Variations of Major Glucosinolates in Diverse Chinese Cabbage (Brassica rapa ssp. pekinensis) Germplasm as Analyzed by UPLC-ESI-MS/MS.

In this study, the variability of major glucosinolates in the leaf lamina of 134 Chinese cabbage accessions was investigated using Acquity ultra-performance liquid chromatography (UPLC-ESI-MS/MS). A total of twenty glucosinolates were profiled, of which glucobrassicanapin and gluconapin were identified as the predominant glucosinolates within the germplasm. These two glucosinolates had mean concentration levels above 1000.00 µmol/kg DW. Based on the principal component analysis, accessions IT186728, IT120044, IT221789, IT100417, IT278620, IT221754, and IT344740 were separated from the rest in the score plot. These accessions exhibited a higher content of total glucosinolates. Based on the VIP values, 13 compounds were identified as the most influential and responsible for variation in the germplasm. Sinigrin (r = 0.73), gluconapin (r = 0.78), glucobrassicanapin (r = 0.70), epiprogoitrin (r = 0.73), progoitrin (r = 0.74), and gluconasturtiin (r = 0.67) all exhibited a strong positive correlation with total glucosinolate at p < 0.001. This indicates that each of these compounds had a significant influence on the overall glucosinolate content of the various accessions. This study contributes valuable insights into the metabolic diversity of glucosinolates in Chinese cabbage, providing potential for breeding varieties tailored to consumer preferences and nutritional demands.

Germination Increases the Glucomoringin Content in Moringa Sprouts via Transforming Tyrosine.

Moringa seeds are an excellent dietary source of phytochemicals (i.e., glucosinolates, GSLs; isothiocyanates, ITCs) with health-beneficial effects. Although numerous studies have been conducted on moringa seeds, the effect of germination on the regulation of GSLs remains scarcely explored. The present study investigated the dynamic changes of GSLs in moringa seeds during germination (at 25, 30, and 35 °C for 6 days in the dark) through an untargeted metabolomics approach and compared the antioxidant capacity of ungerminated and germinated moringa seeds. Our results showed that germination significantly increased the total GSL content from 150 (day 0) to 323 µmol/g (35 °C, day 6) on a dry weight (DW) basis, especially glucomoringin (GMG), the unique glucosinolate in moringa seeds, which was significantly upregulated from 61 (day 0) to 149 µmol/g DW (35 °C, day 4). The upregulation of GMG corresponded to the metabolism of tyrosine, which might be the initial precursor for the formation of GMG. In addition, germination enhanced the total ITC content from 85 (day 0) to 239 µmol SE/g DW (35 °C, day 6), indicating that germination may have also increased the activity of myrosinase. Furthermore, germination remarkably increased the total phenolic content (109-507 mg GAE/100 g DW) and antioxidant capacity of moringa seeds. Our findings suggest that moringa sprouts could be promoted as a novel food and/or ingredient rich in GMG.

Myrosinase isogenes in wasabi (Wasabia japonica Matsum) and their putative roles in glucosinolate metabolism.

BACKGROUND: Wasabi, a Brassicaceae member, is well-known for its unique pungent and hot flavor which is produced from glucosinolate (GSL) degradation. Myrosinase (MYR) is a principle enzyme catalyzing the primary conversion of GSLs to GSL hydrolysis products (GHPs) which is responsible for plant defense system and food quality. Due to the limited information in relation to MYRs present in wasabi (Wasabia japonica M.), this study aimed to identify the MYR isogenes in W. japonica and analyze their roles in relation to GSL metabolism. RESULTS: In results, WjMYRI-1 was abundantly expressed in all organs, whereas WjMYRI-2 showed only trace expression levels. WjMYRII was highly expressed in the aboveground tissues. Interestingly, WjMYRII expression was significantly upregulated by certain abiotic factors, such as methyl jasmonate (more than 40-fold in petioles and 15-fold in leaves) and salt (tenfold in leaves). Young leaves and roots contained 97.89 and 91.17 µmol‧g-1 of GSL, whereas less GSL was produced in mature leaves and petioles (38.36 and 44.79 µmol‧g-1, respectively). Similar pattern was observed in the accumulation of GHPs in various plant organs. Notably, despite the non-significant changes in GSL production, abiotic factors treated samples enhanced significantly GHP content. Pearson's correlation analysis revealed that WjMYRI-1 expression significantly correlated with GSL accumulation and GHP formation, suggesting the primary role of WjMYRI-1-encoding putative protein in GSL degradation. In contrast, WjMYRII expression level showed no correlation with GSL or GHP content, suggesting another physiological role of WjMYRII in stress-induced response. CONCLUSIONS: In conclusions, three potential isogenes (WjMYRI-1, WjMYRI-2, and WjMYRII) encoding for different MYR isoforms in W. japonica were identified. Our results provided new insights related to MYR and GSL metabolism which are important for the implications of wasabi in agriculture, food and pharmaceutical industry. Particularly, WjMYRI-1 may be primarily responsible for GSL degradation, whereas WjMYRII (clade II) may be involved in other regulatory pathways induced by abiotic factors.

