Safety and tolerability of a natural supplement containing glucosinolates, phytosterols and citrus flavonoids in adult women: a randomized phase I, placebo-controlled, multi-arm, double-blinded clinical trial

OBJECTIVE

To evaluate the safety and tolerability of an oral herbal supplement containing glucosinolates, phytosterols, and citrus flavonoids (Warmi®, Lima Perú;) in otherwise healthy adult women.

METHODS

This was a phase-I, randomized parallel three arms, double-blinded, and a placebo-controlled clinical trial. A total of 55 participants aged 18-40 were randomly assigned to one of three groups to receive for three months: (1) an oral herbal supplement of 1650 mg/day; (2) an oral herbal supplement of 3300 mg/day; or (3) an oral placebo 3300 mg/day. The primary endpoints were oral safety and tolerability of the supplement. The secondary endpoint was its effect on vital functions, anthropometrics, and laboratory tests. We used an exploratory approach by covariance analysis (ANCOVA) adjusted for the variables' baseline value for the secondary outcomes.

RESULTS

All women completed three months of follow-up, reporting no side effects. Our exploratory analysis revealed that treatment with the herbal supplement of 1650 mg/day was associated with increased glucose and uric acid levels. In comparison, the herbal supplement 3300 mg/day was associated with reduced breathing rate, increased basal temperature, and systolic blood pressure, both compared to the placebo group. However, despite significant differences, none of these was clinically significant.

CONCLUSION

The oral herbal supplement had a favorable safety and tolerability profile in studied women. There is a need to study its potential as an option to treat menopausal symptoms.

Effects of different levels of rapeseed cake containing high glucosinolates in steer ration on rumen fermentation, nutrient digestibility and the rumen microbial community

This trial was conducted to study the effects of dietary rapeseed cake (RSC) containing high glucosinolates (GLS) on rumen fermentation, nutrient digestion and the rumen microbial community in steers. Eight growing steers and four rations containing RSC (GLS 226·1 μmol/g DM) at 0·00, 2·65, 5·35 and 8·00 % DM were assigned in a replicate 4 × 4 Latin square design. The results indicated that increasing RSC levels increased the ruminal concentration of thiocyanate (SCN) (P < 0·01), decreased the ruminal concentration of ammonia nitrogen (NH3-N) and the molar proportion of isovalerate (P < 0·05), did not affect the ruminal concentration of total volatile fatty acids (P > 0·05), decreased the crude protein (CP) digestibility (P < 0·05) and increased the ether extract (EE) digestibility (P < 0·01). Increasing RSC levels tended to decrease the abundances of ruminal Ruminobacter amylophilus (P = 0·055) and Ruminococcus albus (P = 0·086) but did not affect methanogens, protozoa, fungi and other bacteria (P > 0·05). Increasing RSC levels in the ration did not affect the ruminal bacterial diversity (P > 0·05), but it increased the operational taxonomic units and the bacterial richness (P < 0·05) and affected the relative abundances of some bacteria at the phylum level and genus level (P < 0·05). In conclusion, RSC decreased the ruminal concentration of NH3-N and the CP digestibility, increased the EE digestibility and partly affected the ruminal bacterial community. SCN, as the metabolite of GLS, could be a major factor affecting these indices.

Bioavailability of Sulforaphane Following Ingestion of Glucoraphanin-Rich Broccoli Sprout and Seed Extracts with Active Myrosinase: A Pilot Study of the Effects of Proton Pump Inhibitor Administration

We examined whether gastric acidity would affect the activity of myrosinase, co-delivered with glucoraphanin (GR), to convert GR to sulforaphane (SF). A broccoli seed and sprout extract (BSE) rich in GR and active myrosinase was delivered before and after participants began taking the anti-acid omeprazole, a potent proton pump inhibitor. Gastric acidity appears to attenuate GR bioavailability, as evidenced by more SF and its metabolites being excreted after participants started taking omeprazole. Enteric coating enhanced conversion of GR to SF, perhaps by sparing myrosinase from the acidity of the stomach. There were negligible effects of age, sex, ethnicity, BMI, vegetable consumption, and bowel movement frequency and quality. Greater body mass correlated with reduced conversion efficiency. Changes in the expression of 20 genes in peripheral blood mononuclear cells were evaluated as possible pharmacodynamic indicators. When grouped by their primary functions based on a priori knowledge, expression of genes associated with inflammation decreased non-significantly, and those genes associated with cytoprotection, detoxification and antioxidant functions increased significantly with bioavailability. Using principal components analysis, component loadings of the changes in gene expression confirmed these groupings in a sensitivity analysis.

Interleukin-22 protects intestinal stem cells against genotoxic stress

Environmental genotoxic factors pose a challenge to the genomic integrity of epithelial cells at barrier surfaces that separate host organisms from the environment. They can induce mutations that, if they occur in epithelial stem cells, contribute to malignant transformation and cancer development1-3. Genome integrity in epithelial stem cells is maintained by an evolutionarily conserved cellular response pathway, the DNA damage response (DDR). The DDR culminates in either transient cell-cycle arrest and DNA repair or elimination of damaged cells by apoptosis4,5. Here we show that the cytokine interleukin-22 (IL-22), produced by group 3 innate lymphoid cells (ILC3) and γδ T cells, is an important regulator of the DDR machinery in intestinal epithelial stem cells. Using a new mouse model that enables sporadic inactivation of the IL-22 receptor in colon epithelial stem cells, we demonstrate that IL-22 is required for effective initiation of the DDR following DNA damage. Stem cells deprived of IL-22 signals and exposed to carcinogens escaped DDR-controlled apoptosis, contained more mutations and were more likely to give rise to colon cancer. We identified metabolites of glucosinolates, a group of phytochemicals contained in cruciferous vegetables, to be a widespread source of genotoxic stress in intestinal epithelial cells. These metabolites are ligands of the aryl hydrocarbon receptor (AhR)6, and AhR-mediated signalling in ILC3 and γδ T cells controlled their production of IL-22. Mice fed with diets depleted of glucosinolates produced only very low levels of IL-22 and, consequently, the DDR in epithelial cells of mice on a glucosinolate-free diet was impaired. This work identifies a homeostatic network protecting stem cells against challenge to their genome integrity by AhR-mediated 'sensing' of genotoxic compounds from the diet. AhR signalling, in turn, ensures on-demand production of IL-22 by innate lymphocytes directly regulating components of the DDR in epithelial stem cells.

