High-performance liquid chromatographic separation of natural and synthetic desulphoglucosinolates and their chemical validation by UV, NMR and chemical ionisation-MS methods

Effect of Ultrasound and High Hydrostatic Pressure Processing on Quality and Bioactive Compounds during the Shelf Life of a Broccoli and Carrot By-Products Beverage

Vegetable beverages are a convenient strategy to enhance the consumption of horticultural commodities, with the possibility of being fortified with plant by-products to increase functional quality. The main objective was to develop a new veggie beverage from broccoli stalks and carrot by-products seasoned with natural antioxidants and antimicrobial ingredients. Pasteurization, Ultrasound (US), and High Hydrostatic Pressure (HHP) and their combinations were used as processing treatments, while no treatment was used as a control (CTRL). A shelf-life study of 28 days at 4 °C was assayed. Microbial load, antioxidant capacity, and bioactive compounds were periodically measured. Non-thermal treatments have successfully preserved antioxidants (~6 mg/L ΣCarotenoids) and sulfur compounds (~1.25 g/L ΣGlucosinolates and ~5.5 mg/L sulforaphane) throughout the refrigerated storage, with a longer shelf life compared to a pasteurized beverage. Total vial count was reduced by 1.5-2 log CFU/mL at day 0 and by 6 log CFU/mL at the end of the storage in HHP treatments. Thus, the product developed in this study could help increase the daily intake of glucosinolates and carotenoids. These beverages can be a good strategy to revitalize broccoli and carrot by-products with high nutritional potential while maintaining a pleasant sensory perception for the final consumer.

Palliating Salt Stress in Mustard through Plant-Growth-Promoting Rhizobacteria: Regulation of Secondary Metabolites, Osmolytes, Antioxidative Enzymes and Stress Ethylene

The severity of salt stress is alarming for crop growth and production and it threatens food security. Strategies employed for the reduction in stress are not always eco-friendly or sustainable. Plant-growth-promoting rhizobacteria (PGPR) could provide an alternative sustainable stress reduction strategy owning to its role in various metabolic processes. In this study, we have used two strains of PGPR, Pseudomonas fluorescens (NAIMCC-B-00340) and Azotobacter chroococcum Beijerinck 1901 (MCC 2351), either singly or in combination, and studied their effect in the amelioration of salt toxicity in mustard cultivar Pusa Jagannath via its influence on plants' antioxidants' metabolism, photosynthesis and growth. Individually, the impact of Pseudomonas fluorescens was better in reducing stress ethylene, oxidative stress, photosynthesis and growth but maximal alleviation was observed with their combined application. MDA and H₂O₂ content as indicator of oxidative stress decreased by 27.86% and 45.18% and osmolytes content (proline and glycine-betaine) increased by 38.8% and 26.3%, respectively, while antioxidative enzymes (SOD, CAT, APX and GR) increased by 58.40, 25.65, 81.081 and 55.914%, respectively, over salt-treated plants through the application of Pseudomonas fluorescens. The combined application maximally resulted in more cell viability and less damage to the leaf with lesser superoxide generation due to higher antioxidative enzymes and reduced glutathione formation (GSH). Considering the obtained results, we can supplement the PGPR in combination to plants subjected to salt stress, prevent photosynthetic and growth reduction, and increase the yield of plants.

Chemical Analysis of Eruca sativa Ethanolic Extract and Its Effects on Hyperuricaemia

In vivo assays and chemical analyses were performed on the ethanolic extract from leaves of Eruca sativa. UHPLC-ESI-QTOF analysis confirmed the presence of glucosinolates and flavonol glucosides. The major flavonoid of the ethanolic extract, kaempferol-3,4'-di-O-β-glucoside, was isolated, a HPLC-DAD method developed and validated to quantify its content in the extract. In vivo experiments were carried out on Wistar rats with hyperuricaemia induced by potassium oxonate and uric acid. A hypouricaemic effect was observed in hyperuricaemic Wistar rats treated with ethanolic extract at dose of 125 mg/kg and kaempferol-3,4'-di-O-β-glucoside at dose of 10 mg/kg. The main anti-hyperuricaemic mechanism observed in the extract was uricosuric. Kaempferol-3,4'-di-O-β-glucoside was identified as an important component responsible for the total activity of the ethanolic extract and was considered as a good chemical and biological marker of the ethanolic extract of E. sativa. The obtained results indicated the potential of E. sativa in the treatment of hyperuricaemia and its comorbidities.

