Effect of naturally occurring organosulfur compounds on nitric oxide production in lipopolysaccharide-activated macrophages

Excessive nitric oxide (NO) production is involved in cellular injury and possibly in the multistage process of carcinogenesis. In this study, we investigated the effect of organosulfur compounds (S-allyl cysteine, allyl sulfide, diallyl disulfide, allyl isothiocyanate, phenyl isothiocyanate, and benzyl isothiocyanate) that are found in allium or cruciferous vegetables on NO production in J774.1 macrophages activated with lipopolysaccharide (LPS). Diallyl disulfide, allyl, phenyl, and benzyl isothiocyanates inhibited NO production, as evaluated by nitrite formation at 25 microM. Allyl and benzyl isothiocyanates, the most active of the six organosulfur compounds, exhibited dose-dependent inhibition and had IC(50) values of 1.6 and 2.7 microM, respectively. Western blot analysis suggested that suppression of the induction of inducible NO synthase (iNOS) expression is responsible for the inhibition of NO production by allyl and benzyl isothiocyanates. In contrast, these isothiocyanates increased LPS-stimulated tumor necrosis factor alpha (TNF-alpha) release, suggesting their selective action on genes activated by LPS. Our results demonstrate that certain organosulfur compounds inhibit NO synthesis in LPS-activated macrophages, and the inhibitory effect may be a significant component of their anticarcinogenic activity.     

A review of isothiocyanates biofumigation activity on plant parasitic nematodes

Natural isothiocyanates (ITCs) are toxic to a range of soil-borne pest and pathogens, including nematodes and fungi, and can thus be used as natural fumigants called biofumigants. Glucosinolates, β-thioglucoside N-hydroxysulfates, are secondary metabolites of Brassicales plants, stored in the S-cells vacuoles. Upon plant tissue damage myrosinase (thioglucoside glycohydrolase, EC 3.2.3.1), stored in contiguous cells, hydrolyses glucosinalates to an unstable aglycone that eventually eliminates sulfate group producing a wide range of different volatile isothiocyanates that are extremely toxic to root-knot nematodes. In fact, among synthetic commercial nematicidal formulates we can find isothiocyanates as active ingredients. Conventional nematode control practices have included soil sterilants of great environmental impact, most of which are now banned making mandatory the development of eco-sustainable alternative tools. We reviewed the nematicidal activity of isothiocyanates as components of botanical matrixes in the frame of a holistic nematode control approach encompassing secondary beneficial effects on soil structure and microbiology, beneficial preservation, enhanced residual life of biological activity and plant growth.     

球孢白僵菌对大豆蚜毒力的室内生物学测定

对来源于吉林省不同地区的15株球孢白僵菌Beauveria bassiana(Bals.)Vuill.菌种对大豆蚜Aphis glycines Matsumura毒力进行了室内生物学测定。所有供试菌株对大豆蚜虫均有一定的致病性,杀虫效率差异明显,杀虫效率与孢子浓度和作用时间均呈正相关。通过对大豆蚜毒力室内生物学测定结果的综合分析,菌株S14-X-1为毒力较高菌株,具有进一步研究应用价值。     

Synthesis and antiproliferative activity of novel α- and β-dialkoxyphosphoryl isothiocyanates

A series of 15 mostly new dialkoxyphosphoryl alkyl and aralkyl isothiocyanates were synthesized using two alternative strategies, and their in vitro antiproliferative activity against several cancer cell lines (including drug resistant) is here demonstrated. The IC₅₀ values measured for the new compounds are within the range of 6.3-21.5 μM, and they are quite similar to the activity of two best and most extensively investigated natural benzyl isothiocyanate (A) and phenethyl isothiocyanate (B). Preliminary studies utilizing the cell cycle and reduced glutathione level analysis performed on A549 lung cancer cell line using representative compounds revealed important differences in the mechanism of action possibly correlated with their chemical properties. Hydrophobic compounds react mainly with the cytosolic glutathione reduced leading to its depletion, causing an oxidative stress and cell cycle arrest in G0/G1 phase. On the other hand, hydrophilic compounds cause moderate cell cycle arrest and massive cell death associated with moderate reduced glutathione depletion. These suggest that significant changes in the chemical structure of isothiocyanates, which do not lead to the significant changes in antiproliferative activity, but simultaneously cause a differences in the mechanism of action are possible.     

