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Glucosinolates, isothiocyanates and human health
Abstract
Concurrent with the increase in our knowledge of the genetic and environmental factors that lead to glucosinolate accumulation
in plants, and the role of these compounds and their derivatives in mediating plant–herbivore interactions, there has been
significant advances in our understanding of how glucosinolates and their products may contribute to a reduction in risk of
carcinogenesis and heart disease when consumed as part of the diet. In this paper, we review the epidemiological evidence
for the health promoting effects of cruciferous vegetables, the processes by which glucosinolates and isothiocyanates are
absorbed and metabolised by humans, with particular regard to the role of glutathione S-transferases, and the biological activity
of isothiocyanates towards mammalian cells and tissues.
... ITCs are conjugated with glutathione to dithiocarbamates by glutathione S-transferases (GST). Dithiocarbamates are cleaved via mercapturic acid pathway to cysteine-ITC conjugates, then become converted to the corresponding N-acetyl-S-cysteine conjugates by N-acetyl transferase [10,30,[48][49][50][51]. ...
... In AD, I3C lessened Aβ 1-42 aggregation and at high concentration inhibited Aβ 1-42 fibril polymerization [114]. Comparable but superior effect has been achieved on Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) , as I3C significantly inhibited and destabilized already formed Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) aggregates and prevented Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) -induced damage to brain mitochondria [299]. Moreover, I3C's induction of AhR promoted endogenous Aβ catabolic enzyme Neprilysin expression and activity, reduced Aβ 42 levels and ameliorated cognition dysfunction; it was proposed that AhR might serve as a therapeutic target in the treatment of AD [115]. ...
... In AD, I3C lessened Aβ 1-42 aggregation and at high concentration inhibited Aβ 1-42 fibril polymerization [114]. Comparable but superior effect has been achieved on Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) , as I3C significantly inhibited and destabilized already formed Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) aggregates and prevented Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) -induced damage to brain mitochondria [299]. Moreover, I3C's induction of AhR promoted endogenous Aβ catabolic enzyme Neprilysin expression and activity, reduced Aβ 42 levels and ameliorated cognition dysfunction; it was proposed that AhR might serve as a therapeutic target in the treatment of AD [115]. ...
Neurodegenerative diseases (NDDs) and cardiovascular diseases (CVDs) are illnesses that affect the nervous system and heart, all of which are vital to the human body. To maintain health of the human body, vegetable diets serve as a preventive approach and particularly Brassica vegetables have been associated with lower risks of chronic diseases, especially NDDs and CVDs. Interestingly, glucosinolates (GLs) and isothiocyanates (ITCs) are phytochemicals that are mostly found in the Cruciferae family and they have been largely documented as antioxidants contributing to both cardio- and neuroprotective effects. The hydrolytic breakdown of GLs into ITCs such as sulforaphane (SFN), phenylethyl ITC (PEITC), moringin (MG), erucin (ER), and allyl ITC (AITC) has been recognized to exert significant effects with regards to cardio- and neuroprotection. From past in vivo and/or in vitro studies, those phytochemicals have displayed the ability to mitigate the adverse effects of reactive oxidation species (ROS), inflammation, and apoptosis, which are the primary causes of CVDs and NDDs. This review focuses on the protective effects of those GL-derived ITCs, featuring their beneficial effects and the mechanisms behind those effects in CVDs and NDDs.
... Among the hydrolysis products, isothiocyanates have a direct positive effect on human health. Some isothiocyanates activate phase 2 detoxification enzymes, resulting in the inhibition of cancer growth and carcinogens [10]. Additionally, in Chinese cabbage, it is known that glucosinolate degradation products play a role in defense against other insects [11]. ...
... The decomposition byproducts of indole glucosinolates, such as GBS, have been recognized as phytoalexins in several species of Brassica, and they are acknowledged to have a significant role in plants defense metabolism [23]. In addition, sulforaphane, indole-3-carbinol, and glucobrassin (GBS), produced by myrosinase, are known to have anticancer functions [10].. They inhibit phase 1 detoxification enzyme activity and induce the activity of phase 2 detoxification enzymes to suppress cancer development [24,25]. ...
The genebank at the National Agrobiodiversity Center (RDA-Genebank, Jeonju, Republic of Korea), conserves approximately 8000 germplasms of Brassica spp., of which Chinese cabbage (Brassica rapa L. ssp. pekinensis) is one of the major crops actively used as food in Northeast Asia, including Korea, as the main ingredient for kimchi. Glucosinolates are a major class of compounds in Chinese cabbage that are responsible for their distinctive flavor, and RDA-Genebank is constantly building a related database (DB) to select suitable germplasms required by consumers and provide resources for breeding programs. In this study, ten glucosinolates were analyzed in sixty Chinese cabbage germplasms. Six aliphatic glucosinolates were the major components, accounting for 85.00% to 91.98% of total glucosinolates in each germplasm. Among them, gluconapin (333.26 to 23,501.58 μmol∙kg−1 DW) was highly represented, followed by glucobrassicanapin (545.60 to 10,344.70 μmol∙kg−1 DW) and progoitrin (155.28 to 8536.51 μmol∙kg−1 DW). In addition, we selected germplasms with a high content of each studied glucosinolate. To analyze the diversity and distribution of glucosinolates among the studied germplasms, Pearson’s correlation was performed, and the related results were interpreted through their biosynthetic pathways. The k-means clustering indicated four optimal clusters, which were confirmed through principal component analysis. Orthogonal projection to latent structure discriminant analysis (OPLS-DA) was also performed on the status (landrace and cultivar) and origin (Korea, China, Taiwan, and Japan) passport data of the germplasms, followed by the calculation of variable importance in the projection (VIP) values. These results are part of a continuous series of studies to analyze the glucosinolates of Brassica germplasms that are being conserved at RDA-Genebank. We aim to provide related results through a public platform accessible to everyone and thereby improve the distribution of Brassica germplasms.
... Mankind has made use of the biological activities and physicochemical properties of these metabolites for millenia, for example by using plant preparations or isolated plant compounds as medicines, stains, pesticides, spices, or perfumes (Appendino and Pollastro 2009;Dias et al. 2012). Besides these applications, specialized metabolites are endogenous components of plant-derived foods, equipping them with flavors, smells and colors as well as health-beneficial or, in some cases, adverse effects (Moreira et al. 2018;Traka and Mithen 2009;Zimmermann and Wagner 2021). Despite their long history of human usage, applications of specialized metabolites as pure compounds are often limited by their occurrence in small quantities and/ or as complex mixtures. ...
... Glucosinolates, a relatively small group of sulfur-containing specialized metabolites, which occur primarily in plants of the Brassicales order, have attracted a lot of interest in both fundamental and applied research (Blažević et al. 2020;Halkier and Gershenzon 2006). For example, their biosynthesis, transport, metabolism and biological roles can be studied in Arabidopsis, a natural glucosinolate producer, while potential health benefits associated with the ingestion of glucosinolatecontaining vegetables such as broccoli have prompted the desire to breed high-glucosinolate varieties, to conduct clinical studies for evaluation of health effects, and to understand their mechanisms of action (Bednarek et al. 2009;Fahey et al. 2017;Frerigmann and Gigolashvili 2014;Nour-Eldin et al. 2012;Traka and Mithen 2009). As a consequence, heterologous production of glucosinolates has been studied intensively to provide a stable supply of structurally diverse glucosinolates or to use them in planta in pest management strategies or as functional foods (Petersen et al. 2018). ...
Glucosinolates, a group of sulfur-containing specialized metabolites of the Brassicales, have attracted a lot of interest in nutrition, medicine and agriculture due to their positive health effects and their involvement in plant defense. Their biological activities and the extensive knowledge of their biosynthesis have inspired research into development of crops with enhanced glucosinolate contents as well as their biotechnological production in homologous and heterologous systems. Here, we provide proof-of-concept for transgenic suspension cultures of carrot (Daucus carota, Apiacae) as a scalable production platform for plant specialized metabolites using benzylglucosinolate as a model. Two T-DNAs carrying in total six genes of the benzylglucosinolate biosynthesis pathway from Arabidopsis thaliana as well as NPTII and BAR as selectable markers were transferred to carrot cells by Agrobacterium tumefaciens-mediated transformation. Putative transformants selected based on their kanamycin and BASTA resistances were subjected to HPLC-MS analysis. Of 79 putative transformants, 17 produced benzylglucosinolate. T-DNA-integration was confirmed for the five best producers. Callus from these transformants was used to establish suspension cultures for quantitative analysis. When grown in 60-ml-cultures, the best transformants produced roughly 2.5 nmol (g fw)⁻¹ benzylglucosinolate, together with up to 10 nmol (g fw)⁻¹ desulfobenzylglucosinolate. Only one transformant produced more benzylglucosinolate than desulfobenzylglucosinolate. The concentration of sulfate in the medium was not a major limiting factor. High production seemed to be associated with poor growth and vice versa. Therefore, future research should try to optimize medium and cultivation process and to separate growth and production phase by using an inducible promoter.
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... It is believed that glucosinolates and their breakdown productsisothiocyanates -are responsible for the characteristic taste and smell of Brassica vegetables (Drewnowski & Gomez-Carneros, 2000;Fenwick, Heaney, & Mullin, 1983;Van Doorn et al., 1998), however, literature data in this matter are ambiguous and many sources negate this hypothesis (Bell & Wagstaff, 2014;Molina-Vargas, 2013;Schreiber, Jin, & Winkler, 2011;Zabaras, Roohani, Krishnamurthy, Cochet, & Delahunty, 2013). The problem seems to be particularly significant, mainly due to the bioactive properties of isothiocyanates which have undergone extensive research on their anticancer properties in recent years (Traka & Mithen, 2009). The progress in analytical techniques allowed to develop the concept of sensomics (Dresel, Dunkel, & Hofmann, 2015), which allowed to broaden knowledge about the relationships determining consumer acceptance of foods and the impact of technological or culinary treatments on their changes. ...
... It is probably due to the complicated cleanup procedure which is necessary to obtain appropriate amounts and purity for a sensory evaluation. Some glucosinolates, like glucoraphanin -the most abundant glucosinolate in broccoli -have shown a lack of any association with the bitter taste in Brassica vegetables (Traka & Mithen, 2009). The same situation occurred with glucoraphanin degradation productsulforaphanewhich despite the high concentration of its precursor was not visible on the chromatogram from sensitive GC × GC analysis (Wieczorek & Jeleń, 2019). ...
Main groups of sensory active compounds - glucosinolates, isothiocyanates, phenolics and sugars in 3 cultivars of broccoli, 5 of Brussels sprout, 3 of cauliflower, and 4 of kohlrabi, both raw and cooked, were analyzed and correlated with selected sensory traits. The differences in the concentration of these components were significant between different vegetables and also noticeable between cultivars of one vegetable. The bitterness of Brussels sprouts and broccoli was correlated with glucosinolates, though Brussel sprouts contained definitely higher concentration (>1 g/kg fw) of these substances than their concentration in broccoli (<0.3 g/kg fw), or other vegetables. A positive correlation between sugar concentration and general desirability was observed in Brussels sprouts (0.91 — raw), kohlrabi (0.53 — raw; 0.8 — cooked), and raw cauliflower (0.85). According to sensory analysis, the high correlation between sweetness level and general desirability was observed, however, sweetness intensity was not correlated with total sugars concentration. A lack of any correlation between phenolic content and taste was observed. The results of research in this work emphasized the diversity of investigated Brassica vegetables from both phytochemical and sensory point of view.
... The most abundant GSLs in broccoli is glucoraphanin (GRA), which can be hydrolyzed into sulforaphane by myrosinase [6]. Sulforaphane can effectively prevent or reverse cancers, hepatic, steatosis, and cardiovascular diseases [7][8][9][10]. ...
... In the microwave method, sulforaphane contents in the two varieties showed high rates of increases at 5 min. The content increased by 29.40% relative to that in the fresh florets of 'Yanxiu' but decreased by 10 Sulforaphane content in broccoli florets first decreased, then increased, and finally decreased with increasing cooking time in the three cooking methods, similar to AGS content ( Figure 5C,D). In the boiling method, sulforaphane contents in the two varieties showed high rates of increases at 5 min, but the values were lower than those obtained at 0 min. ...
The effects of storage conditions and cooking methods on chlorophyll, glucosinolate (GSL), and sulforaphane content in broccoli florets were investigated in this study. For the storage experiment, fresh broccoli florets were stored for 2, 4, and 6 days at 10, 4, and 0 °C with or without 1-methylcyclopropene (1-MCP) treatment. For the cooking experiment, fresh broccoli florets were cooked for 1, 3, 5, 7, and 9 min under three cooking methods, namely, steaming, microwaving, and boiling. Results showed that the contents of chlorophyll, aliphatic GSL, indole GSL, and sulforaphane in broccoli florets of two cultivars decreased with prolonged storage time. The retained contents of chlorophyll, GSLs, and sulforaphane under 0 °C storage condition were significantly higher than those under 10 °C storage condition after 6 days of storage. The sulforaphane content was increased by 1-MCP treatment but differed among varieties. The cooking experiment showed that aliphatic GSL content decreased with increased cooking time under three cooking methods, and indole GSL and sulforaphane contents had a fluctuating trend with increasing cooking time after steaming and microwaving. Sulforaphane content increased by 17.15–50.16% relative to that in fresh broccoli florets and was considerably affected by cooking time. The highest level of sulforaphane content was retained for 7 min during steaming or 5 min during microwaving. Therefore, the combination of 1-MCP treatment and 0 °C storage condition had the best performance in preserving chlorophyll, GSLs, and sulforaphane. Moreover, steaming for 7 min or microwaving for 5 min is a more effective method for preserving the quality and increasing the sulforaphane content of broccoli florets than boiling.