The Effect of Broccoli Glucoraphanin Supplementation on Ameliorating High-Fat-Diet-Induced Obesity through the Gut Microbiome and Metabolome Interface.

SCOPE: Obesity and its metabolic comorbidities pose a major global challenge for public health. Glucoraphanin (GRN) is a natural bioactive compound enriched in broccoli that is known to have potential health benefits against various human chronic diseases. METHODS AND RESULTS: This study investigats the effects of broccoli GRN supplementation on body weight, metabolic parameters, gut microbiome and metabolome associated with obesity. The study is conducted on an obese-related C57BL/6J mouse model through the treatment of normal control diet, high-fat diet (HFD)and GRN-supplemented HFD (HFD-GRN) to determine the metabolic protection of GRN. The results shows that GRN treatment alleviates obesity-related traits leading to improved glucose metabolism in HFD-fed animals. Mechanically, the study noticed that GRN significantly shifts the gut microbial diversity and composition to an eubiosis status. GRN supplement also significantly alters plasma metabolite profiles. Further integrated analysis reveal a complex interaction between the gut microbes and host metabolism that may contribute to GRN-induced beneficial effects against HFD. CONCLUSION: These results indicate that beneficial effects of broccoli GRN on reversing HFD-induced adverse metabolic parameters may be attributed to its impacts on reprogramming microbial community and metabolites. Identification of the mechanistic functions of GRN further warrants it as a dietary candidate for obesity prevention.

Do Brassica Vegetables Affect Thyroid Function?-A Comprehensive Systematic Review.

Brassica vegetables are widely consumed all over the world, especially in North America, Asia, and Europe. They are a rich source of sulfur compounds, such as glucosinolates (GLSs) and isothiocyanates (ITCs), which provide health benefits but are also suspected of having a goitrogenic effect. Adhering to PRISMA guidelines, we conducted a systematic review to assess the impact of dietary interventions on thyroid function, in terms of the potential risk for people with thyroid dysfunctions. We analyzed the results of 123 articles of in vitro, animal, and human studies, describing the impact of brassica plants and extracts on thyroid mass and histology, blood levels of TSH, T3, T4, iodine uptake, and the effect on thyroid cancer cells. We also presented the mechanisms of the goitrogenic potential of GLSs and ITCs, the limitations of the studies included, as well as further research directions. The vast majority of the results cast doubt on previous assumptions claiming that brassica plants have antithyroid effects in humans. Instead, they indicate that including brassica vegetables in the daily diet, particularly when accompanied by adequate iodine intake, poses no adverse effects on thyroid function.

Formation of DNA Adducts by 1-Methoxy-3-indolylmethylalcohol, a Breakdown Product of a Glucosinolate, in the Mouse: Impact of the SULT1A1 Status-Wild-Type, Knockout or Humanised.