Chemical Genetics Applied to Elucidate the Physiological Role of Stress-Signaling Molecules on the Wound-Induced Accumulation of Glucosinolates in Broccoli

Wounding stress is an effective strategy to induce glucosinolate (GS) biosynthesis in broccoli. However, there is insufficient knowledge on the physiological and molecular mechanisms underlying this stress response. Herein, a chemical-genetic approach was applied to elucidate the role of jasmonic acid (JA), ethylene (ET), and reactive oxygen species (ROS) on the wound-induced biosynthesis of GS. Broccoli was processed into chops to induce wounding stress. Broccoli chops were treated with phenidone (PHEN) and diphenyleneiodonium chloride (DPI) as inhibitors of JA and ROS biosynthesis, respectively, whereas 1-methylcyclopropene (1-MCP) was applied as an inhibitor of ET action. Wounding stress induced the expression of genes related to the biosynthesis of indolic and aliphatic GS, which was correlated with the accumulation of GS and modulated by the inhibitors of signaling molecules applied. Results of gene expression analysis indicated that JA played a key role in the activation of most genes, followed by ROS. Furthermore, except for the CYP79B2 gene, PHEN and 1-MCP synergistically downregulated the expression of GS biosynthetic genes evaluated, showing that the interaction between JA and ET was fundamental to modulate GS biosynthesis. Results presented herein increased our knowledge of the physiological and molecular mechanisms governing the wound-induced biosynthesis of GS in broccoli.

Rapid screening and characterization of glucosinolates in 25 Brassicaceae tissues by UHPLC-Q-exactive orbitrap-MS

Glucosinolates (GSLs) are secondary plant metabolites that occur mainly in the Brassicaceae plants, which are desirable compounds in human foods due to their diverse biological activities. In this study, we developed an integrated data filtering and identification strategy to characterize the GSLs. An in-depth GSLs profiling was performed on 25 commonly Brassicaceae tissues in Jinan, China. By comparison with the reference standards and previous researches, we tentatively identified 47 GSLs including 8 unknown ones. The GSLs profiles of 25 Brassicaceae tissues were established, and 11 markers of GSLs could be used to distinguish the Brassica and Raphanus. This approach enables accurately characterization the GSLs of Brassicaceae tissues, and demonstrates the potential of GSLs profiles for Brassicaceae species discrimination.

Nanoparticles induce genetic, biochemical, and ultrastructure variations in Salvadora persica callus

BACKGROUND

Salvadora persica is an endangered medicinal plant due to difficulties in its traditional propagation. It is rich in bioactive compounds that possess many pharmaceutical, antimicrobial activities and widely used in folk medicine. The current study aims at in vitro propagation of Salvadora persica and the application of different nanoparticles (NPs) to induce the synthesis of bioactive and secondary metabolites within the plant. The cellular and genetic responses to the application of different NPs were evaluated.

RESULTS

The impact of nanoparticles NPs (ZnO, SiO₂, and Fe₃O₄) on callus growth of Salvadora persica and the production of its active constituent benzyl isothiocyanate was examined, regarding some oxidative stress markers, antioxidant enzymes, and genetic variabilities. An encouraging impact of 0.5 mg/l ZnO NPs on benzyl isothiocyanate production was shown reaching up to 0.905 mg/g callus fresh weight in comparison to 0.539 mg/g in control callus. This was associated with decreasing hydrogen peroxide content and increasing superoxide dismutase and peroxidase activities. The deposition of the NPs on cellular organelles was detected using a transmission microscope. Fifteen Inter-Simple Sequence Repeats (ISSR) primers detected an overall, 79.1% polymorphism among different treatments. A reduction in genomic DNA template stability (GTS) was made and was more pronounced in higher doses of different NPs.

CONCLUSION

This study is a stepping stone in developing a productive protocol for in vitro production of benzyl isothiocyanate from Salvadora persica using NPs as a valuable anticancer compound.