FMRFamide-like immunoreactivity within the nervous system of the nematodes Panagrellus redivius, Caenorhabditis elegans and Heterodera glycines

A polyclonal antiserum raised against the molluscan neuromodulatory peptide Phe-Met-Arg-Phe-amide (FMRFamide) reacts with nervous tissue in the free-living nematodes Panagrellus redivius and Caenorhabditis elegans and in infective juveniles (J₂) of the soybean cyst nematode Heterodera glycines . Sectioning of the nematodes was unnecessary but penetration of the antibody was improved by cutting the animals or by use of plasma etching to breach the cuticle before incubation in antiserum. Both procedures required subsequent exposure to detergents or partial digestion with protease K for optimum immunoreactivity. A positive reaction was observed for all three nematodes in the longitudinal nerve cords, nerve ring and ventral and lateral ganglia. Neurones were also visualized in association with the vulva in the free-living species and the spicules of male P. redivius . In H. glycines , neurones innervating the pharynx reacted positively, as did two loops of neural tissue on either side of the ventral nerve cord slightly anterior to the anus. Immunoreactivity was also noted in the amphidial pouches of H. glycines after prolonged (15 min) protease treatment. Further work is needed to establish the structure of the peptide antigen localized in these nematodes.     

Potential of Leguminous Cover Crops in Management of a Mixed Population of Root-knot Nematodes (Meloidogyne spp.)

Root-knot nematode is an important pest in agricultural production worldwide. Crop rotation is the only management strategy in some production systems, especially for resource poor farmers in developing countries. A series of experiments was conducted in the laboratory with several leguminous cover crops to investigate their potential for managing a mixture of root-knot nematodes (Meloidogyne arenaria, M. incognita, M. javanica). The root-knot nematode mixture failed to multiply on Mucuna pruriens and Crotalaria spectabilis but on Dolichos lablab the population increased more than 2- fold when inoculated with 500 and 1,000 nematodes per plant. There was no root-galling on M. pruriens and C. spectabilis but the gall rating was noted on D. lablab. Greater mortality of juvenile root-knot nematodes occurred when exposed to eluants of roots and leaves of leguminous crops than those of tomato; 48.7% of juveniles died after 72 h exposure to root eluant of C. spectabilis. The leaf eluant of D. lablab was toxic to nematodes but the root eluant was not. Thus, different parts of a botanical contain different active ingredients or different concentrations of the same active ingredient. The numbers of root-knot nematode eggs that hatched in root exudates of M. pruriens and C. spectabilis were significantly lower (20% and 26%) than in distilled water, tomato and P. vulgaris root exudates (83%, 72% and 89%) respectively. Tomato lacks nematotoxic compounds found in M. pruriens and C. spectabilis. Three months after inoculating plants with 1,000 root-knot nematode juveniles the populations in pots with M. pruriens, C. spectabilis and C. retusa had been reduced by approximately 79%, 85% and 86% respectively; compared with an increase of 262% nematodes in pots with Phaseolus vulgaris. There was significant reduction of 90% nematodes in fallow pots with no growing plant. The results from this study demonstrate that some leguminous species contain compounds that either kill root-knot nematodes or interfere with hatching and affect their capacity to invade and develop within their roots. M. pruriens, C. spectabilis and C. retusa could be used with effect to decrease a mixed field populations of root-knot nematodes.     