... Currently accepted hypotheses propose antioxidant properties as being the origin of the B. rapa health benefits [10]. It could be assumed that the best way to confirm this antioxidant property would be to compare B. rapa plant consumption to an oxidant molecule. ...
... Foods 2021, 10, 2720 ...
Brassica rapa L. subsp. rapa (turnip greens), a traditionally consumed vegetable, is well-known due to its high content of glucosinolates, which are secondary metabolites with a positive biological activity for human health. Our hypothesis has been based on the relation between B. rapa glucosinolate content and its healthy properties, and our aim is to establish guidelines for safe B. rapa vegetable consumption. Three B. rapa cultivars (143N5, 143N7 and 163N7) have been characterized by HPLC analysis of purified extracts from leaf samples in order to determine their glucosinolate content and to relate this content to beneficial effects on DNA protection, lifespan extension and chemoprevention. In order to ascertain the heath properties in vitro and in vivo, toxicity activities were assayed in the Drosophila melanogaster and leukaemia cell models; genomic safety was also assessed in both models using genotoxicity, fragmentation and comet assay. The Drosophila model has also been used to study the antioxidative activity and the longevity induction. Our results showed a relationship between B. rapa glucosinolate content and its safety and benefices in its consumption. Gluconapin, the main B. rapa glucosinolate, was directly related with these wholesome effects. The relevant conclusion in the present research is focused on B. rapa cultivar 163N7 due to its high gluconapin content and low progoitrin content, which exert anti-cancer and DNA protection properties and could be recommended as being safe and healthy for human consumption.
... The beneficial effects of selenium on GSL biosynthesis are likely due to the shared transporters of selenium and sulfur and the application of selenium can influence the expression of genes encoding for these transporters, thereby increasing the accumulation of GSLs. Moreover, the amino acids methionine and tryptophan, precursors of aliphatic and indolic GSLs respectively, could increase GSLs content in broccoli (Traka & Mithen, 2008). Aliphatic GSL levels were dramatically increased by 32% when the sulfur-containing amino acid methionine was administered at a concentration of 5 mM. ...
Background
Cruciferous sprout is a new form of vegetable product that is gaining attention due to its high content of bioactive compounds such as glucosinolates. As a diverse class of phytochemicals, glucosinolates and glucosinolate-derived products such as isothiocyanates are popular targets for scientific research because of their health associated benefits.
Scope and approach
The present review highlights the unique properties of beneficial glucosinolates and bioactive derivatives, the biosynthetic and metabolic regulatory networks of glucosinolates, and their role in cruciferous sprouts for producing health-promoting glucosinolates biofortification benefits along the entire agro-food chain.
Key findings and conclusions
Glucosinolates and their bioactive derivatives have been extensively studied for their beneficial effects on human health. Among various plant products, cruciferous sprouts are more suitable as a functional food due to their high content of health-promoting glucosinolates and bioactive derivatives. This review describes the unique properties of glucosinolates and their bioactive derivatives contained in cruciferous sprouts with potential health benefits. We discussed the glucosinolate metabolic pathway as well as their regulatory mechanisms. Furthermore, we proposed to apply the integrative and sustainable treatment approaches in cruciferous sprout industry including breeding for glucosinolates-biofortified cultivars, pre-harvest treatment to improve glucosinolates accumulation, followed by postharvest handlings and processing methods for benefit glucosinolates retention along the whole agro-food chain to fight health-promoting glucosinolates deficiency in human daily diet. This review presents a comprehensive overview of effective health-promoting glucosinolates biofortification in cruciferous sprouts along the entire agro-food chain, which is potential in the sustainable cruciferous sprouts industry as well as significance in human nutrition.
... These compounds are highly volatile and are responsible for the biological activity and specific taste of horseradish. ITCs have been intensively researched recently, as they are recognized to have antitumor, bactericidal and fungicidal effects [28]. Zhang [29] reported the inhibition of tumor cells proliferation by extracts from horseradish roots. ...
... Consumption of Brassica vegetables has been consistently shown to be beneficial to human health as they contain health-promoting compounds, including glucosinolates (GSLs) and phenolic compounds, such as flavonoids and hydroxycinnamic acids [1][2][3]. GSLs are associated with risk reduction in many kinds of cancer, such as colorectal, lung and prostate cancers [4,5]. As Brassica vegetables contain high levels of antioxidants, it has been claimed that they could additionally prevent other chronic diseases, such as diabetes and cardiovascular disease [6]. ...
Brassica vegetables are bitter, predominantly because they contain bitter-tasting glucosinolates. Individuals with high bitter taste sensitivity are reported to have lower consumption of bitter vegetables. Studies reported that cooking methods can alter the sensory characteristics of vegetables, increasing acceptability. This study investigated consumer liking of turnip cooked by four methods (boiled-pureed, roasted, steamed-pureed and stir-fried) and related this to sensory characteristics. Additionally, this study examined the effect of the bitter taste genotype on taste perception and liking of the cooked turnip samples. Participants (n = 74) were recruited and the TAS2R38 genotype was measured. Liking, consumption intent, perception of bitterness and sweetness of turnip were evaluated. A sensory profile of the cooked turnip variants was also determined by a trained sensory panel. There were significant differences in the overall (p = 0.001) and taste (p = 0.002) liking between cooking methods. Turnip liking was increased when preparation led to sweeter taste profiles. The TAS2R38 genotype had a significant effect on bitter perception (p = 0.02) but did not significantly affect taste liking. In conclusion, the cooking method affected turnip liking, and the bitter perception in turnip was influenced by the TAS2R38 genotype. However, taste sensitivity did not predict turnip liking in this UK adult cohort.
... This study identified eight ITCs in zhacai, with allyl isothiocyanate (E1) expressed as the dominant component, which was consistent with previous studies (Liu, 2009). Allyl isothiocyanate elicits strong pungent smells, and also has anti-inflammatory, anticancer, antibacterial, and other biological activities (Traka & Mithen, 2009), affording zhacai a variety of physiological and health benefits. ...
Abstract The salt‐reducing pickling method has been applied to the industrial production of zhacai. In order to reveal the succession of the microbial community structure and flavor components during the pickling process, this study used PacBio Sequel to sequence the full length of 16S rRNA (bacteria, 1400 bp) and ITS (fungi, 1200 bp) genes, and detected flavor components simultaneously, including organic acids, volatile flavor components (VFC), monosaccharides, and amino acids. Eleven phyla and 148 genera were identified in the bacterial community, and 2 phyla and 60 genera in the fungal community. During the four stages of pickling, the dominant bacterial genera were Leuconostoc, Lactobacillus, Leuconostoc, and Lactobacillus, while the dominant fungal genera were Aspergillus, Kazachstania, Debaryomyces, and Debaryomyces, respectively. There were 32 main flavor components (5 organic acids, 19 VFCs, 3 monosaccharides, and 5 amino acids). Correlation heat mapping and bidirectional orthogonal partial least squares (O2PLS) analysis showed that the flora having close relation to flavor components included 14 genera of bacteria (Leuconostoc, Clostridium, Devosia, Lactococcus, Pectobacterium, Sphingobacterium, Serratia, Stenotrophomonas, Halanaerobium, Tetragenococcus, Chromohalobacter, Klebsiella, Acidovorax, and Acinetobacter) and 3 genera of fungi (Filobasidium, Malassezia, and Aspergillus). This study provides detailed data regarding the microbial community and flavor components during the salt‐reducing pickling process of zhacai, which can be used as a reference for the development and improvement of salt‐reducing pickling methods.
... Currently, several families are candidates to be exploited in microgreen production. Among these, many species of the Brassicaceae family present high amounts of micronutrients such as polyphenols, ascorbic acid, carotenoids, tocopherols [15][16][17][18], selenium, sulfur, calcium, and glycosylates [19][20][21], which are very effective in neutralizing radiation-induced oxidative damage and the risk of the occurrence of several types of cancer [7,20,[22][23][24]. These secondary metabolites are tightly linked to plant protection and defense pathways, and may be influenced by environmental conditions and agricultural practices [25][26][27]. ...
An adequate and balanced diet is fundamental in preserving the health of astronauts from several space-induced diseases. Therefore, the integration of a diet with fresh food, rich in bioactive compounds such as microgreens produced directly onboard, may be useful in space for human nutrition. However, ionizing radiation (IR) in space represents a significant hindrance for organisms, with potential critical outcomes on plant morpho-anatomical, eco-physiological, and biochemical aspects, depending on the plant and IR features (e.g., species, developmental stage, IR dose, and type). In this study, we analyzed the effect of different doses of X-rays (0-control, 0.3, 1, 10, 20, and 30 Gy) on the morpho-anatomical and nutritional traits of microgreens of Brassica rapa L., irradiated at the stage of germinated seeds. After the irradiation, microgreens were cultivated in controlled conditions. At harvest, the morpho-biometric traits were analyzed, along with the leaf functional anatomical traits and the phytochemical content of the aboveground biomass. The results showed that X-ray exposure does not induce detrimental effects on growth, while it stimulates the production of antioxidants, improving plant defense and nutritional value. The overall results support the idea of using this species in space as a supplemental functional food.
... Cruciferous crops are economically important as vegetables, edible and industrial oil sources, animal feeds, manure and biofuel [1]. Cruciferous vegetables are rich in nutrients and also have medical benefits for human health [2,3]. With growing market demands for yield and quality, the global needs for efficient and sustainable cultivation of cruciferous crops are increasing. ...
Clubroot, caused by Plasmodiophora brassicae, is a severe soil-borne disease that restricts the production of cruciferous crops worldwide. A better understanding of biotic and abiotic factors regulating germination of P. brassicae resting spores in the soil is significant for developing novel control methods. Previous studies reported that root exudates can trigger P. brassicae resting spore germination, thus enabling a targeted attack of P. brassicae on host plant roots. However, we found that native root exudates collected under sterile conditions from host or non-host plants cannot stimulate the germination of sterile spores, indicating that root exudates may not be direct stimulation factors. Instead, our studies demonstrate that soil bacteria are essential for triggering germination. Through 16s rRNA amplicon sequencing analysis, we found that certain carbon sources and nitrate can reshape the initial microbial community to an inducing community leading to the germination of P. brassicae resting spores. The stimulating communities significantly differed in composition and abundance of bacterial taxa compared to the non-stimulating ones. Several enriched bacterial taxa in stimulating community were significantly correlated with spore germination rates and may be involved as stimulation factors. Based on our findings, a multi-factorial 'pathobiome' model comprising abiotic and biotic factors is proposed to represent the putative plant-microbiome-pathogen interactions associated with breaking spore dormancy of P. brassicae in soil. This study presents novel views on P. brassicae pathogenicity and lays the foundation for novel sustainable control strategies of clubroot.
... Particularly, aromatic isothiocyanates containing phenethyl-, benzyl-, and benzoyl-groups exhibit a wide range of antimicrobial activity due to their ability to cross and depolarize bacterial membranes [21]. ITCs are also known to possess anticancer activity by inducing apoptosis and cytokine production, as well as anti-inflammatory and cardio-protective properties [22]. It was also found that the MLE contained megastigmatrienone (also known as tabanone), one of the main terpene components. ...
In this study, we report the green synthesis of silver nanoparticles (AgNPs) from Morus alba or white mulberry leaf extract (MLE) and assess their antibacterial and anticancer potential. The GC–MS analysis of MLE confirmed the existence of phenolic compounds, serving as reducing, capping, and stabilizing agents in the biosynthesis of AgNPs. The MLE-AgNPs were spherical, with an average particle size of 20–44.5 nm and a face-centered cubic structure. EDX spectra confirmed the formation of AgNPs, and a negative zeta potential value (−14.5 mV) suggested their physicochemical stability. Excellent antibacterial activity was demonstrated by MLE-AgNPs against Acinetobacter baumannii strains with a MIC of 2 μg/mL, while good activity was observed against other Gram-negative (Escherichia coli and Salmonella typhimurium) and Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacteria with a MIC of 32 μg/mL. In vitro cytotoxic effects on MCF-7 (human breast cancer cells) and MCF-10A (normal human mammary epithelial cells) were investigated by the MTT assay. The half-maximal inhibitory concentrations (IC50) against MCF-7 cells were 18 and 33 μg/mL for MLE-AgNPs and MLE, respectively, with no effect on normal MCF-10A cells. Altogether, the results support the high antibacterial and anticancer potential of biosynthesized AgNPs by white mulberry leaf extract.