Dietary glucoraphanin prevents the onset of psychosis in the adult offspring after maternal immune activation

Maternal immune activation (MIA) contributes to behavioral abnormalities relevant to schizophrenia in adult offspring, although the molecular mechanisms underlying MIA-induced behavioral changes remain unclear. Here we demonstrated that dietary intake of glucoraphanin (GF), the precursor of a natural antioxidant sulforaphane, during juvenile and adolescent stages prevented cognitive deficits and loss of parvalbumin (PV) immunoreactivity in the medial prefrontal cortex (mPFC) of adult offspring after MIA. Gene set enrichment analysis by RNA sequencing showed that MIA caused abnormal expression of centrosome-related genes in the PFC and hippocampus of adult offspring, and that dietary intake of GF improved these abnormal gene expressions. Particularly, MIA increased the expression of suppressor of fermentation-induced loss of stress resistance protein 1 (Sfi1) mRNA in the PFC and hippocampus of adult offspring, and dietary intake of GF prevented the expression of Sfi1 mRNA in these regions. Interestingly, we found altered expression of SFI1 in the postmortem brains and SFI1 mRNA in hair follicle cells from patients with schizophrenia compared with controls. Overall, these data suggest that centrosome-related genes may play a role in the onset of psychosis in offspring after MIA. Therefore, dietary intake of GF-rich vegetables in high-risk psychosis subjects may prevent the transition to psychosis in young adulthood.

Harnessing the Power of Cruciferous Vegetables: Developing a Biomarker for Brassica Vegetable Consumption Using Urinary 3,3'-Diindolylmethane

Glucobrassicin in Brassica vegetables gives rise to indole-3-carbinol (I3C), a compound with potent anticancer effects in preclinical models. We previously showed that the urinary metabolite 3,3'-diindolylmethane (DIM) could discriminate between volunteers fed high and low doses of Brassica vegetables. However, the quantitative relationship between glucobrassicin exposure and urinary DIM level is unclear. We conducted a clinical trial to examine the hypotheses that a range of glucobrassicin exposure from Brassica vegetables is reflected in urinary DIM and that this effect plateaus. Forty-five subjects consumed vegetables, a mixture of brussels sprouts and/or cabbage, at one of seven discrete dose levels of glucobrassicin ranging from 25 to 500 μmol, once daily for 2 consecutive days. All urine was collected for 24 hours after each vegetable-eating session. Urinary DIM was measured using our published liquid chromatography-electrospray ionization-tandem mass spectrometry-selected reaction monitoring (LC/ESI-MS/MS-SRM) method. Urinary DIM excretion increased predictably with increasing glucobrassicin dose and plateaued between 200 and 300 μmol of glucobrassicin. The association between glucobrassicin dose and urinary DIM was strong and positive (R² = 0.68). The majority of DIM was excreted in the first 12 hours after vegetable consumption. We conclude that urinary DIM is a reliable biomarker of glucobrassicin exposure and I3C uptake and that feeding glucobrassicin beyond 200 μmol did not consistently lead to more urinary DIM, suggesting a plateau in potential chemopreventive benefit. Cancer Prev Res; 9(10); 788-93. ©2016 AACR.

Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase

Glucoraphanin from broccoli and its sprouts and seeds is a water soluble and relatively inert precursor of sulforaphane, the reactive isothiocyanate that potently inhibits neoplastic cellular processes and prevents a number of disease states. Sulforaphane is difficult to deliver in an enriched and stable form for purposes of direct human consumption. We have focused upon evaluating the bioavailability of sulforaphane, either by direct administration of glucoraphanin (a glucosinolate, or β-thioglucoside-N-hydroxysulfate), or by co-administering glucoraphanin and the enzyme myrosinase to catalyze its conversion to sulforaphane at economic, reproducible and sustainable yields. We show that following administration of glucoraphanin in a commercially prepared dietary supplement to a small number of human volunteers, the volunteers had equivalent output of sulforaphane metabolites in their urine to that which they produced when given an equimolar dose of glucoraphanin in a simple boiled and lyophilized extract of broccoli sprouts. Furthermore, when either broccoli sprouts or seeds are administered directly to subjects without prior extraction and consequent inactivation of endogenous myrosinase, regardless of the delivery matrix or dose, the sulforaphane in those preparations is 3- to 4-fold more bioavailable than sulforaphane from glucoraphanin delivered without active plant myrosinase. These data expand upon earlier reports of inter- and intra-individual variability, when glucoraphanin was delivered in either teas, juices, or gelatin capsules, and they confirm that a variety of delivery matrices may be equally suitable for glucoraphanin supplementation (e.g. fruit juices, water, or various types of capsules and tablets).

Isatis canescens is a rich source of glucobrassicin and other health-promoting compounds

BACKGROUND

Glucobrassicin (GBS), a glucosinolate contained in many brassica vegetables, is the precursor of chemopreventive compounds such as indole-3-carbinol. Large amounts of GBS would be needed to perform studies aimed at elucidating its role in the diet. This study was mainly undertaken to evaluate the flower buds of Isatis canescens as a source for GBS purification. In order to investigate the health-promoting potential of this species, glucosinolate, phenol and flavonoid content as well as the whole antioxidant capacity were also determined. Flower bud samples were collected in four localities around Mount Etna in Sicily, Italy, where I. canescens is widespread, as they are locally traditionally eaten.

RESULTS

I. canescens flower buds displayed high GBS concentrations, up to 60 µmol g(-1) dry weight. The purification method consisted of two chromatographic steps, which made it possible to obtain GBS with a purity of 92-95%, with a yield of 21 g kg(-1) . The total glucosinolates, phenols, flavonoids and antioxidant activity were considerable, with the southern locality showing the highest concentrations for all the phytochemicals.