We previously found that feeding rats with broccoli or cauliflower leads to the formation of characteristic DNA adducts in the liver, intestine and various other tissues. We identified the critical substances in the plants as 1-methoxy-3-indolylmethyl (1-MIM) glucosinolate and its degradation product 1-MIM-OH. DNA adduct formation and the mutagenicity of 1-MIM-OH in cell models were drastically enhanced when human sulfotransferase (SULT) 1A1 was expressed. The aim of this study was to clarify the role of SULT1A1 in DNA adduct formation by 1-MIM-OH in mouse tissues in vivo. Furthermore, we compared the endogenous mouse Sult1a1 and transgenic human SULT1A1 in the activation of 1-MIM-OH using genetically modified mouse strains. We orally treated male wild-type (wt) and Sult1a1-knockout (ko) mice, as well as corresponding lines carrying the human SULT1A1-SULT1A2 gene cluster (tg and ko-tg), with 1-MIM-OH. N2-(1-MIM)-dG and N6-(1-MIM)-dA adducts in DNA were analysed using isotope-dilution UPLC-MS/MS. In the liver, caecum and colon adducts were abundant in mice expressing mouse and/or human SULT1A1, but were drastically reduced in ko mice (1.2-10.6% of wt). In the kidney and small intestine, adduct levels were high in mice carrying human SULT1A1-SULT1A2 genes, but low in wt and ko mice (1.8-6.3% of tg-ko). In bone marrow, adduct levels were very low, independently of the SULT1A1 status. In the stomach, they were high in all four lines. Thus, adduct formation was primarily controlled by SULT1A1 in five out of seven tissues studied, with a strong impact of differences in the tissue distribution of mouse and human SULT1A1. The behaviour of 1-MIM-OH in these models (levels and tissue distribution of DNA adducts; impact of SULTs) was similar to that of methyleugenol, classified as "probably carcinogenic to humans". Thus, there is a need to test 1-MIM-OH for carcinogenicity in animal models and to study its adduct formation in humans consuming brassicaceous foodstuff.

Flavin-containing monooxygenases FMOGS-OXs integrate flowering transition and salt tolerance in Arabidopsis thaliana.

Salt stress substantially leads to flowering delay. The regulation of salt-induced late flowering has been studied at the transcriptional and protein levels; however, the involvement of secondary metabolites has rarely been investigated. Here, we report that FMOGS-OXs (EC 1.14.13.237), the enzymes that catalyze the biosynthesis of glucosinolates (GSLs), promote flowering transition in Arabidopsis thaliana. It has been reported that WRKY75 is a positive regulator, and MAF4 is a negative regulator of flowering transition. The products of FMOGS-OXs, methylsulfinylalkyl GSLs (MS GSLs), facilitate flowering by inducing WRKY75 and repressing the MAS-MAF4 module. We further show that the degradation of MS GSLs is involved in salt-induced late flowering and salt tolerance. Salt stress induces the expression of myrosinase genes, resulting in the degradation of MS GSLs, thereby relieving the promotion of WRKY75 and inhibition of MAF4, leading to delayed flowering. In addition, the degradation products derived from MS GSLs enhance salt tolerance. Previous studies have revealed that FMOGS-OXs exhibit alternative catalytic activity to form trimethylamine N-oxide (TMAO) under salt stress, which activates multiple stress-related genes to promote salt tolerance. Therefore, FMOGS-OXs integrate flowering transition and salt tolerance in various ways. Our study shed light on the functional diversity of GSLs and established a connection between flowering transition, salt resistance, and GSL metabolism.

Pseudomonas syringae infectivity correlates to altered transcript and metabolite levels of Arabidopsis mediator mutants.

Rapid metabolic responses to pathogens are essential for plant survival and depend on numerous transcription factors. Mediator is the major transcriptional co-regulator for integration and transmission of signals from transcriptional regulators to RNA polymerase II. Using four Arabidopsis Mediator mutants, med16, med18, med25 and cdk8, we studied how differences in regulation of their transcript and metabolite levels correlate to their responses to Pseudomonas syringae infection. We found that med16 and cdk8 were susceptible, while med25 showed increased resistance. Glucosinolate, phytoalexin and carbohydrate levels were reduced already before infection in med16 and cdk8, but increased in med25, which also displayed increased benzenoids levels. Early after infection, wild type plants showed reduced glucosinolate and nucleoside levels, but increases in amino acids, benzenoids, oxylipins and the phytoalexin camalexin. The Mediator mutants showed altered levels of these metabolites and in regulation of genes encoding key enzymes for their metabolism. At later stage, mutants displayed defective levels of specific amino acids, carbohydrates, lipids and jasmonates which correlated to their infection response phenotypes. Our results reveal that MED16, MED25 and CDK8 are required for a proper, coordinated transcriptional response of genes which encode enzymes involved in important metabolic pathways for Arabidopsis responses to Pseudomonas syringae infections.

