Glucosinolates and their breakdown products in cruciferous crops, foods and feedingstuffs

Brassicaceae Mustards: Phytochemical Constituents, Pharmacological Effects, and Mechanisms of Action against Human Disease

The Brassicaceae genus consists of many economically important mustards of value for food and medicinal purposes, namely Asian mustard (Brassica juncea), ball mustard (Neslia paniculata), black mustard (B. nigra), garlic mustard (Alliaria petiolata), hedge mustard (Sisymbrium officinale), Asian hedge mustard (S. orientale), oilseed rape (B. napus), rapeseed (B. rapa), treacle mustard (Erysimum repandum), smooth mustard (S. erysimoides), white ball mustard (Calepina irregularis), white mustard (Sinapis alba), and Canola. Some of these are commercially cultivated as oilseeds to meet the global demand for a healthy plant-derived oil, high in polyunsaturated fats, i.e., B. napus and B. juncea. Other species are foraged from the wild where they grow on roadsides and as a weed of arable land, i.e., E. repandum and S. erysimoides, and harvested for medicinal uses. These plants contain a diverse range of bioactive natural products including sulfur-containing glucosinolates and other potentially valuable compounds, namely omega-3-fatty acids, terpenoids, phenylpropanoids, flavonoids, tannins, S-methyl cysteine sulfoxide, and trace-elements. Various parts of these plants and many of the molecules that are produced throughout the plant have been used in traditional medicines and more recently in the mainstream pharmaceutical and food industries. This study relates the uses of mustards in traditional medicines with their bioactive molecules and possible mechanisms of action and provides an overview of the current knowledge of Brassicaceae oilseeds and mustards, their phytochemicals, and their biological activities.

Optimization of cultivar, germination time and extraction for radish sprout extract with high sulforaphene content

BACKGROUND

Cruciferous vegetable sprout has been highlighted as a promising functional material rich in bioactive compounds called isothiocyanates (ITCs) and it can be grown in very short periods in controlled indoor farms. However, because ITCs content depends on multiple factors such as cultivar, germination time and myrosinase activity, those variables need to be controlled during germination or extraction to produce functional materials enriched in ITCs. Sulforaphene (SFEN), an ITC found primarily in radishes (Raphanus sativus L.), exerts beneficial effects on obesity. However, the optimal germination and extraction conditions for radish sprout (RSP) to increase SFEN content remain unascertained, and the extract's anti-obesity effect has yet to be evaluated.

RESULTS

The present study found that the SFEN content was highest in purple radish sprout (PRSP) among the six cultivars investigated. Optimal SFEN content occurred after 2 days of PRSP germination (2 days PRSP). To maximize the dry matter yield, total ITCs and SFEN contents in RSP extract, we found the optimal conditions for extracting PRSP [27.5 °C, 60 min, 1:75.52 solute/solvent (w/v), no ascorbic acid] using response surface methodology. Consistent with high SFEN content, 2 days PRSP extract significantly outperformed 3 days or 4 days PRSP extract in inhibiting lipid accumulation in 3T3-L1 cells. Moreover, 2 days PRSP extract suppressed adipogenesis and lipogenesis-related protein expression.

CONCLUSION

Regarding the cultivar, germination time and extraction conditions, optimally produced PRSP extract contains high SFEN content and exerts anti-obesity effects. Thus, we suggest PRSP extract as a potent functional material for obesity prevention. © 2024 Society of Chemical Industry.

Spectral Reflectance Indexes Reveal Differences in the Physiological Status of Brassica oleracea with Contrasting Glucosinolate Content under Biotic Stress

Brassica species produce glucosinolates, a specific group of secondary metabolites present in the Brassicaceae family with antibacterial and antifungal properties. The employment of improved varieties for specific glucosinolates would reduce the production losses caused by pathogen attack. However, the consequences of the increment in these secondary metabolites in the plant are unknown. In this work, we utilized reflectance indexes to test how the physiological status of Brasica oleracea plants changes depending on their constitutive content of glucosinolates under nonstressful conditions and under the attack of the bacteria Xanthomonas campestris pv. campestris and the fungus Sclerotinia sclerotiorum. The modification in the content of glucosinolates had consequences in the resistance to both necrotrophic pathogens, and in several physiological aspects of the plants. By increasing the content in sinigrin and glucobrassicin, plants decrease photosynthesis efficiency (PR531, F_vF_m), biomass production (CHL-NDVI, SR), pigment content (SIPI, NPQI, RE), and senescence (YI) and increase their water content (WI900). These variables may have a negative impact in the productivity of crops in an agricultural environment. However, when plants are subjected to the attack of both necrotrophic pathogens, an increment of sinigrin and glucobrassicin confers an adaptative advantage to the plants, which compensates for the decay of physiological parameters.

Consumption of Cruciferous Foods, Ingestion of Glucosinolates and Goiter in a Region of Eastern Algeria

This study is about the estimation of the consumption of cruciferous vegetables, and the search for a possible relationship between the ingestion of glucosinolates provided by these foods and the emergence of endemic goiter. A prospective cohort survey was carried out on 1098 subjects residing in the district of EL-MILIA (Algeria) where endemic goiter is known to estimate the consumption of crucifers. Total glucosinolates levels in cruciferous vegetables, cabbage, cauliflower, fresh and cooked turnip and radish were determined by the glucose release method. The goiter was detected by clinical investigation. Both various fresh and cooked cruciferous vegetables have the same total glucosinolates levels as reported in other studies. The prevalence of endemic goiter was 17.5 %. The average consumption of crucifers was 380.30 g per person a week, i.e. 54.32 g per person a day, and the weekly ingestion of glucosinolates per person was 369.4 μmoles, or 52.7 μmoles per day. No dependence was observed between the consumption of glucosinolates and the disease in general. However, isolated stage 2 and 3 of goiter were dependent on the consumption of glucosinolates ; stage 1 was not related to the disease. Despite the current consumption, at EL-MILIA, we estimate that glucosinolate’s ingestion does not cause goiter, but may worsen the condition of subjects already affected.