... Glucosinolates are plant-specialized metabolites of the order Brassicales, which includes agriculturally and nutritionally important crops of Brassicaceae, such as cabbage, broccoli, kale, mustard and oilseed rape [1][2][3][4]. The presence of glucosinolates in these crops has attracted considerable interest, as they play a role in plant chemical defense against herbivores, and microbial pathogens and are of interest as health-beneficial components in the human diet (e.g., [5][6][7][8][9]). Most of the biological activities associated with glucosinolates are due to their breakdown products, which are formed when glucosinolates are mixed with their hydrolytic enzymes, thioglucoside glucohydrolases known as myrosinases (EC 3.2.1.147) ...
Glucosinolates, specialized metabolites of the Brassicales including Brassica crops and Arabidopsis thaliana, have attracted considerable interest as chemical defenses and health-promoting compounds. Their biological activities are mostly due to breakdown products formed upon mixing with co-occurring myrosinases and specifier proteins, which can result in multiple products with differing properties, even from a single glucosinolate. Whereas product profiles of aliphatic glucosinolates have frequently been reported, indole glucosinolate breakdown may result in complex mixtures, the analysis of which challenging. The aim of this study was to assess the breakdown of indole glucosinolates in A. thaliana root and rosette homogenates and to test the impact of nitrile-specifier proteins (NSPs) on product profiles. To develop a GC-MS-method for quantification of carbinols and nitriles derived from three prominent indole glucosinolates, we synthesized standards, established derivatization conditions, determined relative response factors and evaluated applicability of the method to plant homogenates. We show that carbinols are more dominant among the detected products in rosette than in root homogenates of wild-type and NSP1- or NSP3-deficient mutants. NSP1 is solely responsible for nitrile formation in rosette homogenates and is the major NSP for indolic nitrile formation in root homogenates, with no contribution from NSP3. These results will contribute to the understanding of the roles of NSPs in plants.
... This first reaction may explain why SFN-GSH was only detected in the cellular lysates (Fig. 5C). In addition, SFN-GSH could be released by cells in order to reach systemic circulation, but a high dissociation percentage has been found (Traka & Mithen, 2009). In Baenas et al. (2015), SFN-GSH concentrations were undetectable at 24 h in HepG2, which suggests the higher dissociation of these molecules in culture conditions. ...
Isothiocyanates (ITCs) have low stability in aqueous conditions, reducing their bioavailability when used as food ingredients. Therefore, the aim of this work was to increase the stability of the ITCs present in extracts of Bimi® edible parts by nanoencapsulation using cauliflower-derived plasma membrane vesicles. The bioactivity of these nanoencapsulates was evaluated in a HepG2 hepatocyte cell line in a model for low-grade chronic inflammation. The vesicles showed a higher capacity of retention in the in vitro gastrointestinal digestion for 3,3-diindolylmethane (DIM), indole-3-carbinol (I3C) and sulforaphane (SFN). Furthermore, Transmission Electron Microscopy (TEM) analysis of the vesicles revealed a decreased size under acidic pH and a release of their cargo after the intestinal digestion. The HepG2 experiments revealed differences in metabolism under the condition of chronic inflammation. The cauliflower-derived plasma membrane vesicles are able to enhance the stability of ITCs through the in vitro gastrointestinal digestion, improving their bioaccesibility and potential bioavailability.
... The high chemopreventive effects of Cruciferae, compared to other plants, are associated with the high content of glucosinolates (GSLs). GSLs [10][11][12][13][14][15][16][17] were discovered more than 200 years ago and they contain sulfur secondary metabolites. In 1956, Ettlinger and Lundeen [18] proposed general structures of GSLs (Figure 1). ...
For decades, various plants have been studied as sources of biologically active compounds. Compounds with anticancer and antimicrobial properties are the most frequently desired. Cruciferous plants, including Brussels sprouts, broccoli, and wasabi, have a special role in the research studies. Studies have shown that consumption of these plants reduce the risk of lung, breast, and prostate cancers. The high chemopreventive and anticancer potential of cruciferous plants results from the presence of a large amount of glucosinolates, which, under the influence of myrosinase, undergo an enzymatic transformation to biologically active isothiocyanates (ITCs). Natural isothiocyanates, such as benzyl isothiocyanate, phenethyl isothiocyanate, or the best-tested sulforaphane, possess anticancer activity at all stages of the carcinogenesis process, show antibacterial activity, and are used in organic synthesis. Methods of synthesis of sulforaphane, as well as its natural or synthetic bifunctional analogues with sulfinyl, sulfanyl, sulfonyl, phosphonate, phosphinate, phosphine oxide, carbonyl, ester, carboxamide, ether, or additional isothiocyanate functional groups, and with the unbranched alkyl chain containing 2–6 carbon atoms, are discussed in this review. The biological activity of these compounds are also reported. In the first section, glucosinolates, isothiocyanates, and mercapturic acids (their metabolites) are briefly characterized. Additionally, the most studied anticancer and antibacterial mechanisms of ITC actions are discussed.
... Some of these have been found to have antipest and antipathogen properties (Halkier and Gershenzon 2006), whereas others are anticarcinogenic. However, there are others that show antinutritional and goitrogenic properties in seed meal (Fahey et al. 1997;Jugeet al. 2007;Cartea and Velasco 2008;Traka and Mithen 2009;Augustine et al. 2013). The biosynthesis of glucosinolates occurs in three important phases: (1) recruitment of precursor amino acids and elongation of side chain, (2) formation of the core glucosinolate structure, and (3) side group modification (Halkier and Gershenzon 2006). ...
In recent years, the development of transgenic Brassica juncea with enhanced tolerance to biotic and abiotic stress conditions has been
reported by several research groups worldwide. Herein, we present an exhaustive compilation of the studies published on this subject, with a special focus on long noncoding RNAs and development of regulatory
genes of B. juncea as potential candidates for alleviation of stress. The transgenic approaches for abiotic stress mitigation and disease resistance have also been discussed. The potential of genetically modified B. juncea plants as edible vaccines has also been touched upon.
... The glucosinolates biosynthesis network is shown in Fig. 1, and their bioactivity and variety affect the flavor and aroma of vegetable edible organs, and defend plants from insect and microbial attack (Dinkova-Kostova and Kostov, 2012). What's more, glucosinolates and their hydrolysates have important biological functions in reducing the risk of carcinogenesis and heart disease in humans (Higdon et al., 2007;Traka and Mithen, 2009). Several studies have suggested that the biosynthesis and accumulation of glucosinolates can be modified by monochromatic light (Jeon et al., 2018;Jin et al., 2015;Xue et al., 2020). ...
Blue light can improve the nutritional value of vegetables grown in greenhouse, while the mechanisms about the biosynthesis and accumulation of glucosinolates regulated by light signaling still unknown. Here, the soluble amino acid and glucosinolate profiles under supplementary different blue light intensities (T50, T100, T150) for 10 days were investigated in green-leaf and red-leaf pakchoi. The results indicated that blue light could significantly increase the contents of glucoalyssin, glucobrassicin, glucobrassicanapin, gluconapin and total glucosinolates, and shown a dose effect. The soluble amino acid profiles and the contents of glucosinolates precursor amino acid were also enhanced to varying degrees. Besides, in green-leaf and red-leaf pakchoi, the expression levels of photoreceptor genes under T100 were significantly higher compared with the CK. Supplementary blue light also promoted the expression of key transcription factors and key genes of glucosinolate biosynthesis pathway in two cultivars pakchoi. Therefore, the beneficial functions of blue light supplementary on the biosynthesis of glucosinolates in pakchoi under greenhouse conditions are owing to the promoted in the contents of precursor amino acids and the expressions of glucosinolate-related genes mediated by light signal transduction.
... Broccoli, one of the most consumed vegetables globally, has gained popularity due to the consumer's interest in functional foods. Broccoli consumption has beneficial health effects, including anticancer (Traka and Mithen, 2009) and antioxidant activity (Lopez-Cervantes et al., 2013), due to the presence of a range of bioactive compounds, including glucosinolates (GSLs), vitamins, phenols, and flavonoids (Bhandari and Kwak, 2014;Sok et al., 2003;Wang et al., 2013). Among the different bioactive compounds, GSLs are specific functional compounds found exclusively in Brassicales. ...
Three commercial cultivars and eleven inbred broccoli lines were used to investigate the glucosinolate (GSL) profile, hydrolysate and nitrile contents, and nitrile formation rate. Glucobrassicin (BRA) and glucoraphanin (GRA) were the most dominant GSLs in all lines. The 5405 and 5406 lines exhibited the highest total GSL content (18.39 and 22.97 μmol·g⁻¹ DW, respectively). Altogether, five lines (5306, 5311, 5312, 5404, and 5406) were selected as potential highly functional broccoli lines based on GSL content. Three lines (5405, 5406, and 5311) exhibited relatively higher total hydrolysates than the other lines. Three inbred lines (5404, 5407, and 5410) with low nitrile formation rate showed a high isothiocyanate (ITC) formation (2.29 ± 0.40, 2.16 ± 0.08, 2.24 ± 0.47 μmol·g⁻¹ DW) and low nitrile formation (0.72 ± 0.12, 0.64 ± 0.12, 0.90 ± 0.20 μmol·g⁻¹ DW). Therefore, lines 5404, 5407, and 5410 were selected as functional broccoli breeding lines based on their hydrolysate content and nitrile formation rates. Consequently, hydrolysate and GSL content are more reliable than GSL content only for selecting and developing highly functional varieties.
... Thus, glucosinolates are some of the most important secondary metabolites in the Brassicaceae family. These sulfur compounds are hydrolyzed by the myrosinase enzyme (present endogenously in these plants) producing hydrolysis breakdown products (isothiocyanates), which have a protective and preventive effect against several kinds of cancer [6,[8][9][10]. Among the inorganic micronutrients, Se plays a relevant role in human nutrition, forming part of the active site of glutathione peroxidase, one of the main antioxidant enzymes [11,12]. ...
In northwest Spain and Portugal, there is a long tradition of cultivating B. rapa subsp. rapa to obtain turnip greens and turnip tops. Brassica rapa L. subsp. rapa (turnip greens and turnip tops) were grown under conventional and organic conditions in two Farms in southern Spain. Glucosinolatescontents were higher in Brassicas grown under conventional conditions than those grown under organic ones. Average Ca total and bioaccessible contents ranged between 14.6–23.4 mg/g; 8.9–12.0 mg/g for turnip greens and 6.4–8.9 mg/g; 4.3–4.8 mg/g for turnip tops. According to these concentrations, an intake of 100–200 g (fresh weight) of the studied Brassica rapa fulfills Ca dietary reference intakes (DRI) (considering the total content data) and complies with 72–100% Ca DRI percentage (considering the bioaccessible data). Se concentrations ranged between 0.061–0.073 µg/g and 0.039–0.053 µg/g for turnip greens and turnip tops respectively. Se bioaccessibility values were high, with percentages of around 90%. Finally, the total glucosinolate content ranged between 13.23–21.28 µmol/g for turnip greens and 13.36–20.20 µmol/g for turnip tops. In general, the bioaccessibility of the total glucosinolates analyzed in this study was high, with mean values of around 73% and 66% for turnip greens and turnip tops, respectively. Brassica rapa vegetables grown under both organic and conventional conditions in southern Spain are an excellent dietary source of Ca, Se, and glucosinolates with a high bioaccessibility.
... Considering that usually only these vegetables inflorescences are consumed, a large quantity of by-products is produced. The brassica family is rich in glucosinolates, which are the precursors of isothiocyanates, that have been extensively studied for its biological activities (Juge et al., 2007;Traka & Mithen, 2009). Glucoraphanin and (neo) glucobrassicin were identified as main glucosinolates in broccoli leaves and stalks Liu et al., 2018a). ...
In a world with eminent scarcity of natural resources and increasing incidence of chronic diseases related to unhealthy eating habits, the search for biologically active and environmentally friendly food products is raising among customers. Agro-industrial by-products have caught special attention from the scientific community for being an available, cost-effective and sustainable source of a wide array of bioactive compounds. Review papers frequently restrain their research to by-products derived from the production of most worldwide consumed crops. Therefore, the aim of this review is to summarize the latest overall research, which focus on the biological potential of agro-industrial by-products and their bioactive compound profile, targeting their application as food ingredients, including not only researches with worldwide consumed crops, but also local foodstuff. A total of 152 research papers, browsed in 2 databases, and involving more than 30 countries were gathered. The richness of bioactive compounds of food by-products from different industries, from fruits to marine products, is ascertained throughout this review. The diversity of food residue being investigated for their nutritional and biological capabilities and the content of specific molecules in each food group are remarkable points. Higher literature reports about fruits by-products may be explained by its wide range of bioactive compounds, especially in Latin American fruits, which includes all flavonoids subclasses, besides betaxanthins, carotenoids and phytosterols. Researchers mainly focus on the quantification of fiber, polyphenols and antioxidant capacity of the investigated by-products, obstructing the investigation of specific biological activities, which are precisely related to the main phytochemicals of the residue matrix, as each molecule has an individual mechanism of action that should be considered when evaluating its biological capabilities. Furthermore, the addition of food by-products has also been advantageous in the production of fortified or enriched bakery, dairy and meat products and functional beverages. All along this literature review, it becomes clearer the high nutritional and nutraceutical value that many by-products possess, besides their attested biological activities, such as antioxidant, anticarcinogenic, antimicrobial, among others.
