|Antioxidant and antiproliferative
activities of common vegetables.
Chu YF, Sun J, Wu X, Liu RH.
Department of Food Science and Institute of Comparative and Environmental
Toxicology, Cornell University, Ithaca, New York 14853, USA.
Epidemiological studies have shown that consumption of fruits and vegetables
is associated with reduced risk of chronic diseases. Increased consumption
of fruits and vegetables containing high levels of phytochemicals has been
recommended to prevent chronic diseases related to oxidative stress in the
human body. In this study, 10 common vegetables were selected on the basis
of consumption per capita data in the United States. A more complete profile
of phenolic distributions, including both free and bound phenolics in these
vegetables, is reported here using new and modified methods. Broccoli
possessed the highest total phenolic content, followed by spinach, yellow
onion, red pepper, carrot, cabbage, potato, lettuce, celery, and cucumber.
Red pepper had the highest total antioxidant activity, followed by broccoli,
carrot, spinach, cabbage, yellow onion, celery, potato, lettuce, and
cucumber. The phenolics antioxidant index (PAI) was proposed to evaluate the
quality/quantity of phenolic contents in these vegetables and was calculated
from the corrected total antioxidant activities by eliminating vitamin C
contributions. Antiproliferative activities were also studied in vitro using
HepG(2) human liver cancer cells. Spinach showed the highest inhibitory
effect, followed by cabbage, red pepper, onion, and broccoli. On the basis
of these results, the bioactivity index (BI) for dietary cancer prevention
is proposed to provide a simple reference for consumers to choose vegetables
in accordance with their beneficial activities. The BI could be a new
alternative biomarker for future epidemiological studies in dietary cancer
prevention and health promotion.
PMID: 12405796 [PubMed - indexed for MEDLINE]
|J Nutr 2002 Oct;132(10):2991-4
Brassica, biotransformation and cancer risk: genetic
polymorphisms alter the preventive effects of cruciferous vegetables.
Lampe JW, Peterson S.
Cancer Prevention Research Program, Fred Hutchinson Cancer Research Center,
Seattle, WA 98109, USA. firstname.lastname@example.org
The chemoprotective effect of cruciferous vegetables is due to their high
glucosinolate content and the capacity of glucosinolate metabolites, such as
isothiocyanates (ITC) and indoles, to modulate biotransformation enzyme
systems (e.g., cytochromes P450 and conjugating enzymes). Data from
molecular epidemiologic studies suggest that genetic and associated
functional variations in biotransformation enzymes, particularly glutathione
S-transferase (GST)M1 and GSTT1, which metabolize ITC, alter cancer risk in
response to cruciferous vegetable exposure. Moreover, genetic polymorphisms
in receptors and transcription factors that interact with these compounds
may further contribute to variation in response to cruciferous vegetable
intake. This review outlines the metabolism and mechanisms of action of
cruciferous vegetable constituents, discusses the recent human studies
testing effects of cruciferous vegetables on biotransformation systems and
summarizes the epidemiologic and experimental evidence for an effect of
genetic polymorphisms in these enzymes on response to cruciferous vegetable
intake. Taken together, genetic differences in biotransformation enzymes and
the factors that regulate them, as well as variation in glucosinolate
content of cruciferous vegetables and the methods used to prepare these
foods underscore the multiple layers of complexity that affect the study of
gene-diet interactions and cancer risk in humans.
PMID: 12368383 [PubMed - indexed for MEDLINE]
|Arch Tierernahr 2001;55(4):333-50|| |
Effects of rapeseed-press cake glucosinolates and iodine
on the performance, the thyroid gland and the liver vitamin A status of
Schone F, Tischendorf F, Leiterer M, Hartung H, Bargholz J.
Agricultural Institute of Thuringia, Jena, Germany.