Lipopolysaccharide perception in Arabidopsis thaliana: Diverse LPS chemotypes from Burkholderia cepacia, Pseudomonas syringae and Xanthomonas campestris trigger differential defence-related perturbations in the metabolome

Lipopolysaccharides (LPSs) are microbe-associated molecular pattern molecules (MAMPs) from Gram-negative bacterial pathogens that potentially contain three different MAMPs (the O-polysaccharide chain, the oligosaccharide core and lipid A). LPSs was purified from Burkholderia cepacia, Pseudomonas syringae and Xanthomonas campestris and electrophoretically profiled. Outcomes of the interactions of the three different LPS chemotypes with Arabidopsis thaliana, as reflected in the induced defence metabolites, profiled at 12 h and 24 h post elicitation, were investigated. Plants were pressure-infiltrated with LPS solutions and methanol-based extractions at different time points were performed for untargeted metabolomics using ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Multivariate data modelling and chemometric analysis were applied to generate interpretable biochemical information from the multidimensional data sets. The three LPSs triggered differential metabolome changes in the plants as apparent from chromatographically distinct MS chromatograms. Unsupervised and supervised multivariate data models exhibited time- and treatment-related variations, and revealed discriminating metabolite variables. Heat map models comparatively displayed the up-regulated pathways affecting the metabolomes and Venn diagrams indicated up-regulated and shared metabolites among the three LPS treatments. The altered metabolomes reflect the up-regulation of metabolites from not only the glucosinolate pathway, but also from the shikimate-phenylpropanoid-flavonoid -, terpenoid - and indolic/alkaloid pathways, as well as oxygenated fatty acids. Distinct phytochemical profiles, especially at the earlier time point, suggest differences in the perception of the three LPS chemotypes, associated with the molecular patterns within the tripartite lipoglycans.

Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

The glucosinolates (GSLs) is a well-defined group of plant metabolites characterized by having an S-β-d-glucopyrano unit anomerically connected to an O-sulfated (Z)-thiohydroximate function. After enzymatic hydrolysis, the sulfated aglucone can undergo rearrangement to an isothiocyanate, or form a nitrile or other products. The number of GSLs known from plants, satisfactorily characterized by modern spectroscopic methods (NMR and MS) by mid-2018, is 88. In addition, a group of partially characterized structures with highly variable evidence counts for approximately a further 49. This means that the total number of characterized GSLs from plants is somewhere between 88 and 137. The diversity of GSLs in plants is critically reviewed here, resulting in significant discrepancies with previous reviews. In general, the well-characterized GSLs show resemblance to C-skeletons of the amino acids Ala, Val, Leu, Trp, Ile, Phe/Tyr and Met, or to homologs of Ile, Phe/Tyr or Met. Insufficiently characterized, still hypothetic GSLs include straight-chain alkyl GSLs and chain-elongated GSLs derived from Leu. Additional reports (since 2011) of insufficiently characterized GSLs are reviewed. Usually the crucial missing information is correctly interpreted NMR, which is the most effective tool for GSL identification. Hence, modern use of NMR for GSL identification is also reviewed and exemplified. Apart from isolation, GSLs may be obtained by organic synthesis, allowing isotopically labeled GSLs and any kind of side chain. Enzymatic turnover of GSLs in plants depends on a considerable number of enzymes and other protein factors and furthermore depends on GSL structure. Identification of GSLs must be presented transparently and live up to standard requirements in natural product chemistry. Unfortunately, many recent reports fail in these respects, including reports based on chromatography hyphenated to MS. In particular, the possibility of isomers and isobaric structures is frequently ignored. Recent reports are re-evaluated and interpreted as evidence of the existence of "isoGSLs", i.e. non-GSL isomers of GSLs in plants. For GSL analysis, also with MS-detection, we stress the importance of using authentic standards.

Isothiocyanates and Glucosinolates from Sisymbrium officinale (L.) Scop. ("the Singers' Plant"): Isolation and in Vitro Assays on the Somatosensory and Pain Receptor TRPA1 Channel

Sisymbrium officinale (L.) Scop. is a wild common plant of the Brassicaceae family. It is known as “the singers’ plant” for its traditional use in treating aphonia and vocal disability. Despite its wide use in herbal preparations, the molecular mechanism of action of S. officinale extracts is not known. The plant is rich in glucosinolates and isothiocyanates, which are supposed to be its active compounds. Some members of this family, in particular allylisothiocyanate, are strong agonists of the transient receptor potential ankyrin 1 (TRPA1) channel, which is involved in the somatosensory perception of pungency as well as in the nociception pathway of inflammatory pain. This study aims to isolate the glucosinolates and isothiocianates from fresh S. officinale to identify the major components and test their activity in in vitro assays with a cloned TRPA1 channel. Samples of cultivated S. officinale have been extracted and the active compounds isolated by column chromatography, HPLC and PTLC. The main components glucoputranjivin, isopropylisothiocyanate and 2-buthylisothiocianate have been tested on TRPA1. The glucosinolates glucoputranjivin and sinigrin turned out to be inactive, while isopropylisothiocyanate and 2-buthylisothiocyanate are potent agonists of TRPA1, with an EC₅₀ in the range of the high potency natural agonists identified so far for this somatosensory channel.

