Inhibition of oxidative DNA damage in vitro by extracts of brussels sprouts

Extraction of Bioactive Compounds from Different Vegetable Sprouts and Their Potential Role in the Formulation of Functional Foods against Various Disorders: A Literature-Based Review

In this review, we discuss the advantages of vegetable sprouts in the development of food products as well as their beneficial effects on a variety of disorders. Sprouts are obtained from different types of plants and seeds and various types of leafy, root, and shoot vegetables. Vegetable sprouts are enriched in bioactive compounds, including polyphenols, antioxidants, and vitamins. Currently, different conventional methods and advanced technologies are used to extract bioactive compounds from vegetable sprouts. Due to some issues in traditional methods, increasingly, the trend is to use recent technologies because the results are better. Applications of phytonutrients extracted from sprouts are finding increased utility for food processing and shelf-life enhancement. Vegetable sprouts are being used in the preparation of different functional food products such as juices, bread, and biscuits. Previous research has shown that vegetable sprouts can help to fight a variety of chronic diseases such as cancer and diabetes. Furthermore, in the future, more research is needed that explores the extraordinary ways in which vegetable sprouts can be incorporated into green-food processing and preservation for the purpose of enhancing shelf-life and the formation of functional meat products and substitutes.

Sinigrin inhibits production of inflammatory mediators by suppressing NF-κB/MAPK pathways or NLRP3 inflammasome activation in macrophages

Sinigrin (2-propenyl glucosinolate) is found mainly in broccoli, brussels sprouts, and black mustard seeds. Recently, sinigrin has received attention for its role in disease prevention and health. This study investigated the effect of sinigrin on macrophage function, including the activity of Nod-like receptor protein 3 (NLRP3) inflammasome. In a concentration-dependent manner, sinigrin inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) production and the expression of COX-2 and prostaglandin E2 (PGE2) in RAW 264.7 cells. In addition, sinigrin significantly suppressed the production of tumor necrosis factor (TNF)-α and interleukin (IL)-6 via suppression of MAPK phosphorylation and nuclear factor-kappa B (NF-κB) activity. Treatment with sinigrin decreased IL-1β and IL-18 production and concurrently suppressed NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and caspase-1 expression in LPS/ATP-stimulated cells, suggesting that the blocking of NLRP3 inflammasome activation prevented the production of both cytokines. Collectively, these results suggest that sinigrin has immunomodulatory effects by suppressing the production of inflammatory mediators, possibly by inhibiting the NF-κB/MAPK pathways or NLRP3 inflammasome activation. Our findings also provide evidence that the pharmacological modulation of sinigrin could have an anti-inflammatory effect.

Assessment of DNA damage and repair in adults consuming allyl isothiocyanate or Brassica vegetables

Allyl isothiocyanate (AITC) is a dietary component with possible anticancer effects, though much information about AITC and cancer has been obtained from cell studies. To investigate the effect of AITC on DNA integrity in vivo, a crossover study was conducted. Adults (n=46) consumed AITC, AITC-rich vegetables [mustard and cabbage (M/C)] or a control treatment with a controlled diet for 10 days each. On day 11, volunteers provided blood and urine before and after consuming treatments. Volunteers were characterized for genotype for GSTM1 and GSTT1 (glutathione S-transferases) and XPD (DNA repair). DNA integrity in peripheral blood mononuclear cells was assessed by single-cell gel electrophoresis. Urine was analyzed for 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and creatinine. Ten-day intake of neither AITC nor M/C resulted in statistically significant differences in DNA strand breaks [least squares mean (LSmean) % DNA in tail±S.E.M.: 4.8±0.6 for control, 5.7±0.7 for AITC, 5.3±0.6 for M/C] or urinary 8-oxodG (LSmean μg 8-oxodG/g creatinine±S.E.M.: 2.95±0.09 for control, 2.88±0.09 for AITC, 3.06±0.09 for M/C). Both AITC and M/C increased DNA strand breaks 3 h postconsumption (LSmean % DNA in tail±S.E.M.: 3.2±0.7 for control, 8.3±1.7 for AITC, 8.0±1.7 for M/C), and this difference disappeared at 6 h (4.2±0.9 for control, 5.7±1.2 for AITC, 5.5±1.2 for M/C). Genotypes for GSTM1, GSTT1 and XPD were not associated with treatment effects. In summary, DNA damage appeared to be induced in the short term by AITC and AITC-rich products, but that damage disappeared quickly, and neither AITC nor AITC-rich products affected DNA base excision repair.