Rapeseed press cake (per kg DM 181 g EE, 341 g CP and 23.3 mmol
glucosinolates) was tested in a long-term experiment with a total of sixty
pigs (live weight range 24 to 104 kg). The 3 x 2 factorial design consisted
of three rapeseed press cake levels (no rapeseed press cake--control, 75 g
or 150 g rapeseed press cake per kg diet) each with two iodine dosages (125
or 250 micrograms supplementary iodine per kg diet). Reduced feed intake and
depressed weight gain were found in groups receiving 150 g rapeseed press
cake per kg diet, which correspond to 3.2 mmol glucosinolates per kg diet.
At an inclusion level of 75 g rapeseed-press cake per kg diet no differences
in feed intake and growth intensity were recorded in comparison to the rape
feed free control. The rapeseed-press cake diet increased the weight of
thyroid gland and liver and decreased the serum thyroxine (T4)
concentration. Higher iodine dosage increased the serum T4 concentration of
pigs receiving 75 g rapeseed press cake per kg diet (= 1.6 mmol
glucosinolates per kg diet) to the level of the control group and retarded
the enlargement of the thyroid gland. Intake of rapeseed products lowered
the iodine content of the thyroid gland, however, there was no significant
difference between groups given 1.6 and 3.2 mmol glucosinolates per kg diet.
The vitamin A content of the whole liver and the vitamin A serum
concentration were not influenced by the diets tested. However, rapeseed
press cake and the glucosinolates, respectively, decreased the vitamin A
concentration per gram liver due to the organ enlargement and the resulting
PMID: 12357593 [PubMed - indexed for MEDLINE]
|Nutr Cancer 2002;42(1):1-9|| |
Brassica vegetables and prostate cancer risk: a review of
the epidemiological evidence.
Kristal AR, Lampe JW.
Cancer Prevention Research Program, Fred Hutchinson Cancer Research Center,
Seattle, WA 98109, USA. email@example.com
Epidemiological studies have yielded conflicting results on the associations
of diet with prostate cancer. We review evidence that Brassica vegetables
are associated with reduced prostate cancer risk. Brassica vegetables, which
include broccoli, cabbage, mustard and collard greens, and bok choy, contain
glucosinolates, the metabolic breakdown products of which are potent
modulators of xenobiotic-metabolizing enzymes that protect DNA from damage.
Twelve published studies give some information about Brassica vegetables and
prostate cancer risk; six of these studies can be clearly interpreted. Of
these, three reported statistically significant reduced risks (P < 0.05) and
one reported a borderline significant reduced risk (P = 0.06) with high
Brassica vegetable consumption. The epidemiological literature provides
modest support for the hypothesis that high intakes of Brassica vegetables
reduce prostate cancer risk.
PMID: 12235639 [PubMed - in process]
J Agric Food Chem 2002 Sep 11;50(19):5490-5
Antioxidant effects of isorhamnetin
3,7-di-O-beta-D-glucopyranoside isolated from mustard leaf (Brassica juncea)
in rats with streptozotocin-induced diabetes.
Yokozawa T, Kim HY, Cho EJ, Choi JS, Chung HY.
Institute of Natural Medicine, Toyama Medical and Pharmaceutical University,
Sugitani, Toyama 930-0194, Japan. firstname.lastname@example.org
To investigate the effects of isorhamnetin 3,7-di-O-beta-D-glucopyranoside (isorhamnetin
diglucoside), a major flavonoid compound of mustard leaf, on oxidative
stress due to diabetes mellitus, in vivo and in vitro studies were carried
out. Oral administration of isorhamnetin diglucoside (10 or 20 mg/kg of body
weight/day for 10 days) to rats with streptozotocin-induced diabetes
significantly reduced serum levels of glucose and 5-(hydroxymethyl)furfural
(5-HMF), which is glycosylated with hemoglobin and is an indicator of
oxidative stress. After intraperitoneal administration, isorhamnetin
diglucoside did not show these activities. In addition, after oral
administration, the thiobarbituric acid-reactive substance levels of serum,
and liver and kidney mitochondria declined significantly compared with the
control group in a dose-dependent manner, whereas after intraperitoneal
administration these levels fell only slightly. On the basis of the oral and
intraperitoneal results, it was hypothesized that isorhamnetin diglucoside
was converted to its metabolite in vivo, and its conversion to its aglycone,
isorhamnetin, by beta-glucosidase was confirmed; isorhamnetin acted as an
antioxidant. Moreover, it was observed that isorhamnetin diglucoside had no
effect on the 1,1-diphenyl-2-picrylhydrazyl radical, whereas isorhamnetin
showed a potent antioxidant effect in vitro. In addition, intraperitoneal
administration of isorhamnetin reduced serum glucose and 5-HMF levels.