Effects of α-, β- and maltosyl-β-cyclodextrins use on the glucoraphanin-sulforaphane system of broccoli juice

Cyclodextrins (CDs) are macromolecules with several industrial applications, being particularly used in the food industry as health-promoting compounds protection agents, as flavour stabilizers, or to eliminate undesired tastes and browning reactions, among others. This study shows the effects of α- (10, 30 and 40 mmol L^-1 ), β- (3, 6 and 10 mmol L^-1 ) and maltosyl-β-CDs (30, 60 and 90 mmol L^-1 ) use on the health-promoting glucoraphanin-sulforaphane system of a broccoli juice up to 24 h at 22 °C. Maltosyl-β-CD (90 mmol L^-1 ) highly retained glucoraphanin content after 24 h at 22 °C, showing better effectiveness than β-CD (10 mmol L^-1 ). Sulforaphane was efficiently encapsulated with β-CD at just 3 mmol L^-1 , and the sulforaphane formed was stable during 3 h at 22 °C. On the other hand, 40 mmol L^-1 α-CD retained a high glucoraphanin content in broccoli juice. In contrast, glucoraphanin levels in juice without CDs decreased by 71% after 24 h. Consequently, CDs addition may potentially preserve glucoraphanin in this broccoli juice during industrial processing with the possibility to be later transformed by endogenous myrosinase after ingestion to the health-promoting sulforaphane. © 2018 Society of Chemical Industry.

Rhizosphere Bacterial Communities Differ According to Fertilizer Regimes and Cabbage (Brassica oleracea var. capitata L.) Harvest Time, but Not Aphid Herbivory

Rhizosphere microbial communities are known to be highly diverse and strongly dependent on various attributes of the host plant, such as species, nutritional status, and growth stage. High-throughput 16S rRNA gene amplicon sequencing has been used to characterize the rhizosphere bacterial community of many important crop species, but this is the first study to date to characterize the bacterial and archaeal community of Brassica oleracea var. capitata. The study also tested the response of the bacterial community to fertilizer type (organic or synthetic) and N dosage (high or low), in addition to plant age (9 or 12 weeks) and aphid (Myzus persicae) herbivory (present/absent). The impact of aboveground herbivory on belowground microbial communities has received little attention in the literature, and since the type (organic or mineral) and amount of fertilizer applications are known to affect M. percicae populations, these treatments were applied at agricultural rates to test for synergistic effects on the soil bacterial community. Fertilizer type and plant growth were found to result in significantly different rhizosphere bacterial communities, while there was no effect of aphid herbivory. Several operational taxonomic units were identified as varying significantly in abundance between the treatment groups and age cohorts. These included members of the S-oxidizing genus Thiobacillus, which was significantly more abundant in organically fertilized 12-week-old cabbages, and the N-fixing cyanobacteria Phormidium, which appeared to decline in synthetically fertilized soils relative to controls. These responses may be an effect of accumulating root-derived glucosinolates in the B. oleracea rhizosphere and increased N-availability, respectively.

Stability of Bioactive Compounds in Broccoli as Affected by Cutting Styles and Storage Time

Broccoli contains bioactive molecules and thus its consumption is related with the prevention of chronic and degenerative diseases. The application of wounding stress to horticultural crops is a common practice, since it is the basis for the fresh-cut produce industry. In this study, the effect of four different cutting styles (CSs) (florets (CS1), florets cut into two even pieces (CS2), florets cut into four even pieces (CS3), and florets processed into chops (CS4)) and storage time (0 and 24 h at 20 °C) on the content of bioactive compounds in broccoli was evaluated. Immediately after cutting, 5-O-caffeoylquinic acid and caffeic acid content increased by 122.4% and 41.6% in CS4 and CS2, respectively. Likewise, after storage, 3-O-caffeoylquinic acid and 5-O-caffeoylquinic acid increased by 46.7% and 98.2%, respectively in CS1. Glucoerucin and gluconasturtiin content decreased by 62% and 50%, respectively in CS3; whereas after storage most glucosinolates increased in CS1. Total isothiocyanates, increased by 133% immediately in CS4, and after storage CS1 showed 65% higher levels of sulforaphane. Total ascorbic acid increased 35% after cutting in CS2, and remained stable after storage. Results presented herein would allow broccoli producers to select proper cutting styles that preserve or increase the content of bioactive molecules.