... Lycopenes are major functional compounds in red-fleshed watermelons and have a major influence on fruit quality, such as glucosinolate in Chinese cabbage [24,25], capsaicin in red pepper [26], and quercetin in onion [27][28][29]. Interest in breeding watermelon cultivars with HL contents is increasing [30][31][32] owing to their applications in processed foods, including juice [33], snacks [34], jam [35], and fresh-cut processing, in which nutritional components decrease during distribution and sales [36]. ...
Trans-lycopene is a functional phytochemical abundant in red-fleshed watermelons, and its contents vary among cultivars. In this study, the genetic basis of high trans-lycopene contents in scarlet red flesh was evaluated. Three near-isogenic lines (NILs) with high trans-lycopene contents were derived from the scarlet red-fleshed donor parent DRD and three coral red-fleshed (low trans-lycopene contents) recurrent parents. The lycopene contents of DRD (589.4 ± 71.8 µg/g) were two times higher than that of the recurrent parents, and values for NILs were intermediate between those of the parents. Coral red-fleshed lines and F1 cultivars showed low trans-lycopene contents (135.7 ± 18.0 µg/g to 213.7 ± 39.5 µg/g). Whole-genome resequencing of two NILs and their parents and an analysis of genome-wide single-nucleotide polymorphisms revealed three common introgressed regions (CIRs) on chromosomes 6, 9, and 10. Twenty-eight gene-based cleaved amplified polymorphic sequence (CAPS) markers were developed from the CIRs. The CAPS markers derived from CIR6 on chromosome 6, spanning approximately 1 Mb, were associated (R2 = 0.45–0.72) with the trans-lycopene contents, particularly CIR6-M1 and CIR6-M4. Our results imply that CIR6 is a major genomic region associated with variation in the trans-lycopene contents in red-fleshed watermelon, and CIR6-M1 and CIR6-M4 may be useful for marker-assisted selection.
... ITC imparts the characteristic flavor to cruciferous vegetables such as radish, turnip, Chinese cabbage, and broccoli sprouts. Numerous researchers have investigated the antibacterial, antiplatelet, antioxidant, and anticancer effects of GLS and ITC (Morimitsu et al., 2000;Tierens et al., 2001;Traka & Mithen, 2009;Yuan et al., 2010;Zhang et al., 2013). Some of the biosynthetic pathways for the generation of GLS are similar to those observed for the generation of branchedchain amino acids (BCAAs), including valine, leucine, isoleucine, thereby suggesting certain interrelation (Binder et al., 2007). ...
The traditional Japanese fermented pickle, takuan‐zuke, is produced via dehydration and salt‐aging of the Japanese winter radish root (Raphanus sativus L.). It has been reported that γ‐aminobutyric acid (GABA; antihypertensive factor) accumulates during this production. Herein, the results of the comprehensive study (metabolites, enzyme activity, and gene expression levels were investigated) on the mechanism of branched‐chain amino acid (BCAA) synthesis and glucosinolate (GLS)–myrosinase system of daikon dehydration have been reported. BCAAs, GLS, and their precursors were temporarily upregulated, and the genes linked to BCAA, GLS, and isothiocyanate synthesis (BCAT4, MAM3, IPMDH1, RMB1, RMB2, and GRS1) were upregulated during daikon dehydration. BCAAs and GLS accumulated in daikon during dehydration owing to the upregulation of genes, encoding these synthases as a stress response. These results suggest that the biological response of daikon adds characteristic flavor and health functionality to takuan‐zuke and helps optimize the processing parameters to produce pickles with improved health benefits.
Practical applications
Takuan‐zuke is a popular pickle in Japan, which is produced from a Japanese winter radish root (Raphanus sativus L.), commonly referred to as daikon in Japan. Takuan‐zuke is produced by dehydrating daikon either by the process of salt‐pressing (shio‐oshi) or sun‐drying (hoshi). The processes influence the variations in the nutritional value of the final product. The results reveal that both the daikon dehydration processes can be followed to generate increased amounts of health‐promoting components (e.g., branched‐chain amino acid and glucosinolate) in takuan‐zuke.
The amino acid L-serine (Ser) is indispensable for several cellular processes. In addition to forming part of proteins, Ser is required for the synthesis of other amino acids, nitrogen bases, and lipids and is a source of one-carbon units (1C) for methylation reactions. Unlike animals, plants synthesize Ser through different pathways, which has complicated the understanding of the amino acid homeostasis. Three Ser biosynthesis pathways have been described in plants: the glycolate pathway, associated with photorespiration, and two non-photorespiratory pathways, the phosphorylated and the glycerate pathway of Ser biosynthesis. In recent years, the specific contribution of each pathway to Ser homeostasis and how they are coordinated to participate in plant metabolism and development have started to be elucidated. Current knowledge on serine biosynthesis and functions in plants is reviewed here and, whenever possible, compared with current knowledge in mammals. We focus on recent advances that link Ser with other metabolic processes, such as the Ser-glycine-1C network, and nitrogen and sulfur metabolism. We also discuss the role of Ser metabolic reprogramming in the plant response to biotic and abiotic stresses and how it can be affected by climate change.KeywordsGlycineNitrogen metabolismOne-carbon metabolismSerineSulfur metabolism
Orange Chinese cabbage (Brassica rapa L. ssp. pekinensis) is an excellent source of health-promoting nutrients that could reduce the risk of chronic diseases. This study mainly investigated the accumulation patterns of eight lines of orange Chinese cabbage for indolic glucosinolates (GLSs) and pigment content from representative plant organs across multiple developmental stages. The indolic GLSs were highly accumulated at the rosette stage (S2), especially in inner and middle leaves, and the order of indolic GLSs accumulation in non-edible organs was flower > seed > stem > silique. The expression levels of biosynthetic genes in light signaling, MEP, carotenoids, and GLS pathways were consistent with the metabolic accumulation patterns. The results of a principal component analysis show a clear separation of high indolic GLS lines (15S1094 and 18BC6) from low indolic GLS lines (20S530). A negative correlation between the accumulation of indolic GLS and carotenoids was identified in our study. Our work contributes to providing valuable knowledge required to breed, grow, and select orange Chinese cabbage varieties and their eatable organs with higher nutritional value.
Nowadays, the yeast Saccharomyces cerevisiae is the platform of choice for demonstrating the proof of concept of the production of metabolites with a complex structure. However, introducing heterologous genes and rewiring the endogenous metabolism is still not standardized enough, affecting negatively the readiness-to-market of such metabolites. We developed the Easy Modular Integrative fuSion-ready Expression (Easy-MISE) toolkit, which is a novel combination of synthetic biology tools based on a single Golden Gate multiplasmid assembly meant to further ameliorate the rational predictability and flexibility of the process of yeast engineering. Thanks to an improved cloning screening strategy, double and independent transcription units are easily assembled and subsequently integrated into previously characterized loci. Moreover, the devices can be tagged for localization. This design allows for a higher degree of modularity and increases the flexibility of the engineering strategy. We show with a case study how the developed toolkit accelerates the construction and the analysis of the intermediate and the final engineered yeast strains, leaving space to better characterize the heterologous biosynthetic pathway in the final host and, overall, to improve the fermentation performances. Different S. cerevisiae strains were built harboring different versions of the biochemical pathway toward glucobrassicin (GLB) production, an indolyl-methyl glucosinolate. In the end, we could demonstrate that in the tested conditions the best-producing strain leads to a final concentration of GLB of 9.80 ± 0.267 mg/L, a titer 10-fold higher than the best result previously reported in the literature.
Production of plant-derived nutraceuticals using mutation, elicitation, precursor feeding, genetic transformation and metabolic engineering.
The objective was to study the phytochemical profile of yellow (Sinapis alba) and oriental mustard (Brassica juncea) flour and bran fractions. The HS-SPME-GC/MS technique was used to determine the volatile profile. Up to 53 volatiles, including isothiocyanates, alkanes, alcohols, ketones and esters were identified in the mustard powders. In addition, the free and bound bioactive fraction was studied and the determination was performed by UHPLC-MS/MS. A total of 26 compounds (phenolic acids, flavonoids and glucosinolates) were identified in the mustard samples. Sinapis alba, including the bran fraction, was richer in p-hydroxybenzoic, ferulic and p-coumaric acids compared to Brassica juncea. In addition, the volatile profile in yellow mustard seeds, as analysed by HS-SPME-GC/MS, has been described for the first time in this work. The study of the principal components showed that according to the bioactive compounds profile it is possible to differentiate between the two mustard species analysed. Moreover, the bran fraction, as a by-product of the seed processing, is a matrix rich in bioactive compounds and could be applied for the recovery of polyphenols for agro-industrial or pharmaceutical application.
The role of underground starchy crops in global food security is widely recognized. These are subsistence crops considered as neglected and underutilized. However, these have become the new focus of international community for providing income opportunities and presenting different potential uses. The social and economic trajectories of most South American countries are linked to these crops, with emphasis on cassava, yams, potatoes, and sweet potatoes, responsible for 93% of the root and tuber species consumed worldwide. However, there are several other neglected plant species that are cultivated by traditional communities with commercial-scale potential. These were not widely recognized in the literature and mainly include contain phosphorus, mucilage, and high levels of phenolic compounds. This chapter highlights the role of South America in the origin, evolution, and domestication of underground starchy species and how local communities have shaped the genetic architecture and biodiversity of these plants.
Cytochrome b5 (CB5) is a small heme-binding protein, known as an electron donor delivering reducing power to the terminal enzymes involved in oxidative reactions. In plants, the CB5 protein family is substantially expanded both in its isoform numbers and cellular functions, compared to its yeast and mammalian counterparts. As an electron carrier, plant CB5 proteins function not only in fatty acid desaturation, hydroxylation and elongation, but also in the formation of specialized metabolites such as flavonoids, phenolic esters, and heteropolymer lignin. Furthermore, plant CB5s are found to interact with different non-catalytic proteins such as ethylene signaling regulator, cell death inhibitor, and sugar transporters, implicating their versatile regulatory roles in coordinating different metabolic and cellular processes, presumably in respect to the cellular redox status and/or carbon availability. Compared to the plentiful studies on biochemistry and cellular functions of mammalian CB5 proteins, the cellular and metabolic roles of plant CB5 proteins have received far less attention. This article summarizes the fragmentary information pertaining to the discovery of plant CB5 proteins, and discusses the conventional and peculiar functions that plant CB5s might play in different metabolic and cellular processes. Gaining comprehensive insight into the biological functions of CB5 proteins could offer effective biotechnological solutions to tailor plant chemodiversity and cellular responses to environment stimuli.
Isothiocyanates are the highly reactive organo-sulphur phytochemicals and are product of hydrolysis of glucosinolates which are present mainly in the cruciferous vegetables. These compounds due to their unique chemical reactivity possess anti-cancer, anti-inflammatory, and neuroprotective properties. Epidemiological and experimental evidences suggest that isothiocyanates reduce oxidative stress and act as indirect antioxidants as well as antimicrobials, therefore, have received attention from the researchers for their possible application in pharmacological and food industry. However, due to high volatility and heat sensitivity of these bioactive compounds, their extraction is very challenging and requires the application of various innovative technologies. In addition to that, their fate during the processing conditions also needs to be considered as these processes tend to affect their bioavailability. Isothiocyanates exhibit wide range of antimicrobial activity due to their ability of reducing oxygen consumption and depolarizing the mitochondrial membrane in bacterial cells. They are generally regarded as safe (GRAS) compounds and hence are allowed to be added to the food as preservatives. Due to their antimicrobial properties, isothiocyanates incorporated food packaging films have become popular in the last decade. They are known to act as substrates to activate lactoperoxidases (LPO) for extension of shelf life of dairy products due to its bactericidal and bacteriostatic properties. This review addresses the detailed evidences supporting the biological activities, bioavailability and stability, methods of extraction, and explanation for their taste perception, as well as utilization of these isothiocyanates in food packaging as natural antimicrobials or natural preservatives to improve shelf life of foodstuffs.
Numerous herbivores orally secrete defense compounds to detoxify plant toxins. However, little is known about the role of orally secreted enzymes by a specialized pest, Plutella xylostella, in the detoxification of plant defense compounds. Three glucosinolate sulfatases (GSSs) or two sulfatase-modifying factors (SUMF1s) mutant strains were established on the basis of CRISPR/Cas9 technology to validate the existence of a species-specific GSSs−SUMF1s system. In comparison to the bioassay data from mutant strains of GSS1/GSS2 or SUMF1a/SUMF1b, GSS3 had a minimal role because no significant change was found in GSS3−/− under different feeding contexts. Antibody-based technologies were used to examine GSSs-related deficient strains, and the results showed that the GSS1 protein was primarily released through larval oral secretion. On the basis of high-performance liquid chromatography, we found that GSS1 was secreted to pre-desulfate the typical plant defensive glucosinolates known as 4-(methylsulfinyl)butyl glucosinolate (4MSOB-GL) to suppress the production of the toxic substance, which is referred to as predetoxification strategy. These findings highlighted that the GSSs−SUMF1s system is the key factor for counteradaptation of P.
xylostella to cruciferous plants, which strengthens the concept that herbivores deploy pre-detoxification strategies to disrupt the plant
chemical defenses to facilitate the colonization process.