Phenolic and Volatile Composition and Antioxidant Properties of the Leaf Extract of Brassica fruticulosa subsp. fruticulosa (Brassicaceae) Growing Wild in Sicily (Italy)

In continuation of research conducted on species of the spontaneous flora of Sicily (Italy) belonging to the Brassicaceae family, Brassica fruticulosa subsp. fruticulosa was selected. It is an edible species utilized in Sicilian traditional medicine. In this study, for the first time, the phenolic and the volatile compounds and the antioxidant properties of the hydroalcoholic extract obtained from the leaves of B. fruticulosa subsp. fruticulosa were characterized. Through HPLC-PDA/ESI-MS analysis, a total of 22 polyphenolic compounds (20 flavonoids and 2 phenolic acids) were identified, with 3-hydroxiferuloylsophoroside-7-O-glucoside (1.30 mg/g ± 0.01) and kaempferol-3-O-feruloylsophoroside-7-O-glucoside (1.28 mg/g ± 0.01) as the most abundant compounds. Through SPME-GC/MS several volatiles belonging to different chemical classes were characterized, with nitriles and aldehydes accounting for more than 54% of the whole volatile fraction. The extract of B. fruticulosa subsp. fruticulosa showed moderate activity in the DPPH assay (IC50 = 1.65 ± 0.08 mg/mL), weak reducing power (17.47 ± 0.65 ASE/mL), and good chelating properties (IC50 = 0.38 ± 0.02 mg/mL), reaching approximately 90% activity at the highest tested concentration. Lastly, the extract was non-toxic against Artemia salina, indicating its potential safety. According to the findings, it can be stated that B. fruticulosa subsp. fruticulosa represents a new valuable source of bioactive compounds.

Comparison of Pharmacokinetics and Anti-Pulmonary Fibrosis-Related Effects of Sulforaphane and Sulforaphane N-acetylcysteine

Sulforaphane (SFN), belonging to the isothiocyanate family, has received attention owing to its beneficial activities, including chemopreventive and antifibrotic effects. As sulforaphane N-acetylcysteine (SFN-NAC), a major sulforaphane metabolite, has presented similar pharmacological activities to those of SFN, it is crucial to simultaneously analyze the pharmacokinetics and activities of SFN and SFN-NAC, to comprehensively elucidate the efficacy of SFN-containing products. Accordingly, the anti-pulmonary fibrotic effects of SFN and SFN-NAC were assessed, with simultaneous evaluation of permeability, metabolic stability, and in vivo pharmacokinetics. Both SFN and SFN-NAC decreased the levels of transforming growth factor-β1-induced fibronectin, alpha-smooth muscle actin, and collagen, which are major mediators of fibrosis, in MRC-5 fibroblast cells. Regarding pharmacokinetics, SFN and SFN-NAC were metabolically unstable, especially in the plasma. SFN-NAC degraded considerably faster than SFN in plasma, with SFN being formed from SFN-NAC. In rats, SFN and SFN-NAC showed a similar clearance when administered intravenously; however, SFN showed markedly superior absorption when administered orally. Although the plasma SFN-NAC concentration was low owing to poor absorption following oral administration, SFN-NAC was converted to SFN in vivo, as in plasma. Collectively, these data suggest that SFN-NAC could benefit a prodrug formulation strategy, possibly avoiding the gastrointestinal side effects of SFN, and with improved SFN-NAC absorption.

Analysis of Chemical Composition and In Vitro and In Vivo Antifungal Activity of Raphanus raphanistrum Extracts against Fusarium and Pythiaceae, Affecting Apple and Peach Seedlings

The goal of this investigation was to evaluate the in vitro and in vivo efficiency of Raphanus raphanistrum extracts against Fusarium and Pythiaceae species associated with apple and peach seedling decline in Tunisian nurseries. A chemical composition of organic extracts was accomplished using liquid chromatography, thin layer chromatography, and gas chromatography analysis. The in vitro test of three aqueous extract doses of R. raphanistrum against some apple and peach decline agents showed its efficacy in reducing mycelia growth. The in vivo assay of fine powder of this plant on peach seedlings revealed that treatment 8-weeks before the inoculation and planting was more efficient than the treatment before one week. This experiment revealed that the root weight of peach seedlings inoculated by F. oxysporum was improved to 207.29%. For apple seedlings, the treatment 8 weeks before the inoculation and plantation was more efficient than the treatment one week before; it reduced the root browning index. The study of R. raphanistrum chemical composition and its efficiency showed that the glucosinolates products: nitrile (4-Hydroxy-3-(4-methylphenylthio) butane nitrile, benzene acetonitrile, 4-fluoro,butane nitrile, 4-hydroxy-3-[(4-methylphenyl) thio] nitrile), and thiocyanate molecules (thiocyanic acid, ethyle) are responsible for the anti-fungal activities.

