The first ever double-blind placebo
controlled human trial of apple
polyphenol extracts and cholesterol shows "significant
reduction" in LDL and total cholesterol. An interview with researchers
on the details of this groundbreaking study will be available soon.
In a lucid and important presentation,
Cornell scientists outline a new approach to treating high cholesterol, and
conclude that "apple
phytochemicals can potentially improve human cardiovascular health by
both lowering blood
LDL cholesterol and
preventing LDL
oxidation."
Research from Cornell University suggests "astrong link between dietary intake of
apple phenolics and
flavonoids and reducedrisk of cardiovascular disease."
Two more human study reported that apple juice and
apple polyphenol extractsreduced plasma LDL oxidation in
healthy volunteers.
In a large-scale human study in Finland, researchers
found that consumption of
phytochemicals from apples and onions, but not other fruits and
vegetables, was associated with fewer deaths by heart
disease, and fewer deaths overall.
Serum Cholesterol-Lowering Effect of Apple
Polyphenols in Healthy Subjects
Yoko NAGASAKO-AKAZOME1), Tomomasa KANDA1), Mitsuo IKEDA1) and Hiroyuki
SHIMASAKI2)
1) Fundamental Research Laboratory, Asahi Breweries, Ltd.
2) Department of Biochemistry, Teikyo University School of Medicine
Abstract: We performed a clinical
study using healthy male and female subjects who had slightly
elevated cholesterol levels in their serum to examine the effects of food
tablets containing
apple polyphenols (Applephenon®), which are effective for improving
serum cholesterol concentrations in rats, on lipid metabolism in humans. The
total period of this study was four weeks and we obtained blood samples at
week 0 and week 4. Total
cholesterol levels of the intervention groups decreased significantly and
dose-dependently compared with that of the control group. We also
found LDL-cholesterol decreased
significantly and HDL-cholesterol increased. No abnormalities
were detected in biochemical examinations of any of the subjects during the
test period. We concluded that the study product is
useful as a food additive that
improves serum cholesterol concentrations. Such improvement is
expected to decrease the risk of
atherosclerosis for people with a slightly elevated total
cholesterol level.
Cornell Institute
of Food Science Symposium, May 22-24 2005
Cardioprotective potentials of apple
phytochemicals in LDL oxidation and LDL receptor expression
Yi-Fang Chu and Rui Hai Liu, Cornell
University
Cardiovascular disease is the
leading cause of death in most industrialized countries. Both
elevated blood LDL cholesterol level and LDL oxidation lead to an enhanced
atherogenicity. Therapeutic strategies have been developed based on
targeting the pathogenesis; one is to prevent LDL oxidation by increasing
antioxidant levels, and another, as employed by statin drugs, is to lower
levels of plasma LDL cholesterol by increasing LDL uptake by hepatocytes
through LDL receptors and subsequent sterol excretion through bile acids.
Our objectives were to determine: 1) the effect of
apple extracts on
human LDL oxidation; 2) if apple
extracts affected hepatic LDL receptor expression and the level
of intracellular cholesterol in HepG2 hepatocytes; 3) if
apple extracts
affected the expression of sterol regulatory-element binding proteins (SREBPs).
Apple phytochemicals
were extracted using 80% acetone. LDL was isolated from human plasma by
sequential ultracentrifugation. Prevention of human LDL oxidation was
studied using a LDL Oxidation Model for Antioxidant Capacity (LOMAC) assay.
The expression of LDL receptors and SREBPs in HepG2 hepatocytes was
quantified by western blotting. Intracellular cholesterol was measured by
gas chromatography. Apple
extracts had potent antioxidant capacity against human LDL oxidationand increased delay and
suppression of LDL oxidation in a dose-dependent manner.