Furthermore, lipid peroxidation in blood, liver, and kidney associated with
diabetes mellitus declined after the administration of isorhamnetin. These
results suggest that isorhamnetin diglucoside is metabolized in vivo by
intestinal bacteria to isorhamnetin and that isorhamnetin plays an important
role as an antioxidant.
PMID: 12207497 [PubMed - indexed for MEDLINE]
Cancer Lett 2002 Aug 8;182(1):1-10
Inhibitory effect of whole strawberries, garlic juice or
kale juice on endogenous formation of N-nitrosodimethylamine in humans.
Chung MJ, Lee SH, Sung NJ.
Department of Food and Nutrition, Gyeongsang National University, Jinju
660-701, South Korea.
In vitro and in vivo experiments were performed on inhibition of nitrosation
by strawberry, garlic, and kale extracts. Strawberry, garlic, and kale
extracts inhibited nitrosation in vitro. However, garlic extract has a
greater ability to inhibit the chemical nitrosation in vitro than strawberry
and kale extracts. The garlic methanol-soluble fraction of the garlic
extract was fractionated into G1-G4 fractions by Prep-LC. Fraction G1
inhibited N-nitrosodimethylamine (NDMA) formation by 84+/-1%. We studied the
formation of the carcinogen NDMA in humans after administration of nitrate
(400 mg/day) in combination with an amine-rich diet and its possible
inhibition by administration of whole strawberries (300 g), garlic juice
(200 g: 75 g garlic juice in drinking water), or kale juice (200 g) in 27
males and 13 females (ten healthy volunteers in each group) of age 24+/-3
years. Nitrate intake resulted in a significant rise in mean salivary
nitrate and nitrite concentrations. Also, nitrate excretion in urine during
the experimental day was significantly increased compared with the control
days. When whole strawberries, garlic juice, or kale juice was provided
immediately after an amine-rich diet with a nitrate, NDMA excretion was
decreased by 70, 71, and 44%, respectively, compared with NDMA excretion
after ingestion of an amine-rich diet with a nitrate. These results suggest
that consumption of whole strawberries, garlic juice, or kale juice can
reduce endogenous NDMA formation.
PMID: 12175517 [PubMed - indexed for MEDLINE]
Indian J Med Res 1995 Nov;102:223-6
Role of goitrogens in iodine deficiency disorders & brain
Rao PS, Lakshmy R.
National Institute of Nutrition, Hyderabad.
Although iodine deficiency has primarily been implicated in the causation of
goitre, the significant role played by food goitrogens in the etiology of
iodine deficiency disorder (IDD) is being increasingly recognized. Impaired
brain development is the major cause of concern in IDD. Detailed
experimental studies were undertaken to ascertain various biochemical
changes associated with developing brain in response to treatment with a
goitrogens--thiocyanate. Addition of thiocyanate to food deprived of KI
brought down significantly the circulating levels of thyroxine (T4) in rats.
