Glucosinolates in Brassica: occurrence and significance as cancer-modulating agents

3,3'-Diindolylmethane and indole-3-carbinol: potential therapeutic molecules for cancer chemoprevention and treatment via regulating cellular signaling pathways

Dietary compounds in cancer prevention have gained significant consideration as a viable method. Indole-3-carbinol (I3C) and 3,3'-diindolylmethane (DIM) are heterocyclic and bioactive chemicals found in cruciferous vegetables like broccoli, cauliflower, cabbage, and brussels sprouts. They are synthesized after glycolysis from the glucosinolate structure. Clinical and preclinical trials have evaluated the pharmacokinetic/pharmacodynamic, effectiveness, antioxidant, cancer-preventing (cervical dysplasia, prostate cancer, breast cancer), and anti-tumor activities of I3C and DIM involved with polyphenolic derivatives created in the digestion showing promising results. However, the exact mechanism by which they exert anti-cancer and apoptosis-inducing properties has yet to be entirely understood. Via this study, we update the existing knowledge of the state of anti-cancer investigation concerning I3C and DIM chemicals. We have also summarized; (i) the recent advancements in the use of I3C/DIM as therapeutic molecules since they represent potentially appealing anti-cancer agents, (ii) the available literature on the I3C and DIM characterization, and the challenges related to pharmacologic properties such as low solubility, and poor bioavailability, (iii) the synthesis and semi-synthetic derivatives, (iv) the mechanism of anti-tumor action in vitro/in vivo, (v) the action in cellular signaling pathways related to the regulation of apoptosis and anoikis as well as the cell cycle progression and cell proliferation such as peroxisome proliferator-activated receptor and PPARγ agonists; SR13668, Akt inhibitor, cyclins regulation, ER-dependent-independent pathways, and their current medical applications, to recognize research opportunities to potentially use these compounds instead chemotherapeutic synthetic drugs.

Comparative Analysis of the Metabolic Profiles of Yellow- versus Black-Seeded Rapeseed Using UPLC-HESI-MS/MS and Transcriptome Analysis

The high levels of secondary metabolites in rapeseed play important roles in determining the oil quality and feeding value. Here, we characterized the metabolic profiles in seeds of various yellow- and black-seeded rapeseed accessions. Two hundred and forty-eight features were characterized, including 31 phenolic acids, 54 flavonoids, 24 glucosinolates, 65 lipid compounds, and 74 other polar compounds. The most abundant phenolic acids and various flavonoids (epicatechin, isorhamnetin, kaempferol, quercetin, and their derivatives) were widely detected and showed significant differences in distribution between the yellow- and black-seeded rapeseed. Furthermore, the related genes (e.g., BnTT3, BnTT18, BnTT10, BnTT12, and BnBAN) involved in the proanthocyanidin pathway had lower expression levels in yellow-seeded rapeseed, strongly suggesting that the seed coat color could be mainly determined by the levels of epicatechin and their derivatives. These results improve our understanding of the primary constituents of rapeseed and lay the foundation for breeding novel varieties with a high nutritional value.

Exogenous 3,3'-diindolylmethane increases Brassica napus L. seedling shoot growth through modulation of superoxide and hydrogen peroxide content

Brassica napus L. (cv. AV Garnet) seeds were pre-treated with 15μM 3,3'-diindolylmethane (DIM) to investigate whether DIM could enhance seed germination. Further treatment of seedlings with 15μM DIM for 14days explored the effects on seedling shoot growth. Exogenous DIM led to improved germination percentage, increased seedling shoot lengths, and increased fresh and dry weights. Furthermore, DIM triggered induction of superoxide radical (O2(-)) and hydrogen peroxide (H2O2) content however, no change in malondialdehyde (MDA) content and cell death (assessed with Evans Blue assay) was detected for both the control and DIM treated seedling shoots. We also observed increases in superoxide dismutase (SOD) activity and ascorbate peroxidase (APX) activity in response to exogenous DIM, two fundamental enzymes in the control of reactive oxygen species (ROS) in plants. These results indicate that exogenous DIM treatment enhances seed germination and improves seedling shoot growth through possible activation of a reactive oxygen species signalling pathway involving O2(-) and H2O2 in B. napus.