CONCLUSION

I. canescens flower buds represent a naturally rich source of GBS, at a level suitable for its purification. Furthermore, flower bud consumption could provide an intake of health-promoting compounds, with possible antioxidant and chemopreventive properties.

Feeding of selenium alone or in combination with glucoraphanin differentially affects intestinal and hepatic antioxidant and phase II enzymes in growing rats

The anti-carcinogenic effects of sulforaphane (SFN) are based on the up-regulation of antioxidant enzymes (AE) and phase II enzymes (PIIE) through the transcription factor Nrf2. Current knowledge on the roles of the SFN precursor glucoraphanin (GRA) on these processes is limited. Anti-carcinogenic effects of Se depending on glutathione peroxidase (GPx) activity have also been reported. We studied effects and possible synergisms of Se and GRA on the expression and activity of a broad spectrum of AE and PIIE in jejunum, colon and the liver of rats fed diets differing in Se and GRA concentration. In all organs, GPx1 mRNA expression was 70 % to 90 % lower in Se deficiency than in Se sufficiency. GPx2 expression increased in jejunum and liver under Se deficiency and decreased in the colon. Se deficiency increased most colonic AE and PIIE compared to Se adequacy. Adequate and in particular supranutritive Se combined with GRA increased colonic AE and PIIE expression up to 3.72-fold. In the liver Se deficiency raised the expression of AE and PIIE up to 4.49-fold. GRA attenuated liver AE and PIIE response in Se deficiency. Expression- and correlation analyses revealed that Keap1 mRNA better reflects AE and PIIE gene expression than Nrf2 mRNA. We conclude that: (1) GPx1 sensitively indicates Se deficiency; (2) the influence of Se and Nrf2/Keap1 on GPx2 expression depends on the organ; (3) GRA combined with supranutritive Se may effectively protect against inflammation and colon cancer; (4) future investigations on AE and PIIE expression should consider the role of Keap1 to a higher extent.

The impact of loss of myrosinase on the bioactivity of broccoli products in F344 rats

In vitro, animal, and epidemiological studies all show that broccoli products containing sulforaphane, the bioactive hydrolysis product of glucoraphanin (GRP), lower risk for cancer. As a result, GRP-rich extracts are appearing on the market as dietary supplements. However, these products typically have no hydrolyzing enzyme for sulforaphane (SF) formation. We evaluated safety and compared efficacy to other broccoli preparations. Four daily doses of 0.5 mmol GRP/kg BW, given by gavage to adult male F344 rats, caused temporary cecal inflammation that was essentially resolved four days later. A similar dose dispersed in the diet caused no inflammation. To compare efficacy, we fed rats 20% freeze-dried broccoli (heated or unheated), 3.5% broccoli seed meal, or 4.3% semipurified GRP, each balanced within an AIN93G semipurified diet, for 4 days. Diets lacking myrosinase (semipurified GRP and heated broccoli florets) caused upregulation of NAD(P)H-quinone oxidoreductase 1 (NQO1) in colon but not liver. Surprisingly, broccoli seed, rich in myrosinase and GRP, also caused NQO1 upregulation in colon but not liver. In contrast, unheated broccoli florets caused upregulation in both colon and liver. These data suggest that GRP supplements may not exert systemic effects. We hypothesize that within whole broccoli additional components enhanced sulforaphane-dependent upregulation of NQO1 in liver.

Brassicaceae tissues as inhibitors of nitrification in soil

Brassicaceae crops often produce an unexplained increase in plant-available soil N possibly related to bioactive compounds produced from glucosinolates present in the tissues. Our objective was to determine if glucosinolate-containing tissues inhibit nitrification, thereby potentially explaining this observation. Ammonium, NO(2)(-), and NO(3)(-) N were measured in soils amended with Brassicaceae ( Isatis tinctoria L., Brassica napus L., Brassica juncea L., and Sinapis alba L.) tissues containing different glucosinolate types and concentrations or Kentucky bluegrass ( Poa pratensis L.) residues with equivalent C/N ratios as the Brassicaceae samples. There was greater accumulation of NH(4)(+) N in soils amended with tissues containing high glucosinolate concentrations as compared to soils amended with tissues containing no or low glucosinolate concentrations. Nitrite N was detected only in soils amended with Brassicaceae tissues having the highest glucosinolate concentrations. The positive correlation of both NH(4)(+) and NO(2)(-) N accumulation with the glucosinolate concentration indicates the participation of glucosinolate hydrolysis products in nitrification inhibition.

Effect of meal composition and cooking duration on the fate of sulforaphane following consumption of broccoli by healthy human subjects

The isothiocyanate, sulforaphane, has been implicated in the cancer-protective effects of brassica vegetables. When broccoli is consumed, sulforaphane is released from hydrolysis of glucoraphanin by plant myrosinase and/or colonic microbiota. The influence of meal composition and broccoli-cooking duration on isothiocyanate uptake was investigated in a designed experiment. Volunteers (n 12) were each offered a meal, with or without beef, together with 150 g lightly cooked broccoli (microwaved 2.0 min) or fully cooked broccoli (microwaved 5.5 min), or a broccoli seed extract. They received 3 g mustard containing pre-formed allyl isothiocyanate (AITC) with each meal. Urinary output of allyl (AMA) and sulforaphane (SFMA) mercapturic acids, the biomarkers of production of AITC and sulforaphane respectively, were measured for 24 h after meal consumption. The estimated yield of sulforaphane in vivo was about 3-fold higher after consumption of lightly cooked broccoli than fully cooked broccoli. Absorption of AITC from mustard was about 1.3-fold higher following consumption of the meat-containing meal compared with the non meat-containing alternative. The meal matrix did not significantly influence the hydrolysis of glucoraphanin and its excretion as SFMA from broccoli. Isothiocyanates may interact with the meal matrix to a greater extent if they are ingested pre-formed rather than after their production from hydrolysis of glucosinolates in vivo. The main influence on the production of isothiocyanates in vivo is the way in which brassica vegetables are cooked, rather than the effect of the meal matrix.

