Transcript Structure-Degradation Relationships of Flavonoids and

STRUCTUREDEGRADATION
RELATIONSHIPS OF
FLAVONOIDS AND
THEIR CORRELATION
TO BIOAVAILABILITY
Suzanne Hendrich, PhD
University Professor, Iowa State University
LEARNING OUTCOMES
Identify key flavonoid structures & classes
 Identify key food sources of major dietary
flavonoids
 Describe structure/activity relationships
influencing bioavailability of flavonoids
 Synthesize a current picture of research
approaches and issues in studying SARs for
bioactive food components using flavonoids as an
example

INTRODUCTION – WHAT ARE
FLAVONOIDS?

Polyphenolic compounds synthesized in plants
Pollinator attractors
 Plant growth regulators
 Nitrogen fixing bacteria activators
 UV filters

STRUCTURE OF FLAVONOIDS—
HYDROXYLATED POLYPHENOLS
3'
2'
B
8
O
7
O
A
4'
O
5'
2
6'
C
3
6
5
4
flavanol
O
3'
O
flavone
2'
8
+
O
7
A
OH
isoflavone
4'
B
5'
2
6'
C
3
6
O
5
4
O
anthocyanidin
proanthocyanidin
(anthocyanidin oligomers)
O
flavanone
OH
O
flavonol
WHERE ARE THEY FOUND?
 Refer
to USDA flavonoid database 2007 (see
course materials)—best sources?
 Commonly ingested in fruits, vegetables, herbs
and dietary supplements
 Estimated daily intake can reach up to 1 gram
Flavonoid Subclass
Common Flavonoids
Major Food Sources
Flavone
apigenin, luteolin
parsley, celery
Flavanone
naringenin, hesperetin
citrus
Flavonol
quercetin, kaempferol
onions, tea, broccoli, apples, red wine
Isoflavone
genistein, daidzein
soybeans
Flavanol
catechin, epicatechin
apples, tea
Anthocyanidin
cyanidin
cherries, grapes, cocoa powder
INTRODUCTION-BIOLOGICAL
PROPERTIES
Antioxidant activity
catechol group
OH
OH
2-3 double bond
HO
O
OH
OH
O
3-hydroxyl group
Bors et al. 1990
ANTIOXIDANT ACTIVITY AND
ATHEROSCLEROSIS
Inhibition of low density lipoprotein (LDL)
oxidation; this oxidation is needed for
atherosclerosis (heart disease)
 Flavonoids inhibited human LDL oxidation in
vitro. Quercetin and morin were most effective
(Hou et al., 2004).
 LDL isolated from atherosclerotic mice fed
catechin, quercetin (each 50 µg/day) or red wine
(0.5 mL/day), were less oxidized than the mice
fed a placebo (Hayek et al., 1997).
 In 805 men ages 65-84 y in the Netherlands, an
inverse association was found between high
flavonoid intake (around 30 mg/day) and heart
disease mortality rate compared to those with
low flavonoid intake (less than 19 mg/day)
(Hertog et al., 1995).

ANTIOXIDANT ACTIVITY AND CANCER
Free radical scavengers
 In human melanoma HMB-2 cells, flavonoids
decreased chromosomal abberations at 20-50 uM
(Horvathova et al., 2005).
 Male Fisher-344 rats pre-treated with 50 mg/kg
quercetin before a cancer-causing chemical
showed fewer pre-cancerous lesions (SanchezPerez et al., 2005).
 Flavonoid intake from fruits and vegetables were
inversely associated with gut and lung cancer
risk in 738 men ages 65-84 y (Hertog et al.,
1993).

ESTROGENIC ACTIVITY—WHAT WOULD YOU
PREDICT FOR FLAVONOIDS IN GENERAL (LOOK AT
STRUCTURES)?
5'
R2
6
R1
O
5
4
OH
6'
4'
3'
3
2'
7
HO
2
O
8
Soy isoflavones
18
12
10
2
13
8
14
7
5
4
16
9
3
HO
OH
17
11
1
CH3
6
17β-estradiol
15
ESTROGENIC ACTIVITY AND CANCER
Estrogen receptor binding
 Isoflavones bound to the estrogen receptor 100010,000-fold lower than estradiol and were
positive in the E-SCREEN assay--estrogen
receptor binding induced proliferation of human
MCF-7 breast cancer cells and human BG-1
ovarian cancer cells (Schmitt et al., 2001).
 Mammary tumors were delayed in mice fed 250
mg/kg daidzein or genistein from 7 wk of age to
34 wk (Jin et al., 2002).
 In a population based case-control study in
Shanghai, China, regular consumption of soy
isoflavones was inversely associated (p=0.01)
with the risk of endometrial cancer in 1678
women ages 30-69 y (Xu et al., 2004).