Morpho-Physiochemical Indices and Transcriptome Analysis Reveal the Role of Glucosinolate and Erucic Acid in Response to Drought Stress during Seed Germination of Rapeseed.

The global expansion of rapeseed seed quality has been focused on maintaining glucosinolate (GSL) and erucic acid (EA) contents. However, the influence of seed GSL and EA contents on the germination process under drought stress remains poorly understood. Herein, 114 rapeseed accessions were divided into four groups based on GSL and EA contents to investigate their performance during seed imbibition under drought stress. Our results revealed significant variations in seed germination-related traits, particularly with higher GSL and EA, which exhibited higher germination % (G%) and lower mean germination time (MGT) under drought stress conditions. Moreover, osmoregulation, enzymatic system and hormonal regulation were improved in high GSL and high EA (HGHE) versus low GSL and low EA (LGLE) seeds, indicating the essential protective role of GSL and EA during the germination process in response to drought stress. The transcriptional regulation mechanism for coordinating GSL-EA-related pathways in response to drought stress during seed imbibition was found to involve the differential expression of sugar metabolism-, antioxidant-, and hormone-related genes with higher enrichment in HGHE compared to LGLE seeds. GO enrichment analysis showed higher variations in transcription regulator activity and DNA-binding transcription factors, as well as ATP and microtubule motor activity in GSL-EA-related pathways. Furthermore, KEGG analysis identified cellular processes, environmental information processing, and metabolism categories, with varied gene participation between GSL, EA and GSL-EA-related pathways. For further clarification, QY7 (LGLE) seeds were primed with different concentrations of GSL and EA under drought stress conditions. The results showed that 200 µmol/L of GSL and 400 µmol/L of EA significantly improved G%, MGT, and seedling fresh weight, besides regulating stress and fatty acid responsive genes during the seed germination process under drought stress conditions. Conclusively, exogenous application of GSL and EA is considered a promising method for enhancing the drought tolerance of LGLE seeds. Furthermore, the current investigation could provide a theoretical basis of GSL and EA roles and their underlying mechanisms in stress tolerance during the germination process.

A Comparative Review of Key Isothiocyanates and Their Health Benefits.

Isothiocyanates are biologically active products resulting from the hydrolysis of glucosinolates predominantly present in cruciferous vegetables belonging to the Brassicaceae family. Numerous studies have demonstrated the diverse bioactivities of various isothiocyanates, encompassing anticarcinogenic, anti-inflammatory, and antioxidative properties. Nature harbors distinct isothiocyanate precursors, glucosinolates such as glucoraphanin and gluconastrin, each characterized by unique structures, physical properties, and pharmacological potentials. This comprehensive review aims to consolidate the current understanding of Moringa isothiocyanates, mainly 4-[(α-L-rhamnosyloxy) benzyl] isothiocyanate), comparing this compound with other well-studied isothiocyanates such as sulforaphane and phenyl ethyl isothiocyanates. The focus is directed toward elucidating differences and similarities in the efficacy of these compounds as agents with anticancer, anti-inflammatory, and antioxidative properties.

Natural H2S-donors: A new pharmacological opportunity for the management of overweight and obesity.

The prevalence of overweight and obesity has progressively increased in the last few years, becoming a real threat to healthcare systems. To date, the clinical management of body weight gain is an unmet medical need, as there are few approved anti-obesity drugs and most require an extensive monitoring and vigilance due to risk of adverse effects and poor patient adherence/persistence. Growing evidence has shown that the gasotransmitter hydrogen sulfide (H2S) and, therefore, H2S-donors could have a central role in the prevention and treatment of overweight/obesity. The main natural sources of H2S-donors are plants from the Alliaceae (garlic and onion), Brassicaceae (e.g., broccoli, cabbage, and wasabi), and Moringaceae botanical families. In particular, polysulfides and isothiocyanates, which slowly release H2S, derive from the hydrolysis of alliin from Alliaceae and glucosinolates from Brassicaceae/Moringaceae, respectively. In this review, we describe the emerging role of endogenous H2S in regulating adipose tissue function and the potential efficacy of natural H2S-donors in animal models of overweight/obesity, with a final focus on the preliminary results from clinical trials. We conclude that organosulfur-containing plants and their extracts could be used before or in combination with conventional anti-obesity agents to improve treatment efficacy and reduce inflammation in obesogenic conditions. However, further high-quality studies are needed to firmly establish their clinical efficacy.