Incorporation of a Fluorescent Compound by Live Heterodera glycines

The incorporation of fluorescein isothiocyanate (FITC) by J2 of Heterodera glycines, the soybean cyst nematode, and the resulting effects on fitness were determined. Live soybean cyst nematode J2 incubated in FITC fluoresced, primarily in the intestinal region, beyond auto-fluorescence. Dissection of animals, as well as fluorescence-quenching techniques, indicated that FITC was not simply bound to the cuticle. FITC was also found to cross the egg shell. Fluorescence increased in relation to FITC concentration and incubation time. Nematodes incubated in FITC remained active and did not lose their fluorescence even after two weeks at room temperature. Fluorescence of nematodes was not stable through development. Males which developed from fluorescent juveniles did not retain the stain. Both FITC and the DMF solvent reduced the hatching rate. However, those individuals that successfully hatched remained viable and able to infect roots. Incorporation of FITC was found to occur in three other genera of nematodes. Rhodamine B isothiocyanate was also found to be incorporated by H. glycines.     

Toxicity of 2,4-diacetylphloroglucinol (DAPG) to Plant-parasitic and Bacterial-feeding Nematodes

The antibiotic 2,4-diacetylphloroglucinol (DAPG) is produced by some isolates of the beneficial bacterium Pseudomonas fluorescens. DAPG is toxic to many organisms, and crop yield increases have been reported after application of DAPG-producing P. fluorescens. This study was conducted to determine whether DAPG is toxic to selected nematodes. The plant-parasitic nematodes Heterodera glycines, Meloidogyne incognita, Pratylenchus scribneri and Xiphinema americanum, and the bacterial-feeding nematodes Caenorhabditis elegans, Pristionchus pacificus, and Rhabditis rainai, were immersed in concentrations ranging from 0 to 100 μg/ml DAPG. Egg hatch and viability of juveniles and adults were determined. DAPG was toxic to X. americanum adults, with an LD(50) of 8.3 μg/ml DAPG. DAPG decreased M. incognita egg hatch, but stimulated C. elegans hatch during the first hours of incubation. Viability of M. incognita J2 and of C. elegans J1 and adults was not affected. There were no observed effects on the other nematodes. The study indicated that DAPG is not toxic to all nematodes, and did not affect the tested species of beneficial bacterial-feeding nematodes. Augmentation of DAPG-producing P. fluorescens populations for nematode biocontrol could be targeted to specific nematode species known to be affected by this compound and by other antibiotics produced by the bacteria, or these bacteria could be used for other possible effects, such as induced plant resistance.     

Effects of fungal culture filtrates of Verticillium lecanii (Lecanicillium spp.) hybrid strains on Heterodera glycines eggs and juveniles

Many nematode-antagonistic fungi produce secondary metabolites and enzymes that demonstrate toxicity against plant-parasitic nematodes. The objective of this study was to evaluate the effects of fungal culture filtrates of Verticillium lecanii hybrid strains on mature eggs, embryonated eggs (eggs fertilized but without development of juveniles), and second-stage juveniles (J2) of Heterodera glycines and to compare these effects with those of their parental strains. The fungal culture filtrates of certain hybrid strains inhibited egg hatch of mature eggs. Furthermore, the fungal culture filtrates of two hybrid strains, AaF23 and AaF42, exhibited high toxicity against embryonated eggs of H. glycines. However, most of the fungal culture filtrates of V. lecanii did not inactivate J2. These results suggested that enzymes or other active compounds produced by the fungal culture filtrates of V. lecanii exhibit activity against specific stages in the H. glycines life cycle. In addition, based on a visual assessment of the morphological changes in eggs caused by filtrates of each strain, there were differences between the hybrid strains and their respective parental strains with regard to the active substances produced by V. lecanii against the embryonated eggs. As a result of promoting recombination of whole genomes via protoplast fusion, several hybrid strains may have enhanced production of active substances that are different from those produced by their parental strains. It was concluded that natural substances produced by V. lecanii are one of the important factors involved in the suppression of H. glycines damage.     

A new method for collecting isothiocyanates released from plant residues incorporated in soil

A method was developed for collecting isothiocyanates (ITCs) from compost and their detection by gas chromatography–mass spectrometry. Identification of the compounds was based on retention time, molecular weight and previously published information (Wiley Database, Hewlett Packard ChemStation Library). The release of ITCs from freeze-dried plant material of Brassica carinata , Cleome spinosa and Tropaeolum majus cultivars was investigated by incorporation in compost contained in pots. Allyl isothiocyanate, methyl isothiocyanate and benzyl isothiocyanate, respectively, were released after hydrolysis of plant tissues. Abundance of ITCs was monitored for 12 days and was shown to decrease rapidly following incorporation until the fourth day for all types of plant tissue.     

