (IX) and Xanthohumol (X): not estrogens but much higher concentrations.

Metabolism of 8-PN, IX and X?

Isoxanthohumol acts as pro-estrogen (1)

IX can be activated into 8-PN!

Isoxanthohumol acts as pro-estrogen (2)

Desmethyl-xanthohumol

+

6-Prenylnaringenin

OH

O

OH OH

OMe

Xanthohumol (X)

O

OH O

OH

OMe

Isoxanthohumol (IX)

Michael addition

OOH

OH O

OH

12

6

8

OOH

OH

OH

O

8-Prenylnaringenin (8-PN)

Michael addition

MicrobialO-

demethylation

OO H

O HOH

O H

Isoxanthohumol acts as pro-estrogen (3)

IX can be activated into 8-PN! Relevance:

8-PN conc in beer are too low for biological effects

Activation of IX: much higher exposure to 8-PN! BUT: interindividual differences

Interindividual differences?

Interindividual differences in vitro (1)

Experiment with 51 fecal samples Incubation immediately after defecation

BHI + fecal samples (5%) 25 mg/L IX 37°C, anaerobic conditions HPLC and LC/MS analysis

% high, moderate and slow 8-PN producers?

Possemiers et al., Journal of Nutrition, July 2006

Interindividual differences in vitro (2)

2/3!

Interindividual differences: 3 significant groups!

Interindividual differences in vivo (1)In vivo evaluation of the bioavailability and biotransformation of hop prenylflavonoids

5 day intervention study (5.5 mg IX/d) 50 postmenopauzal women urine collection:

Absorption prenylflavonoids Detection and identification of metabolites

Fecal sample collection In vitro IX into 8-PN conversion Molecular fingerprinting of intestinal community

In vivo (2): fecal samples

High (A), moderate (C) and slow (B) IX-converter

In vivo (3): urine

High (A), moderate (C) and slow (B) 8-PN excretion Good correlation between in vitro and in vivo!

Conclusions Intestinal transformation of hop flavonoids:

Interindividual differences 1/3rd converted IX into hopein (8-PN)

Good correlation in vitro and in vivo Intestinal bacteria are responsible for the conversion in vivo

IX acts as pro-estrogen in food and supplements Up to 4 mg IX/L in beer and 5 mg/supplement Possible health effects not negligible! Exposure dependent on intestinal microbial community!

Contact information Posters:

Possemiers et al. Bolca et al.

LabMET – Ghent UniversityCoupure Links 653B-9000 Gentsam.possemiers@ugent.behttp://labMET.ugent.be/+32/9/264.59.76