Apple extracts also significantly
induced expression of hepatic LDL receptors in a dose-dependent
manner (p<0.05) and increased intracellular uptake of cholesterol by HepG2
hepatocytes (p<0.05). These results suggest that
apple phytochemicals could lower
plasma LDL cholesterol by enhancing uptake of LDL in liver and
increase subsequent sterol excretion as bile acids. The attenuated level of
active SREBP expression by apple
phytochemicals indicates a decrease in intracellular lipogenesis
and cholesterol synthesis,
similar to the results caused by statin drugs such as Lipitor.
Apple phytochemicals can potentially improve human cardiovascular health by
both lowering blood LDL
cholesterol and preventing LDL
oxidation.
Br J Nutr,
May 1, 2005; 93(5): 581-91
Differential inhibition of oxidized
LDL-induced apoptosis in human endothelial cells treated with different
flavonoids
YJ Jeong, YJ Choi, HM Kwon, SW Kang, HS Park, M Lee, and YH Kang
Division of Life Sciences, Hallym University, Chuncheon, South Korea.
High plasma level of cholesterol is a well-known risk factor for
atherosclerotic diseases.
Oxidized LDL induces cellular and nuclear damage that leads to
apoptotic cell death. We tested the hypothesis that flavonoids may function
as antioxidants with regard to LDL incubated with 5 mum-Cu(2+) alone or in
combination with human umbilical vein endothelial cells (HUVEC).
Cytotoxicity and formation of thiobarbituric acid-reactive substances
induced by Cu(2+)-oxidized LDL were examined in the presence of various
subtypes of flavonoid. Flavanols, flavonols and flavanones at a non-toxic
dose of 50 mum markedly inhibited
LDL oxidation by inhibiting the formation of peroxidative products.
In contrast, the flavones luteolin and apigenin had no such effect, with >30
% of cells killed after exposure to 0.1 mg LDL/ml. Protective flavonoids,
especially (-)-epigallocatechin gallate,
quercetin, rutin and
hesperetin, inhibited HUVEC nuclear condensation and fragmentation induced
by Cu(2+)-oxidized LDL. In addition, immunochemical staining and Western
blot analysis revealed that anti-apoptotic Bcl-2 expression was enhanced
following treatment with these
protective flavonoids. However, Bax expression and caspase-3
cleavage stimulated by 18 h incubation with oxidized LDL were reduced
following treatment with these protective flavonoids. The down-regulation of
Bcl-2 and up-regulation of caspase-3 activation were reversed by the
cytoprotective flavonoids, (-)-epigallocatechin gallate,
quercetin and
hesperetin, at >/=10 mum. These
results suggest that flavonoids may differentially prevent Cu(2+)-oxidized
LDL-induced apoptosis and promote cell survival as potent antioxidants.
Survival potentials of certain flavonoids against cytotoxic oxidized LDL
appeared to stem from their disparate chemical structure.
Furthermore, dietary flavonoids
may have therapeutic potential for protecting the endothelium from oxidative
stress and oxidized LDL-triggered atherogenesis.
PMID: 15975156
J.
Nutr. 135:172-178, February 2005
Biochemical and Molecular Actions of Nutrients
The Flavonoid Phloretin Suppresses
Stimulated Expression of Endothelial Adhesion Molecules and Reduces
Activation of Human Platelets
Verena Stangl*,1, Mario Lorenz*, Antje Ludwig*, Nicole Grimbo*, Carola
Guether*, Wasiem Sanad*, Sabine Ziemer , Peter Martus**, Gert Baumann* and
Karl Stangl*
* Medizinische Klinik und Poliklinik, Schwerpunkt Kardiologie, Angiologie,
Pneumologie; Institut für Laboratoriumsmedizin und Pathobiochemie; and **
Institut für Medizinische Informatik, Biometrie und Epidemiologie, Charité
der Humboldt-Universität, Campus Mitte, Berlin, Germany
1To whom correspondence should be addressed. E-mail:
verena.stangl@charite.de.
Atherosclerosis is a chronic inflammatory disease accompanied by the
expression of endothelial adhesion molecules.