QM/MM study of the catalytic reaction of aphid myrosinase.

Brevicoryne brassicae, an aphid species, exclusively consumes plants from the Brassicaceae family and employs a sophisticated defense mechanism involving a myrosinase enzyme that breaks down glucosinolates obtained from its host plants. In this work, we employed combined quantum mechanical and molecular mechanical (QM/MM) calculations and molecular dynamics (MD) simulations to study the catalytic reaction of aphid myrosinase. A proper QM region to study the myrosinase reaction should contain the whole substrate, models of Gln-19, His-122, Asp-124, Asn-166, Glu-167, Lys-173, Tyr-180, Val-228, Tyr-309, Tyr-346, Ile-347, Glu-374, Glu-423, Trp-424, and a water molecule. The calculations show that Asp-124 and Glu-423 must be charged, His-122 must be protonated on NE2, and Glu-167 must be protonated on OE2. Our model reproduces the anomeric retaining characteristic of myrosinase and indicates that the deglycosylation reaction is the rate-determining step of the reaction. Based on the calculations, we propose a reaction mechanism for aphid myrosinase-mediated hydrolysis of glucosinolates with an overall barrier of 15.2 kcal/mol. According to the results, removing a proton from Arg-312 or altering it to valine or methionine increases glycosylation barriers but decreases the deglycosylation barrier.

Plant glucosinolate biosynthesis and breakdown pathways shape the rhizosphere bacterial/archaeal community.

Rhizosphere microbial community assembly results from microbe-microbe-plant interactions mediated by small molecules of plant and microbial origin. Studies with Arabidopsis thaliana have indicated a critical role of glucosinolates in shaping the root and/or rhizosphere microbial community, likely through breakdown products produced by plant or microbial myrosinases inside or outside of the root. Plant nitrile-specifier proteins (NSPs) promote the formation of nitriles at the expense of isothiocyanates upon glucosinolate hydrolysis with unknown consequences for microbial colonisation of roots and rhizosphere. Here, we generated the A. thaliana triple mutant nsp134 devoid of nitrile formation in root homogenates. Using this line and mutants lacking aliphatic or indole glucosinolate biosynthesis pathways or both, we found bacterial/archaeal alpha-diversity of the rhizosphere to be affected only by the ability to produce aliphatic glucosinolates. In contrast, bacterial/archaeal community composition depended on functional root NSPs as well as on pathways of aliphatic and indole glucosinolate biosynthesis. Effects of NSP deficiency were strikingly distinct from those of impaired glucosinolate biosynthesis. Our results demonstrate that rhizosphere microbial community assembly depends on functional pathways of both glucosinolate biosynthesis and breakdown in support of the hypothesis that glucosinolate hydrolysis by myrosinases and NSPs happens before secretion of products to the rhizosphere.

Stability and bioaccessibility of micronutrients and phytochemicals present in processed leek and Brussels sprouts during static in vitro digestion.

Vegetables are frequently processed before consumption. However, vegetable functionalization continues beyond ingestion as the human digestive tract exposes vegetable products to various conditions (e.g. elevated temperature, pH alterations, enzymes, electrolytes, mechanical disintegration) which can affect the stability of micronutrients and phytochemicals. Besides the extent to which these compounds withstand the challenges posed by digestive conditions, it is equally important to consider their accessibility for potential absorption by the body. Therefore, this study investigated the impact of static in vitro digestion on the stability (i.e. concentration) and bioaccessibility of vitamin C, vitamin K1, glucosinolates, S-alk(en)yl-l-cysteine sulfoxides (ACSOs) and carotenoids in Brussels sprouts (Brassica oleracea var. gemmifera) and leek (Allium ampeloprasum var. porrum). Water-soluble compounds, glucosinolates and ACSOs, remained stable during digestion while vitamin C decreased by >48%. However, all water-soluble compounds were completely bioaccessible. Lipid-soluble compounds were also stable during digestion but were only bioaccessible for 26-81%.