Glucosinolates, myrosinase hydrolysis products, and flavonols found in rocket (Eruca sativa and Diplotaxis tenuifolia)

Rocket species have been shown to have very high concentrations of glucosinolates and flavonols, which have numerous positive health benefits with regular consumption. This review highlights how breeders and processors of rocket species can utilize genomic and phytochemical research to improve varieties and enhance the nutritive benefits to consumers. Plant breeders are increasingly looking to new technologies such as HPLC, UPLC, LC-MS, and GC-MS to screen populations for their phytochemical content to inform plant selections. This paper collates the research that has been conducted to date in rocket and summarizes all glucosinolate and flavonol compounds identified in the species. The paper emphasizes the importance of the broad screening of populations for phytochemicals and myrosinase degradation products, as well as unique traits that may be found in underutilized gene bank resources. This review also stresses that collaboration with industrial partners is becoming essential for long-term plant breeding goals through research.

Bioactivity of phytochemicals in some lesser-known plants and their effects and potential applications in livestock and aquaculture production systems

Livestock and aquaculture production is under political and social pressure, especially in the European Union (EU), to decrease pollution and environmental damage arising due to animal agriculture. The EU has banned the use of antibiotics and other chemicals, which have been shown to be effective in promoting growth and reducing environment pollutants because of the risk caused to humans by chemical residues in food and by antibiotic resistance being passed on to human pathogens. As a result of this, scientists have intensified efforts in exploiting plants, plant extracts or natural plant compounds as potential natural alternatives for enhancing the livestock productivity. This paper discusses work on the effects of various phytochemicals and plant secondary metabolites in ruminant and fish species. The focus is on (i) plants such as Ananas comosus (pine apple), Momordica charantia (bitter gourd) and Azadirachta indica (neem) containing anthelmintic compounds and for their use for controlling internal parasites; (ii) plants containing polyphenols and their applications for protecting proteins from degradation in the rumen, increasing efficiency of microbial protein synthesis in rumen and decreasing methane emission; for using as antioxidants, antibacterial and antihelmintic agents; and for changing meat colour and for increasing n-3 fatty acids and conjugated linoleic acid in meat; (iii) saponin-rich plants such as quillaja, yucca and Sapindus saponaria for increasing the efficiency of rumen fermentation, decreasing methane emission and enhancing growth; for producing desired nutritional attributes such as lowering of cholesterol in monogastric animals; for increasing growth of fish (common carp and Nile tilapia) and for changing male to female ratio in tilapia; and for use as molluscicidal agents; (iv) Moringa oleifera leaves as a source of plant growth factor(s), antioxidants, beta-carotene, vitamin C, and various glucosinolates and their degraded products for possible use as antibacterial, antioxidant, anticarcinogenic and antipest agents; (v) Jatropha curcas toxic variety with high levels of various phytochemicals such as trypsin inhibitor, lectin, phytate and phorbol esters in seeds limiting the use of seed meal in fish and livestock diets; and the use of phorbol esters as bio-pesticidal agent; and (vi) lesser-known legumes such as Entada phaseoloides seeds containing high levels of trypsin inhibitor and saponins, Sesbania aculeate seeds rich in non-starch polysaccharides and Mucuna pruriens var. utilis seeds rich in l-3,4-dihydroxyphenylalanine and their potential as fish feed; Cassia fistula seeds as a source of antioxidants; and the use of Canavalia ensiformis, C. gladiata and C. virosa seeds containing high levels of trypsin inhinitor, lectins and canavanine. The paper also presents some challenges and future areas of work in this field.

Health benefits and possible risks of broccoli - an overview

Chemopreventive effects of broccoli, a highly valued vegetable, have been known for a long time. Several studies have demonstrated that broccoli might be beneficial by reducing the risk for the development of certain forms of cancer. These effects are generally attributed to glucosinolate-derived degradation products like isothiocyanates and indoles which are formed by the hydrolytic action of plant myrosinase and/or glucosidases deriving from the human microbial flora. However, recent in vitro and experimental animal studies indicate that broccoli, its extracts and the glucosinolate-derived degradation products might also have undesirable effects, especially genotoxic activities. However, the relevance of the genotoxic activities to human health is not known yet. This paper gives an overview on genotoxic, anti-genotoxic/chemopreventive, nutritive and antinutritive properties of broccoli, its ingredients and their degradation products. A qualitative comparison of the benefit and risk of broccoli consumption benefit-risk assessment shows that the benefit from intake in modest quantities and in processed form outweighs potential risks. For other preparations (fortified broccoli-based dietary supplements, diets with extraordinary high daily intake, consumption as a raw vegetable) further studies both for potential risks and beneficial effects are needed in order to assess the benefit and risk in the future.