Brassicaceae vegetables are an important traditional daily food in China and around the world, which provide nutrients and phytochemicals that are beneficial for human health. Among them, Brassica and Raphanus are widely cultivated and eaten, have been evolved and/or bred for special characteristics during the long history of cultivation. Epidemiological studies suggest that the health benefits of Brassicaceae vegetables are mainly associated with glucosinolates (GSLs) and their hydrolytic products. In this review, we discuss the diversity of common consumed Brassicaceae vegetables and their GSL composition in edible parts. We also discuss the diversity factors affecting GSL content, and the diversity roles and functions of GSL. The information in this review provides guidance for consumers to select vegetables with a high GSL content, optimum edible stages, suitable edible methods, and provides a theoretical basis for crop molecular breeding and market development of GSL products.
The food waste generated by small and medium agro-industrial enterprises requires appropriate management and valorization in order to decrease environmental problems and recover high-value products, respectively. In this study, the Camelina sativa seed by-product was used as a source of glucosinolates. To begin, the chemical profile of the extract obtained using an international organization for standardization (ISO) procedure was determined by UPLC-HRMS/MS analysis. In addition, an extraction method based on ultrasound-assisted extraction was developed as an alternative and green method to recover glucosinolates. Main parameters that affect extraction efficiency were optimized using a response surface design. Under optimized conditions, the extract showed an improvement in extraction yield with a reduction in organic solvent amount compared to those obtained using the ISO procedure. Finally, the extract obtained with the ultrasound-assisted method was purified, tested on human colorectal cancer cell lines, and showed promising results.
The present work investigated the effects of soaking followed by heating on the metabolism of glucosinolates (GLs) in rocket seeds and sprouts. Soaking for 1 h increased myrosinases (MYR) activity of seeds. Heating at 70°C for 10 min after soaking resulted in the highest isothiocyanates (ITCs) formation in seeds. Both immerse-heating and steam-heating decreased the total GLs content in seeds and 2-day old sprouts. However, steam-heating showed minor effect on total GLs content when compared with immerse-heating. Both methods showed a decreased MYR activity in seeds and sprouts. Nevertheless, heating had a positive impact on ITCs formation. Under immerse-heating, ITCs formation was the highest in seeds and sprouts at 70°C heating. However, under steam-heating, ITCs formation in seeds and sprouts was higher at 70 and 60°C, respectively. The results indicated that steam-heating treatment was effective for improving ITCs formation in rocket seeds and 2-day old sprouts.
One of the best-studied plant chemical defenses is the glucosinolate-myrosinase system found in plants of the family Brassicaceae. There is considerable quantitative and qualitative variation among plant genotypes, tissues, and ontogenetic stages, which poses unique challenges to insect herbivores. Enzyme myrosinase, which is stored in specialized plant cells, hydrolyzes glucosinolates to more toxic isothiocyanates upon tissue disruption. Breakdown of glucosinolates differs depending on the physiological condition of the plant. Glucosinolate hydrolysis products may protect the plant either directly by having an effect on the biology/behavior of insects or indirectly by attracting the pest’s natural enemies. However, a variety of generalist and specialist insect herbivores are known to infest these crops and cause major yield losses. In order to overcome chemical defenses, many insects have developed a number of counteradaptations which function either before or after consumption of food. In this chapter, we have attempted to review these glucosinolate-myrosinase-based defenses and their role in insect-plant interactions.Keywords
Brassica
Mustard oil bombPlant defensePlant secondary metabolitesThioglucosides
The mitigation of plant toxins (detoxification) in the larvae of Lepidoptera (caterpillars) provides a rich milieu in which to understand the mechanisms driving the evolution and maintenance of ecological specialization. The field of coevolution was born through an intensive study of the interactions between secondary compounds of plants and Lepidoptera. Here, we summarize progress on our knowledge of the proximate (e.g., target site insensitivity to toxins) and ultimate (e.g., top-down vs. bottom-up) mechanisms used by caterpillars to cope with and even co-opt plant toxins. As new molecular tools become available, linking these two ends of the mechanistic spectrum (proximate and ultimate) is becoming possible. Our discussion of proximate mechanisms includes behavioral sensors of toxins (olfactory receptors, ionotropic receptors, gustatory receptors, transient receptor potential proteins, non-receptor chemosensory gene families), prevention of defense response induction, diversion strategies for precursor toxins, physical barriers, target site insensitivity, detoxification through xenobiotic metabolism, and microbial interactions. Ultimate mechanisms include those shaped by both bottom-up and top-down agents of natural selection in the context of detoxification, with clear links to other chapters of this volume (e.g., sequestration, parasitoids). Lessons learned about detoxification from arthropods other than Lepidoptera are covered as well, which can in turn be applied to caterpillars once appropriate tools become available.
The Brassicaceae family, known as cruciferous vegetables, includes many economic species, mainly edible oil plants, vegetable species, spice plants, and feed plants. Cruciferous vegetables are the foods rich in nutritive composition and are also a good source of dietary fiber. Besides, cruciferous vegetables contain various bioactive chemicals known as glucosinolates and S-methyl cysteine sulfoxide, including sulphur-containing cancer-protective chemicals. Numerous studies have reported that daily intake of sulphurous vegetables helps prevent cancer formation and reduces cancer incidence especially in colorectal cancer through various mechanisms. The potential mechanisms of these compounds in preventing cancer in experimental studies are as follows: protecting cells against DNA damage, inactivating carcinogenic substances, showing antiviral and antibacterial effects, triggering apoptosis in cells with disrupted structure, inhibiting tumour cell migration causing metastasis and the development of tumour-feeding vessels (angiogenesis). These beneficial anticancer effects of cruciferous vegetables are generally associated with glucosinolates in their composition and some secondary metabolites as well as other phenolic compounds, seeds oils and dietary fiber in the literature. This review aims to examine to the roles of cruciferous vegetables and their important bioactive metabolites in the prevention and treatment of colorectal cancer.
Abiotic stresses such as increase in daily mean temperature, changed patterns of precipitation, increase in episodes of drought and floods in future are faced by the plants and pose threats to crop production and food security. Induction of secondary metabolites by several abiotic stress conditions can be helpful in the crop protection against biotic stress and can be a major link between biotic and biotic stress. Plants also face threats by injury caused by herbivores and insects that chew on plants. Plant develops, coordinates and combines defence mechanism to cope with the challenges caused by the injuries. The plant family Brassicaceae (or Cruciferae) includes some of the world’s most economically important crops; especially members of the genera Brassica L. Brassicaceae vegetables are a good source of secondary metabolite that is Glucosinolates. Which are responsible for characteristic flavour and odour, when degraded. Glucosinolates and their degradation products play important roles in stress tolerance, plants respond to abiotic and abiotic stress by systematically accumulating higher levels primary and secondary metabolites for increasing their resistance. Glucosinolates play important role and have a relation with biotic and abiotic stress in Brassica plant family, as they can act as a signalling molecules and affect the physiology of plant.
Existence of microorganisms, pesticide residue on fresh vegetables has a potential hazard to human health. The demand for safe green Chinese kale (Brassica oleracea var. alboglabra) has increased recently. Chinese kale is a healthy botanical attached to the Brassicaceae class. It contains numerous nutritional and phytochemical constituents beneficial for human health. Besides health benefits, this green vegetable also poses food safety concerns due to pathogen and pesticide residue during cultivation. Non-thermal physical technology like pulsed light (PL) will be a promising alternative to eradicate microbial and pesticide residue while preserving the best physicochemical properties and phytochemical components. This research evaluated the influence of different pulsed light intensities (1.2-10.8 J/cm2) on the removal of microbial load and pesticide residue as well as weight attrition, texture hardness, dry matter, vitamin C, total phenolic content in the treated Chinese kale. Results showed that pulsed light intensity 8.4 J/cm2 was appropriate to completely eliminate pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, Salmonella; pesticide substances such as carbendazim, abamectin, cypermethrin, chlorpyrifos ethyl, mancozeb. At pulsed light intensity 8.4 J/cm2, weight attrition in the treated sample was lower than weight attrition in the untreated; meanwhile textural hardness, dry matter, ascorbic acid and total phenolic content remained higher in the treated sample compared to the untreated. The results reveals that the pulsed light technique should be applied as a promising decontamination approach for removal of the pathogen as well as pesticide residue with minor impact on physicochemical properties and phytochemical constituents.
Traditional therapeutic procedures using antioxidant-rich fruits and vegetables have been in vogue for the development of evidence-based biomarkers for assessing reproductive health. Present investigation was designed to study the antioxidative potential of broccoli sprouts aqueous extract (BE), against ovarian toxicity in female rats induced by triazophos (TZ). In the experimental setup, six groups of rats were formed; Control (group 1), BE (group 2), TZ (group 3), and also BE+TZ groups such as BE1 (group 4), BE2 (group 5) and BE3 (group 6) groups. Body weight was weekly recorded of all the rats, while vaginal smear was observed daily during 30 days experiment. After sacrifice, oxidative stress (OS) biomarkers levels viz; catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and lipid peroxidation (LPO) were determined along with histopathological and apoptotic observation. Results revealed differentially modified changes in OS biomarkers as CAT, SOD, GR, GPx, and GST, while LPO levels were significantly improved with broccoli supplementation compared to TZ group rats. Plasma progesterone and estradiol levels were also restored along with improved ovarian histoarchitecture among all BE+TZ treated rats. Reduced apoptotic granulosa cells with reduced atresia and normal ovarian surface epithelium height were also observed with BE treatment. BE exerts multi-mechanistic protective effects against TZ induced ovarian toxicity which is attributable to its antioxidant and protective actions.
Gnotobiotic growing rats harbouring either a whole human faecal flora or single human strains of Escherichia coli (EM0) or Bacteroides vulgatus (BV8H1) were fed for 7 weeks on semi-synthetic diets in which the protein source was either soya-bean meal (SM) or rape-seed meal (RM). For each bacterial status the RM-diet group was compared with the control group fed on the SM diet. The association of human faecal flora with the RM diet was responsible for reduced feed intake and reduced weight gain, an enlargement of the liver and thyroid and a decrease in both thyroxine and triiodothyronine plasma levels. The association of the B. vulgatus BV8H1 strain with the RM diet reproduced all these effects, except that triiodothyronine plasma levels were not significantly modified. Rats inoculated with the E. coli EM0 strain and fed on the RM diet exhibited a goitre and lowered thyroxine and triiodothyronine plasma levels. These results show that the human intestinal microflora may be involved in glucosinolate metabolism when cruciferous vegetables are consumed by man. The specificity of the symptoms observed according to the rat bacterial status supports the hypothesis that bacteria yield specific toxic glucosinolate derivatives according to their enzymic potential.
Sulforaphane (SUL), an isothiocyanate found in broccoli and other cruciferous vegetables, has been shown to induce phase II detoxification enzymes, inhibit chemically induced mammary tumors in rats, and more recently to induce cell cycle arrest and apoptosis in cancer cells of the colon. Here, we provide evidence that SUL also acts as a breast cancer anti-proliferative agent. The BALB/c mouse mammary carcinoma cell line F3II was treated with SUL at concentrations up to 15 microM and examined for markers of cell cycle arrest and apoptosis. Treatment of asynchronous F3II cells with 15 microM SUL resulted in G2/M cell cycle arrest, elevated p34cdc2 (cdc2) kinase activity, Bcl-2 down-regulation, evidence of caspase activation, and aggregation of condensed nuclear chromatin. Subsequent exposure of synchronized cells to 15 microM SUL resulted in elevated numbers of prophase/prometaphase mitotic figures, indicating cell cycle progression beyond G2 and arrest early within mitosis. Moreover, cells treated with 15 microM SUL displayed aberrant mitotic spindles, and higher doses of SUL inhibited tubulin polymerization in vitro. In addition, BALB/c mice injected s.c. with F3II cells and subsequently injected daily i.v. with SUL (15 nmol/day for 13 days) developed significantly smaller tumors (approximately 60% less in mass) than vehicle-treated controls. Western blot analysis of tumor proteins demonstrated significantly (P<0.05) reduced PCNA and elevated PARP fragmentation in samples from animals dosed with SUL. Taken together, these results indicate that SUL has mammary cancer suppressive actions both in cell culture and in the whole animal. Inhibition of mammary carcinogenesis appears in part to involve perturbation of mitotic microtubules and early M-phase block associated with cdc2 kinase activation, indicating that cells arrest prior to metaphase exit.