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.

[Non-nutritive biologically active plant components: glucosinolates, their sources and their nutritional significance]

Numerous epidemiological studies as well as experimental animal studies suggest that a high intake of cruciferous vegetables is associated with a reduced risk of various forms of cancer. This protective effect has been linked to the high glucosinolate content of these vegetables. Glucosinolate breakdown products, particularly isothiocyanates and nitriles have been shown to modulate carcinogen metabolising enzyme systems, induce cell cycle arrest or apoptosis. The anticancer potential of the different glucosinolate metabolites is diverse and their effect on the above mentioned cellular mechanisms is also affected by the model system employed. Results of in vivo studies with isolated glucosinolates or isothiocyanates compared to those with cruciferous vegetables demonstrate that the chemopreventive effect of cruciferous vegetables is due to combined effect of the different glucosinolate metabolites and the optimal combination of these compounds found in Cruciferae provide the beneficial health effects.

Cruciferous vegetables and colo-rectal cancer

Cruciferous vegetables have been studied extensively for their chemoprotective effects. Although they contain many bioactive compounds, the anti-carcinogenic actions of cruciferous vegetables are commonly attributed to their content of glucosinolates. Glucosinolates are relatively biologically inert but can be hydrolysed to a range of bioactive compounds such as isothiocyanates (ITC) and indoles by the plant-based enzyme myrosinase, or less efficiently by the colonic microflora. A number of mechanisms whereby ITC and indoles may protect against colo-rectal cancer have been identified. In experimental animals cruciferous vegetables have been shown to inhibit chemically-induced colon cancer. However, the results of recent epidemiological cohort studies have been inconsistent and this disparity may reflect a lack of sensitivity of such studies. Possible explanations for the failure of epidemiological studies to detect an effect include: assessment of cruciferous vegetable intake by methods that are subject to large measurement errors; the interaction between diet and genotype has not been considered: the effect that post-harvest treatments may have on biological effects of cruciferous vegetables has not been taken into account.

The time-dependent effect of gluconasturtiin and phenethyl isothiocyanate on metabolic and antioxidative parameters in rats

The effect of gluconasturtiin (GNST) and phenethyl isothiocyanate (PEITC) on some metabolic changes and antioxidative parameters in the rat was tested using different doses of PEITC and duration of GNST or PEITC ingestion. Their effect on antioxidative processes was previously observed, however, their influence on metabolic changes is still poorly characterized. In the performed experiment, the effect of GNST (0.5 mg/kg BW) and PEITC (0.1 mg/kg BW or 0.3 mg/kg BW) administered intragastrically after 4 h or 14 days to growing male rats was studied. PEITC at both doses after 4 h of its administration caused a considerable increase in liver cholesterol and triglyceride content with a concomitant drop in the amount of glycogen. Blood glucose, free fatty acids, phospholipids and total, free, esterified cholesterol as well as cholesterol in high-density lipoprotein were not altered. GNST, at its short-time ingestion, augmented significantly the concentration of triglycerides in blood serum. The compounds tested had no influence on metabolic changes after a longer period of action with the exception of glycogen values in liver, which were substantially augmented by PEITC at both doses. Our trial revealed a lack of GNST and PEITC influence on the content of liver sulphhydryl groups and on glutathione peroxidase and glutathione-S-transferase activities. The only distinct change in the content of malonodialdehyde was observed after short-time action of lower dose of PEITC. Our research showed that the short-term PEITC action constituted a significant factor interfering with liver metabolism. Although PEITC has been repeatedly advocated as very promising anticancer agent, in our experiment, the lower dose of PEITC was revealed as a pro-oxidative substance. These inconsistent properties seem to depend on its dose and time of action.

Glutathione S-transferase M1 polymorphism and metabolism of sulforaphane from standard and high-glucosinolate broccoli

BACKGROUND

Broccoli consumption is associated with a reduction in the risk of cancer, particularly in persons with a functional glutathione S-transferase M1 allele, as opposed rotrose whose GSTM1 gene has been deleted. Sulforaphane, the major isothiocyanate derived from 4-methylsulfinylbutyl glucosinolate, is thought to be the main agent conferring protection.

OBJECTIVE

We compared sulforaphane metabolism in GSTM1-null and GSTM1-positive subjects after they consumed standard broccoli and high-glucosinolate broccoli (super broccoli).

DESIGN

Sixteen subjects were recruited into a randomized, 3-phase crossover dietary trial of standard broccoli, super broccoli, and water. Liquid chromatography linked to tandem mass spectrometry was used to quantify sulforaphane and its thiol conjugates in plasma and urine.

RESULTS

GSTM1-null subjects had slightly higher, but statistically significant, areas under the curve for sulforaphane metabolite concentrations in plasma, a greater rate of urinary excretion of sulforaphane metabolites during the first 6 h after broccoli consumption, and a higher percentage of sulforaphane excretion 24 h after ingestion than did GSTM1-positive subjects. Consumption of high-glucosinolate broccoli led to a 3-fold greater increase in the areas under the curve and maximum concentrations of sulforaphane metabolites in plasma, a greater rate of urinary excretion of sulforaphane metabolites during the first 6 h after consumption, and a lower percentage of sulforaphane excretion after its ingestion than did the consumption of standard broccoli.

CONCLUSIONS

GSTM1 genotypes have a significant effect on the metabolism of sulforaphane derived from standard or high-glucosinolate broccoli. It is possible that the difference in metabolism may explain the greater protection that GSTM1-positive persons gain from consuming broccoli. The potential consequences of consuming glucosinolate-enriched broccoli for GSTM1-null and -positive persons are discussed.

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.