Phytochemicals of Brassicaceae in plant protection and human health--influences of climate, environment and agronomic practice

In this review, we provide an overview of the role of glucosinolates and other phytochemical compounds present in the Brassicaceae in relation to plant protection and human health. Current knowledge of the factors that influence phytochemical content and profile in the Brassicaceae is also summarized and multi-factorial approaches are briefly discussed. Variation in agronomic conditions (plant species, cultivar, developmental stage, plant organ, plant competition, fertilization, pH), season, climatic factors, water availability, light (intensity, quality, duration) and CO(2) are known to significantly affect content and profile of phytochemicals. Phytochemicals such as the glucosinolates and leaf surface waxes play an important role in interactions with pests and pathogens. Factors that affect production of phytochemicals are important when designing plant protection strategies that exploit these compounds to minimize crop damage caused by plant pests and pathogens. Brassicaceous plants are consumed increasingly for possible health benefits, for example, glucosinolate-derived effects on degenerative diseases such as cancer, cardiovascular and neurodegenerative diseases. Thus, factors influencing phytochemical content and profile in the production of brassicaceous plants are worth considering both for plant and human health. Even though it is known that factors that influence phytochemical content and profile may interact, studies of plant compounds were, until recently, restricted by methods allowing only a reductionistic approach. It is now possible to design multi-factorial experiments that simulate their combined effects. This will provide important information to ecologists, plant breeders and agronomists.

Glucosinolates in Brassica vegetables: the influence of the food supply chain on intake, bioavailability and human health

Glucosinolates (GLSs) are found in Brassica vegetables. Examples of these sources include cabbage, Brussels sprouts, broccoli, cauliflower and various root vegetables (e.g. radish and turnip). A number of epidemiological studies have identified an inverse association between consumption of these vegetables and the risk of colon and rectal cancer. Animal studies have shown changes in enzyme activities and DNA damage resulting from consumption of Brassica vegetables or isothiocyanates, the breakdown products (BDP) of GLSs in the body. Mechanistic studies have begun to identify the ways in which the compounds may exert their protective action but the relevance of these studies to protective effects in the human alimentary tract is as yet unproven. In vitro studies with a number of specific isothiocyanates have suggested mechanisms that might be the basis of their chemoprotective effects. The concentration and composition of the GLSs in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, the effects of various factors in the supply chain of Brassica vegetables including breeding, cultivation, storage and processing on intake and bioavailability of GLSs are extensively discussed in this paper.

Volatile constituents throughout Brassica oleracea L. Var. acephala germination

In this work, the volatile composition of kale ( Brassica oleracea L. var. acephala) and its variation during germination were monitored during the first 9 days of seedling development by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography/ion trap-mass spectrometry (GC/IT-MS). Differences were found among the materials in the distinct analyzed periods. A total of 66 volatile compounds, distributed in several chemical classes, were determined: alcohols, carbonyl compounds (ketones, aldehydes, and esters), norisoprenoids, and terpenes, among others, sulfur compounds being the most abundant group in seeds and sprouts that exhibited allyl isothiocyanate as the major compound. Leaves of fully developed ground plant had the highest content of norisoprenoids, alcohols, and carbonyl compounds; in opposition, they showed lower levels of sulfur compounds, suggesting that these are important molecules for the development of kale, whereas the others are produced mainly during its growth.

A New Medium-term Rat Colorectal Bioassay Applying Neoplastic Lesions as End Points for Detection of Carcinogenesis Modifiers Effects with Weak or Controversial Modifiers

We have established a two-stage, medium-term rat colorectal carcinogenesis model featuring induction of neoplastic lesions within ten weeks. In the present study, we examined the ability of this model to detect weak modifiers. F344 male rats were given three subcutaneous (sc) injections of 1,2-dimethyl-hydrazine (DMH, 40 mg/kg b.w.) in one week followed by drinking water containing 1% dextran sodium sulfate (DSS) for a second week. One week after this regimen, basal diet alone, or diets containing 10% perilla oil, 10% corn oil, 10% dextrin, or 0.1% indole-3-carbinol (I3C) were supplied. The perilla oil and corn oil groups did not show significant differences in the numbers of aberrant crypt foci (ACF) and incidences or multiplicity of proliferative lesions as compared to the controls at either time point. In the dextrin group, the total number of ACF at week ten was significantly increased. With I3C, the total number of ACF and incidence and multiplicities of adenocarcinomas at week ten and the incidence of invasive tumors at week twenty were significantly increased. These data essentially correspond with earlier reported results, except in the vegetable oil cases. Thus, the system is suitable for detection of colorectal carcinogenesis modifiers with advantages over previous models using ACF alone as end points.

Consumption of cruciferous vegetables and glucosinolates in a Spanish adult population

OBJECTIVE

To assess the intake of glucosinolates and cruciferous vegetables among Spanish adults.