Mild osmotic stress promotes 4-methoxy indolyl-3-methyl glucosinolate biosynthesis mediated by the MKK9-MPK3/MPK6 cascade in Arabidopsis

MKK9-MPK3/MPK6 cascade positively regulates IGSs' biosynthetic genes. Glucosinolates (GSs), secondary metabolites well known for their roles in plant defense, have been implicated to play an important role in plant abiotic stress response; however, the exact role in these processes and the underlying regulatory mechanisms remain elusive. Mitogen-activated protein kinase (MAPK) cascades are extensively involved in plant abiotic stress response. In this study, we examined the levels of four indolic glucosinolates (IGSs) in the shoots of Arabidopsis seedlings under mild osmotic stress conditions and found that 4-methoxy indolyl-3-methyl glucosinolate (4MI3G) accumulated and that MPK3 and MPK6 were activated. Loss of MPK3 or MPK6 function led to a reduction in mild osmotic stress-induced 4MI3G. Further analyses revealed that MKK9 acts upstream of MPK3 and MPK6 to promote 4MI3G accumulation. The level of 4MI3G induced by mild osmotic stress was reduced in the mkk9 mutant. Conversely, 4MI3G increased in MKK9 ^DD , a constitutively activate mutant of MKK9. Gene expression analyses indicated that the activated MKK9-MPK3/MPK6 cascade upregulates the IGS biosynthetic genes. Moreover, the lack of MYB51, the transcription factor controlling biosynthetic genes responsible for synthesizing the IGS core structure, or CYP81F2, the enzyme catalyzing core structure modification to 4MI3G, significantly reduced mild osmotic stress- and MKK9 ^DD -induced 4MI3G. Thus, our study demonstrates that mild osmotic stress promotes 4MI3G biosynthesis and the accumulation in Arabidopsis through activation of the MKK9-MPK3/MPK6 cascade and provides an MAPK-mediated signaling pathway for the IGS response to abiotic stress in plants.

Effects of salt stress imposed during two growth phases on cauliflower production and quality

BACKGROUND

Cultivation of cauliflower is diffused in Mediterranean areas where water salinity results in the need to identify alternative irrigation sources or management strategies. Using saline water during two growth phases (from transplanting to visible appearance of inflorescence or from appearance of inflorescence to head harvest), the present study aimed to identify the growth period that is more suitable for irrigation with low quality water in relation to cauliflower production and quality.

RESULTS

Salinity affected cauliflower growth mainly when imposed in the first growth phase. The growth reduction depended mainly on ion-specific effects, although slight nutrient imbalances as a result of Na⁺ and Cl^- antagonisms were observed. The use of non-saline water in the first or second growth period reduced both the osmotic and toxic effects of salinity. When salinity was applied during inflorescence growth, yield was reduced because of a restriction of water accumulation in the head.

CONCLUSION

The results of the present study demonstrate the possibility of producing marketable cauliflower heads under conditions of salinity by timing the application of the best quality water during the first growth phase to improve fruit quality and during the second phase to reduce the negative effects of salinity on yield. © 2016 Society of Chemical Industry.

Identification and Quantification of Glucosinolates in Kimchi by Liquid Chromatography-Electrospray Tandem Mass Spectrometry

A novel and simple method for detecting five glucosinolates (glucoalyssin, gluconapin, glucobrassicanapin, glucobrassicin, and 4-methoxyglucobrassicin) in kimchi was developed using liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). The chromatographic peaks of the five glucosinolates were successfully identified by comparing their retention times, mass spectra. The mobile phase was composed of A (acetonitrile) and B (water). As for glucosinolate, the relative quantities were found through sinigrin, and five different compounds that have not been previously discovered in kimchi were observed. Monitoring was carried out on the glucosinolate in 20 kimchis distributed in markets, and this study examined the various quality and quantity compositions of the five components. The glucoalyssin content ranged from 0.00 to 7.07 μmol/g of day weight (DW), with an average content of 0.86 μmol/g of DW, whereas the gluconapin content ranged from 0.00 to 5.85 μmol/g of DW, with an average of 1.17 μmol/g of DW. The content of glucobrassicanapin varied between 0.00 and 11.87 μmol/g of DW (average = 3.03 μmol/g of DW), whereas that of glucobrassicin varied between 0.00 and 0.42 μmol/g of DW (average = 0.06 μmol/g of DW). The 4-methoxyglucobrassicin content ranged from 0.12 to 9.36 μmol/g of DW (average = 3.52 μmol/g of DW). A comparison of the contents revealed that, in most cases, the content of 4-methoxyglucobrassicin was the highest.