Relationship between mustard pungency and allyl-isothiocyanate content: A comparison of sensory and chemical evaluations

The correlation of sensory and chemically evaluated pungency of mustard products was investigated via a time-intensity (TI) study and quantification of allyl isothiocyanate (AITC) contents using high-performance liquid chromatography (HPLC). Sweet, medium hot, hot, and extra hot commercial mustard products from different brands were examined. Notably, we found significant differences (p < 0.05) between the maximum perceived pungency intensity of various mustard products. The maximum perceived intensity (I_max ), the duration of the decreasing phase (DUR_Dec ), and the area under the curve (AUC) values increased proportionally to the increase in the sample AITC content and were also higher in products classified as hot than in sweet mustards. The AITC concentration varied greatly between products from different brands and also between different sensory evaluated pungency levels. Furthermore, sensory evaluations and analytical results were correlated using regression analysis. The best correlation (correlation coefficient 0.891) was observed between the AITC concentration and AUC, when compared to that between the AITC concentration and DUR_Dec (correlation coefficient 0.856) or the I_max value (correlation coefficient 0.803). The calculated regression model indicates that a higher AITC content induces an intensified trigeminal pungency sensation and that the sensory and chemical evaluations of mustard products were positively correlated. Therefore, by using this regression model, the sensory rating of mustard products may be predicted by chemical analysis of the AITC contents. PRACTICAL APPLICATION: This research paper provides a method to quantify the pungency inducing irritant allyl isothiocyanate in commercial mustard products and demonstrates a correlation between sensory and chemical data. Therefore, the amounts of sensory tests in product quality assurance can be reduced and replaced or at least supported by chemical quantification of pungent substances (especially AITC) in mustard products.

The glucosinolates and their bioactive derivatives in Brassica: a review on classification, biosynthesis and content in plant tissues, fate during and after processing, effect on the human organism and interaction with the gut microbiota

The present study is a systematic review of the scientific literature reporting content, composition and biosynthesis of glucosinolates (GLS), and their derivative compounds in Brassica family. An amended classification of brassica species, varieties and their GLS content, organized for the different plant organs and in uniformed concentration measure unit, is here reported for the first time in a harmonized and comparative manner. In the last years, the studies carried out on the effect of processing on vegetables and the potential benefits for human health has increased rapidly and consistently the knowledge on the topic. Therefore, there was the need for an updated revision of the scientific literature of pre- and post-harvest modifications of GLS content, along with the role of gut microbiota in influencing their bioavailability once they are ingested. After analyzing and standardizing over 100 articles and the related data, the highest GLS content in Brassica, was declared in B. nigra (L.) W. D. J. Koch (201.95 ± 53.36 µmol g^-1), followed by B. oleracea Alboglabra group (180.9 ± 70.3 µmol g^-1). The authors also conclude that food processing can influence significantly the final content of GLS, considering the most popular methods: boiling, blanching, steaming, the latter can be considered as the most favorable to preserve highest level of GLS and their deriviatives. Therefore, a mild-processing strategic approach for GLS or their derivatives in food is recommended, in order to minimize the loss of actual bioactive impact. Finally, the human gut microbiota is influenced by Brassica-rich diet and can contribute in certain conditions to the increasing of GLS bioavailability but further studies are needed to assess the actual role of microbiomes in the bioavailability of healthy glucosinolate derivatives.

New Insights on the Role of Allyl Isothiocyanate in Controlling the Root Knot Nematode Meloidogyne hapla

Biofumigation, although a well-known method, is still controversially debated as a management strategy for plant-parasitic nematodes (PPN). Its controlling effect is attributed to the production of isothiocyanates (ITCs) following the action of myrosinase on glucosinolates (GSLs). Different ITCs are formed from different GSLs, depending on the plant species. To better understand the potential of ITCs, eight cultivars from three Brassicaceae species were investigated as biofumigation crops to control the root knot nematode Meloidogyne hapla. Since results were inconsistent, the nematicidal effect of selected ITCs were further evaluated in vitro. Based on its nematicidal potential, allyl ITC (AITC) was specifically investigated under different soil:sand compositions. A significantly lower nematicidal activity was observed in soil compared to sand. AITC was also evaluated as an additive to the biofumigation in a greenhouse trial. Its supplementation to the biofumigation process with Brassica juncea cv. Terrafit controlled M. hapla, while no control was observed using Raphanus sativus cv. Defender. Thus, the success of biofumigation seems to be strongly dependent on the soil characteristics and the ITC produced during the biofumigation process. Therefore, the supplementation of AITC in combination with the right cover crop can improve the biofumigation process to control M. hapla.

The effect of elevated ozone on floral chemistry of Brassicaceae species

Tropospheric ozone is a major atmospheric pollutant; it is phytotoxic and has a strong effect on phytochemicals, which are constitutively present in plant tissues, but also produced de novo in response to stress. It has been shown that ozone exposure can modify volatile phytochemical emissions from leaves, which could disturb interactions between plants and other organisms. However, there is a lack of knowledge on the effects of ozone on floral chemistry. The aim of this study was to determine the effects of two elevated ozone exposure scenarios (80 and 120 ppb during daylight hours for 5 consecutive days) on the floral volatile emissions and floral chemical (molecular size range C₆-C₂₀) content of four Brassicaceae species: Sinapis alba, Sinapis arvensis, Brassica napus and Brassica nigra. The results showed that the emissions of individual compounds and their relative contributions to volatile blends are both affected by ozone exposure. In addition, for all four species studied, three diterpenes (neophytadiene, cis-phytol and trans-phytol) were present in significantly lower amounts and a fourth diterpene (hexahydrofarnesyl acetone) in significantly greater amounts in ozone-exposed plants. Consistent effects of ozone exposure on volatile emissions and terpene content were observed for each of the four species studied with no significant effect of exposure level. It appeared that B. napus is the most ozone-sensitive species, whereas B. nigra is the most ozone-tolerant. Since earlier studies have indicated that ratios of phytochemicals can have substantial effects on the efficacy of chemical use by pollinators, these changes may have ecological and biological relevance that should be the focus of further elucidation.

Statistical modeling for estimating glucosinolate content in Chinese cabbage by growth conditions

BACKGROUND

Glucosinolate in Chinese cabbage (Brassica campestris L. ssp. pekinensis (Lour.) Rupr) has potential benefits for human health, and its content is affected by growth conditions. In this study, we used a statistical model to identify the relationship between glucosinolate content and growth conditions, and to predict glucosinolate content in Chinese cabbage.