Engineering Brassica Crops to Optimize Delivery of Bioactive Products Postcooking.

Glucosinolates are plant-specialized metabolites that can be hydrolyzed by glycosyl hydrolases, called myrosinases, creating a variety of hydrolysis products that benefit human health. While cruciferous vegetables are a rich source of glucosinolates, they are often cooked before consumption, limiting the conversion of glucosinolates to hydrolysis products due to the denaturation of myrosinases. Here we screen a panel of glycosyl hydrolases for high thermostability and engineer the Brassica crop, broccoli (Brassica oleracea L.), for the improved conversion of glucosinolates to chemopreventive hydrolysis products. Our transgenic broccoli lines enabled glucosinolate hydrolysis to occur at higher cooking temperatures, 20 °C higher than in wild-type broccoli. The process of cooking fundamentally transforms the bioavailability of many health-relevant bioactive compounds in our diet. Our findings demonstrate the promise of leveraging genetic engineering to tailor crops with novel traits that cannot be achieved through conventional breeding and improve the nutritional properties of the plants we consume.

n-Butanol fraction of moringa seed attenuates arsenic intoxication by regulating the uterine inflammatory and apoptotic pathways.

The adverse effects of arsenic-chelating drugs make it essential to replace invasive chelating therapy with non-invasive oral therapy for arsenic poisoning. The goal of the current investigation was to determine whether the uterine damage caused by arsenization could be repaired by the n-butanol fraction of Moringa oleifera seed (NB). The rats were orally administered with arsenic (10 mg/kg BW) for the initial 8 days, followed by NB (50 mg/kg) for the next 8 days without arsenic. The probable existence of different components in NB was evaluated by HPLC-MS. Pro and anti-inflammatory indicators were assessed by RT-PCR and western blot. ESR-α was detected via immunostaining. Arsenic-exposed rats had significantly increased lipid peroxidation and decreased antioxidant enzyme activity, which were markedly reduced after NB treatment. Weaker ESR-α expression and distorted uterine histomorphology following arsenication were retrieved significantly by NB. Meaningful restoration by NB was also achieved for altered mRNA and protein expression of various inflammatory and apoptotic indicators. Molecular interaction predicted that glucomoringin and methyl glucosinolate of moringa interact with the catalytic site of caspase-3 in a way that limits its activity. However, NB was successful in restoring the arsenic-mediated uterine hypofunction. The glucomoringin and methyl glucosinolate present in n-butanol fraction may play a critical role in limiting apoptotic event in the arsenicated uterus.

Sinigrin improves cerebral ischaemia-reperfusion injury by inhibiting the TLR4 pathway-mediated oxidative stress.

Cerebral ischaemia-reperfusion (CIR) injury occurs in stroke patients after the restoration of cerebral perfusion. Sinigrin, a phytochemical found in cruciferous vegetables, exhibits strong antioxidant activity. This study investigated the role of sinigrin in oxidative stress using a CIR injury model. The effects of sinigrin were studied in middle cerebral artery occlusion (MCAO) rats and oxygen-glucose deprivation/reoxygenation (OGD/R)-injured SH-SY5Y cells. Sinigrin treatment improved brain injury and neurological deficits induced by MCAO surgery in rats. Sinigrin inhibited apoptosis in brain tissues and SH-SY5Y cells following OGD/R induction. Additionally, sinigrin elevated the levels of superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GSH-Px) while reducing malondialdehyde (MDA) levels. Furthermore, sinigrin inhibited the toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signalling pathway. The anti-apoptotic and antioxidant activities of sinigrin in OGD/R-injured SH-SY5Y cells were reversed by TLR4 overexpression. In conclusion, sinigrin inhibits oxidative stress in CIR injury by suppressing the TLR4/MyD88 signalling pathway.

Acidification and tissue disruption affect glucosinolate and S-methyl-l-cysteine sulfoxide hydrolysis and formation of amines, isothiocyanates and other organosulfur compounds in red cabbage (Brassica oleracea var. capitata f. rubra).