Phloretin is a plant-derived
phytochemical that is mainly present in apples. Because phloretin
is reported to promote antioxidative activities, we investigated the
effects of phloretin on cytokine-induced expression of intercellular
adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1),
and endothelial leukocyte adhesion molecule-1 (E-selectin) in human
umbilical vein endothelial cells (HUVECs). Phloretin prevented TNF-
-stimulated upregulation of VCAM-1, ICAM-1, and E-selectin expression in a
concentration-dependent manner. To the same extent as for TNF- ,
phloretin also inhibited
IL-1ß-induced upregulation in expression of
all 3 adhesion molecules.
Inhibition of cytokine-induced adhesion molecule expression for VCAM-1,
ICAM-1, and E-selectin was detected already at the level of mRNA.
Preincubation with phloretin dose-dependently attenuated TNF- -stimulated
adhesion of monocytic THP-1 cells to HUVECs and human aortic endothelial
cells. Phloretin did not affect TNF- -stimulated activation of nuclear
factor B (NF- B) but inhibited activation of interferon regulatory factor 1,
a transcription factor involved in the regulation of endothelial cell
adhesion molecule expression. In
human platelets, phloretin diminished adenosine diphosphate (ADP)
and thrombin receptor-activating peptide–stimulated expression of the
activated form of the GPIIb/IIIa complex and
reduced platelet aggregation
stimulated by ADP. Thus phloretin
may have beneficial effects in the onset and progression of cardiovascular
diseases.
Chronic treatment with flavonoids prevents
endothelial dysfunction in spontaneously hypertensive rat aorta.
A Machha and MR Mustafa
Department of Pharmacology, Faculty of
Medicine, University of Malaya, Kuala Lumpur, Malaysia.
Flavonoids are known to possess
cardioprotective properties. Vascular endothelial function is a
surrogate marker for cardiovascular diseases, including hypertension. We
have studied the effects of chronic flavonoid treatment on vascular
endothelial functions in spontaneously hypertensive rats (SHR). Starting
from 6-7 weeks old, SHR were given flavonoids (baicalein, flavone, or
quercetin) orally (10
mg/kg, once daily) to the SHRs for 4 weeks. Aortas from all the flavonoid-treated
animals showed remarkably higher endothelium-dependent relaxations to
acetylcholine, to a similar extent as those pretreated with the angiotensin-converting
enzyme inhibitor, captopril. However, in contrast to other experimental
groups, flavone pretreatment also enhanced the endothelium-independent
relaxations to sodium nitroprusside. In addition, treatment with either
flavone or quercetin induced a
significant attenuation in systolic blood pressure of the
hypertensive animals. The present results suggest that
chronic treatment with the
flavonoids(baicalein, flavone, and quercetin)
preserves vascular endothelial
functions in hypertensive animals through several possible
actions, including increasing endothelial nitric oxide production and
bioavailability and reduction in
blood pressure.
BMJ. 1996 Feb
24;312(7029):478-81
Flavonoid
intake and coronary mortality in Finland: a cohort study.
Knekt P, Jarvinen R, Reunanen A, Maatela J.
National Public Health Institute, Helsinki, Finland.
OBJECTIVE: To study the association between dietary intake of flavonoids and
subsequent coronary mortality. DESIGN: A cohort study based on data
collected at the Finnish mobile clinic health examination survey from
1967-72 and followed up until 1992. SETTINGS: 30 communities from different
parts of Finland. SUBJECTS: 5133 Finnish men and women aged 30-69 years and
free from heart disease at baseline. MAIN OUTCOME MEASURE: Dietary intake of
flavonoids, total mortality, and coronary mortality. RESULTS:
In women a
significant inverse gradient was observed between dietary intake of
flavonoids and total and coronary mortality. The relative risks between
highest and lowest quarters of flavonoid intake adjusted for age, smoking,
serum cholesterol concentration, blood pressure, and body mass index were
0.69 (95% confidence interval 0.53 to 0.90) and 0.54 (0.33 to 0.87) for
total and coronary mortality, respectively. The corresponding values for men
were 0.76 (0.63 to 0.93) and 0.78 (0.56 to 1.08), respectively. Adjustment
for intake of antioxidant vitamins and fatty acids weakened the associations
for women; the relative risks for coronary heart disease were 0.73 (0.41 to
1.32) and 0.67 (0.44 to 1.00) in women and men, respectively.