FLAVONOID BIOAVAILABILITY

Proportion of flavonoid that is absorbed and
available to exert biological activity at target
sites
BIOAVAILABILITY
Absorption
Excretion
Human and
Microbial
Metabolism
Distribution
GUT MICROBIAL FLAVONOID
DEGRADATION: WHAT SARS DO YOU
SEE HERE? (SIMONS ET AL. 2010)
In Vitro
Flavonoid
hesperetin
naringenin
genistein
apigenin
quercetin
luteolin
glycitein
kaempferol
Chrysin
5,4’-dihydroxyflavone
5,3’-dihydroxyflavone
flavone
daidzein
7,4’-dihydroxyflavone
6,4’-dihydroxyflavone
myricetin
Degradation Rate
(h-1)
0.75±0.05a
0.47±0.28b
0.38±0.32b
0.37±0.18b
0.35±0.31b
0.21±0.16b
0.18±0.09bc
0.12±0.17b
0.08±0.05c
0.08±0.05c
0.07±0.04c
0.07±0.02c
0.07±0.03c
0.05±0.02c
0.04±0.03c
0.04±0.04c
RAPIDLY DEGRADED FLAVONOIDS
OH
HO
OH
O
OH
HO
O
OH
APIGENIN
(5,7,4’-TRIHYDROXYFLAVONE)
OH
HO
O
O
NARINGENIN
(5,7,4’-TRIHYDROXYFLAVANONE)
(DIHYDRO-APIGENIN)
HO
O
O
OH
OH
O
OH
KAEMPFEROL
(5,7,4’-TRIHYDROXYFLAVONOL)
(3,5,7,4’-TETRAHYDROXYFLAVONE)
O
OH
GENISTEIN
(5,7,4’-TRIHYDROXYISOFLAVONE)
OH
OH
OH
OH
HO
O
HO
O
OH
OH
O
LUTEOLIN
(5,7,3’,4’-TETRAHYDROXYFLAVONE)
OH
O
QUERCETIN
(3,5,7,3’,4’-PENTAHYDROXYFLAVONE)
(5,7,3’,4’-TETRAHYDROXYFLAVONOL)
FLAVONOID BIOAVAILABILITY—10 SUBJECTS
CONSUMED SOY MILK (GENISTEIN & DAIDZEIN),
ONIONS (QUERCETIN) OR GRAPEFRUIT JUICE
(NARINGENIN, HESPERETIN)
plasma concentration (uM)
genistein
0.02
daidzein
naringenin
0.015
hesperetin
quercetin
0.01
0.005
0
0
5
10
15
Time (hours)
(Simons et al. 2010)
20
FLAVONOID BIOAVAILABILITY AS SEEN IN
URINARY EXCRETION
70
Bioavailability (% of ingested dose)
(
a
60
50
40
30
20
b
c
10
b
b
Hesperetin
Quercetin
0
Genistein
Daidzein
(Simons et al. 2010)
Naringenin
Degradation rate k (1/h)
high
1.75
1.50
HO
1.25
O
1.00
0.75
moderate
low
0.50
OH
OH
0.25
19
18
14
29
17
25
24
12
27
Subject ID
*
15
10
5
Lo
w
M
od
er
at
e
ig
h
0
H
Genistein urinary recovery (%)
6
0.00
What does this suggest
about flavonoid
absorption?
20
O
Genistein degradation phenotype
Human saliva microbial degradation rates are similar to that seen
from human fecal samples (Ye 2008)
a, b, c, d: Different letters indicate differences between individual compound
p<0.01
Oral microbes associated with differing flavonoid
degradation rates in humans
High degrader
Low degrader
10 13 7 17 15 3 5 14 8 11
Lactobacillus brevis
or
Lactobacillus reuteri
Ribosomal Database Project
BLAST Assembled Genomes
CONCLUSIONS AND IMPLICATIONS