RESULT

Multiple regression analysis was employed to develop the model's growth condition parameters of growing period, temperature, humidity and glucosinolate content measured in Chinese cabbage grown in a plant factory. The developed model was represented by a second-order multi-polynomial equation with two independent parameters: growth duration and temperature (adjusted R²  = 0.81), and accurately predicted glucosinolate content after 14 days of seeding.

CONCLUSION

To our knowledge, this study presents the first statistical model for evaluating glucosinolate content, suggesting a useful methodology for designing glucosinolate-related experiments, and optimizing glucosinolate content in Chinese cabbage cultivation. © 2018 Society of Chemical Industry.

Indole-3-carbinol: a plant hormone combatting cancer

A diet rich in cruciferous vegetables such as cauliflower, broccoli, and cabbage has long been considered healthy, and various epidemiological studies suggest that the consumption of cruciferous vegetables contributes to a cancer-protecting diet. While these vegetables contain a vast array of phytochemicals, the mechanism by which these vegetables counteract cancer is still largely unresolved. Numerous in situ studies have implicated indole-3-carbinol, a breakdown product of the glucosinolate indole-3-ylmethylglucosinolate, as one of the phytochemicals with anti-cancer properties. Indole-3-carbinol influences a range of cellular processes, but the mechanisms by which it acts on cancer cells are slowly being revealed. Recent studies on the role of indole-3-carbinol in Arabidopsis opens the door for cross-kingdom comparisons that can help in understanding the roles of this important phytohormone in both plant biology and combatting cancer.

Taste and Flavor Perceptions of Glucosinolates, Isothiocyanates, and Related Compounds

Brassicaceae plants are renowned for their taste, aroma and trigeminal characteristics; predominantly bitter taste, sulfurous aroma, and pungency. Compounds responsible for these sensations include the glucosinolates (GSLs) and their hydrolysis products, particularly isothiocyanates (ITCs), but also sulfur-containing volatile compounds. This article reviews the relative importance of taste and flavor perceptions resulting from such compounds; collating evidence from papers where findings are based on sensory analytical correlations, and those that have extracted specific compounds prior to sensory evaluation. Where specific GSLs impart bitterness and many ITCs impart pungency, this is clearly not true for all GSLs and ITCs. Designing crop improvement strategies for sensory traits based on total GSL content would be flawed, as it does not consider the relative differences in sensory characteristics of different GSLs and ITCs, nor the contribution from other GSL hydrolysis products. In addition, some Brassicaceae plants are consumed raw, whilst others are cooked; this affects not only the hydrolysis of GSLs, but also the generation and release of sulfides. Therefore, in breeding new plant varieties, it is prudent to consider the individual GSLs, the typical cooking conditions the plant is subjected to, enzyme stability, and resultant composition of both GSL hydrolysis products (including ITCs) and sulfides.

Determination of isothiocyanate-protein conjugates in milk and curd after adding garden cress (Lepidium sativum L.)

Isothiocyanates (ITC) play an important role in health promotion and cancer prevention due to their anti-bacterial, anti-inflammatory, and anti-cancerogenic properties. However, ITC are highly reactive so that a reaction with further food components is very likely. For example, a reaction of ITC with nucleophilic amino acid side chains of proteins such as cysteine and lysine can occur, reducing the bioavailability of indispensable amino acids and protein functions may be altered. Therefore, it is of great interest to investigate the fate of ITC in the food matrix. Accordingly, the aim of the present study was to investigate the interaction of milk proteins and the ITC benzyl isothiocyanate (BITC) and allyl isothiocyanate (AITC) forming dithiocarbamates and thioureas in milk and curd. After incubating milk and curd with pure ITC or ITC-containing garden cress (Lepidium sativum L.), proteins were isolated, digested, and analyzed via LC-ESI-MS/MS as amino acid derivatives ("conjugates"). Protein conjugates of AITC and BITC were detected in all samples investigated. Further, the acidic pH value in curd favored the formation of dithiocarbamates over the formation of thioureas. Slightly acidic or neutral conditions like in fresh milk favored the formation of thioureas. The investigations also indicated that AITC shows a higher reactivity and dithiocarbamates are formed preferably, whereas incubation with BITC lead to less protein conjugates and the ratio of thioureas and dithiocarbamates was more balanced. In addition, amino acid modifications were often analyzed with indirect methods like measuring the decline of the amino acid residues. In this study, the modified amino acids were analyzed directly leading to more reliable results concerning the amount of modification.

Allyl isothiocyanate shows promise as a naturally produced suppressant of the potato cyst nematode, Globodera pallida, in biofumigation systems

The ability of isothiocyanates to suppressGlobodera pallidawas evaluated throughin vitroassays. Several isothiocyanates increased juvenile mortality, the most effective being allyl isothiocyanate, which caused 100% mortality at both 25 and 50 ppm after 72 and 24 h exposure, respectively. In a hatching assay, allyl isothiocyanate was able to suppress hatch; in addition, replenishing allyl isothiocyanate every 3 days increased hatch suppression, and viability staining indicated that egg mortality was increased. Allyl isothiocyanate above concentrations of 50 ppm significantly affected both hatch suppression and mortality. Differing effects of isothiocyanates onG. pallidasuggest that their toxicity depends on the pest of interest and this study shows that allyl isothiocyanate is a good candidate for the control of potato cyst nematodes using biofumigation.