Intakes of
onions and apples, the main dietary sources of flavonoids, presented similar
associations. The relative risks for coronary mortality between highest and
lowest quarters of apple intake were 0.57 (0.36 to 0.91) and 0.81 (0.61 to
1.09) for women and men, respectively. The corresponding values for onions
were 0.50 (0.30 to 0.82) and 0.74 (0.53 to 1.02), respectively. CONCLUSIONS:
The results suggest that people with very low intakes of
flavonoids have
higher risks of coronary disease.
Excerpts: "The consumption of
apples
and onions was inversely associatedwith total and coronary
mortality.
The relations wereagain stronger
in women than in men. Adjustment for
the intakeof other fruits and vegetables, not notably including
flavonoids,did not materially alter the results (data not
shown)."
"Our results thus support the
suggested beneficialeffect of flavonoid intake against coronary
heart disease."
PMID: 8597679 [PubMed - indexed for MEDLINE]
American Journal of
Clinical Nutrition, Vol. 78, No. 3, 517S-520S, September 2003
Health benefits of fruit and vegetables are
from additive and synergistic combinations of phytochemicals1,2,3,4
Rui Hai Liu
1 From the Department of Food Science and the Institute of Comparative and Environmental Toxicology,
Cornell University, Ithaca, NY.
Cardiovascular disease and cancer are ranked as the first
andsecond leading causes of death in the United States and in
mostindustrialized countries. Regular consumption of fruit and
vegetablesis associated with
reduced risks of cancer,
cardiovascular disease,stroke, Alzheimer disease, cataracts, and
some of the functionaldeclines associated with aging.
Prevention is a more effectivestrategy than is treatment of
chronic diseases. Functional foodsthat contain significant
amounts of bioactive components mayprovide desirable health
benefits beyond basic nutrition andplay important roles in the
prevention of chronic diseases.
The key question is whether a
purified phytochemical has thesame health benefit as does the
whole food or mixture of foodsin which the phytochemical is
present. Our group found, forexample, that the vitamin C
in apples
with skin accounts foronly 0.4% of the total antioxidant
activity, suggesting thatmost of the antioxidant activity of
fruit and vegetables maycome from phenolics and flavonoids in
apples.
We propose thatthe additive and synergistic effects of
phytochemicals in fruitand vegetables are responsible for their potent antioxidantand
anticancer activities, and that the benefit of a diet rich
in fruit and vegetables is attributed to the complex mixtureof
phytochemicals present in whole foods.
Excerpts: "Oxidative
stress can cause oxidative damage to large biomolecules
such as proteins, DNA, and lipids,
resulting in an increasedrisk for cancer and cardiovascular
disease. To preventor slow down the oxidative stress
induced by free radicals,sufficient amounts of antioxidants need
to be consumed. Fruitand vegetables contain a wide variety of
antioxidant compounds(phytochemicals) such as
phenolics and carotenoids
that mayhelp protect cellular systems from oxidative damage and
lowerthe risk of chronic
diseases."
"Role of phytochemicals in the prevention of
cardiovascular disease
Numerous investigations have been undertaken that
suggest astrong link
between dietary intake of phytochemicals and reducedrisk of
cardiovascular disease. Dietary flavonoid intake was
significantly inversely associated with mortality from
coronaryartery disease
and inversely related (more weakly but stillsignificantly) with
incidence of myocardial infarction.In a study in Finland, intake of
apples and onions, both highin quercetin, was inversely
correlated with total mortalityand coronary mortality. In
a recent Japanese study, thetotal intake of flavonoids (quercetin, myricetin, kaempferol,luteolin, and ficetin) was inversely
correlated with the plasmatotal cholesterol and low-density
lipoprotein (LDL) cholesterolconcentrations. Intake of
quercetin alone was inverselyrelated to total cholesterol and LDL plasma levels.