DESIGN

Cross-sectional analysis of a prospective cohort study.

SETTING

The Spanish cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC).

SUBJECTS

We analysed data from 40 684 men and women aged 35-64 years from the EPIC-Spain cohort. The usual diet was assessed by means of the dietary history method, and glucosinolate intake was calculated using a published food composition database.

RESULTS

The average intake of cruciferous vegetables was 11.3 g/day, accounting for about 5% of total vegetable consumption, whereas the daily intake of total glucosinolates was 6.5 mg, among which 35% were of indole type. The absolute intake of glucosinolates was in average higher in men than in women (6.8 vs 6.2 mg/day), whereas glucosinolate density per energy unit was higher in women's diet (3.4 vs 2.7 mg/4200 kJ). Northern regions consumed in average 36% more glucosinolates than Southern regions (7.3 vs 5.4 mg/day). There was a positive association of glucosinolate intake with body mass index, physical activity, educational level and an inverse relationship with alcohol consumption.

CONCLUSIONS

Contrary to the pattern seen for total vegetable intake, our estimate of consumption of cruciferous vegetables, and hence of glucosinolates, is relatively low within Europe, which in turn is lower than in North America and several Asian populations.

Antioxidant effect of squeezed juice from black radish (Raphanus sativus L. var niger) in alimentary hyperlipidaemia in rats

Black radish (Raphanus sativus L. var. niger) root has been used in folk medicine since antiquity as a natural drug for the stimulation of bile function. According to in vitro studies the squeezed juice from black radish root exhibited significant antioxidant properties. In the present study, the beneficial effect of the black radish juice on some free radical reactions in rats fed with a diet rich in lipids (20% sunflower oil, 2% cholesterol, 0.5% cholic acid in normal chow) was examined. Thiobarbituric acid reactive substances and conjugated diene concentrations were significantly higher, while the antioxidant enzyme activities and the free radical scavenging capacity were lower in hyperlipidaemic rats compared with normal controls. Supplementation of the lipid-rich diet with black radish juice resulted in a significant improvement of the parameters mentioned above. Although the exact mechanism of the biologically active compounds in black radish on the lipid metabolism and lipid peroxidation is not clear yet, a beneficial effect of the drug was evident in alimentary hyperlipidaemia.

Dietary habits and risk of urothelial cancer death in a large-scale cohort study (JACC Study) in Japan

In the present study, the associations of dietary habits with the risk of urothelial cancer death were evaluated taking into consideration sex, age, and smoking habits. The Japan Collaborative Cohort Study was established in 1988-1990 and consisted of 47,997 men and 66,520 women observed until the end of 1999. A self-administered food-frequency questionnaire was used as a baseline survey. Hazard ratios for dietary factors were calculated by Cox's proportional hazards model. During the observation period, 63 men and 25 women died of urothelial cancer. Increasing age, male gender, and history of smoking were all significantly associated with increased risk of urothelial cancer death. A high intake of milk and fruits other than oranges reduced the risk significantly and dose dependently, in particular among subjects with smoking history. However, consumption of butter and yogurt had no associations with the risk. Intakes of cabbage, lettuce, green leafy vegetables, carrots, squash, tomatoes, and oranges were not significantly associated with the risk. It was suggested that urothelial cancer death could be potentially preventable by smoking cessation and regular intake of milk and fruit.

Dietary Habits and Risk of Urothelial Cancer Incidence in the JACC Study

BACKGROUND: The relationships between dietary habits and urothelial cancer have been discussed in many epidemiologic studies, however, they have not been sufficiently elucidated. In the present study, the associations of dietary habits with the risk of urothelial cancer incidence were evaluated taking into consideration sex, age, and smoking habits.

METHODS: The Japan Collaborative Cohort Study (JACC Study) was planned in the late 1980s as a large-scale cohort study surveying people comprehensively and detailing their lifestyles, and the study subjects were followed up until the end of 1997. Among the total of 110,792 participants, 26,464 men and 38,720 women were in areas where incident cases with cancer were identified. During the observation period, 95 men and 28 women suffered from urothelial cancer. Hazard ratios for dietary factors were calculated by Cox’s proportional hazards model.

RESULTS: Increasing age, male gender, and smoking history were all significantly associated with the risk of urothelial cancer. High consumption of pork was significantly associated with the risk. In contrast, high intakes of milk and fresh fish were significantly inversely associated with the risk. High intakes of Chinese cabbage and fruits were also significantly inversely associated with the risk of urothelial cancer.

CONCLUSIONS: It is suggested that high intakes of milk, fresh fish, Chinese cabbage, and fruits have preventive effects against urothelial cancer.