Cabbages are rich in sulfur-containing metabolites like glucosinolates (GLSs) and S-methyl-l-cysteine sulfoxide (SMCSO). Tissue disruption initiates hydrolysis of these compounds and bioactive volatile hydrolysis products such as isothiocyanates (ITCs), sulfides, and thiosulfinates are formed. However, nitriles, epithionitriles, or amines can also result from GLSs. Here, the influence of hydrolysis time, extent of tissue disruption (chopping vs. homogenization), and addition of lemon juice or vinegar on the outcome of enzymatic hydrolysis of GLSs and SMCSO was investigated in red cabbage. Chopping led to partial hydrolysis of GLSs, whereas homogenization completely degraded GLSs but only had a small effect on SMCSO. Homogenization increased amine formation from alkenyl and methylthioalkyl ITCs, but not from methylsulfinylalkyl ITCs. Acidification inhibited formation of products from SMCSO. Further, it reduced nitrile and epithionitrile formation and stopped amine formation, thereby increasing ITC levels. Therefore, acidification is a valuable mean to enhance ITC levels in fresh Brassica foods.

An UMAMIT-GTR transporter cascade controls glucosinolate seed loading in Arabidopsis.

Many plant species translocate maternally synthesized specialized metabolites to the seed to protect the developing embryo and later the germinating seedling before it initiates its own de novo synthesis. While the transport route into the seed is well established for primary metabolites, no model exists for any class of specialized metabolites that move from maternal source tissue(s) to embryo. Glucosinolate seed loading in Arabidopsis depends on plasma membrane localized exporters (USUALLY MULTIPLE AMINO ACIDS MOVE IN AND OUT TRANSPORTERs, UMAMITs) and importers (GLUCOSINOLATE TRANSPORTERs, GTRs), but the critical barriers in the seed loading process remain unknown. Here we dissect the transport route of glucosinolates from their source in the reproductive organ to the embryo by re-introducing the transporters at specific apoplastic barriers in their respective mutant backgrounds. We find that UMAMIT exporters and GTR importers form a transporter cascade that is both essential and sufficient for moving glucosinolates across at least four plasma membrane barriers along the route. We propose a model in which UMAMITs export glucosinolates out of the biosynthetic cells to the apoplast, from where GTRs import them into the phloem stream, which moves them to the unloading zone in the chalazal seed coat. From here, the UMAMITs export them out of maternal tissue and ultimately, the GTRs import them into the embryo symplasm, where the seed-specific glucosinolate profile is established by enzymatic modifications. Moreover, we propose that methylsulfinylalkyl glucosinolates are the predominant mobile form in seed loading. Elucidation of the seed loading process of glucosinolates identifies barrier-specific targets for transport engineering strategies to eliminate or over-accumulate a specialized metabolite in seeds with minimal interruption of other cellular processes.

The Antioxidant Properties of Glucosinolates in Cardiac Cells Are Independent of H2S Signaling.

The organic sulfur-containing compounds glucosinolates (GSLs) and the novel gasotransmitter H2S are known to have cardioprotective effects. This study investigated the antioxidant effects and H2S-releasing potential of three GSLs ((3E)-4-(methylsulfanyl)but-3-enyl GSL or glucoraphasatin, 4-hydroxybenzyl GSL or glucosinalbin, and (RS)-6-(methylsulfinyl)hexyl GSL or glucohesperin) in rat cardiac cells. It was found that all three GSLs had no effect on cardiac cell viability but were able to protect against H2O2-induced oxidative stress and cell death. NaHS, a H2S donor, also protected the cells from H2O2-stimulated oxidative stress and cell death. The GSLs alone or mixed with cysteine, N-acetylcysteine, glutathione, H2O2, iron and pyridoxal-5'-phosphate, or mouse liver lysates did not induce H2S release. The addition of GSLs also did not alter endogenous H2S levels in cardiac cells. H2O2 significantly induced cysteine oxidation in the cystathionine gamma-lyase (CSE) protein and inhibited the H2S production rate. In conclusion, this study found that the three tested GSLs protect cardiomyocytes from oxidative stress and cell death but independently of H2S signaling.