Food matrix effects on bioactivity of broccoli-derived sulforaphane in liver and colon of F344 rats

Sulforaphane (SF) is considered to be the major anticarcinogenic component in broccoli. The effects of feeding rats purified SF (5 mmol/kg of diet), broccoli containing SF formed in situ during laboratory hydrolysis (broccoli-HP; 20% freeze-dried broccoli diet, 0.16 mmol of SF/kg of diet), and broccoli containing intact glucosinolates (broccoli-GS; 20% freeze-dried broccoli diet, 2.2 mmol of glucoraphanin/kg of diet) were compared. Rats (male F344 rats, five per group) were fed control (modified AIN-76 B-40), SF, broccoli-HP, or broccoli-GS for 5 days. In rats fed broccoli-GS, quinone reductase activities (QR) in the colon and liver were greater (4.5- and 1.4-fold over control, respectively) than in rats fed broccoli-HP (3.2- and 1.1-fold over control, respectively). Broccoli-GS and SF diets increased QR to the same extent, even though the broccoli-GS diet contained far less SF (as the unhydrolyzed glucosinolate, glucoraphanin) than the purified SF diet. In a second experiment, rats were fed one of six diets for 5 days: (1) control; (2) 20% broccoli-GS; (3) diet 2 + low SF (0.16 mmol/kg of diet); (4) diet 2 + high SF (5 mmol/kg of diet); (5) low SF (0.32 mmol/kg of diet); or (6) high SF (5.16 mmol/kg of diet). In both liver and colon, QR was increased most by high SF plus broccoli-GS; individually, high SF and broccoli-GS had similar effects, and adding the low-dose SF to broccoli-GS had either no effect or a negative effect. In both experiments, urinary SF-mercapturic acid correlated with QR activity, not with dietary intake. It was concluded that all diets were substantially more effective in the colon than in the liver and that broccoli-GS was more potent than SF or broccoli-HP.

Non-nutritive bioactive constituents of plants: dietary sources and health benefits of glucosinolates

A high intake of cruciferous vegetables is associated with a reduced risk of cancer, particularly lung and those of the gastrointestinal tract. This protective effect has been linked to the presence of glucosinolates in these vegetables. Certain metabolites of the glucosinolates, particularly the isothiocyanates and nitriles have been shown to both modify xenobiotic metabolising enzymes and induce cell cycle arrest and apoptosis. Different metabolites are more or less effective in mediating each response depending on the model system employed. It is likely that a combination of these responses explains the chemo-preventive characteristics of Brassicas and that a combination of different cruciferous vegetables will provide optimal protection.

Effects of rapeseed-press cake glucosinolates and iodine on the performance, the thyroid gland and the liver vitamin A status of pigs

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 dilution effect.

Effects of rapeseed meal-glucosinolates on thyroid metabolism and feed utilization in rainbow trout

Two rapeseed meals (RM1 and RM2), containing glucosinolates at a concentration of 26 and 40 micromol/g, respectively, were incorporated at increasing levels (10, 20, and 30% for RM1 and 30 and 50% for RM2) in diets of juvenile rainbow trout. Disturbances in the thyroid axis appeared after 14 days of feeding (with a dietary incorporation level of 10%). The dietary supplementation with T(3) or iodine induced an increase in plasma T(3) levels, compared to that in fish fed the RM diets, and reduced the deleterious effect of RM on growth. When trout were reared in seawater, there was also a slight increase in thyroid hormone levels. TSH treatment had no effect on the thyroid hormone plasma levels. The incorporation of 30% of RM1, which induced a lower dietary content of toxic compounds than RM2, led to a rapid decrease of plasma T(4) and T(3) levels, but growth was affected only after 6 months of feeding. During these studies, the deiodinase activities responded in a complex manner to restore plasma and tissue levels of T(3).

Biochemical effects of dietary intake of different broccoli samples. II. Multivariate analysis of contributions of specific glucosinolates in modulating cytochrome P-450 and antioxidant defense enzyme activities

Dietary broccoli exposure modulates various cytochrome P-450 (CYP)-associated activities and antioxidant defense enzyme activities in liver, colon, and kidney of rats. We present an analysis by the partial least-square method (PLS) of the contribution of single glucosinolates in modulating xenobiotic metabolizing and antioxidant defense enzyme activities. Generally, modulation of colonic enzyme activities was well described (58% to 75%) by models consisting of 3 principal components (PCs). The indolyl glucosinolates were not the only major contributors to the regulation of colonic 7-ethoxyresorufin O-deethylase (EROD) and 7-methoxyresorufin O-demethylase (MROD) activities, as would be expected from results of previous experiments testing the pure compounds, glucobrassicin (GB), neoglucobrassicin (NeoGB), and 4-methoxyglucobrassicin (4-MeOGB). In hepatic and renal microsomes, the modulation of enzyme activities could be partly described for hepatic and renal 7-pentoxyresorufin O-deethylase (PROD) activities (42% to 44%, 3 to 4 PCs), hepatic superoxide dismutase activity (45%, 2 PCs), and renal glutathione peroxidase (GSH Px) and glutathione reductase (GSSG Red) activities (43%, 3 PCs). These results indicate that substances other than glucosinolates in the complex mixtures modulate hepatic EROD, MROD, GSH Px, and GSSG Red activities or that the active glucosinolate metabolites vary in their systemic disposition.

Effects of the bacterial status of rats on the changes in some liver cytochrome P450 (EC 1.14.14.1) apoproteins consequent to a glucosinolate-rich diet

The aim of the present work was to investigate the influence of the intestinal microflora on the changes in hepatic cytochrome P450 apoproteins induced by dietary glucosinolates. Ten rats harbouring a conventional digestive microflora were offered either a diet containing 390 g myrosinase-free rapeseed meal/kg (n 5) or a control diet devoid of glucosinolates (n 5). A similar trial was performed using germ-free rats. After 4 weeks of exposure to the dietary regimens, animals were slaughtered and their livers removed for preparation of microsomes and analysis of cytochrome P450 (EC 1.14.14.1). The glucosinolate-rich diet decreased the concentration of total cytochrome P450 in conventional rats only (-34%). The bacterial status did not modify the concentration of apoproteins CYP1A2 and CYP2B1/B2, but greatly decreased the concentration of the male constitutive isoform CYP2C11 (-53 and -45% respectively in conventional and germ-free rats). Germ-free rats fed on the glucosinolate-rich diet had a greater concentration of CYP3A (+139%) and a lower concentration of CYP2E1 (-32%) than their counterparts fed on the control diet. However, these differences were absent in conventional animals. On the whole, the influence of the intestinal microflora on the changes in hepatic cytochrome P450 due to the consumption of cruciferous vegetables is very complex and obviously involves different mechanisms according to the apoprotein.