The development of hybrid broccoli genotypes with enhanced levels of 4-methylsulphinylbutyl glucosinolate, the precursor of anticarcinogenic isothiocyanate sulforaphane (SF), by introgressing genomic segments from the wild ancestor Brassica villosa is described. We demonstrate that to obtain enhanced levels of either 3-methylsulphinylpropyl or 4-methylsulphinylbutyl glucosinolate it is necessary to have B. villosa alleles in either a homozygous or heterozygous state at a single quantitative trait locus (QTL) on O2. The ratio of these two glucosinolates, and thus whether iberin or SF is generated upon hydrolysis, is determined by the presence or absence of B. villosa alleles at this QTL, but also at an additional QTL2 on O5. We further demonstrate that following mild cooking high glucosinolate broccoli lines generate about three fold higher levels of SF than conventional varieties. Commercial freezing processes and storage of high glucosinolate broccoli maintains the high level of glucosinolates compared to standard cultivars, although the blanching process denatures the endogenous myrosinase activity.
Cruciferous vegetables contain glucosinolates that, after conversion to isothiocyanates (ITC), are capable of inducing cytoprotective genes. We examined whether broccoli seeds can elicit a chemoprotective response in mouse organs and rodent cell lines and investigated whether this response requires nuclear factor-erythroid 2 p45-related factor 2 (Nrf2). The seeds studied contained glucosinolate at 40 mmol/kg, of which 59% comprised glucoiberin, 19% sinigrin, 8% glucoraphanin, and 7% progoitrin. Dietary administration of broccoli seeds to nrf2+/+ and nrf2-/- mice produced a [~]1.5-fold increase in NAD(P)H:quinone oxidoreductase 1 (NQO1) and glutathione S-transferase (GST) activities in stomach, small intestine, and liver of wild-type mice but not in mutant mice; increased transferase activity was associated with elevated levels of GSTA1/2, GSTA3, and GSTM1/2 subunits. These seeds also increased significantly the level of glutamate cysteine ligase catalytic (GCLC) subunit in the stomach and the small int
The glucosinolates (GSs) were estimated in the normally eaten portions of 72 cultivars of Oriental brassica vegetables including mustard greens ( Brassica juncea L.), Chinese kale ( B. oleracea L. Alboglabra Group Bail.), Chinese cabbage ( B. rapa L. Pekinensis Group Bail.), pak choy ( B. rapa Chinensis Group Bail.), tendergreen ( B. rapa Perviridis Group Bail.), turnip ( B. rapa L. Rapifera Group Bail., B. narinosa Bail., and B. nipposinica Bail.). Variation in GS profiles was complex. There was variation in percentages of major GSs and total GS among B. juncea, B. oleracea , and the combination B. rapa plus narinosa and nipposinica and among four subspecific groups of rapa plus the two species closely related to rapa: narinosa and nipposinica. B. juncea had distinctively high proportions of allyl-GS, ranging from 81% to 94%, whereas B. oleracea had distinctively high proportions of 4-methylsulfinylbutyl-GS, ranging from 9% to 68%. Differences in GS profiles among the rapa groups, narinosa and nipposinica , were less distinctive. Cultivars of pak choy from China differed in percentages of three minor GSs from cultivars from Japan and elsewhere. There was also variation among cultivars of Chinese kale and between turnip foliage and roots.
Fourteen cultivars of turnip [ Brassica rapa, rapifera group, also B. campestris L. ssp. rapifera (Metzg.) Sinsk.] recommended for human consumption of either tops or tops and roots and five cultivars recommended for consumption of roots were selected to compare glucosinolate (GS) levels in tops and roots. Also, two cultivars used for animal feed were included. The study revealed significantly lower levels of 1-methylpropyl-GS and 2-hydroxy-3-butenyl-GS in tops and roots of cultivars grown for greens, compared to those used for animal feed. Contents of 1-methylpropyl-, 3-butenyl-, and 4-pentenyl-GSs were higher in turnip tops than in roots, while 2-hydroxy-3-butenyl-, 4-(methylthio)butyl-, 4-(methylsulfinyl)butyl-, 2-hydroxy-4-pentenyl-, 5-(methylthio)pentyl-, 2-phenylethyl-, 3-indolylmethyl-GSs and total GS were all higher in the roots. GS patterns for seeds tended to correlate with those of the tops.
Correlation coefficients based on relative concentrations of 13 glucosinolates in the edible parts of 30 cultivars were determined. Brussels sprouts ( Brassica oleracea L. gemmifera group), cauliflower ( B. oleracea L. botrytis group), and either marrow-stem or smooth-leafed kale ( B. oleracea L. acephala group) had similar glucosinolate patterns based on significant correlations ( P < 0.01). The glucosinolates of ‘Morris Heading’ collards [( B. oleracea L. acephala group (var. sabellica )] were highly correlated with those of curly kale [ B. oleracea L. acephala group (var. selensia )]. Mustard greens [ B. juncea (L.) Czern. & Coss. var. rugosa Bailey] and the corresponding seeds were the most highly correlated of the 17 cultivars for which the edible parts and seeds were compared. Seed analyses indicated relationships among the cultivars somewhat similar to those seen for the edible portions.
The effects of two aromatic thiocyanates, benzyl thiocyanate (BTC) and benzyl isothiocyanate (BITC), on methylazoxymethanol (MAM) acetate-induced intestinal carcinogenesis were examined using female ACI/N rats. Starting at 5 weeks of age, animals were fed diets containing 100 or 400 p.p.m. BTC, 400 p.p.m. BITC or a control diet At 6 weeks of age, all animals were treated with i.p. injections of MAM acetate (25 mg/kg body wt, once weekly for 3 weeks) or saline. Animals fed experimental diets were changed to the control diet from a week after the last carcinogen treatment Three groups of animals fed the control diet were switched to 100 p.p.m. BTC, 400 p.p.m. BTC or 400 p.p.m. BITC diet from a week after carcinogen treatment Animals given the high-dose BTC diet at the initiation and the post-initiation phase showed smaller incidence (5% and 17%) and multiplicity (0.05 ± 0.21 and 0.17 ± 0.37) of tumors in small intestine compared with those of rats exposed to the carcinogen alone (61% and 1.06 ± 1.18). The incidence and multiplicity of tumors in small intestine (21% and 032 ± 0.73) and the incidence of colon tumors of rats given BITC in the initiation phase (47%) were significantly lower than those of animals treated with carcinogen alone (61%, 1.06 ± 1.18 and 83%). Bromodeoxyuridine labeling indices of the intestinal mucosal cells were measured. The labeling indices were reduced by BTC and BITC exposure at initiation phase in both small intestine and colon. The results of measurement of labeling indices correlated with the decreased tumor incidence and multiplicity in the intestine. These data suggest that BTC and BITC could be promising chemopreventive agents for human intestinal neoplasia.
The catalytic properties of four human glutathione transferases (GSTs), A1-1, M1-1, M4-4 and P1-1, were examined with 14 isothiocyanate (R-NCS) substrates. The compounds include aliphatic and aromatic homologues, some of which are natural constituents of human food, namely sulphoraphane [1-isothiocyanato-4-(methylsulphinyl)butane], erucin [1-isothiocyanato-4-(methylthio)butane], erysolin [1-isothiocyanato-4-(methylsulphonyl)butane], benzyl-NCS, phenethyl-NCS and allyl-NCS. All isothiocyanates investigated were substrates for the four GSTs. The enzymes promote addition of the thiol group of GSH to the electrophilic central carbon of the isothiocyanate group to form dithiocarbamates [R-NH-C(=S)-SG] which have high UV absorption at 274 nm. Molar absorption coefficients and non-enzymic rate constants as well as standardized enzyme assay conditions for all compounds were established. Of the four isoenzymes investigated, GSTs M1-1 and P1-1 were generally the most efficient catalysts, whereas GST M4-4 was the least efficient. Isothiocyanates are among the GST substrates that are most rapidly conjugated. On the basis of rate-enhancement data and binding energies, the isothiocyanates were compared with 4-hydroxyalkenals, another class of natural GST substrates previously subjected to systematic kinetic analysis. The incremental transition-state stabilization attributable to an increased number of methylene groups in homologous alkyl isothiocyanates is similar to that previously noted for homologous 4-hydroxyalkenals.
The effect of consumption of Brussels sprouts on levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in human urine was
investigated in 10 healthy, male, non-smoking volunteers. Following a 3 week run-in period, five volunteers continued on a
diet free of cruciferous vegetables for a subsequent 3 week intervention period (control group), while the other five (sprouts
group) consumed 300 g of cooked Brussels sprouts per day, at the expense of 300 g of a glucosinolate-free vegetable. Levels
of 8-oxodG in 24 h urine samples were measured by HPLC. In the control group there was no difference between the two periods
in levels of 8-oxodG (P = 0.72). In contrast, in the sprouts group the levels of 8-oxodG were decreased by 28% during the intervention period (P = 0.039). The present findings support the results of epidemiologic studies that consumption of cruciferous vegetables may
result in a decreased cancer risk.
The broccoli constituent sulforaphane (1-isothiocyanate-4-methylsulfinylbutane) has previously been shown to protect rats
against 9, 10-dimethyl-1, 2-benz[a]anthracene tumori-genesis, thought to be due, at least in part, to induction of phase II detoxification. We investigated
the ability of sulforaphane to also inhibit the phase I enzyme cytochrome P450 isoenzyme 2E1 (CYP2E1), which is responsible
for activation of several carcinogens, including dialkylnitros-amines. Using the p-nitrophenol hydroxylation assay in microsomes from livers of acetone-treated Sprague-Dawley rats, sulforaphane was shown
to be a potent competitive inhibitor of CYP2E1 with a K1pg of 347.0 ± 4.5 μM. In view of this result, we studied the capacity of sulforaphane to inhibit the genotoxicity of N-nitrosodimethylamine (NDMA). Sulforaphane at concentrations of >0.8 μM inhibited the mutagenicity of NDMA (4.4 mg/plate)
in Salmonella typhimurium strainDTA100 after pre-incubation for 45 min with cytosol extract from livers of Balb/c mice pre-treated with acetone. Unsecheduled
DNA synthesis induced by NDMA (33.5 μM)in mouse hepatocytes was inhibited in a dose-dependent manner by sulforaphane at 0.064–20
μM. Sulforaphane was unable to inhibit mutagenicity of sodium azide (5 μg/plate), a direct acting mutagen, in the Salmonella assay. It was not itself genotoxic in hepatocytes, as measured by unscheduled DNA synthesis, or mutagenic in the strain of
Salmonella employed and cytotoxic only at high concentrations (≧0.5 mM). These findings suggest that inhibition of CYP2E1 by sulforaphane
may offer chemoprotection against carcinogenic substrates of this enzyme.
Chemoprevention involves the use of natural or synthetic substances to reduce the risk of developing cancer. Two dietary components capable of mediating chemopreventive activity in animal models by modulation of drug-metabolizing enzymes are sulforaphane, an aliphatic isothiocyanate, and brassinin, an indole-based dithiocarbamate, both found in cruciferous vegetables. We currently report the synthesis and activity of a novel cancer chemopreventive agent, (+/-)-4-methylsulfinyl-1-(S-methyldithiocarbamyl)-butane (trivial name, sulforamate), an aliphatic analogue of brassinin with structural similarities to sulforaphane. This compound was shown to be a monofunctional inducer of NAD(P)H:quinone oxidoreductase [quinone reductase (QR)], a Phase II enzyme, in murine Hepa 1c1c7 cell culture and two mutants thereof. Induction potential was comparable to that observed with sulforaphane (concentration required to double the specific activity of QR, approximately 0.2 microM), but cytotoxicity was reduced by about 3-fold (IC50 approximately 30 microm). In addition, sulforaphane, as well as the analogue, increased glutathione levels about 2-fold in cultured Hepa 1c1c7 cells. Induction of QR was regulated at the transcriptional level. Using Northern blotting techniques, time- and dose-dependent induction of QR mRNA levels were demonstrated in Hepa 1c1c7 cell culture. To further investigate the mechanism of induction, HepG2 human hepatoma cells were transiently transfected with QR-chloramphenicol acetyltransferase plasmid constructs containing various portions of the 5'-region of the QR gene. Sulforaphane and the analogue significantly induced (P < 0.0001) CAT activity at a concentration of 12.5 microM by interaction with the antioxidant responsive element (5-14-fold induction) without interacting with the xenobiotic responsive element. Moreover, both compounds significantly induced mouse mammary QR and glutathione S-transferase activity (feeding of 3 mg/mouse intragastric for 4 days), whereas the elevation of hepatic enzyme activities was less pronounced. Both sulforaphane and the analogue were identified as potent inhibitors of preneoplastic lesion formation in carcinogen-treated mouse mammary glands in organ culture (84 and 78% inhibition at 1 microm, respectively). On the basis of these results, the sulforaphane analogue can be regarded as a readily available promising new cancer chemopreventive agent.