The Lipopolysaccharide-Induced Metabolome Signature in Arabidopsis thaliana Reveals Dynamic Reprogramming of Phytoalexin and Phytoanticipin Pathways

Lipopolysaccharides (LPSs), as MAMP molecules, trigger the activation of signal transduction pathways involved in defence. Currently, plant metabolomics is providing new dimensions into understanding the intracellular adaptive responses to external stimuli. The effect of LPS on the metabolomes of Arabidopsis thaliana cells and leaf tissue was investigated over a 24 h period. Cellular metabolites and those secreted into the medium were extracted with methanol and liquid chromatography coupled to mass spectrometry was used for quantitative and qualitative analyses. Multivariate statistical data analyses were used to extract interpretable information from the generated multidimensional LC-MS data. The results show that LPS perception triggered differential changes in the metabolomes of cells and leaves, leading to variation in the biosynthesis of specialised secondary metabolites. Time-dependent changes in metabolite profiles were observed and biomarkers associated with the LPS-induced response were tentatively identified. These include the phytohormones salicylic acid and jasmonic acid, and also the associated methyl esters and sugar conjugates. The induced defensive state resulted in increases in indole-and other glucosinolates, indole derivatives, camalexin as well as cinnamic acid derivatives and other phenylpropanoids. These annotated metabolites indicate dynamic reprogramming of metabolic pathways that are functionally related towards creating an enhanced defensive capacity. The results reveal new insights into the mode of action of LPS as an activator of plant innate immunity, broadens knowledge about the defence metabolite pathways involved in Arabidopsis responses to LPS, and identifies specialised metabolites of functional importance that can be employed to enhance immunity against pathogen infection.

In situ Identification of Labile Precursor Compounds and their Short-lived Intermediates in Plants using in vivo Nanospray High-resolution Mass Spectrometry

INTRODUCTION

Many secondary metabolites in plants are labile compounds which under environmental stress, are difficult to detect and track due to the lack of rapid in situ identification techniques, making plant metabolomics research difficult. Therefore, developing a reliable analytical method for rapid in situ identification of labile compounds and their short-lived intermediates in plants is of great importance.

OBJECTIVE

To develop under atmospheric pressure, a rapid in situ method for effective identification of labile compounds and their short-lived intermediates in fresh plants.

METHODOLOGY

An in vivo nanospray high-resolution mass spectrometry (HR-MS) method was used for rapid capture of labile compounds and their short-lived intermediates in plants. A quartz capillary was partially inserted into fresh plant tissues, and the liquid flowed out through the capillary tube owing to the capillary effect. A high direct current (d.c.) voltage was applied to the plant to generate a spray of charged droplets from the tip of the capillary carrying bioactive molecules toward the inlet of mass spectrometer for full-scan and MS/MS analysis.

RESULTS

Many labile compounds and short-lived intermediates were identified via this method: including glucosinolates and their short-lived intermediates (existing for only 10 s) in Raphanus sativus roots, alliin and its conversion intermediate (existing for 20 s) in Allium sativum and labile precursor compound chlorogenic acid in Malus pumila Mill.

CONCLUSION

The method is an effective approach for in situ identification of internal labile compounds and their short-lived intermediates in fresh plants and it can be used as an auxiliary tool to explore the degradation mechanisms of new labile plant compounds. Copyright © 2016 John Wiley & Sons, Ltd.

Plants as Biofactories: Postharvest Stress-Induced Accumulation of Phenolic Compounds and Glucosinolates in Broccoli Subjected to Wounding Stress and Exogenous Phytohormones