Structural stability and Sin a 1 anti-epitope antibody binding ability of yellow mustard (Sinapis alba L.) napin during industrial-scale myrosinase inactivation process

This study investigated the structural stability of yellow mustard (YM, Sinapis alba L.) napin and the changes of its Sin a 1 anti-epitope antibody-binding ability during myrosinase enzyme inactivation process. The food industry uses myrosinase-inactive non-pungent YM for uses beyond spice applications. Napin was isolated from seeds received from an industrial processor before (YM + M) and after (YM - M) myrosinase inactivation. Secondary and tertiary structural features and surface hydrophobicity parameters of napin were analyzed. The Sin a 1 content in YM seeds and the stability of Sin a 1-containing napin during simulated in vitro gastrointestinal (GI) digestion were determined by a non-competitive indirect enzyme-linked immunosorbent assay using the Sin a 1 anti-epitope antibody (AE-Ab) as the primary Ab. YM napin retained the dominant alpha-helical components of secondary and tertiary structure folds during this process. YM - M napin showed changes in hydrophobicity parameters of the molecules and binding ability of AE-Ab: 2.19 ± 0.48 g per 100 g of YM - M seeds vs. 1.49 ± 0.16 g per 100 g YM + M seeds. YM - M proteins were more susceptible for in vitro GI digestion and also showed a 30% reduction in AE-Ab binding ability upon digestion of napins. This suggests that the myrosinase inactivation process has induced the surface modification of napin, exposing Sin a 1 epitope, leading to an increase in AE-Ab binding. However, the epitope region of YM - M napin showed improved susceptibility for hydrolysis during GI digestion resulting in fewer available epitope regions, suggesting a possible reduction in napin immune reactivity.

A mechanistic perspective on process-induced changes in glucosinolate content in Brassica vegetables: a review

Brassica vegetables are consumed mostly after processing, which is expected to give beneficial effects on the vegetable properties, such as improved palatability and bioavailability of nutrients, or shelf life extension. But processing also results to various changes in the content of health promoting phytochemicals like glucosinolates. This paper reviews the effects of processing on the glucosinolates content by using a mechanism approach underlying processing method employed. Cultural differences between Eastern and Western preparation practices and their possible effect on glucosinolate retention are highlighted. Boiling and blanching considerably reduce the glucosinolate content mainly due to mechanisms of cell lysis, diffusion, and leaching, and partly due to thermal and enzymatic degradation. Steaming, microwave processing, and stir frying either retain or slightly reduce the glucosinolates content due to low degrees of leaching; moreover, these methods seem to enhance extractability of glucosinolates from the plant tissue. Fermentation reduces the glucosinolate content considerably, but the underlying mechanisms are not yet studied in detail. Studying the changes of glucosinolates during processing by a mechanistic approach is shown to be valuable to understand the impact of processing and to optimize processing conditions for health benefits of these compounds.

The Effect of pH and Temperature on Cabbage Volatiles During Storage

During storage of shredded cabbage, characteristic sulfurous volatile compounds are formed affecting cabbage aroma both negatively and positively. Selected ion flow tube-mass spectrometry (SIFT-MS) was used to measure the concentration of cabbage volatiles during storage. The volatile levels of cabbage samples were measured at pH 3.3 to 7.4 at 4 °C for 14 d, and pH 3.3 at 25 °C for 5 d in order to determine the effect of pH and temperature. Aroma intensity, best aroma, freshness, and off odor were evaluated in a sensory test of the samples at 4 °C. The desirable volatile allyl isothiocyanate was lower in high pH samples (pH 7.4 and 6.4), whereas higher concentrations were detected in low pH samples (pH 3.3 and 4.6). Lipoxygenase volatiles, which produce a fresh green and leafy aroma in cabbage, were generated in very low amounts at any pH value. High pH samples generated significantly higher concentrations of off odors such as dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, and methanethiol. Sensory tests showed that higher pH samples had significantly stronger off odor and lower desirable cabbage aroma than lower pH samples. Thus, sensory results matched the volatile results in that samples at higher pH levels formed the highest amount of undesirable volatiles and the least amount of desirable volatiles. Storage at 25 °C produced similar concentrations of allyl isothiocyanate, but significantly higher levels of off odors, than at 4 °C. Shredded cabbage products should be stored in low pH dressings to minimize formation of off odors and maximize formation of characteristic, desirable cabbage odor.

Characterization of glutathione transferases involved in the pathogenicity of Alternaria brassicicola

BACKGROUND

Glutathione transferases (GSTs) represent an extended family of multifunctional proteins involved in detoxification processes and tolerance to oxidative stress. We thus anticipated that some GSTs could play an essential role in the protection of fungal necrotrophs against plant-derived toxic metabolites and reactive oxygen species that accumulate at the host-pathogen interface during infection.

RESULTS

Mining the genome of the necrotrophic Brassica pathogen Alternaria brassicicola for glutathione transferase revealed 23 sequences, 17 of which could be clustered into the main classes previously defined for fungal GSTs and six were 'orphans'. Five isothiocyanate-inducible GSTs from five different classes were more thoroughly investigated. Analysis of their catalytic properties revealed that two GSTs, belonging to the GSTFuA and GTT1 classes, exhibited GSH transferase activity with isothiocyanates (ITC) and peroxidase activity with cumene hydroperoxide, respectively. Mutant deficient for these two GSTs were however neither more susceptible to ITC nor less aggressive than the wild-type parental strain. By contrast mutants deficient for two other GSTs, belonging to the Ure2pB and GSTO classes, were distinguished by their hyper-susceptibility to ITC and low aggressiveness against Brassica oleracea. In particular AbGSTO1 could participate in cell tolerance to ITC due to its glutathione-dependent thioltransferase activity. The fifth ITC-inducible GST belonged to the MAPEG class and although it was not possible to produce the soluble active form of this protein in a bacterial expression system, the corresponding deficient mutant failed to develop normal symptoms on host plant tissues.

CONCLUSIONS

Among the five ITC-inducible GSTs analyzed in this study, three were found essential for full aggressiveness of A. brassicicola on host plant. This, to our knowledge is the first evidence that GSTs might be essential virulence factors for fungal necrotrophs.