The isothiocyanate sulforaphane (SF) is thought to be a potential chemoprotective agent. Its effects on Phase I and Phase II enzymes of carcinogen metabolism in primary cultures of rat and human hepatocytes have been investigated. Northern blot analyses of rat hepatocytes showed a dose-dependent induction of mRNAs for rat glutathione S-transferases (rGSTs) A1/A2 and P1 but not M1. This was associated with enhanced levels of not only rGSTA1, A2, A4, A5, and P1 but also of rGSTs M1 and M2. On the other hand, the enzyme activities in rat hepatocytes associated with cytochromes P-450 (CYPs) 1A1 and 2B1/2, namely ethoxyresorufin-O-deethylase and pentoxyresorufin-O-dealkylase, respectively, were decreased in a dose-dependent manner. In SF-treated human hepatocytes, hGSTA1/2 but not hGSTM1 mRNAs were induced, and the expression of CYP1A2 was unaffected, whereas the expression of CYP3A4, the major CYP in human liver, was markedly decreased at both mRNA and activity levels. These observations demonstrate that in intact human and rat hepatocytes, SF may both induce a number of GSTs and cause enzyme inhibition of some but not all CYPs and, in the case of CYP3A4, inhibit both its enzyme activity and its expression.
Isothiocyanates (ITCs) are a family of biologically active compounds that are distributed widely in cruciferous vegetables. Although studies in rodents have shown that these compounds are effective and versatile inhibitors of tumorigenesis, the role of dietary ITCs in the protection against human cancers remains to be established. A prerequisite of human studies is to develop an uptake biomarker for dietary ITCs. In this study, we describe a rapid high-performance liquid chromatography-based assay to measure the total ITC level in human urine. This assay is based on a previously described reaction of ITCs or their thiol conjugates with 1,2-benzenedithiol to yield a cyclocondensation product, 1,3-benzodithiole-2-thione, which then can be quantified by reverse phase high-performance liquid chromatography with UV detection. This new assay was validated by analyzing urine samples from 14 subjects who had consumed a known amount of watercress or brown mustard in a controlled experiment. The N-acetylcysteine conjugates of phenethyl ITC and allyl ITC from watercress and brown mustard, respectively, were quantified and compared with the results obtained from the current assay. Results of the two methods were highly correlated (r = 0.978), indicating the specificity of this new assay for dietary ITCs. The feasibility of this assay for population-based studies was examined using stored urine samples collected from nine participants of a prospective cohort study in Shanghai, China, who indicated that they were daily consumers of dark green vegetables. There was a 10-fold variation in urinary ITC contents among these samples, ranging from 0.7 to 7.0 micromol/g creatinine. These results show the potential use of this uptake biomarker in epidemiological studies to identify the role of dietary ITCs in modifying cancer risks in humans.
The putative anticarcinogenic activity of Brassica vegetables has been associated with the presence of certain glucosinolates. 4-Methylsulphinylbutyl isothiocyanate (sulphoraphane), derived from the corresponding glucosinolate found in broccoli, has previously been identified as a potent inducer of the anticarcinogenic marker enzyme quinone reductase [NADP(H):quinone-acceptor oxidoreductase] in murine hepatoma Hepa 1c1c7 cells. We have therefore produced a broccoli hybrid with increased levels of this anticarcinogenic glucosinolate and tested the ability of extracts to induce quinone reductase. A 10-fold increase in the level of 4-methylsulphinylbutyl glucosinolate was obtained by crossing broccoli cultivars with selected wild taxa of the Brassica oleracea (chromosome number, n = 9) complex. Tissue from these hybrids exhibited a >100-fold increase in the ability to induce quinone reductase in Hepa 1c1c7 cells over broccoli cultivars, due to both an increase in 4-methylsulphinylbutyl glucosinolate content and increased percentage conversion to sulphoraphane.
Transcription factor Nrf2 is essential for the antioxidant responsive element (ARE)-mediated induction of phase II detoxifying and oxidative stress enzyme genes. Detailed analysis of differential Nrf2 activity displayed in transfected cell lines ultimately led to the identification of a new protein, which we named Keap1, that suppresses Nrf2 transcriptional activity by specific binding to its evolutionarily conserved amino-terminal regulatory domain. The closest homolog of Keap1 is a Drosophila actin-binding protein called Kelch, implying that Keap1 might be a Nrf2 cytoplasmic effector. We then showed that electrophilic agents antagonize Keap1 inhibition of Nrf2 activity in vivo, allowing Nrf2 to traverse from the cytoplasm to the nucleus and potentiate the ARE response. We postulate that Keap1 and Nrf2 constitute a crucial cellular sensor for oxidative stress, and together mediate a key step in the signaling pathway that leads to transcriptional activation by this novel Nrf2 nuclear shuttling mechanism. The activation of Nrf2 leads in turn to the induction of phase II enzyme and antioxidative stress genes in response to electrophiles and reactive oxygen species.
The genes glutathione S-transferase M1 (GSTM1) (chromosome 1p13.3) and glutathione S-transferase T1 (GSTT1) (22q11.2) code for cytosolic enzymes glutathione S-transferase (GST)-μ and GST-θ, respectively, which are involved in phase 2 metabolism. Both genes may be deleted. There is
geographic and ethnic variation in genotype frequencies for both genes. In developed countries, colorectal cancer is the second
most common cancer. Colorectal cancer has been inconsistently associated with polycyclic aromatic hydrocarbons in diet and
tobacco. Because GST enzymes are involved in polycyclic aromatic hydrocarbon metabolism, it has been postulated that genotype
may modify colorectal cancer risk associated with polycyclic aromatic hydrocarbon exposure. No consistent associations between
GSTM1 or GSTT1 genotype and colorectal cancer have been observed. However, most studies have methodological limitations. Few have investigated
gene-environment interactions. No interactions between GSTM1 or GSTT1 genotype and smoking and colorectal cancer risk have been reported. One polyp study suggests an interaction between GSTM1 genotype and smoking. Two studies suggest increased disease risk in subjects with high meat intake and GST nonnull genotype,
contrary to the underlying hypothesis. One study suggests a strong inverse relation between colorectal adenomas and broccoli
consumption, particularly in subjects who are GSTM1 null. These finding require confirmation. Methods for determining GSTM1 and GSTT1 genotype are well established. Population testing is not currently justified. Am J Epidemiol 2000; 151:7–32.
Sulforaphane is an isothiocyanate that is present naturally in widely consumed vegetables and has a particularly high concentration in broccoli. This compound has been shown to block the formation of tumors initiated by chemicals in the rat. Although sulforaphane has been proposed to modulate the metabolism of carcinogens, its mechanism of action remains poorly understood. We have previously demonstrated that sulforaphane inhibits the reinitiation of growth and decreases the cellular viability of quiescent human colon carcinoma cells (HT29). Moreover, the weak effect observed on differentiated CaCo2 cells suggests a specific anticancer activity for this compound. Here we investigated the effect of sulforaphane on the growth and viability of HT29 cells during their exponentially growing phase. We observed that sulforaphane induced a cell cycle arrest in a dose-dependent manner, followed by cell death. This sulforaphane-induced cell cycle arrest was correlated with an increased expression of cyclins A and B1. Moreover, we clearly demonstrated that sulforaphane induced cell death via an apoptotic process. Indeed, a large proportion of treated cells display the following: (a) translocation of phosphatidylserine from the inner layer to the outer layer of the plasma membrane; (b) typical chromatin condensation; and (c) ultrastructural modifications related to apoptotic cell death. We also showed that the expression of p53 was not changed in sulforaphane-treated cells. In contrast, whereas bcl-2 was not detected, we observed increased expression of the proapoptotic protein bax, the release of cytochrome c from the mitochondria to the cytosol, and the proteolytic cleavage of poly(ADP-ribose) polymerase. In conclusion, our results strongly suggest that in addition to the activation of detoxifying enzymes, induction of apoptosis is also involved in the sulforaphane-associated chemoprevention of cancer.
Gibberellins (GAs) are key modulators of plant growth and development. PsGA3ox1 (LE) encodes a GA 3β-hydroxylase that catalyzes the conversion of GA20 to biologically active GA1. To further clarify the role of GA3ox expression during pea (Pisum sativum) plant growth and development, we generated transgenic pea lines (in a lele background) with cauliflower mosaic virus-35S-driven expression of PsGA3ox1 (LE). PsGA3ox1 transgene expression led to higher GA1 concentrations in a tissue-specific and development-specific manner, altering GA biosynthesis and catabolism gene expression and plant phenotype. PsGA3ox1 transgenic plants had longer internodes, tendrils, and fruits, larger stipules, and displayed delayed flowering, increased apical meristem life, and altered vascular development relative to the null controls. Transgenic PsGA3ox1 overexpression lines were then compared with lines where endogenous PsGA3ox1 (LE) was introduced, by a series of backcrosses, into the same genetic background (BC LEle). Most notably, the BC LEle plants had substantially longer internodes containing much greater GA1 levels than the transgenic PsGA3ox1 plants. Induction of expression of the GA deactivation gene PsGA2ox1 appears to make an important contribution to limiting the increase of internode GA1 to modest levels for the transgenic lines. In contrast, PsGA3ox1 (LE) expression driven by its endogenous promoter was coordinated within the internode tissue to avoid feed-forward regulation of PsGA2ox1, resulting in much greater GA1 accumulation. These studies further our fundamental understanding of the regulation of GA biosynthesis and catabolism at the tissue and organ level and demonstrate that the timing/localization of GA3ox expression within an organ affects both GA homeostasis and GA1 levels, and thereby growth.
Myrosinase in cell-free extract of Enterobacter cloacae, no. 506, was purified about 1, 000 fold by precipitation with ammonium sulfate, chromatography on CM-Sephadex and gelfiltration on Sephadex G-200 and Sephadex G-100. The enzyme was shown to be homogeneous by chromatography and by ultracentrifuge. Molecular weight obtained by gelfiltration was 61, 000 and the sedimentation coefficient was 4.5S. Maximum activity occurred at pH 6.8. The enzyme was stable in a pH range of 5.0 to 7.0 at temperature below 40°C and for 24 hr. Copper(I) and (II), mercury (II) and ferrous(II) ions strongly inhibited the activity. Sulfhydryl reagents had little effect but EDTA was a strong inhibitor. In contrast to plant myrosinase, this enzyme was inhibited by L-ascorbic acid. Many glucosides and sugars inhibited the enzyme. The relation between bacterial myrosinase and β-glucosidase is discussed in comparison to plant and fungous myrosinases. Some comparative properties of bacterial, fungous and plant myrosinases are discussed.
Epidemiological studies have linked consumption of broccoli to a reduced risk of colon cancer in individuals with the glutathione S-transferase M1 (GSTM1) null genotype. GSTs are involved in excretion and elimination of isothiocyanates (ITCs), which are major constituents of broccoli and other cruciferous vegetables and have cancer chemopreventive potential, so it is speculated that ITCs may play a role in protection against human colon cancer. However, there is a lack of data from animal studies to support this. We carried out a bioassay to examine whether sulforaphane (SFN) and phenethyl isothiocyanate (PEITC), major ITCs in broccoli and watercress, respectively, and their corresponding N-acetylcysteine (NAC) conjugates, show any chemopreventive activity towards azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) in F344 rats. Groups of six male F344 rats were treated with AOM subcutaneously (15 mg/kg body wt) once weekly for 2 weeks. SFN and PEITC and their NAC conjugates were administered by gavage either three times weekly for 8 weeks (5 and 20 μmol, respectively) after AOM dosing (post-initiation stage) or once daily for 3 days (20 and 50 μmol, respectively) before AOM treatment (initiation stage). The bioassay was terminated on week 10 after the second AOM dosing and ACF were quantified. SFN, SFN-NAC, PEITC and PEITC-NAC all significantly reduced the formation of total ACF from 153 to 100-116 (P < 0.01) and multicrypt foci from 52 to 27-38 (more than four crypts/focus; P < 0.05) during the post-initiation treatment. However, only SFN and PEITC were effective during the initiation phase, reducing the total ACF from 153 to 109-115 (P < 0.01) and multicrypt foci from 52 to 35 (more than four crypts/focus; P < 0.05). The NAC conjugates were inactive as anti-initiators against AOM-induced ACF. These findings provide important laboratory evidence for a potential role of SFN and PEITC in the protection against colon cancer.
Screening tests were undertaken to obtain microorganisms which produce myrosinase. One strain of microorganism indicated a strong capasity for producing myrosinase. The morphological and physiological characteristics of this strain were studied. The organism was identified as Enterobacter cloacae, no. 506.
Enzyme production was induced by the addition of 0.01% sinigrin and 6% mustard extract*2 to the culture medium. The highest production was obtained after 36_??_40 hr cultivation when the strain was cultivated at 28°C in a medium containing 0.01% sinigrin, 6% Mustard ext., 0.1% KH2PO4, 0.1% NH4Cl, 0.1% NaCl and 0.1% MgSO4•7aq, (pH 7.0).
Glucoraphanin in Brassica vegetables breaks down to either sulforaphane or sulforaphane nitrile depending on the conditions, and sulforaphane can be further conjugated with glutathione. Using a high-throughput microtitre plate assay and TaqMan real time quantitative RT-PCR to measure mRNA, we show that sulforaphane and its glutathione conjugate, but not the nitrile, increased significantly (P < 0.05) both UGT1A1 and GSTA1 mRNA levels in HepG2 and HT29 cells. These changes were accompanied by an increase in UGT1A1 protein, as assessed by immunoblotting, and a 2‐8-fold increase in bilirubin glucuronidation. When treated together, the nitrile derivative did not affect sulforaphane induction. The induction of UGT1A1 and GSTA1 mRNA by sulforaphane was time and concentration dependent. The results show a functional induction of glucuronidation by sulforaphane but not sulforaphane nitrile, and show that the pathway of metabolism of glucosinolates in Brassica vegetables is important in determining the resulting biological and anticarcinogenic activities.