"Mechanisms for the prevention of arteriosclerosis by
antioxidantshave been proposed. In the LDL oxidation hypothesis,
oxidizedLDL cholesterol
has been suggested as the atherogenic factorthat contributes to
heart disease. Oxidized LDL istypically taken up by
macrophage scavenger receptors, thus promotingcholesterol ester
accumulation and foam cell formation, whichpromotes
atherosclerotic disease. Dietary antioxidants thatare
incorporated in LDL are themselves oxidized when these LDLare
exposed to prooxidative conditions before any extensiveoxidation
can occur in the sterol or polyunsaturated fatty acids. In addition,
phytochemicals have been shown to have rolesin the
reduction of platelet aggregation,
modulation of cholesterolsynthesis and absorption, and reduction
of blood pressure. Recently,C-reactive protein, a marker
of systemic inflammation, has beenreported to be a stronger
predictor of cardiovascular diseasethan LDL cholesterol,
suggesting that inflammation is acritical factor in
cardiovascular disease. Inflammation notonly promotes initiation
and progression of atherosclerosisbut also causes acute
thrombotic complications of atherosclerosis.Therefore,
the antiinflammatory activity of
phytochemicals mayplay an important role in the prevention of
cardiovascular disease."
Journal of Medicinal Food,
Volume 3, Number 4, 2000
Apple Juice
Consumption Reduces Plasma Low-Density Lipoprotein Oxidation in Healthy Men
and Women
DIANNE HYSON, M.S., R.D.,1DEBORAH STUDEBAKER-HALLMAN, B.S.,1PAUL A. DAVIS,
Ph.D.,1,2and M. ERIC GERSHWIN.
Epidemiological studies show that consumption of fruits and vegetables is
associated with beneficial effects on human health including reduced risk of
coronary artery disease (CAD).
Fruits and their juices contain phytochemicals that inhibit in vitro
low-density lipoprotein (LDL) oxidation and may account, in part, for
their protective effect. However, reports of in
vivo
antioxidant effects from fruit intake are limited. We conducted a human
trial to examine the in vivo effect of consumption of apples (both
whole and juice) in an unblinded, randomized,
crossover design. Healthy men and women added 375 ml of unsupplemented apple
juice or 340 g of cored whole apple to their
daily diet for 6 weeks, then crossed over to the alternate product for 6
weeks. Blood samples were obtained at baseline and after each dietary
period. Compliance was monitored via biweekly 5-day food records, bodyweight
checks, and meetings with study personnel. There were no significant
differences between groups in intake of dietary fat, cholesterol, total
carbohydrate, sugar, or calories throughout the study. Dietary fiber intake
increased by 22% with whole apple consumption.
Body weight, fasting serum lipid concentration, and other lipoprotein
parameters were unchanged. Apple juice
consumption increased ex vivo copper (Cu )-mediated LDL oxidation lag
time by 20% compared with baseline. Apples and apple
juice both reduced conjugated diene formation. Moderate apple juice consumption provides in vivo
antioxidant activity. In view of the current understanding of CAD,
the observed effect on LDL might be
associated with reduced CAD risk and supports the inclusion of apple juice in a healthy human diet.
American Journal
of Clinical Nutrition, Vol. 76, No. 3, 560-568, September 2002
Paul Knekt, Jorma Kumpulainen, Ritva Järvinen, Harri Rissanen, Markku
Heliövaara, Antti Reunanen, Timo Hakulinen and Arpo Aromaa
Background:Flavonoids are effective
antioxidants and may protectagainst several chronic diseases.
Objective:
The association between flavonoid intake and riskof several
chronic diseases was studied.