Optimisation of microwave-assisted extraction for functional properties of Vitis coignetiae extract by response surface methodology

BACKGROUND

Consumer preference for selection of natural substances, with their safe and beneficial effects on the human body as well as various physiological efficacies, is increasing. In this study, response surface methodology (RSM) was used to monitor the extraction characteristics of Vitis coignetiae (wild grape) and thereby optimise the functional properties of the resulting extract.

RESULTS

A maximum total polyphenol content (TPC) of 415.74 mg per 100 g was obtained at a microwave power (MWP) of 102.36 W, an ethanol concentration (ETC) of 42.62% (by volume) and an extraction time (EXT) of 12.35 min. Electron-donating ability (EDA) reached a maximum of 69.20% at 125.65 W MWP, 41.81% ETC and 13.65 min EXT. The maximum nitrite-scavenging ability (NSA) obtained was 87.50% at 119.13 W MWP, 37.41% ETC and 13.20 min EXT. Superoxide dismutase (SOD) showed a maximum pseudo-activity (SDA) of 56.74% at 69.54 W MWP, 94.88% ETC and 10.32 min EXT. The effect of ETC was most prominent among the studied factors.

CONCLUSION

Based on the superimposition of four-dimensional response surfaces with respect to TPC, EDA, NSA and SDA, the optimum ranges of extraction conditions were 70-150 W MWP, 30-50% ETC and 8-18 min EXT.

DNA repair and the accumulation of oxidatively damaged DNA are affected by fruit intake in mice

AGING is associated with elevated oxidative stress and DNA damage. To achieve healthy aging, we must begin to understand how diet affects cellular processes. We postulated that fruit-enriched diets might initiate a program of enhanced DNA repair and thereby improve genome integrity. C57Bl/6 J mice were fed for 14 weeks a control diet or a diet with 8% peach or nectarine extract. The activities of DNA repair enzymes, the level of DNA damage, and gene expression changes were measured. Our study showed that repair of various oxidative DNA lesions was more efficient in liver extracts derived from mice fed fruit-enriched diets. In support of these findings, gas chromatography-mass spectrometry analysis revealed that there was a decrease in the levels of formamidopyrimidines in peach-fed mice compared with the controls. Additionally, microarray analysis revealed that NTH1 was upregulated in peach-fed mice. Taken together, these results suggest that an increased intake of fruits might modulate the efficiency of DNA repair, resulting in altered levels of DNA damage.

Cancer prevention with natural compounds

Botanical and nutritional compounds have been used for the treatment of cancer throughout history. These compounds also may be useful in the prevention of cancer. Population studies suggest that a reduced risk of cancer is associated with high consumption of vegetables and fruits. Thus, the cancer chemopreventive potential of naturally occurring phytochemicals is of great interest. There are numerous reports of cancer chemopreventive activity of dietary botanicals, including cruciferous vegetables such as cabbage and broccoli, Allium vegetables such as garlic and onion, green tea, Citrus fruits, soybeans, tomatoes, berries, and ginger, as well as medicinal plants. Several lead compounds, such as genistein (from soybeans), lycopene (from tomatoes), brassinin (from cruciferous vegetables), sulforaphane (from asparagus), indole-3-carbinol (from broccoli), and resveratrol (from grapes and peanuts) are in preclinical or clinical trials for cancer chemoprevention. Phytochemicals have great potential in cancer prevention because of their safety, low cost, and oral bioavailability. In this review, we discuss potential natural cancer preventive compounds and their mechanisms of action.

Increase in cruciferous vegetable intake in women previously treated for breast cancer participating in a dietary intervention trial

Consumption of cruciferous vegetables has been associated with reduced breast cancer risk mechanistically and in population-based studies, although evidence has been inconsistent. This inconsistency may be related to limitations in quantifying and qualifying cruciferous vegetable exposure using standard instruments for dietary assessment (for example, food-frequency questionnaires, FFQs) or due to low levels of intake demonstrated among U.S. population samples. Cruciferous vegetable intake data are presented from a longitudinal study of a high-vegetable dietary intervention to reduce breast cancer recurrence among breast cancer survivors (n=1,156; 536 intervention and 620 comparison group subjects). Intake was assessed using repeat administration of an FFQ and cross-sectional administration of a cruciferous vegetable-specific FFQ (CVFFQ). Mean intake in the intervention group assessed using the standard FFQ was 37.7 g/day at baseline and increased to 57.1 g/day at 12 mo (P=0.0001) and was sustained through 48 mo. Broccoli and cabbage were the most commonly consumed cruciferous vegetables, regardless of the instrument used to assess intake. Differences in intake by group assignment were shown for raw cruciferous vegetables (30.2 g/day vs. 24.6 g/day, assessed using the CVFFQ), suggesting increased exposure to biologically active, cancer-preventive food constituents. These data suggest that this study population will be the first U.S. population sample to provide ample quantity and variety in cruciferous intake to examine whether these vegetables are protective against breast cancer recurrence.