Broccoli contains high levels of bioactive molecules and is considered a functional food. In this study, postharvest treatments to enhance the concentration of glucosinolates and phenolic compounds were evaluated. Broccoli whole heads were wounded to obtain florets and wounded florets (florets cut into four even pieces) and stored for 24 h at 20 °C with or without exogenous ethylene (ET, 1000 ppm) or methyl jasmonate (MeJA, 250 ppm). Whole heads were used as a control for wounding treatments. Regarding glucosinolate accumulation, ET selectively induced the 4-hydroxylation of glucobrassicin in whole heads, resulting in ∼223% higher 4-hydroxyglucobrassicin than time 0 h samples. Additionally, glucoraphanin was increased by ∼53% in whole heads treated with ET, while neoglucobrassicin was greatly accumulated in wounded florets treated with ET or MeJA, showing increases of ∼193 and ∼286%, respectively. On the other hand, although only whole heads stored without phytohormones showed higher concentrations of phenolic compounds, which was reflected in ∼33, ∼30, and ∼46% higher levels of 1,2,2-trisinapoylgentiobose, 1,2-diferulolylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose, respectively; broccoli florets stored under air control conditions showed enhanced concentrations of 3-O-caffeoylquinic acid, 1,2-disinapoylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose (∼22, ∼185, and ∼65% more, respectively). Furthermore, exogenous ET and MeJA impeded individual phenolics accumulation. Results allowed the elucidation of simple and effective postharvest treatment to enhance the content of individual glucosinolates and phenolic compounds in broccoli. The stressed-broccoli tissue could be subjected to downstream processing in order to extract and purify bioactive molecules with applications in the dietary supplements, agrochemical and cosmetics markets.

Root Glucosinolate Profiles for Screening of Radish (Raphanus sativus L.) Genetic Resources

Radish (Raphanus sativus L.), a root vegetable, is rich in glucosinolates (GLs), which are beneficial secondary metabolites for human health. To investigate the genetic variations in GL content in radish roots and the relationship with other root phenotypes, we analyzed 71 accessions from 23 different countries for GLs using HPLC. The most abundant GL in radish roots was glucoraphasatin, a GL with four-carbon aliphatic side chain. The content of glucoraphasatin represented at least 84.5% of the total GL content. Indolyl GL represented only 3.1% of the total GL at its maximum. The principal component analysis of GL profiles with various root phenotypes showed that four different genotypes exist in the 71 accessions. Although no strong correlation with GL content and root phenotype was observed, the varied GL content levels demonstrate the genetic diversity of GL content, and the amount that GLs could be potentially improved by breeding in radishes.

UGT74B1 from Arabidopsis thaliana as a versatile biocatalyst for the synthesis of desulfoglycosinolates

A glucosyltransferase is able to catalyze the formation of the thioglycosidic bond and lead to desulfoglycosinolates.

Improving red radish anthocyanin yield and off flavor removal by acidified aqueous organic based medium

In view of the high content of the highly stable anthocyanin in red radish roots, the plant is considered as a potent source of natural anthocyanins.

Non-indolyl cruciferous phytoalexins: Nasturlexins and tridentatols, a striking convergent evolution of defenses in terrestrial plants and marine animals?

Highly specialized chemical defense pathways are a particularly noteworthy metabolic characteristic of sessile organisms, whether terrestrial or marine, providing protection against pests and diseases. For this reason, knowledge of the metabolites involved in these processes is crucial to producing ecologically fit crops. Toward this end, the elicited chemical defenses of the crucifer watercress (Nasturtium officinale R. Br.), i.e. phytoalexins, were investigated and are reported. Almost three decades after publication of cruciferous phytoalexins derived from (S)-Trp, phytoalexins derived from other aromatic amino acids were isolated; their chemical structures were determined by analyses of their spectroscopic data and confirmed by synthesis. Nasturlexin A, nasturlexin B, and tridentatol C are hitherto unknown phenyl containing cruciferous phytoalexins produced by watercress under abiotic stress; tridentatol C is also produced by a marine animal (Tridentata marginata), where it functions in chemical defense against predators. The biosynthesis of these metabolites in both a terrestrial plant and a marine animal suggests a convergent evolution of unique metabolic pathways recruited for defense.

Flavonolignans and other constituents from Lepidium meyenii with activities in anti-inflammation and human cancer cell lines

From the roots of Lepidium meyenii Walpers (Brassicaceae) have been isolated and identified 2 flavonolignans, tricin 4'-O-[threo-β-guaiacyl-(7″-O-methyl)-glyceryl] ether (1) and tricin 4'-O-(erythro-β-guaiacyl-glyceryl) ether (2), along with 11 other known compounds, tricin (3), pinoresinol (4), 4-hydroxycinnamic acid (5), guanosine (6), glucotropaeolin (7), desulfoglucotropaeolin (8), 3-hydroxybenzylisothiocyanate (9), malic acid benzoate (10), 5-(hydroxymethyl)-2-furfural (11), d-phenylalanine (12), and vanillic acid 4-O-β-d-glucoside (13). Structures were elucidated on the basis of NMR and MS data. Some isolates and previously isolated lepidiline B (14) were tested for cytotoxicity in a small panel of human cancer cell lines (Hep G2, COLO 205, and HL-60) and for anti-inflammatory activities in LPS-treated RAW 264.7 macrophage. Among them, compounds 1 and 14 were modestly active for inhibiting nitrite production in macrophage. Compounds 1, 14, and 3 were demonstrated to be selectively active against HL-60 cells with IC50 values of 40.4, 52.0, and 52.1 μM, respectively.