Design: The total dietary intakes of 10 054 men and women duringthe year preceding the baseline examination were determined
with a dietary history method. Flavonoid intakes were estimated,
mainly on the basis of the flavonoid concentrations in Finnish
foods. The incident cases of the diseases considered were identifiedfrom different national public health registers.
Results:Persons with higher quercetin intakes had lower mortalityfrom
ischemic heart disease. The relative risk (RR) betweenthe
highest and lowest quartiles was 0.79 (95% CI: 0.63, 0.99:P
for trend = 0.02). The incidence of cerebrovascular diseasewas
lower at higher kaempferol (0.70; 0.56, 0.86; P = 0.003),
naringenin (0.79; 0.64, 0.98; P = 0.06), and hesperetin (0.80;0.64, 0.99; P = 0.008) intakes. Men with higher
quercetin
intakeshad a lower lung cancer incidence (0.42; 0.25, 0.72; P
= 0.001),and men with higher myricetin intakes had a lower
prostate cancerrisk (0.43; 0.22, 0.86; P = 0.002). Asthma
incidence was lowerat higher
quercetin (0.76; 0.56, 1.01; P
= 0.005), naringenin(0.69; 0.50, 0.94; P = 0.06), and
hesperetin (0.64; 0.46, 0.88;P = 0.03) intakes. A trend toward a reduction in risk
of type2 diabetes was associated with higher
quercetin
(0.81; 0.64,1.02; P = 0.07) and myricetin (0.79; 0.62,
1.00; P = 0.07) intakes.
Conclusion:
The risk of some chronic diseases may be lower athigher dietary
flavonoid intakes.
Apple juice
inhibits human low density lipoprotein oxidation.
Pearson DA, Tan CH, German JB, Davis PA,
Gershwin ME.
Department of Food Science and Technology, University of California at
Davis, 95616, USA.
Dietary phenolic compounds, ubiquitous in vegetables and fruits and their
juices possess antioxidant activity that may have beneficial effects on
human health. The phenolic composition of six commercial apple juices, and
of the peel (RP), flesh (RF)
and whole fresh Red Delicious apples (RW), was determined by high
performance liquid chromatography (HPLC), and total phenols were determined
by the Folin-Ciocalteau method. HPLC analysis identified and quantified
several classes of phenolic compounds: cinnamates, anthocyanins,
flavan-3-ols and flavonols. Phloridzin and hydroxy methyl furfural were also
identified. The profile of phenolic compounds varied among the juices. The
range of concentrations as a percentage of total phenolic concentration was:
hydroxy methyl furfural, 4-30%; phloridzin, 22-36%; cinnamates, 25-36%;
anthocyanins, n.d.; flavan-3-ols, 8-27%; flavonols, 2-10%. The phenolic
profile of the Red Delicious apple extracts differed from those of the
juices. The range of concentrations of phenolic classes in fresh
apple
extracts was: hydroxy methyl furfural, n.d.; phloridzin, 11-17%; cinnamates,
3-27%; anthocyanins, n.d.-42%; flavan-3-ols, 31-54%; flavonols, 1-10%. The
ability of compounds in apple juices
and extracts from fresh apple to protect LDL was assessed using an in
vitro copper catalyzed human LDL oxidation system. The extent of LDL
oxidation was determined as hexanal production using static headspace gas
chromatography. The apple juices and
extracts, tested at 5 microM gallic acid equivalents (GAE),
all inhibited LDL oxidation.
The inhibition by the juices ranged from 9 to 34%, and inhibition by RF, RW
and RP was 21, 34 and
38%, respectively. Regression
analyses revealed no significant correlation between antioxidant activity
and either total phenolic concentration or any specific class of phenolics.
Although the specific components in the apple juices and extracts that
contributed to antioxidant activity have yet to be identified, this study
found that both fresh apple and commercial apple juices inhibited
copper-catalyzed LDL oxidation. The in vitro antioxidant activity of apples
support the inclusion of this fruit and its juice in a healthy human diet.