Development of a food composition database for the estimation of dietary intakes of glucosinolates, the biologically active constituents of cruciferous vegetables

Evidence indicates that cruciferous vegetables are protective against a range of cancers with glucosinolates and their breakdown products considered the biologically active constituents. To date, epidemiological studies have not investigated the intakes of these constituents due to a lack of food composition databases. The aim of the present study was to develop a database for the glucosinolate content of cruciferous vegetables that can be used to quantify dietary exposure for use in epidemiological studies of diet-disease relationships. Published food composition data sources for the glucosinolate content of cruciferous vegetables were identified and assessed for data quality using established criteria. Adequate data for the total glucosinolate content were available from eighteen published studies providing 140 estimates for forty-two items. The highest glucosinolate values were for cress (389 mg/100 g) while the lowest values were for Pe-tsai chinese cabbage (20 mg/100 g). There is considerable variation in the values reported for the same vegetable by different studies, with a median difference between the minimum and maximum values of 5.8-fold. Limited analysis of cooked cruciferous vegetables has been conducted; however, the available data show that average losses during cooking are approximately 36 %. This is the first attempt to collate the available literature on the glucosinolate content of cruciferous vegetables. These data will allow quantification of intakes of the glucosinolates, which can be used in epidemiological studies to investigate the role of cruciferous vegetables in cancer aetiology and prevention.

Inhibition of clastogenicity of benzo[a]pyrene and of its trans-7,8-dihydrodiol in mice in vivo by fruits, vegetables, and flavonoids

In the in vivo mouse bone marrow micronucleus assay, homogenates of spinach, artichoke, peaches, and blue grapes as well as commercial concentrates of these vegetables and fruits reduced induction of micronuclei by benzo[a]pyrene (BaP) by 43-50%. Concentrates of strawberries (31% reduction) and of cauliflower (20% reduction) were less potent. Inhibition of genotoxicity by spinach and peaches was not caused by any delay in maturation of micronucleated erythrocytes as shown by experiments with sampling times of 24, 48, and 72 h after dosing of BaP. Pre-treatment of the mice with spinach 48, 24, and 12h before application of BaP resulted in a 44% reduction of micronuclei while peaches generated only a marginal effect. A post-treatment procedure administering spinach or peaches 6h after dosing of BaP did not indicate any protective effects. When trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (BaP-7,8-OH) was applied for induction of micronuclei spinach and peaches reduced the number of micronuclei by 55 and 48%, respectively. Pre-treatment of mice with spinach 96, 72, and 60 h before sacrifice caused a decline of hepatic 7-ethoxyresorufin-O-dealkylase (EROD) and of 7-pentoxyresorufin-O-dealkylase (PROD) activities by factors of 2.2 and 1.4, respectively. However, statistical significance was not reached. On the other hand, peaches had no influence on hepatic EROD or PROD activities. The flavonoids quercetin and its glucoside isoquercitrin, administered orally in doses of 0.03 mmol/kg body weight simultaneously with intraperitoneally given BaP, reduced the number of micronuclei in polychromatic erythrocytes of the bone marrow of mice by 73 and 33%. Ten-fold higher concentrations, however, reversed the effects with a particular strong increase observed with isoquercitrin (+109%; quercetin: +16%).

Effect of chemopreventive compounds from Brassica vegetables on NAD(P)H:quinone reductase and induction of DNA strand breaks in murine hepa1c1c7 cells

We have compared the effects of aqueous extracts of cooked Brussels sprouts, isolated glucosinolates and their breakdown products on the activity of quinone reductase [NADPH:quinone-reductase] (QR) and on DNA strand breaks induced by hydrogen peroxide in murine hepa1c1c7 cells. QR activity was not significantly altered after incubation of the cells with Brussels sprouts extracts. However, some of the glucosinolates and in particular their myrosinase-catalysed hydrolysis products and the degradation product of indole-glucosinolates, indole-3-carbinole (I3C), di(indol-3-yl)-methane (DIM) and 2,3-bis(indol-3-ylmethyl)indole (TRI) effectively induced QR activity. Isolated isothiocyanates did not influence the QR activity. The extracts of cooked and autolysed Brussels sprouts and some glucosinolates inhibited the DNA strand breaks induced by 100 microM hydrogen peroxide. Maximum inhibition was by 20-38% after 24 h of preincubation. Hydrolysis of the glucosinolates by myrosinase decreased the inhibitory effects, whereas I3C, DIM or TRI had no effect on DNA damage. Accordingly, the protective effect of Brussels sprouts constituents against induction of oxidative DNA damage appears to be unrelated to enzyme inducing properties via the antioxidant responsive element. Both of these effects could be part of the suggested cancer preventive effect of cruciferous vegetables.