Counteracting the negative effects of rapeseed and rapeseed press cake in pig diets

Rapeseed and rapeseed press cake were tested in four long-term experiments with a total of ninety-eight pigs. Rapeseed contained 20 and rapeseed press cake 19 mmol glucosinolates/kg DM. The proportion of the tested rapeseed products in feed amounted to 0 (control), 50, 100 and 150 g/kg diet. Moist-heat-treated rapeseed and rapeseed press cake with an extremely low glucosinolate content were also given at 150 g/kg diet. Each dietary rapeseed product level was given with 125 or 250 microgram supplementary I/kg diet. Reduced feed intake and growth retardation were found in groups receiving 150 g rapeseed products/kg diet; in the case of rapeseed the impairments were significant. Rapeseed products > or = 100g/kg diet increased the thyroid weight and decreased the serum thyroxine (T4) concentration. Higher I dosage brought the serum T4 concentration to the level of the control group and retarded thyroid enlargement. Intake of rapeseed products lowered the I content of the thyroid; however, there was no significant difference between groups given 0.9 mmol glucosinolates/kg diet and those receiving three times as much. Degrading glucosinolates by moisture and heat prevented feed intake depression and growth retardation. In the case of treated rapeseed the decreased serum T4 concentration and increased thyroid weight persisted, indicating formation of some antithyroid compounds due to myrosinase (EC 3.2.3.1) activation. A maximal glucosinolate content of 2 mmol/kg diet and additional I application are a prerequisite for using rapeseed products in pig feeding.

Dietary glucosinolates as blocking agents against carcinogenesis: glucosinolate breakdown products assessed by induction of quinone reductase activity in murine hepa1c1c7 cells

We have tested the ability of a representative range of dietary glucosinolates and their breakdown products, found in high concentrations in cruciferous vegetables, to act as blocking agents against carcinogenesis by inducing the activity of the anticarcinogenic phase II marker enzyme quinone reductase in murine hepa1c1c7 cells. Breakdown of glucosinolates was catalysed by the endogenous plant enzyme thioglucoside glucohydrolase at neutral and acid pH. Only two unmodified glucosinolates, p-hydroxybenzyl and 2-hydroxybut-3-enyl, significantly induced quinone reductase activity. However, after enzymic hydrolysis at near-neutral pH, some of the glucosinolates yielded breakdown products that significantly induced quinone reductase in the order: 3-methylsulphinylpropyl-->prop-2-enyl-->pent-4-enyl approximately 2-phenylethyl approximately benzyl-->all others tested. Incubation with myrosinase at acidic pH resulted in induction of quinone reductase activity by the hydrolysis products of only three of the tested glucosinolates:3-methylsulphinyl-propyl approximately 2-phenylethyl-->benzyl-->all others, activity due to the two alkenyl compounds being lost. The results show that the potential cancer-blocking action of both intact and thioglucoside glucohydrolase-treated glucosinolates, as assessed by induction of phase II enzyme activity, is dependent on the nature of the side chain of the parent glucosinolate.

[The effect of thioglycoside-containing feed on the growth, thyroid hormone and thiocyanate status of swine and poultry]

Feed containing rapeseed meal (RSM) with high glucosinolate content (10 mmol/kg feed) induced a strong increase of thyroid weight in pigs and poultry. Supplementary iodine reduced the antithyroid effect, but, it could not cancel it. Only at a low glucosinolate content (0.7 mmol/kg feed) a normal weight of thyroid was established. As the iodine supplementation increased the serum T4 value increased. The thiocyanate serum level increased irrespective of glucosinolate content of the feed. The urine level was significantly decreased due to lower dietary glucosinolate level. Obviously, the goitrogenic effect of the RSM does not correlate with the increased thiocyanate serum level.

Efficacy of feeding glucosinolate-extracted crambe meal to broiler chicks

Glucosinolates and their breakdown products (nitriles) have long been implicated as toxic factors when feeding rapeseed (Brassica napus) meals and crambe (Crambe abyssinica) meals to poultry. Accordingly, various methods have been developed to remove these compounds from the meals to enhance their value as feed supplements. Glucosinolates and nitriles were extracted from commercially processed, defatted crambe meal by washing with water or various solvent-water mixtures: 50% isopropanol, 50% acetone, or 50% ethanol. In addition, crambe seed was extruded and extracted in the laboratory with isopropanol or hexane. Water washing of commercially defatted meal proved to be the most effective method of extraction, removing 95% of the glucosinolates and nitriles. Meals were fed to 7-d-old broiler chicks at 10% of the diet for 14 d. Weight gain decreased (P < .05) in most groups; however a greater decrease (P < .01) was observed in birds fed meals with high glucosinolate content. Feed intake also decreased (P < .05) in most groups; consequently, feed efficiencies were similar for all groups. No changes in serum chemistries, triiodothyronine, thyroxine, or tissue lesions were associated with glucosinolate or nitrile intake. A relationship (P < .05, r = .74) was found between weight gain and glucosinolate intake. No correlation was found between feed intake and meal glucosinolate or nitrile concentrations.