Nucleic acids and protein content in different regions of brain were
significantly lowered in rat pups exposed to thiocyanate. The rate of
microtubule assembly, which is detrimental for neurite growth was
considerably lowered, thereby influencing both myelin deposition and
synaptogenesis in developing brain. Goitrogen intake not only caused an
adaptive increase in the activity of type II 5'-deiodinase, which governs
availability of triiodothyronine (T3) in brain, it also increased the
latter's binding to brain nuclear receptors under conditions of thiocyanate
induced hypothyroid state. Addition of adequate quantities of KI mitigated
thiocyanate induced alterations by restoring circulating level of thyroxine.
These investigations suggest that goitrogens play a significant role in
influencing biochemical events unique to developing brain.
PMID: 8675242 [PubMed - indexed for MEDLINE]
Horm Metab Res 1995 Oct;27(10):450-4
Iodine metabolism in response to goitrogen induced
altered thyroid status under conditions of moderate and high intake of
Lakshmy R, Rao PS, Sesikeran B, Suryaprakash P.
National Institute of Nutrition, Indian Council of Medical Research,
Metabolic experiments in rats were undertaken to relate excretory pattern of
iodine and thiocyanate, with thyroid weight and the circulating levels of
thyroxine, in response to moderate and high intake of iodine and under
conditions of goitrogen induced altered thyroid status. On a moderate intake
of iodine (by depriving diet of KI) 25 mg of thiocyanate or substitution of
1/3rd proportion of casein based diet with dry cabbage, could significantly
reduce plasma thyroxine level by 60 days. Neither body weight nor the
weights of liver, kidney, heart or spleen were affected due to exposure to
goitrogens. A significant increase in thyroid weight as well as higher
excretion of iodine and thiocyanate were evident in goitrogen-fed rats.
Presence of high amounts of KI, to a certain extent, offered protection from
adverse effects of the goitrogens. Semi quantitative assessment of thyroid,
indicated hypofunctioning of thyroid with follicular hyperplasia in
thiocyanate fed rats. These alterations were of moderate degree in response
to cabbage feeding. These results emphasize that, moderate intake of iodine,
adequate to meet iodine requirement, may not ensure normal functioning of
thyroid in the presence of goitrogens.
PMID: 8575723 [PubMed - indexed for MEDLINE]
|Gen Comp Endocrinol 1992 Jan;85(1):147-55|| |
Measurement of plasma thyroxine binding protein in
relation to thyroidal condition in the turtle, Trachemys scripta, by
Pavgi S, Licht P.
Department of Integrative Biology, University of California, Berkeley 94720.
Polyclonal (rabbit) antisera were generated against a high-affinity plasma
thyroxine (T4) binding protein (TBP) purified from the turtle, Trachemys
scripta, and used to develop a specific radioimmunoassay (RIA). The RIA
demonstrated the presence of an immunochemically related protein in the
plasma of several other species of Trachemys and in members of several other
genera from the same family, Emydidae. Plasma from all nonemydids and some
emydid genera either showed no competition or nonparallelism in RIA. The
presence and level of radioimmunoassayable TBP in diverse species correlated
with results of previous comparative measurements of T4 binding activity.
However, an immunoreactive protein of the same molecular weight as TBP was
identified in all turtles by Western blot analysis. More detailed studies in
T. scripta demonstrated that variations in plasma T4 binding activity
induced by experimental or environmental manipulations were related to
differences in TBP concentrations. The concentration of TBP varied by orders
of magnitude (from less than 1 to ca. 150 mg/liter) in euthyroid animals;
levels showed ontogenetic changes (virtually absent in hatchlings) and were
directly related to thyroidal status. Experimentally induced hypothyroidism
(goitrogen treatment or surgical thyroidectomy) resulted in a marked
suppression of TBP, and T4 treatment prevented its decline or reinstated it.
Thus, in the turtle, this T4 transport protein may exist in higher
concentrations and its levels are more variable and show a different
relationship to thyroid activity than the analogous T4 binding globulin
(TBG) in mammals.
PMID: 1563614 [PubMed - indexed for MEDLINE]