Cruciferous vegetables, isothiocyanates, and prevention of bladder cancer

Approximately 80% of human bladder cancers (BC) are non-muscle invasive when first diagnosed and are usually treated by transurethral tumor resection. But 50-80% of patients experience cancer recurrence. Agents for prevention of primary BC have yet to be identified. Existing prophylactics against BC recurrence, e.g., Bacillus Calmette-Guerin (BCG), have limited efficacy and utility; they engender significant side effects and require urethral catheterization. Many cruciferous vegetables, rich sources of isothiocyanates (ITCs), are commonly consumed by humans. Many ITCs possess promising chemopreventive activities against BC and its recurrence. Moreover, orally ingested ITCs are selectively delivered to bladder via urinary excretion. This review is focused on urinary delivery of ITCs to the bladder, their cellular uptake, their chemopreventive activities in preclinical and epidemiological studies that are particularly relevant to prevention of BC recurrence and progression, and their chemopreventive mechanisms in BC cells and tissues.

Effects of benzyl isothiocyanate and its N-acetylcysteine conjugate on induction of detoxification enzymes in hepa1c1c7 mouse hepatoma cells

The induction of detoxification enzymes by benzyl isothiocyanate (BITC) and its synthetic N-acetyl-L-cysteine (NAC) conjugate (NAC-BITC) was examined in Hepa1c1c7 murine hepatoma cells. BITC and NAC-BITC inhibited Hepa1c1c7 cell growth in a dose-dependent manner. Cell growth was 4.5~57.2% lower in Hepa1c1c7 cells treated with 0.1~10 μM BITC than in control-treated Hepa1c1c7 cells. The NAC-BITC treatment had a similar inhibitory pattern on Hepa1c1c7 cell growth; 0.5 μM and 10 μM NAC-BITC decreased cell growth by 13.6% and 47.4%, respectively. Treatment of Hepa1c1c7 cells with 0.1~2.0 μM BITC also elicited a dose-response effect on the induction of quinone reductase quinone reductase (QR) activity and QR mRNA expression. Treatment with 1 μM and 2 μM BITC caused 1.8- and 2.8-fold inductions of QR mRNA, respectively. By comparison, treatment with 1 μM and 2 μM NAC-BITC caused 1.6- and 1.9-fold inductions of QR mRNA, respectively. Cytochrome P450 (CYP) 1A1 and CYP2E1 induction were lower in 0.1~2 μM BITC-treated cells than in control-treated cells. CYP2E1 activity was 1.2-fold greater in 0.1 μM NAC-BITC-treated cells than in control-treated cells. However, the CYP2E1 activity of cells treated with higher concentrations (i.e., 1~2 μM) of NAC-BITC was similar to the activity of control-treated cells. Considering the potential of isothiocyanatesto prevent cancer, these results provide support for the use of BITC and NAC-BITC conjugates as chemopreventive agents.

Taste and physiological responses to glucosinolates: seed predator versus seed disperser

In contrast to most other plant tissues, fleshy fruits are meant to be eaten in order to facilitate seed dispersal. Although fleshy fruits attract consumers, they may also contain toxic secondary metabolites. However, studies that link the effect of fruit toxins with seed dispersal and predation are scarce. Glucosinolates (GLSs) are a family of bitter-tasting compounds. The fleshy fruit pulp of Ochradenus baccatus was previously found to harbor high concentrations of GLSs, whereas the myrosinase enzyme, which breaks down GLSs to produce foul tasting chemicals, was found only in the seeds. Here we show the differential behavioral and physiological responses of three rodent species to high dose (80%) Ochradenus’ fruits diets. Acomys russatus, a predator of Ochradenus’ seeds, was the least sensitive to the taste of the fruit and the only rodent to exhibit taste-related physiological adaptations to deal with the fruits’ toxins. In contrast, Acomys cahirinus, an Ochradenus seed disperser, was more sensitive to a diet containing the hydrolyzed products of the GLSs. A third rodent (Mus musculus) was deterred from Ochradenus fruits consumption by the GLSs and their hydrolyzed products. We were able to alter M. musculus avoidance of whole fruit consumption by soaking Ochradenus fruits in a water solution containing 1% adenosine monophosphate, which blocks the bitter taste receptor in mice. The observed differential responses of these three rodent species may be due to evolutionary pressures that have enhanced or reduced their sensitivity to the taste of GLSs.

Determination of goitrogenic metabolites in the serum of male wistar rat fed structurally different glucosinolates

Glucosinolates (GLSs) are abundant in cruciferous vegetables and reported to have anti thyroidal effects. Four GLSs (sinigrin, progoitrin, glucoerucin, and glucotropaeolin) were administered orally to rats, and the breakdown products of GLSs (GLS-BPs: thiocyanate ions, cyanide ions, organic isothiocyanates, organic nitriles, and organic thiocyanates) were measured in serum. Thiocyanate ions were measured by colorimetric method, and cyanide ions were measured with CI-GC-MS. Organic isothiocyanates and their metabolites were measured with the cyclocondensation assay. Organic nitriles and organic thiocyanates were measured with EI-GC-MS. In all treatment groups except for progoitrin, thiocyanate ions were the highest among the five GLS-BPs. In the progoitrin treated group, a high concentration of organic isothiocyanates (goitrin) was detected. In the glucoerucin treated group, a relatively low amount of goitrogenic substances was observed. The metabolism to thiocyanate ions happened within five hours of the administration, and the distribution of GLSs varied with the side chain. GLSs with side chains that can form stable carbocation seemed to facilitate the degradation reaction and produce a large amount of goitrogenic thiocyanate ions. Because goitrogenic metabolites can be formed without myrosinase, the inactivation of myrosinase during cooking would have no effect on the anti-nutritional effect of GLSs in cruciferous vegetables.

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.