PMID: 10353589 [PubMed - indexed for MEDLINE]
J Agric Food Chem.
2004 Nov 3;52(22):6818-23.
Novel
low-density lipoprotein (LDL) oxidation model: antioxidant capacity for the
inhibition of LDL oxidation.
Chu YF, Liu RH.
Department of Food Science and Institute of Comparative and Environmental
Toxicology, Cornell University, Ithaca, New York 14853, USA.
A novel model of peroxyl radical initiated low-density lipoprotein (LDL)
oxidation (LDL oxidation model for antioxidant capacity, or LOMAC) was
developed to assess the free radical scavenging capacity of antioxidants and
the extracts of natural products. A water-soluble free radical initiator,
2,2'-azobis(amidinopropane) dihydrochloride, was used at physiological
temperature (37 degrees C) to generate peroxyl radicals to catalyze lipid
oxidation of LDL isolated from human plasma samples. Headspace hexanal, a
major decomposition product of LDL oxidation, was measured by a headspace
gas chromatograph as an indicator of antioxidant capacity of different
concentrations of pure antioxidants (vitamins C and E) and the extracts of
natural products (fresh applephytochemical extracts). All vitamin C and E and
apple
extract concentrations tested resulted in increasing partial suppression and
delay of LDL oxidation. On the basis of the median effective dose
(EC(50)) calculated for each compound or extract tested,
the LOMAC value of 100 g of apple
against LDL oxidation was equivalent to 1470 mg of vitamin E or to 402 mg of
vitamin C. This study shows that the LOMAC assay can be routinely
used to analyze or screen antioxidants or phytochemical extracts against LDL
oxidation to prevent cardiovascular disease. The food-specific LOMAC values
will be very useful as a new alternative biomarker for future
epidemiological studies of cardiovascular disease.
J Agric Food Chem.
2003 Sep 10;51(19):5780-5.
Apple and pear
peel and pulp and their influence on plasma lipids and antioxidant
potentials in rats fed cholesterol-containing diets.
Leontowicz M, Gorinstein S, Leontowicz H, Krzeminski R,
Lojek A, Katrich E, Ciz M, Martin-Belloso O, Soliva-Fortuny R, Haruenkit R,
Trakhtenberg S.
Department of Animal Physiology, Faculty of Veterinary Medicine, Warsaw
Agricultural University, Nowoursynowska 166, 02-787 Warsaw, Poland.
The aim of this study was to assess the bioactive compounds of apple and
pear peel and pulp in vitro and their influence on plasma lipids and
antioxidant potentials in vivo. The antioxidant potentials measured by
1,1-diphenyl-2-picrylhydrazyl (DPPH), beta-carotene bleaching
(beta-carotene), and nitric oxide inhibition radical scavenging (NO) tests
in apple peel and pulp were significantly higher than in pear peel and pulp,
respectively. The ethanol extract of
apple peels showed the strongest inhibition of lipid peroxidation as
a function of its concentration and was comparable to the antioxidant
activity of butylated hydroxyanisole. The pear pulp extract had the weakest
antioxidant ability, whereas other extracts such as apple pulp and pear peel
were nearly equal. The antioxidant activities comprised contributions from
polyphenols, phenolic acids, and flavonoids and correlated well with
polyphenols and flavonoids. The correlation coefficients between polyphenols
and antioxidant activities by DPPH, beta-carotene, and NO were as follows:
0.9207, 0.9350, and 0.9453. Contrarily, the correlation coefficient between
the content of dietary fiber and the antioxidant activities test was low.
The content of all studied indices in apple and pear peel was significantly
higher than in peeled fruits (p < 0.05).
Diets supplemented with fruit peels
exercised a significantly higher positive influence on plasma lipid levels
and on plasma antioxidant capacity of rats than diets with fruit
pulps.
PMID: 12952433 [PubMed - indexed for MEDLINE]
J Nutr Biochem.