Effect of increasing the dietary level of rapeseed meal on intake by growing beef steers

Three experiments were conducted to determine the effects of rapeseed meal on intake by cattle. In the first experiment, the effect of increasing rapeseed meal level on intake, growth, and performance of growing beef steers was evaluated. In the second experiment, the effect of extrusion (glucosinolate reduction) on supplement intake by steers was evaluated. In the third experiment, the effect of increasing dietary rapeseed meal level on supplement intake was evaluated. In the first experiment, rapeseed meal replaced soybean meal at 0, 33, 67, or 100% of the supplemental protein. Dry matter intake, crude protein intake, and serum thyroxine levels were decreased linearly (P < .01) with increasing level of rapeseed meal in the supplement. Protein sources used in Exp. 2 were soybean meal, rapeseed meal, extruded rapeseed meal, and soybean meal containing rapeseed oil at the same level as the rapeseed meal. In Exp. 3, the protein sources were composed of different combinations of rapeseed meal and soybean meal (100% rapeseed meal; 67% rapeseed meal and 33% soybean meal; 33% rapeseed meal and 67% soybean meal; and 100% soybean meal). Supplement intake was measured at .5, 4, and 24 h after feeding in both experiments. Extrusion treatment, which reduced glucosinolate content in rapeseed meal 75%, did not improve (P > .10) supplement intake. Rapeseed meal resulted in lower supplement intakes at .5 and 4 h than the soybean meal and soybean meal+rapeseed oil supplements (P = .003).(ABSTRACT TRUNCATED AT 250 WORDS)

[The extraction particles from winter rapeseed with different glucosinolate fractions in swine with regard to the iodine supply. 3. Apparent digestibility of crude nutrients with special regard to the carbohydrate and nitrogen balance]

In two digestibility and N-balance experiments the following solvent extracted meals were examined in a grain (barley and wheat in equal parts) or in a starch diet with four female pigs/group fitted with urethra catheters during the 5 days sampling period: 48% soyabean meal (SBM) (1), 24% conventional rapeseed meal (RSM) (2), 24 (3) or 48% (4) RSM from a newly bred low glucosinolate variety, groups 1 to 4 with grain, 48% low glucosinolate RSM (5) or 48% SBM (6) both with starch. In numeric order of the groups 88, 85, 86, 84, 79 and 89% N were digested. Pigs responded to the additional faecal N excretion from RSM diets by a lower urinary N excretion and thus they reached the N-balance of the animals fed on SBM. In numeric order of the groups 86, 79, 80, 73, 73 and 92% of the organic matter of the solvent extracted meals were digested. In comparison with SBM even 48% RSM in the feed significantly lowered the digestibility of organic matter. Using detergents the additional faecal organic matter excretion of RSM versus SBM could quantified as two third lignin. In the case of 24% RSM in the diet--i.e. 15% of the carbohydrates given--the carbohydrate digestibility is estimated with a high error, that an energetic feed value should not calculated. Investigating 48% SBM or RSM respectively in a grain diet the net energy content was 9.8 MJ (666 Energetic Feed Units, EFU pig) or 8.3 MJ (569 EFU pig)/kg dry matter (DM). Based on the starch diet, however, little relevant for estimation of normal pig diets, there were evaluated 10.6 MJ (720 EFU pig) for SBM and 8.3 MJ (567 EFU pig) net energy/kg DM for RSM.

[Testing of extracted particles from winter rapeseed with different glucosinolate levels in swine with special reference to the iodine supply. 2. Thyroid hormone status, histomorphometric findings and iodine content of the thyroid gland]

In the experiment, 2 x 12 growing pigs received 19 or 6.7 mmol glucosinolates + aglucones/kg feed via conventional rapeseed meal (RSM) or RSM of a newly bred variety. These pigs and 24 littermates pair fed with a soya bean meal (SBM) diet were subdivided in groups of 4 animals each. Their diet contained either no supplementary iodine or an iodine supplementation of up to 1 mg/kg feed. In the RSM and SBM groups the lack of additional iodine lowered the serum T4 and T3 content below the detection limit and caused goitre with about 1 mg iodine in the total thyroid. The SBM diet with 0.0625 mg supplementary iodine/kg increased the serum T4 level and reversed the thyroid enlargement but not that of epithelial cells. The hypothyroidism (goitre and serum T4 level approximately 10 nmol/l) still existed in the case of this iodine dosage together with the RSM of the newly bred variety. A serum T4 level comparable to that of the animals fed SBM was only reached by supplementing the low glucosinolate diet with 0.25 mg iodine/kg feed. The iodine content of the thyroid, however, was reduced by 50 per cent. Though thyroid and epithelial cells were enlarged, this enlargement was not so obvious as in animals exposed to higher glucosinolate level. In spite of 1 mg supplementary iodine/kg feed, the feeding of the conventional RSM resulted in a lower serum T4 level a reduced thyroid iodine content and the enlargement of thyroid and that of epithelial cells. Compared to the high glucosinolate RSM, a significantly lower antithyroid effect of the low glucosinolate RSM was found in pigs with iodine supply. The degree of thyroid enlargement and the serum T4 level were the criteria.

Effect of varying glucosinolate and iodine intake via rapeseed meal diets on serum thyroid hormone level and total iodine in the thyroid in growing pigs

In a trial with 50 fattening pigs (20 kg initial body weight), the effect of untreated rapeseed meal (RSM) (148 mmol glucosinolates and aglucones per kg dry matter) on the thyroid was compared with RSM treated with Cu2+ (9.5 mmol glucosinolates and aglucones per kg dry matter) and soybean meal (SBM). The diets containing 8% RSM were supplemented with 0.0625-1.0 and the SBM diet (control) with 0.125 mg iodine kg-1 (I). In comparison with SBM fed control, RSM treatment with Cu2+ resulted in a complete normalization of feed intake and growth. Only untreated RSM without I supplementation depressed performance and resulted in symptoms of I deficiency, but the thyroid and liver weight were also increased and the serum T4 content was significantly reduced in animals which were given RSM not supplemented with I, but treated with Cu2+. In young pigs (4 weeks) a plateau of the serum T4 content was achieved from 0.5 mg I kg-1 of the RSM diet onwards. In contrast, when the concentration of goitrogens was reduced by the treatment with Cu2+, the serum T4 level was increased significantly in groups fed with 0.125 mg I kg-1 diet and more. In older pigs (15 weeks) neither the content of goitrogens nor the I dosage affected the serum T4 level. On the other hand, the I content in the thyroid was a good indicator of the different goitrogenicity of the diet in the case of a low I supply. The present investigations show that pig diets with RSM (greater than 10 mmol glucosinolates and aglucones kg-1) should contain at least 0.5 mg I kg-1, but 0.1 mg supplementary I per kg is sufficient in diets without or with a low content (less than 1 mmol glucosinolates and aglucones per kg-1) of antithyroid compounds.