Insecticidal activity of bio-oil from the pyrolysis of straw from Brassica spp

Agricultural crop residues can be converted through thermochemical pyrolysis to bio-oil, a sustainable source of biofuel and biochemicals. The pyrolysis bio-oil is known to contain many chemicals, some of which have insecticidal activity and can be a potential source of value-added pest control products. Brassicacae crops, cabbage, broccoli, and mustards, contain glucosinolates and isocyanates, compounds with recognized anti-herbivore activity. In Canada, canola Brassica napus straw is available from over 6 000 000 ha and mustard Brassica carinata and Brassica juncea straw is available from 200 000 ha. The straw can be converted by microbial lignocellulosic enzymes as a substrate for bioethanol production but can also be converted to bio-oil by thermochemical means. Straw from all three species was pyrolyzed, and the insecticidal components in the bio-oil were isolated by bioassay-guided solvent fractionation. Of particular interest were the mustard straw bio-oil aqueous fractions with insecticidal and feeding repellent activity to Colorado potato beetle larvae. Aqueous fractions further analyzed for active compounds were found not to contain many of the undesirable phenol compounds, which were previously found in other bio-oils seen in the dichloromethane (DCM) and ethyl acetate (EA) solvent phases of the present study. Identified within the most polar fractions were hexadecanoic and octadecanoic fatty acids, indicating that separation of these compounds during bio-oil production may provide a source of effective insecticidal compounds.

Contamination of deconjugation enzymes derived from Helix pomatia with the plant bioactive compounds 3,3'-diindolylmethane, 5-methoxypsoralen, and 8-methoxypsoralen

Bioactive compounds from plant foods are intensely investigated for effects on disease prevention. β-Glucuronidase/arylsulfatase from Helix pomatia (snail) is commonly used when quantifying exposure to metabolized dietary components. However, we describe here the contamination of multiple formulations of this enzyme preparation with 3,3'-diindolylmethane (DIM), 8-methoxypsoralen (8-MOP), and 5-methoxypsoralen (5-MOP), bioactives from cruciferous and apiaceous vegetables under investigation as putative cancer chemopreventive agents. We identified an Escherichia coli preparation of β-glucuronidase as free from contamination with any of the compounds tested. These results demonstrate the importance of selecting appropriate enzyme preparations when quantifying naturally occurring, trace level compounds in biological fluids.

Genetic analysis of health-related secondary metabolites in a Brassica rapa recombinant inbred line population

The genetic basis of the wide variation for nutritional traits in Brassica rapa is largely unknown. A new Recombinant Inbred Line (RIL) population was profiled using High Performance Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR) analysis to detect quantitative trait loci (QTLs) controlling seed tocopherol and seedling metabolite concentrations. RIL population parent L58 had a higher level of glucosinolates and phenylpropanoids, whereas levels of sucrose, glucose and glutamate were higher in the other RIL population parent, R-o-18. QTL related to seed tocopherol (α-, β-, γ-, δ-, α-/γ- and total tocopherol) concentrations were detected on chromosomes A3, A6, A9 and A10, explaining 11%–35% of the respective variation. The locus on A3 co-locates with the BrVTE1gene, encoding tocopherol cyclase. NMR spectroscopy identified the presence of organic/amino acid, sugar/glucosinolate and aromatic compounds in seedlings. QTL positions were obtained for most of the identified compounds. Compared to previous studies, novel loci were found for glucosinolate concentrations. This work can be used to design markers for marker-assisted selection of nutritional compounds in B. rapa.

Interaction of cruciferous phytoanticipins with plant fungal pathogens: indole glucosinolates are not metabolized but the corresponding desulfo-derivatives and nitriles are

Glucosinolates represent a large group of plant natural products long known for diverse and fascinating physiological functions and activities. Despite the relevance and huge interest on the roles of indole glucosinolates in plant defense, little is known about their direct interaction with microbial plant pathogens. Toward this end, the metabolism of indolyl glucosinolates, their corresponding desulfo-derivatives, and derived metabolites, by three fungal species pathogenic on crucifers was investigated. While glucobrassicin, 1-methoxyglucobrassicin, 4-methoxyglucobrassicin were not metabolized by the pathogenic fungi Alternaria brassicicola, Rhizoctonia solani and Sclerotinia sclerotiorum, the corresponding desulfo-derivatives were metabolized to indolyl-3-acetonitrile, caulilexin C (1-methoxyindolyl-3-acetonitrile) and arvelexin (4-methoxyindolyl-3-acetonitrile) by R. solani and S. sclerotiorum, but not by A. brassicicola. That is, desulfo-glucosinolates were metabolized by two non-host-selective pathogens, but not by a host-selective. Indolyl-3-acetonitrile, caulilexin C and arvelexin were metabolized to the corresponding indole-3-carboxylic acids. Indolyl-3-acetonitriles displayed higher inhibitory activity than indole desulfo-glucosinolates. Indolyl-3-methanol displayed antifungal activity and was metabolized by A. brassicicola and R. solani to the less antifungal compounds indole-3-carboxaldehyde and indole-3-carboxylic acid. Diindolyl-3-methane was strongly antifungal and stable in fungal cultures, but ascorbigen was not stable in solution and displayed low antifungal activity; neither compound appeared to be metabolized by any of the three fungal species. The cell-free extracts of mycelia of A. brassicicola displayed low myrosinase activity using glucobrassicin as substrate, but myrosinase activity was not detectable in mycelia of either R. solani or S. sclerotiorum.

Synthetic and green vegetable isothiocyanates target red blood leukemia cancers

Isothiocyanates (ITCs), the breakdown products of glucosinolates found primarily in species of Brassicaceae (Cruciferae), are potential anti-cancer compounds. This review compiles data on how through different modes of action ITCs and their synthetic counterparts target leukemia.