2002 Oct;13(10):603-610.
Comparative
content of some bioactive compounds in apples, peaches and pears and their
influence on lipids and antioxidant capacity in rats.
Leontowicz H, Gorinstein S, Lojek A, Leontowicz M, Ci;z M, Soliva-Fortuny
R, Park YS, Jung ST, Trakhtenberg S, Martin-Belloso O.
Department of Physiology, Biochemistry, Pharmacology and
Toxicology, Faculty of Veterinary Medicine, WarsawAgriculturalUniversity,
Nowoursynowska 166, 02-787, Warsaw, Poland
The aim of this study was to compare some bioactive compounds in apples,
peaches and pears and their influence on lipids and antioxidant capacity in
rats. The content of total polyphenols (g/100g) was 0.23 +/- 0.03; 0.22 +/-
0.03 and 0.68 +/- 0.1 in peeled fruits and 0.48 +/- 0.04, 0.47 +/- 0.04 and
1.2 +/- 0.12 in peels of peaches, pears and apples, respectively. Caffeic,
p-coumaric and ferulic acids and the
total radical-trapping antioxidative potential (TRAP) values in peeled
apples and their peels were significantly higher than in peaches and
pears, respectively. Contrarary, no significant differences in the content
of dietary fiber among the studied fruits were found. The content of all
studied indices in peels was significantly higher than peeled fruits (p <
0.05 ). A good correlation between the total polyphenols and the TRAP values
was found in all fruits. Diets
supplemented with apples and to a less extent with peaches and pears
have improved lipid metabolism and
increased the plasma antioxidant potential especially in rats fed
with added cholesterol. The highest
content of biologically active compounds and the best results in the
experiment on rats makes apple preferable for dietary prevention of
atherosclerosis and other diseases.
PMID: 12550072 [PubMed - as supplied by publisher]
Nutr Cancer.
2003;45(1):46-52.
Effects of
commonly consumed fruit juices and carbohydrates on redox status and
anticancer biomarkers in female rats.
Breinholt VM, Nielsen SE, Knuthsen P, Lauridsen ST, Daneshvar B, Sorensen
A.
Institute of Food Safety and Nutrition, Division of
Biochemical Toxicology, The Danish Veterinary and Food Administration,
Morkhoj Bygade 19, 2860 Soborg, Denmark. vib@fdir.dk
Administration of apple juice,
black currant juice, or a 1:1 combination of the two juices
significantly decreased the level of
the lipid peroxidation biomarker malondialdehyde in plasma of female
rats, whereas the protein oxidation biomarker 2-amino-adipic semialdehyde,
was significantly increased following administration of orange juice, black
currant juice, or the 1:1 combination of apple and black currant juice. A
significant increase in 2-amino-adipic semialdehyde was also observed in
control rats given sucrose, fructose, and glucose in the drinking water at
concentrations approximating the average carbohydrate levels in the employed
fruit juices.
None of the fruit juices were found to affect the activities
of antioxidant enzymes in red blood cells or hepatic glutathione S-transferase.
Hepatic quinone reductase activity, on the other hand, was significantly
increased by grapefruit juice, apple juice, and black currant juice. The
total daily intake of a selected subset of flavonoid aglycones ranged from
0.2 to 4.3 mg, and quercetin was found to be a minor constituent of all the
juices investigated. In a parallel study, rats were fed quercetin at doses
ranging from 0.001 to 10 g/kg of diet. However, no effects were observed on
hepatic glutathione S-transferase or quinone reductase activities, plasma
redox status, or the activity of red blood cell antioxidant enzymes.
Overall, the results of the present study
suggest that commonly consumed fruit
juices can alter lipid and protein oxidation biomarkers in the blood
as well as hepatic quinone reductase activity, and that quercetin may not be
the major active principle. The observation that natural carbohydrates are
capable of mediating oxidative stress in vivo warrants further studies due
to the central role refined and unrefined carbohydrates play in human
nutrition.