Metabolism of sinigrin (2-propenyl glucosinolate) by the human colonic microflora in a dynamic in vitro large-intestinal model

Cruciferous vegetables, such as Brassica, which contain substantial quantities of glucosinolates, have been suggested to possess anticarcinogenic activity. Cutting and chewing of cruciferous vegetables releases the thioglucosidase enzyme myrosinase, which degrades glucosinolates to isothiocyanates and other minor metabolites. Cooking of cruciferous vegetables inactivates the myrosinase enzyme, allowing intact glucosinolates to reach the large intestine, where they can be degraded by the indigenous microflora into isothiocyanates. This local release of isothiocyanates may explain the protective effect of cruciferous vegetables on the colon epithelium. However, little is known about the amounts and identities of glucosinolate metabolites produced by the human microflora. The production of allyl isothiocyanate from sinigrin was investigated in a dynamic in vitro large-intestinal model, after inoculation with a complex microflora of human origin. Sinigrin and allyl isothiocyanate concentrations were analysed in the lumen and dialysis fluid of the model. Peak levels of allyl isothiocyanate were observed between 9 and 12 h after the addition of sinigrin. The model was first set up with a pooled and cultured human microflora, in which 1 and 4% of, respectively, 1 and 15 mM sinigrin, was converted into AITC. However, the conversion rate was remarkably higher if different individual human microflora were used. Between 10% and 30% (mean 19%) of the sinigrin was converted into allyl isothiocyanate. The results of this study suggest that allyl isothiocyanate is converted further into other, yet unknown, metabolites.

Effects of Brussels sprouts extracts on hydrogen peroxide-induced DNA strand breaks in human lymphocytes

Aqueous Brussels sprouts extracts inhibit oxidation of isolated DNA in vitro, possibly through scavenging oxygen radicals. We have studied the effect of preincubating human lymphocytes with aqueous extracts of raw, cooked and autolysed Brussels sprouts and the glucosinolate, sinigrin, on hydrogen peroxide-induced DNA damage, strand breaks and base oxidation, in vitro by means of the Comet assay. DNA repair enzymes endonuclease III (EndoIII) and formamidopyrimidine-DNA glycosylase (FPG) were used to examine the levels of oxidised pyrimidines and purines in DNA, respectively. Aqueous extracts of cooked and autolysed Brussels sprouts and sinigrin decreased DNA strand breaks in human lymphocytes exposed to 100 microM H2O2 for 5 min on ice, although the level of EndoIII and FPG sensitive sites was not reduced. The maximum inhibition was by 38 and 39% at concentrations of cooked and autolysed extracts of 10 microg/ml and 5 microg/ml, respectively, whereas the inhibitory effect decreased with increasing concentrations up to 100 microg/ml. The maximum inhibition by sinigrin was by 54% at 2 microg/ml. Extracts of raw Brussels sprouts or green beans had no DNA-protective effect. The results indicate that compounds, including sinigrin, in cooked and autolysed Brussels sprouts can enhance lymphocyte resistance towards H2O2-induced DNA strand breaks in vitro.

Rapeseed glucosinolates and iodine in sows affect the milk iodine concentration and the iodine status of piglets

I in the chain sow diet --> blood serum of sow --> sow milk --> piglet serum was investigated in two experiments with a total of eighty-one sows and their piglets. In experiments conducted during the last trimester of gravidity and the 28 d of lactation, diets with glucosinolates (1.9 mmol/kg diet via 100 g ground rapeseed/kg diet (Expt 1) and 2.1 and 4.2 mmol/kg diet via 75 and 150 g rapeseed press cake/kg diet (Expt 2)) were compared with control groups without rapeseed products. From 0 to 600 microg I/kg was added to sow diets during lactation. Diets without supplementary I decreased the I concentration particularly in milk and piglet serum. The presence of rapeseed and rapeseed press cake were indicated by a thiocyanate concentration increase, mainly in sow serum. The diets with glucosinolates decreased the milk and piglet serum I concentration. Spot urine and faeces samples from sows eating the rapeseed-press cake diets had increased I concentration. The sows' serum I and thyroxine did not respond to glucosinolates (Expt 1) or these diets caused an increase in concentration (Expt 2). Both these criteria seem unsuitable for the diagnosis of I status of adult animals. Glucosinolates and their degradation compounds may affect the thyroid and the mammary glands resulting in lower I milk transfer and higher renal and intestinal I excretion.