DNA damage, a biomarker of carcinogenesis: its measurement and modulation by diet and environment

Free radicals and other reactive oxygen or nitrogen species are constantly generated in vivo and can cause oxidative damage to DNA. This damage has been implicated to be important in many diseases, including cancer. The assessment of damage in various biological matrices, such as tissues, cells, and urine, is vital to understanding this role and subsequently devising intervention strategies. During the last 20 years, many analytical techniques have been developed to monitor oxidative DNA base damage. High-performance liquid chromatography-electrochemical detection and gas chromatography-mass spectrometry are the two pioneering contributions to the field. Currently, the arsenal of methods available include the promising high-performance liquid chromatography-tandem mass spectrometry technique, capillary electrophoresis, 32P-postlabeling, antibody-base immunoassays, and assays involving the use of DNA repair glycosylases such as the comet assay. The objective of this review is to discuss the biological significance of oxidative DNA damage, evaluate the effectiveness of several techniques for measurement of oxidative DNA damage in various biological samples and review current research on factors (dietary and non-dietary) that influence DNA oxidative damage using these techniques.

Proposed criteria for assessing the efficacy of cancer reduction by plant foods enriched in carotenoids, glucosinolates, polyphenols and selenocompounds

BACKGROUND AND AIMS

The cancer-protective properties of vegetable consumption are most likely mediated through 'bioactive compounds' that induce a variety of physiologic functions including acting as direct or indirect antioxidants, regulating enzymes and controlling apoptosis and the cell cycle. The 'functional food' industry has produced and marketed foods enriched with bioactive compounds, but there are no universally accepted criteria for judging efficacy of the compounds or enriched foods.

SCOPE

Carotenoids, glucosinolates, polyphenols and selenocompounds are families of bioactive compounds common to vegetables. Although numerous studies have investigated the agricultural and human health implications of enriching foods with one or more of these compounds, inadequate chemical identification of compounds, lack of relevant endpoints and inconsistencies in mechanistic hypotheses and experimental methodologies leave many critical gaps in our understanding of the benefits of such compounds. This review proposes a decision-making process for determining whether there is reasonable evidence of efficacy for the both the compound and the enriched food. These criteria have been used to judge the evidence of efficacy for cancer prevention by carotenoids, polyphenols, glucosinolates and selenocompounds.

CONCLUSIONS

The evidence of efficacy is weak for carotenoids and polyphenols; the evidence is stronger for glucosinolates and lycopene, but production of enriched foods still is premature. Additionally there is unacceptable variability in the amount and chemical form of these compounds in plants. The evidence of efficacy for selenocompounds is strong, but the clinical study that is potentially the most convincing is still in progress; also the variability in amount and chemical form of Se in plants is a problem. These gaps in understanding bioactive compounds and their health benefits should not serve to reduce research interest but should, instead, encourage plant and nutritional scientists to work together to develop strategies for improvement of health through food.

Colon cancer proliferating desulfosinigrin in wasabi (Wasabia japonica)

A reduced incidence of different types of cancer has been linked to consumption of Brassica vegetables, and there is evidence that glucosinolates (GSLs) and their hydrolysis products play a role in reducing cancer risk. Wasabi (Wasabia japonica) and horseradish (Armoracia rusticana), both Brassica vegetables, are widely used condiments both in Japanese cuisine and in the United States. Desulfosinigrin (DSS) (1) was isolated from a commercially available wasabi powder and from fresh wasabi roots. Sinigrin (2) was isolated from horseradish roots. DSS and sinigrin were evaluated for their inhibitory effects on cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes, on lipid peroxidation, and on the proliferation of human colon (HCT-116), breast (MCF-7), lung (NCIH460), and central nervous system (CNS, SF-268) cancer cell lines. DSS did not inhibit COX enzymes or lipid peroxidation at 250 microg/ml. Sinigrin inhibited lipid peroxidation by 71% at 250 microg/ml. However, DSS promoted the growth of HCT-116 (colon) and NCI H460 (lung) human cancer cells as determined by the MTT assay in a concentration-dependent manner. At 3.72 microg/ml, a 27% increase in the number of viable human HCT-116 colon cancer cells was observed; the corresponding increases at 7.50 and 15 microg/ml were 42 and 69%, respectively. At 60 microg/ml, DSS doubled the number of HCT-16 colon cancer cells. For NCI H460 human lung cancer cells, DSS at 60 microg/ml increased the cell number by 20%. Sinigrin showed no proliferating effect on the tumor cells tested. This is the first report of the tumor cell-proliferating activity by a desulfoglucosinolate, the biosynthetic precursor of GSLs found in Brassica spp.