[Testing in swine of meal extracted from winter rapeseed with different glucosinolate content with regard to iodine supply. 1. Characterization of rapeseed extraction particles and fattening results]

In a feeding experiment with 48 growing pigs 16% high glucosinolate rapeseed meal (HGRSM) (136 mumol glucosinolates + aglucones/kg dry matter, DM) or low glucosinolate (LG) RSM (48 mumol glucosinolates + aglucones/kg DM) in the feed were compared with 14% soya-bean meal (SBM) in each case. It were established 24 pairs of animals, which received the same quantity of the isonitrogenous but not isocaloric diets with SBM and the both RSM (pair fed). Four of the 2.12 animal pairs were not given supplementary I, four received 0.25 mg supplementary I/kg feed. Further four animals which were fed on LGRSM or HGRSM were provided with 0.0625 or 1 mg supplementary I/kg feed. In case of high glucosinolate intake (HGRSM) the lacking I supplementation decreased feed intake and growth and led to remarkable I deficiency symptoms from the fifth week onwards. The 2/3 lower glucosinolate dosage of the LGRSM diet also decreased performance and provoked I deficiency, however significantly later. The investigated I dosages (greater than 0.0625 mg/kg feed) did not effect the performance. In the experiment the eight animals which received LGRSM with supplementary I consumed 13% more feed than animals fed on HGRSM (P less than 0.05). The additional weight gain was 20% (P less than 0.05). Comparing the live weight gain of the SBM and RSM fed animals (pair fed) there was a significant increase of 9% versus the HGRSM groups and 5% versus the LGRSM groups.

Glucosinolates toxicity in growing rats: interactions with the hepatic detoxification system

1. Glucosinolate-rich diet (RM) in growing rats increased liver (a), kidneys (b), and thyroid (c) weights and depleted feed intake (d), growth curve (e) and T4 and T3 plasma levels (f). 2. Oral administration of phenobarbital enhanced the toxic effect of RM on (b), (d) and (e) and did not modify the toxic effect of RM on (a), (c) and (f). 3. RM had a depleting effect on hepatic microsomal P-450 specific activity. 4. RM had an enhancing effect on hepatic glutathione S-transferase and UDP-glucuronyltransferase specific activities. 5. These results indicate that some glucosinolate derivatives released by gut microflora metabolism are further metabolized by the hepatic detoxification system, and that they could play the role of co-toxic or co-detoxic molecules.

Effects of dietary sinigrin or indole-3-carbinol on O6-methylguanine-DNA-transmethylase activity and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced DNA methylation and tumorigenicity in F344 rats

The effects of dietary sinigrin and indole-3-carbinol (I3C) on DNA methylation and O6-methylguanine--DNA-transmethylase activity, factors which may be of importance in the induction of tumorigenicity by the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), were investigated. Additionally, the effects of dietary sinigrin on NNK tumorigenicity were assessed in a two-year bioassay in F344 rats. DNA methylation in target tissues of NNK tumorigenesis was examined in F344 rats administered [3H-CH3]NNK (0.6 mg/kg, four doses) s.c. and fed control or experimental diets for two weeks. Dietary sinigrin at a concentration of 3 mumol/g diet decreased 7-methylguanine formation in hepatic DNA, but had no effect on 7-methylguanine levels of lung or nasal mucosa DNA. Dietary I3C at a concentration of 30 mumol/g diet increased 7-methylguanine levels in hepatic DNA, but decreased DNA methylation in lung and nasal mucosa. No effects on O6-methylguanine--DNA-transmethylase activity were observed in tissue extracts derived from the livers, lungs and nasal mucosae of rats fed diets containing sinigrin or I3C. These results suggested that dietary sinigrin might reduce the incidence of NNK-induced hepatic tumors with no effect on NNK tumorigenesis of the lung and nasal cavity, whereas I3C might increase hepatic tumor incidence and reduce NNK tumorigenesis of the lung and nasal cavity. The bioassay results showed that dietary sinigrin had no effect on NNK tumorigenesis in these target tissues. However, dietary sinigrin plus NNK resulted in a significant incidence of pancreatic tumors, a rare occurrence in F344 rats. While the results from DNA methylation studies are in agreement with the bioassay data for lung and nasal cavity, the absence of any inhibitory effect of dietary sinigrin on NNK hepatic tumorigenesis indicates that factors other than DNA methylation and O6-methylguanine repair should be considered in assessing the effects of dietary compounds on NNK hepatic tumorigenesis. The contrary effects on NNK-induced hepatic DNA methylation by sinigrin and I3C, two major components of cruciferous vegetables, demonstrate the complexities of dietary modulation of carcinogenesis.

Rapeseed induced liver haemorrhage, reticulolysis and biochemical changes in laying hens: the effects of feeding high and low glucosinolate meals

Rapeseed meal hepatosis was produced by feeding high and low glucosinolate meals as a source of protein (about 200 g kg-1 diet) but could not be distinguished histologically from fatty liver-haemorrhagic syndrome which occurred in birds on the control diet. Both types of meal increased haemorrhage, reticulolysis and lymphoproliferation in the liver, reduced the packed cell volume and caused thyroid enlargement. Haemorrhages emanated from ruptured intrahepatic portal veins, capillaries and sinusoids and were associated with degenerative changes in vessel walls. Haemorrhage and reticulin scores were correlated. Parenchymal necrosis occurred only around large haematomas and caused increased aspartate transaminase activity in the plasma. Both meals also caused hyperglycaemia and reduced the plasma triglyceride content. Only the high glucosinolate meal decreased egg production, caused liver enlargement and reduced the plasma urate level. The addition of myrosinase enhanced its effects on egg production and packed cell volume but did not increase its hepatotoxicity.