Allyl isothiocyanate induced stress response in Caenorhabditis elegans

BACKGROUND

Allyl isothiocyanate (AITC) from mustard is cytotoxic; however the mechanism of its toxicity is unknown. We examined the effects of AITC on heat shock protein (HSP) 70 expression in Caenorhabditis elegans. We also examined factors affecting the production of AITC from its precursor, sinigrin, a glucosinolate, in ground Brassica juncea cv. Vulcan seed as mustard has some potential as a biopesticide.

FINDINGS

An assay to determine the concentration of AITC in ground mustard seed was improved to allow the measurement of AITC release in the first minutes after exposure of ground mustard seed to water. Using this assay, we determined that temperatures above 67°C decreased sinigrin conversion to AITC in hydrated ground B. juncea seed. A pH near 6.0 was found to be necessary for AITC release. RT-qPCR revealed no significant change in HSP70A mRNA expression at low concentrations of AITC (< 0.1 μM). However, treatment with higher concentrations (> 1.0 μM) resulted in a four- to five-fold increase in expression. A HSP70 ELISA showed that AITC toxicity in C. elegans was ameliorated by the presence of ground seed from low sinigrin B. juncea cv. Arrid.

CONCLUSIONS

• AITC induced toxicity in C. elegans, as measured by HSP70 expression.• Conditions required for the conversion of sinigrin to AITC in ground B. juncea seed were determined.• The use of C. elegans as a bioassay to test AITC or mustard biopesticide efficacy is discussed.

Oilseed rape seeds with ablated defence cells of the glucosinolate-myrosinase system. Production and characteristics of double haploid MINELESS plants of Brassica napus L

Oilseed rape and other crop plants of the family Brassicaceae contain a unique defence system known as the glucosinolate-myrosinase system or the 'mustard oil bomb'. The 'mustard oil bomb' which includes myrosinase and glucosinolates is triggered by abiotic and biotic stress, resulting in the formation of toxic products such as nitriles and isothiocyanates. Myrosinase is present in specialist cells known as 'myrosin cells' and can also be known as toxic mines. The myrosin cell idioblasts of Brassica napus were genetically reprogrammed to undergo controlled cell death (ablation) during seed development. These myrosin cell-free plants have been named MINELESS as they lack toxic mines. This has led to the production of oilseed rape with a significant reduction both in myrosinase levels and in the hydrolysis of glucosinolates. Even though the myrosinase activity in MINELESS was very low compared with the wild type, variation was observed. This variability was overcome by producing homozygous seeds. A microspore culture technique involving non-fertile haploid MINELESS plants was developed and these plants were treated with colchicine to produce double haploid MINELESS plants with full fertility. Double haploid MINELESS plants had significantly reduced myrosinase levels and glucosinolate hydrolysis products. Wild-type and MINELESS plants exhibited significant differences in growth parameters such as plant height, leaf traits, matter accumulation, and yield parameters. The growth and developmental pattern of MINELESS plants was relatively slow compared with the wild type. The characteristics of the pure double haploid MINELESS plant are described and its importance for future biochemical, agricultural, dietary, functional genomics, and plant defence studies is discussed.

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.

Health benefits of vitamins and secondary metabolites of fruits and vegetables and prospects to increase their concentrations by agronomic approaches

Fruits and vegetables (FAVs) are an important part of the human diet and a major source of biologically active substances such as vitamins and secondary metabolites. The consumption of FAVs remains globally insufficient, so it should be encouraged, and it may be useful to propose to consumers FAVs with enhanced concentrations in vitamins and secondary metabolites. There are basically two ways to reach this target: the genetic approach or the environmental approach. This paper provides a comprehensive review of the results that have been obtained so far through purely agronomic approaches and brings them into perspective by comparing them with the achievements of genetic approaches. Although agronomic approaches offer very good perspectives, the existence of variability of responses suggests that the current understanding of the way regulatory and metabolic pathways are controlled needs to be increased. For this purpose, more in-depth study of the interactions existing between factors (light and temperature, for instance, genetic factors × environmental factors), between processes (primary metabolism and ontogeny, for example), and between organs (as there is some evidence that photooxidative stress in leaves affects antioxidant metabolism in fruits) is proposed.

Removing the mustard oil bomb from seeds: transgenic ablation of myrosin cells in oilseed rape (Brassica napus) produces MINELESS seeds

Many plant phytochemicals constitute binary enzyme-glucoside systems and function in plant defence. In brassicas, the enzyme myrosinase is confined to specific myrosin cells that separate the enzyme from its substrate; the glucosinolates. The myrosinase-catalysed release of toxic and bioactive compounds such as isothiocyanates, upon activation or tissue damage, has been termed 'the mustard oil bomb' and characterized as a 'toxic mine' in plant defence. The removal of myrosin cells and the enzyme that triggers the release of phytochemicals have been investigated by genetically modifying Brassica napus plants to remove myrosinase-storing idioblasts. A construct with the seed myrosin cell-specific Myr1.Bn1 promoter was used to express a ribonuclease, barnase. Transgenic plants ectopically expressing barnase were embryo lethal. Co-expressing barnase under the control of the Myr1.Bn1 promoter with the barnase inhibitor, barstar, under the control of the cauliflower mosaic virus 35S promoter enabled a selective and controlled death of myrosin cells without affecting plant viability. Ablation of myrosin cells was confirmed with light and electron microscopy, with immunohistological analysis and immunogold-electron microscopy analysis showing empty holes where myrosin cells normally are localized. Further evidence for a successful myrosin cell ablation comes from immunoblots showing absence of myrosinase and negligible myrosinase activity, and autolysis experiments showing negligible production of glucosinolate hydrolysis products. The plants where the myrosin defence cells have been ablated and named 'MINELESS plants'. The epithiospecifier protein profile and glucosinolate levels were changed in MINELESS plants, pointing to localization of myrosinases and a 35 kDa epithiospecifier protein in myrosin cells and a reduced turnover of glucosinolates in MINELESS plants.