Dietary isothiocyanates (ITCs) are highly effective in affording protection against chemically induced cancers in laboratory animals. In the present study, we demonstrate that allyl isothiocyanate (AITC), a constituent of cruciferous vegetables, significantly inhibits proliferation of cultured PC-3 (androgen-independent) and LNCaP (androgen-dependent) human prostate cancer cells in a dose-dependent manner with an IC50 of ~15‐17 mM. On the other hand, survival of a normal prostate epithelial cell line (PrEC) was minimally affected by AITC even at concentrations that were highly cytotoxic to the prostate cancer cells. Reduced proliferation of PC-3 as well as LNCaP cells in the presence of AITC correlated with accumulation of cells in G2/M phase and induction of apoptosis. In contrast, AITC treatment failed to induce apoptosis or cause G2/M phase arrest in PrEC cells. A 24 h treatment of PC-3 and LNCaP cells with 20 mM AITC caused a significant decrease in the levels of proteins that regulate G2/M progression, including Cdk1 (32‐50% reduction), Cdc25B (44‐48% reduction) and Cdc25C (490% reduction). A significant reduction in the expression of cyclin B1 protein (~45%) was observed only in LNCaP cells. A 24 h exposure of PC-3 and LNCaP cells to an apoptosis-inducing concentration of AITC (20 mM) resulted in a significant decrease (31‐68%) in the levels of anti-apoptotic protein Bcl-2 in both cell lines, and ~58% reduction in Bcl-XL protein expression in LNCaP cells. In conclusion, it seems reasonable to hypothesize that AITC, and possibly other ITCs, may find use in the treatment of human prostate cancers.
The putative anticarcinogenic activity of Brassica vegetables has been associated with the presence of certain glucosinolates. 4-Methylsulphinylbutyl isothiocyanate (sulphoraphane), derived from the corresponding glucosinolate found in broccoli, has previously been identified as a potent inducer of the anticarcinogenic marker enzyme quinone reductase [NADP(H):quinone-acceptor oxidoreductase] in murine hepatoma Hepa lclc7 cells. We have therefore produced a broccoli hybrid with increased levels of this anticarcinogenic glucosinolate and tested the ability of extracts to induce quinone reductase. A 10-fold increase in the level of 4-methylsulphinylbutyl glucosinolate was obtained by crossing broccoli cultivars with selected wild taxa of the Brassica oleracea (chromosome number, n = 9) complex. Tissue from these hybrids exhibited a >100-fold increase in the ability to induce quinone reductase in Hepa lclc7 cells over broccoli cultivars, due to both an increase in 4-methylsulphinylbutyl glucosinolate content and increased percentage conversion to sulphoraphane.
We report the RFLP mapping of quantitative trait loci (QTLs) which regulate the total seed aliphaticglucosinolate content in Brassica napus L. A population of 99 F1-derived doubled-haploid (DH) recombinant lines from a cross between the cultivars Stellar (low-glucosinolate) and Major (high-glucosinolate) was used for singlemarker analysis and the interval mapping of QTLs associated with total seed glucosinolates. Two major loci, GSL-1 and GSL-2, with the largest influence on total seed aliphatic-glucosinolates, were mapped onto LG 20 and LG 1, respectively. Three loci with smaller effects, GSL-3, GSL-4 and GSL-5, were tentatively mapped to LG 18, LG 4 and LG 13, respectively. The QTLs acted in an additive manner and accounted for 71 % of the variation in total seed glucosinolates, with GSL-1 and GSL-2 accounting for 33% and 17%, respectively. The recombinant population had aliphatic-glucosinolate levels of between 6 and 160 μmoles per g(-1) dry wt of seed. Transgressive segregation for high seed glucosinolate content was apparent in 25 individuals. These phenotypes possessed Stellar alleles at GSL-3 and Major alleles at the four other GSL loci demonstrating that low-glucosinolate genotypes (i.e. Stellar) may possess alleles for high glucosinolates which are only expressed in particular genetic backgrounds. Gsl-elong and Gsl-alk, loci which regulate the ratio of individual aliphatic glucosinolates, were also mapped. Gsl-elong-1 and Gsl-elong-2, which control elongation of the α-amino-acid precursors, mapped to LG 18 and LG 20 and were coincident with GSL loci which regulate total seed aliphatic glucosinolates. A third tentative QTL, which regulates side-chain elongation, was tentatively mapped to LG 12. Gsl-alk, which regulates H3CS-removal and side-chain de-saturation, mapped to LG 20.
Glucosinolates were evaluated in 5 groups and 65 accessions of Brassica oleracea (50 broccoli, 4 Brussels sprouts, 6 cabbage, 3 cauliflower, and 2 kale) grown under uniform cultural conditions. Glucosinolates and their concentrations varied among the different groups and within each group. The predominant glucosinolates in broccoli were 4-methylsulfinylbutyl glucosinolate (glucoraphanin), 3-butenyl glucosinolate (gluconapin), and 3-indolylmethyl glucosinoate (glucobrassicin). Glucoraphanin concentration in broccoli ranged from 0.8 mu mol g(-1) DW in EV6-1 to 21.7 mu mol g(-1) DW in Brigadier. Concentrations of the other glucosinolates in broccoli varied similarly over a wide range. In Brussels sprouts, cabbage, cauliflower, and kale, the predominant glucosinolates were sinigrin (8.9, 7.8, 9.3, and 10.4 mu mol g(-1) DW, respectively) and glucobrassicin (3.2, 0.9, 1.3, and 1.2 mu mol g(-1) DW, respectively). Brussels sprouts also had significant amounts of gluconapin (6.9 mu mol g(-1) DW). Wide variations in glucosinolate content among genotypes suggest differences in their health-promoting properties and the opportunity for enhancement of their levels through genetic manipulation.
The effect of consumption of glucosinolate-containing Brussels sprouts on α-class glutathione S-transferase levels in human blood plasma was investigated in 10 healthy, male, non-smoking volunteers. Following a 3-week run-in period, five volunteers continued on a glucosinolate-free diet during a subsequent 3-week intervention period (control group), while the other five (sprouts group) consumed 300 g of cooked Brussels sprouts per day, at the expense of 300 g of a glucosinolate-free vegetable. α-Class glutathione S-transferases were measured by radioimmunoassay. In the control group, similar α-class glutathione S-transferase levels were observed in both periods (P=0.814), while in the sprouts group the α-class glutathione S-transferase levels were elevated by a factor of 1.4 P=0.002)
Phenethyl isothiocyanate (PEITC) is a natural product that is among the most effective cancer chemopreventive agents known. Mechanistic studies indicate that the chemopreventive activity of PEITC is associated with its favorable modification of carcinogen metabolism and its induction of apoptosis. Here, we found that PEITC blocks tumor promoter (12-0- tetradecanoylphorbol-13-acetate or epidermal growth factor)-induced cell transformation in mouse epidermal JB6 cells, and this inhibitory activity on cell transformation is correlated with induction of apoptosis. Most importantly, apoptosis induction by PEITC occurs through a p53-depend- ent pathway. This was demonstrated not only by results that PEITC induction of p53 protein expression and p53-dependent transactivation but also by PEITC-induced apoptosis inp53 +/+ cells but not inp53 -/- cells. In contrast, PEITC induced apoptosis in cells with both normal or deficient sphingomyelinase activity. Our results demonstrate for the first time that p53 elevation is required for PEITC-induced apoptosis, which may be involved in its cancer chemopreventive activity.
A case-control study to evaluate risk factors of gastric cancer was carried out in areas with contrasting incidence rates in Sweden. Face-to-face interviews were conducted with 338 of 456 eligible histologically confirmed gastric-cancer cases and 669 of 880 eligible control subjects, sampled from population registers and frequency-matched by age and gender. We focused on 2 periods, adolescence and 20 years prior to interview. The association of gastric-cancer risk with dietary habits during adolescence were similar to that found for the period 20 years before interview; high consumption of wholemeal bread, fruit and vegetables was associated with reduced gastric-cancer risk. In addition, cheese, fish and tea had a protective effect during adolescence. Increased gastric-cancer risk was related to whole-milk consumption, but this association decreased substantially in a multivariate analysis including vegetables. There was a positive relationship between gastric-cancer risk and the age at which the interviewees started using refrigerators. This population-based study confirmed the protective effect of a high consumption of vegetables and fruit in the development of gastric cancer, but failed to find any association between intake of meat, sausage, cold cuts, liver, salt, coffee, the habit of frying, smoking or grilling foods, and risk of gastric cancer.
Total aliphatic and indole/aromatic glucosinolates and vitamin C content (ascorbic+dehydroascorbic acid) were evaluated in the edible portions of fresh harvested broccoli (Brassica oleracea L. var. italica) florets (Marathon cv.) before and after cooking and in the cooking water. High pressure boiling, steam cooking, microwaving and low pressure boiling (conventional) were the four domestic cooking processes used in this work. Results showed great differences among the four cooking processes and their influence on the content of glucosinolates and vitamin C. Thus, clear disadvantages were detected when cooking in a microwave due to the high loss of vitamin C (40%) and total glucosinolates (74%) in comparison with the rest of treatments. High pressure and conventional boiling had a significant loss rate of total glucosinolates (33% and 55% respectively) regarding fresh raw broccoli, due to the leaching into the cooking water. On the other hand, steaming had minimal effects on glucosinolates and vitamin C. Therefore, we can conclude that a large quantity of glucosinolates and vitamin C will be consumed in steamed broccoli when compared to the other cooking processes.
The mechanisms by which brassica vegetables might decrease the risk of cancer are reviewed in this paper. Brassicas, including all types of cabbages, broccoli, cauliflower and Brussels sprouts, may be protective against cancer due to their relatively high glucosinolate content. Glucosinolates are usually broken down through hydrolysis catalyzed by myrosinase, an enzyme that is released from damaged plant cells. Some of the hydrolysis products, viz. indoles and isothiocyanates, are able to influence phase 1 and phase 2 biotransformation enzyme activities, thereby possibly influencing several processes related to chemical carcinogenesis, e.g. the metabolism, DNA-binding and mutagenic activity of promutagens. A reducing effect on tumor formation has been shown in rats and mice. The anticarcinogenic action of isothiocyanates and indoles depends upon many factors, such as the test system, the target tissue, the type of carcinogen challenge and the anticarcinogenic compound, their dosage, as well as the timing of the treatment. Most evidence concerning anticarcinogenic effects of glucosinolate hydrolysis products and brassica vegetables has come from studies in animals. Animal studies are invaluable in identifying and testing potential anticarcinogens. In addition, studies carried out in humans using high but still realistic human consumption levels of indoles and brassica vegetables have shown putative positive effects on health.
The consumption of cruciferous vegetables has long been associated with a reduced risk in the occurrence of cancer at various sites, including the prostate, lung, breast and colon. This protective effect is attributed to isothiocyanates present in these vegetables, and sulforaphane (SF), present in broccoli, is by far the most extensively studied to uncover the mechanisms behind this chemoprotection. The major mechanism by which SF protects cells was traditionally thought to be through Nrf2-mediated induction of phase 2 detoxification enzymes that elevate cell defense against oxidative damage and promote the removal of carcinogens. However, it is becoming clear that there are multiple mechanisms activated in response to SF, including suppression of cytochrome P450 enzymes, induction of apoptotic pathways, suppression of cell cycle progression, inhibition of angiogenesis and anti-inflammatory activity. Moreover, these mechanisms seem to have some degree of interaction to synergistically afford chemoprevention.
Benzyl isothiocyanate and phenethyl isothiocyanate, two aromatic phytochemicals present in substantial concentrations in edible vegetables of the genus Brassica, were investigated for their effects on Caco-2 cell proliferation. Benzyl and phenethyl isothiocyanate inhibited DNA synthesis, with 50% inhibitory concentrations of 5.1 and 2.4 micromol/L, respectively, and significantly increased the doubling times of Caco-2 cells from 32 h to 220 and 120 h, respectively. There was no adverse effect of either chemical on cell viability in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, but benzyl isothiocyanate and phenethyl isothiocyanate both caused an accumulation of cells in the G(2)/M phase of the cell cycle, which was maintained for at least 48 h in cells synchronized at prometaphase with nocodazole and subsequently treated with 10 micromol/L benzyl isothiocyanate or phenethyl isothiocyanate. Both benzyl and phenethyl isothiocyanate increased DNA strand breakage, increased phosphorylation of the G(2)/M checkpoint enforcer Chk2, and induced p21 expression. These results suggest that the antiproliferative effects of benzyl and phenethyl isothiocyanates toward Caco-2 cells are due at least in part to the activation of the G(2)/M DNA damage checkpoint, and that sustained G(2)/M phase cell cycle arrest in response to benzyl and phenethyl isothiocyanates may be maintained through upregulation of p21. This study indicates that some dietary isothiocyanates may exert an antiproliferative effect through activation of the G(2)/M DNA damage checkpoint.