Concentration- and time-dependent effects of isothiocyanates produced from Brassicaceae shoot tissues on the pea root rot pathogen Aphanomyces euteiches

Isothiocyanates (ITCs) hydrolyzed from glucosinolates (GSLs) in Brassicaceae tissue are toxic to soil organisms. In this study, the effect of aliphatic and aromatic ITCs from hydrated dry Brassicaceae shoot tissues on the mycelium and oospores of the pea root rot pathogen Aphanomyces euteiches was investigated. The profile and concentrations of GSLs in two test Brassicaceae species, Sinapis alba and Brassica juncea, and the ITCs from the dominant hydrolyzed parent GSLs were monitored. The concentrations of dominant ITCs and pathogen exposure time were evaluated in in vitro experiments. The greatest effect on the pathogen was observed from aliphatic ITCs hydrolyzed from B. juncea tissue, and the effect depended on the ITC concentration and exposure time. ITCs were more effectively hydrolyzed from B. juncea GSLs than from S. alba GSLs; i.e., the ITC/GSL ratio was higher in B. juncea than in S. alba tissue, giving a different release pattern. The release of phenylethyl isothiocyanate, which was common to both species, followed a pattern similar to that of the dominant ITC in each crop species. This suggests that traits other than GSL content, e.g., plant cell structure, may affect the release of ITCs and should therefore influence the choice of species used for biofumigation purposes.

Glucosinolate metabolism, functionality and breeding for the improvement of Brassicaceae vegetables

Unique secondary metabolites, glucosinolates (S-glucopyranosyl thiohydroximates), are naturally occurring S-linked glucosides found mainly in Brassicaceae plants. They are enzymatically hydrolyzed to produce sulfate ions, D-glucose, and characteristic degradation products such as isothiocyanates. The functions of glucosinolates in the plants remain unclear, but isothiocyanates possessing a pungent or irritating taste and odor might be associated with plant defense from microbes. Isothiocyanates have been studied extensively in experimental in vitro and in vivo carcinogenesis models for their cancer chemopreventive properties. The beneficial isothiocyanates, glucosinolates that are functional for supporting human health, have received attention from many scientists studying plant breeding, plant physiology, plant genetics, and food functionality. This review presents a summary of recent topics related with glucosinolates in the Brassica family, along with a summary of the chemicals, metabolism, and genes of glucosinolates in Brassicaceae. The bioavailabilities of isothiocyanates from certain functional glucosinolates and the importance of breeding will be described with emphasis on glucosinolates.

Nitrates and glucosinolates as strong determinants of the nutritional quality in rocket leafy salads

Rocket is an important leafy vegetable crop and a good source of antioxidants and anticancer molecules such as glucosinolates and other sulfur compounds. Rocket is also a hyper-accumulator of nitrates which have been considered for long time the main factors that cause gastro-intestinal cancer. In this review, the content of these compounds in rocket tissues and their levels at harvest and during storage are discussed. Moreover, the effect of these compounds in preventing or inducing human diseases is also highlighted. This review provides an update to all the most recent studies carried out on rocket encouraging the consumption of this leafy vegetable to reduce the risk of contracting cancer and other cardiovascular diseases.

Rapid estimation of glucosinolate thermal degradation rate constants in leaves of Chinese kale and broccoli (Brassica oleracea) in two seasons

Kinetic modeling was used as a tool to quantitatively estimate glucosinolate thermal degradation rate constants. Literature shows that thermal degradation rates differ in different vegetables. Well-characterized plant material, leaves of broccoli and Chinese kale plants grown in two seasons, was used in the study. It was shown that a first-order reaction is appropriate to model glucosinolate degradation independent from the season. No difference in degradation rate constants of structurally identical glucosinolates was found between broccoli and Chinese kale leaves when grown in the same season. However, glucosinolate degradation rate constants were highly affected by the season (20-80% increase in spring compared to autumn). These results suggest that differences in glucosinolate degradation rate constants can be due to variation in environmental as well as genetic factors. Furthermore, a methodology to estimate rate constants rapidly is provided to enable the analysis of high sample numbers for future studies.