Oral disappearance rates of the compounds differed
as follows: Monophenol and glucoside (caffeic acid &
rutin) were the fastest; both 5-OH and 3-OH
(quercetin & myricetin, naringenin) were faster than
5-OH only (luteolin); the non-5-OH was the slowest
(daidzein); generally corresponding with fecal
degradation rates.
Lactobacillus brevis/Lactobacillus reuteri may be
bacteria that are key for degrading rutin in human
saliva; these bacteria could interfere with prevention
of periodontal disease by flavonoids
YOUR OVERALL CONCLUSIONS?
What difference might it make to someone’s
health if someone were a high or low “degrader”
of flavonoids?
 What future studies would be most helpful to
further clarify SARs for bioactive food
components?
 What general issues or problems must be
addressed in designing studies of SARs for
bioactive food components?

REFERENCES

Bors W, Heller W, Michel C, Saran M. (1990). Flavonoids as antioxidants. Determination of radical-scavanging
efficiences. In Methods in Enzymology (Packer L, Glazer AN, Eds.; Academic Press: San Diego CA) vol. 186, pp. 343–355.

Hayek, T., B. Fuhrman, J. Vaya, M. Rosenblat, P. Belinky, R. Coleman, A. Elis, M. Aviram (1997) Reduced progression
of atherosclerosis in the apolipoprotein E deficient mice following consumption of red wine, or its polyphenols quercetin or catechin,
is associated with reduced susceptibility of LDL to oxidation and aggregation. Arteriosclerosis, Thrombosis and Vascular Biology: 17,
2744–52.

Hertog, M. G. L., P. O. H. Hollman, M. B. Katan, D. Kromhout (1993a) Intake of potentially anticarcinogenic flavonoids
and their determinants in adults in The Netherlands. Nutrition and Cancer: 20, 21–9.

Hertog, M. G., D. Kromhout, C. Aravanis, H. Blackburn, R. Buzina, F. Fidanza, S.Giampaoli, A. Jansen, A. Menotti, S.
Nedeljkovic, M. Pekkarinen, B. S. Simic, H. Toshima, E. J. M. Feskens, P. C. H. Hollman, M. B. Katan (1995) Flavonoid intake and
long-term risk of coronary heart disease and cancer in the seven countries study. Archives of Internal Medicine: 155, 381–6.

Horváthová, K., I. Chalupa, L. Šebová, D. Tóthová & A. Vachálková (2005) Protective effect of quercetin and luteolin in
human melanoma HMB-2 cells. Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 565, 105-112.

Hou, L., B. Zhou, L. Yang & Z.-L. Liu (2004) Inhibition of human low density lipoprotein oxidation by flavonols and
their glycosides. Chemistry and Physics of Lipids, 129, 209-219.

Jin Z, MacDonald RS. Soy isoflavones increase latency of spontaneous mammary tumors in mice. J Nutr. 2002
Oct;132(10):3186-90.

Sánchez-Pérez, Y., C. Carrasco-Legleu, C. García-Cuellar, J. Pérez-Carreón, S. Hernández-García, M. Salcido-Neyoy, L.
Alemán-Lazarini & S. Villa-Treviño (2005) Oxidative stress in carcinogenesis. Correlation between lipid peroxidation and induction
of preneoplastic lesions in rat hepatocarcinogenesis. Cancer Letters, 217, 25-32.

Schmitt E., Dekant W., Stopper, H. (2001) Assaying the estrogenicity of phytoestrogens in cells of different estrogen
sensitive tissues. Toxicol In Vitro 15, 433-9.

Simons AL, Renouf M, Murphy PA, Hendrich S. (2010) Greater apparent absorption of flavonoids is associated with
lesser human fecal flavonoid disappearance rates. J Agric Fd Chem 58:141-147.

Xu H.W., Zheng W., Xiang W. B., Ruan Z. X, Cheng, J. R., Dai, Q., Gao Y.T., Shu X. O. (2004) Soya food intake and risk
of endometrial cancer among Chinese women in Shanghai: population based case-control study. BMJ. 328: 1285.

Ye Z. (2008) Metabolism of herbal phenolics in gut/oral microbiota or Caco-2 cells andbioavailability associated efficacy
of caffeic acid in mouse colitis. Dissertation, Iowa State University, Ames, IA.