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.

Influence of flavan-3-ols and procyanidins on UVC-mediated formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine in isolated DNA

The flavan-3-ols (-)-epicatechin (epicatechin) and (+)-catechin (catechin) and their related oligomers (procyanidins) isolated from cocoa were assayed for their capacity to inhibit the UVC-mediated formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (oxo(8)dG) in calf thymus DNA. The above-mentioned compounds inhibited oxo(8)dG production in a concentration- and time-dependent manner. After 30 min of irradiation (30 kJ/m(2)), 0.1, 1.0, 10, and 100 microM epicatechin inhibited oxo(8)dG formation by 20, 36, 64, and 74%, respectively. For the same dose of UVC, 0.1, 1.0, 10, and 100 microM catechin inhibited oxo(8)dG formation by 1, 23, 50, and 70%, respectively. Epicatechin was more efficient than catechin with respect to inhibiting oxo(8)dG formation (IC(50) 1.7 +/- 0.7 vs 4.0 +/- 0.7 microM). Monomer, tetramer, and hexamer fractions were equally effective in inhibiting oxo(8)dG formation when assayed at 10 microM monomer equivalent concentration. At similar concentrations (1-50 microM), the inhibition of the UVC-mediated oxo(8)dG formation by flavan-3-ols and procyanidins was in the range of that of alpha-tocopherol, Trolox, ascorbate, and glutathione. These results support the concept that flavan-3-ols and their related procyanidins can protect DNA from oxidation at concentrations that can be physiologically relevant. Both epimerism and degree of oligomerization are important determinants of the antioxidant activity of flavan-3-ols and procyanidins.

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.

Effects of a Brussels sprouts extract on oxidative DNA damage and metabolising enzymes in rat liver

The apparent anticarcinogenic effect of cruciferous vegetables found in numerous epidemiological and experimental studies has been associated with their influence on phase I and phase II metabolising enzymes as well as on the antioxidant status. In the present study we investigated the effect of administration of a Brussels sprouts extract on the expression at the mRNA level and/or catalytic activity in rat liver of three phase I enzymes [cytochrome P450-1A2 (CYP1A2),-2B1/2 (CYP2B1/2) and-2E1 (CYP2E1)] and two phase II enzyme [NADPH:quinone reductase (QR) and glutathione S-transferase pi 7 (GSTpi)], all previously suggested to be induced by vegetables. We also examined the activity and/or expression of several important antioxidant enzymes: glutathione peroxidase (GPx), catalase and gamma-glutamyl-cysteine synthetase (GCS) and the activity of the repair enzyme 8-oxoguanine DNA glycosylase (OGG1). QR, GPx and catalase activity was also assessed in the kidneys. In order to examine a possible effect of the Brussels sprouts related to oxidative stress, we measured oxidative DNA damage in terms of 7-hydro-8-oxo-2'-deoxyguanosine (8-oxodG) and lipid peroxidation in terms of malondialdehyde (MDA) formation in the liver. Oral administration of an aqueous Brussels sprouts extract for 4 days was found to induce the expression of GST 1.3-fold (P < 0.05) and the activity of QR 2.6-fold in rat liver (P < 0.05). No significant differences were seen in the expression of the phase I enzymes. No differences in antioxidant enzyme activity/expression or OGG1 activity were observed. In a second experiment, administration of the Brussels sprouts extract for 3 or 7 days was found to increase the level of 8-oxodG in rat liver from 0.75 to 0.97 per 10(5) dG and from 0.81 to 0.97 per 10(5) dG, respectively (P < 0.05). No effects on MDA levels were found. The present results support the data obtained in several studies that consumption of cruciferous vegetables is capable of inducing various phase II enzyme systems. However, the observed increase in oxidative DNA damage raises the question of whether greatly increased ingestion of cruciferous vegetables is beneficial.