Formation of allyl isothiocyanate from sinigrin in the digestive tract of rats monoassociated with a human colonic strain of Bacteroides thetaiotaomicron

A human digestive strain of Bacteroides thetaiotaomicron was tested for its ability to metabolise sinigrin, a glucosinolate commonly found in Brassica vegetables. Gnotobiotic rats harbouring the bacterial strain were orally dosed with 50 micromol sinigrin. HPLC analysis of the digestive contents showed that sinigrin was degraded in the large bowel, where B. thetaiotaomicron was established at a high level. Concurrently, a hydrolysis product of sinigrin, allyl isothiocyanate, was identified by GC-MS analysis, following headspace solid-phase microextraction of the digestive contents; its production peaked at ca. 200 nmol, 12 h after dosing. This is the first study to demonstrate in vivo the involvement of a human colonic predominant bacterium in the bioconversion of a dietary glucosinolate to a potentially anticarcinogenic isothiocyanate.

Functional detection of chemopreventive glucosinolates in Arabidopsis thaliana

Natural isothiocyanates, derived from glucosinolates by myrosinase-catalyzed hydrolysis, are potent chemopreventive agents that favorably modify carcinogen metabolism in mammals by inhibiting metabolic activation of carcinogens and/or by inducing carcinogen-detoxifying enzymes. Methylsulfinylalkyl isothiocyanates are potent selective inducers of mammalian Phase 2 detoxification enzymes such as quinone reductase [NADP(H):quinone-acceptor oxidoreductase, EC 1.6.99.2]. Members of the Cruciferae family, including the model plant species Arabidopsis thaliana (L.) Heyhn, synthesize methylsulfinylalkyl glucosinolates. We have adapted a colorimetric bioassay for quinone reductase activity in Hepa 1c1c7 murine hepatoma cells as a versatile tool to rapidly monitor methylsulfinylalkyl glucosinolate content in A. thaliana leaf extracts. Using wild type plants and mutant plants defective in the synthesis of 4-methylsulfinylbutyl glucosinolate (glucoraphanin), we have demonstrated that A. thaliana (ecotype Columbia) is a rich source of Phase 2 enzyme inducers and that methylsulfinylalkyl glucosinolates, predominantly glucoraphanin, account for about 80% of the quinone reductase inducer potency of Columbia leaf extracts. We have optimized leaf extraction conditions and the quinone reductase bioassay to allow for screening of large numbers of plant extracts in a molecular genetic approach to dissecting glucosinolate biosynthesis in A. thaliana.

The methionine chain elongation pathway in the biosynthesis of glucosinolates in Eruca sativa (Brassicaceae)

Glucosinolates are nitrogen- and sulfur-containing plant natural products that have become increasingly important in human affairs as flavor precursors, cancer-prevention agents, and crop protectants. While many glucosinolates are biosynthesized from common amino acids, the major glucosinolates in economically important species of the Brassicaceae, such as Brassica napus (oilseed rape), are thought to be formed from chain-elongated derivatives of methionine or phenylalanine. We investigated the chain elongation pathway for methionine that is involved in glucosinolate biosynthesis in Eruca sativa. Isotopically labeled methionine and acetate were administered to cut leaves and the major product, 4-methylthiobutylglucosinolate (isolated as its desulfated derivative), was analyzed by MS and NMR. Administration of ¿U-(13)Cmethionine showed that the entire carbon skeleton of this amino acid, with the exception of the COOH carbon, is incorporated as a unit into 4MTB. Administration of ¿(13)C- and ¿(14)Căcetate gave a labeling pattern consistent with the operation of a three-step chain elongation cycle which begins with the condensation of acetyl-CoA with a 2-oxo acid derived from methionine and ends with an oxidative decarboxylation forming a new 2-oxo acid with one additional methylene group. Administration of ¿(15)Nmethionine provided evidence for the transfer of an amino group to the chain-elongated 2-oxo acid, forming an extended amino acid which serves as a substrate for the remaining steps of glucosinolate biosynthesis. The retention of a high level of (15)N in the products suggests that the amino transfer reactions and the chain elongation cycle are localized in the same subcellular compartment.

Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-day Adventists

Results associating diet with chronic disease in a cohort of 34192 California Seventh-day Adventists are summarized. Most Seventh-day Adventists do not smoke cigarettes or drink alcohol, and there is a wide range of dietary exposures within the population. About 50% of those studied ate meat products <1 time/wk or not at all, and vegetarians consumed more tomatoes, legumes, nuts, and fruit, but less coffee, doughnuts, and eggs than did nonvegetarians. Multivariate analyses showed significant associations between beef consumption and fatal ischemic heart disease (IHD) in men [relative risk (RR) = 2.31 for subjects who ate beef > or =3 times/wk compared with vegetarians], significant protective associations between nut consumption and fatal and nonfatal IHD in both sexes (RR approximately 0.5 for subjects who ate nuts > or =5 times/wk compared with those who ate nuts <1 time/wk), and reduced risk of IHD in subjects preferring whole-grain to white bread. The lifetime risk of IHD was reduced by approximately 31% in those who consumed nuts frequently and by 37% in male vegetarians compared with nonvegetarians. Cancers of the colon and prostate were significantly more likely in nonvegetarians (RR of 1.88 and 1.54, respectively), and frequent beef consumers also had higher risk of bladder cancer. Intake of legumes was negatively associated with risk of colon cancer in nonvegetarians and risk of pancreatic cancer. Higher consumption of all fruit or dried fruit was associated with lower risks of lung, prostate, and pancreatic cancers. Cross-sectional data suggest vegetarian Seventh-day Adventists have lower risks of diabetes mellitus, hypertension, and arthritis than nonvegetarians. Thus, among Seventh-day Adventists, vegetarians are healthier than nonvegetarians but this cannot be ascribed only to the absence of meat.

Fruit and vegetable intake and incidence of bladder cancer in a male prospective cohort

BACKGROUND

Previous epidemiologic studies of fruit and vegetable intake and bladder cancer risk have yielded inconsistent results, especially with regard to the types of fruits and vegetables consumed. We examined total fruit and vegetable intake, as well as intakes of subtypes of fruits and vegetables, in relation to bladder cancer risk in a large male prospective cohort study.

METHODS

Two hundred fifty-two cases of incident bladder cancer were diagnosed from 1986 through January 31, 1996, among 47,909 men enrolled in the Health Professionals Follow-up Study. Each participant in this cohort completed a 131-item food-frequency questionnaire in 1986 and subsequently in 1990 and 1994. We used logistic regression analyses to examine fruit and vegetable intake in relation to bladder cancer risk, after adjusting for age, history of cigarette smoking, current smoking status, geographic region, total fluid intake, and caloric intake.

RESULTS

We observed a weak, inverse association that was not statistically significant between total fruit and vegetable intake and bladder cancer risk. Intake of cruciferous vegetables was inversely associated with risk (relative risk = 0.49; 95% confidence interval = 0.32-0.75, for the highest category of cruciferous vegetable intake compared with the lowest), but intakes of yellow or green leafy vegetables or carotenoid-rich vegetables were not associated with risk. Individual cruciferous vegetables, except for coleslaw, were all inversely related to bladder cancer risk, but only the associations for broccoli and cabbage were statistically significant.

CONCLUSIONS

Data from this study indicate that high cruciferous vegetable consumption may reduce bladder cancer risk, but other vegetables and fruits may not confer appreciable benefits against this cancer.

Effects of vegetables-fruit extracts and indole-3-carbinol on stearic acid-modulated intercellular communication and cytochrome P450-IA activity

Modulatory effects were investigated of extracts of a vegetables-fruit mixture and indole-3-carbinol (I3C) on stearic acid-modulated gap junctional intercellular communication (GJIC) and cytochrome P450-IA activity (EROD). In V79 cells, pure water and hexane extracts of a vegetables-fruit mixture and 25 μg/ml I3C significantly protected against decreased GJIC caused by 10 μM stearic acid. Furthermore, pure, 10× and 100× diluted vegetables-fruit extracts significantly maintained their capacity to induce EROD activity in Caco-2 cells, but only when these extracts were added to the cells in media already containing 500 μM stearic acid for 48 h. Stearic acid itself did not induce EROD activity. I3C (10, 25, and 50 μg/ml) clearly induced EROD activity in Caco-2 cells, irrespective of the order at which I3C and stearic acid were added to the cells. In conclusion, the present in vitro study showed that vegetables-fruit extracts and I3C modulate effects of stearic acid on intercellular communication and cytochrome P450-IA activity.

Protective effects of cruciferous seed meals and hulls against colon cancer in mice

Protective effects of diets containing cruciferous seed meals or hulls against chemically-induced colon tumors were examined in male CF1 mice. When commercial crambe meal, autolyzed crambe meal, crambe hulls, high glucosinolate rapeseed meal, or canola meal were fed as 12% of the diets of mice injected with 1,2-dimethylhydrazine, 25-80% of the animals developed colon tumors. Animals fed a soybean meal control diet had a 100% tumor rate. Data suggest that cruciferous seed meals may contain a number of compounds that can exert protective effects against tumor formation and growth.