Transcript Laboratory of Microbial Ecology and Technology (LabMET)

Activation of pro-estrogens from
hops by intestinal bacteria
Production of the phytoestrogen 8-prenylnaringenin
Sam Possemiers, Selin Bolca, Veerle Maervoet,
Tom Van de Wiele, Arne Heyerick, Denis De
Keukeleire & Willy Verstraete
Laboratory of Microbial Ecology & Technology (LabMET)
http://labmet.ugent.be
Phytoestrogens (1)

“Plant constituents which structurally or
functionally mimic the female estrogen 17βestradiol”
CH3
HO
OH
17β-estradiol
 Beneficial role in the prevention of
osteoporosis, menopauzal complaints and
cancers
 Applications!
Phytoestrogens (2)

2 well known groups:

Isoflavones from soy: daidzein, genistein
OH
O
O
HO

OH
genistein
Lignans from linseed, fruits, nuts…
OH
OH
OH
O
O
OH
HO
OH
Secoisolariciresinol
(SECO)
Phytoestrogens (3)
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Common caracteristics:
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Crucial activation by the intestinal microbiota
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Daidzein  equol
SECO  enterodiol, enterolacton
Strong influence on biological activity!
BUT: interindividual differences!!!
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E.g. only 1/3rd of population produces equol
 Beneficial effects depend on microbial community
composition
Phytoestrogens from hop (1)
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Humulus lupulus L. (Hop)
>Cannabaceae (+ Cannabis sativa L.)
Mainly used in beer industry
But also source of the prenylflavonoid 8prenylnaringenin (8-PN)
 3rd group of phytoestrogens
Phytoestrogens from hop (2)
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Research topic:

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Intestinal metabolism?
Cfr other phytoestrogens: intestinal activation?
Hop prenylflavonoids:
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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)
OH
OH
HO
Michael
addition
OH
O
HO
Microbial
OMe
O
OMe
Xanthohumol
(X)
O
O-demethylation
Isoxanthohumol
(IX)
OH
OH
OH
HO
Michael
addition
OH
O
HO
8
1
2
6
OH
O
Desmethylxanthohumol
OH
O
HO
+
OH
O
O
8-Prenylnaringenin
(8-PN)
6-Prenylnaringenin
Isoxanthohumol acts as pro-estrogen (3)
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IX can be activated into 8-PN!
Relevance:
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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)
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Experiment with 51 fecal samples
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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
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5 day intervention study (5.5 mg IX/d)
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50 postmenopauzal women
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urine collection:
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Absorption prenylflavonoids
Detection and identification of metabolites
Fecal sample collection
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In vitro IX into 8-PN conversion
Molecular fingerprinting of intestinal community
In vivo (2): fecal samples
(8-PN/(IX+8-PN) (%)
120
A
B
C
100
80
60
40
20
0
0
3
8
13
Time (days)
 High (A), moderate (C) and slow (B) IX-converter
In vivo (3): urine
8-PN/(8-PN+IX) (%)
50
A
B
C
40
30
20
10
0
0
1
2
3
4
5
Time (days)
 High (A), moderate (C) and slow (B) 8-PN excretion
 Good correlation between in vitro and in vivo!
Conclusions
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Intestinal transformation of hop flavonoids:
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Interindividual differences
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1/3rd converted IX into hopein (8-PN)
Good correlation in vitro and in vivo
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Intestinal bacteria are responsible for the conversion in
vivo
IX acts as pro-estrogen in food and supplements
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Up to 4 mg IX/L in beer and 5 mg/supplement
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Possible health effects not negligible!
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Exposure dependent on intestinal microbial community!
Contact information
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Posters:
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Possemiers et al.
Bolca et al.
LabMET – Ghent University
Coupure Links 653
B-9000 Gent
[email protected]
http://labMET.ugent.be/
+32/9/264.59.76