Physiological resistance and behavioral avoidance responses to residues of four pesticides by six spider mite populations

Six twospotted spider mite populations were assayed for their levels of physiological resistance and behavioral avoidance to residues of four synthetic pesticides. Mortality could not be estimated for bifenthrin and fenvalerate (synthetic pyrethroids) as mites effectively avoided treated surfaces, however significant between-population differences in mortality were detected for chlordimeform and cyhexatin. Considerable variation in walkoff and spindown behavioral response to sub-lethal doses of pesticides was observed among populations within compounds, and within populations among compounds. Within-compound walkoff and spindown behavioral response varied among all mite populations. Few significant between-compound correlations were significant, indicating that spider mites responded differently to the four pesticides. The hypothesis that physiological resistance is negatively correlated with behavioral avoidance was tested. Of the four possible negative correlations between physiological resistance and behavioral avoidance for chlordimeform and cyhexatin, only the correlation between cyhexatin-induced mortality and spindown response was significant. Comparisons of physiological resistance and behavioral avoidance of chlordimeform and cyhexatin by specific pairs of populations did not consistently find these two characters to be related. In a related experiment, the magnitude and direction of the correlation between physiological resistance and behavioral avoidance following selection for increased physiological tolerance to cyhexatin was compared in a highly resistant and a susceptible population of the twospotted spider mite. Mortality in the susceptible population at 2 ppm cyhexatin was similar to mortality in the resistant population at 250 ppm after 72h exposure (ca. 12%). However, at these concentrations, the resistant population exhibited much higher avoidance of the compound through walkoff response.     

Volatile compounds from leaves of the African spider plant (Gynandropsis gynandra) with bioactivity against spider mite (Tetranychus urticae)

Previous studies have demonstrated that Gynandropsis gynandra emits acetonitrile as a foliar volatile from intact plants and isolated leaves, and that this compound is an effective spider mite repellent. This study has used gas chromatography–mass spectrometry to investigate volatile compounds emitted from homogenised G. gynandra leaves to evaluate their tissue acetonitrile content and to look for other compounds that might be exploited for the management of spider mites. Acetonitrile was absent from the homogenised tissues of five lines of G. gynandra, studied over two seasons. Thirteen volatile compounds were emitted by G. gynandra at significantly higher levels than mite‐susceptible pot roses, including isothiocyanates, aldehydes, esters, alcohols and terpenes. Six representative compounds were selected to assess bioactivity. Spider mite populations were completely inactive after a 2 h exposure to butyl isothiocyanate, 2,4‐heptadienal or β‐cyclocitral, when evaporated from 0.5 µL of pure compound in a 100 mL air space. The same level of inactivity was achieved after exposure to 5.0 μL of (Z)‐2‐pentenol or a 25 μL volume of 50% v/v Z‐3‐hexenal or 5% w/v methyl isothiocyanate. Dissipation of β‐cyclocitral following 24 h exposure to its concentration of 5 μL in a 100 mL air space resulted in a 6% recovery of the spider mites but at higher concentrations no recovery was observed. These identified compounds may have potential as extracted products for management of spider mites in roses, and a high constitutive content of them in roses may be of value in targeted plant breeding for enhanced insect resistance. The range of isothiocyanates found in G. gynandra accounts for the bitter taste of the leaves when used as a traditional vegetable in Eastern Africa and provides a target for manipulation to improve palatability.     

Arylisothiocyanate-containing esters of caffeic acid designed as affinity ligands for HIV-1 integrase.

Integrase is an enzyme found in human immunodeficiency virus, which is required for the viral life cycle, yet has no human cellular homologue. For this reason, HIV integrase (IN) has become an important target for the development of new AIDS therapeutics. Irreversible affinity ligands have proven to be valuable tools for studying a number of enzyme and protein systems, yet to date there have been no reports of such affinity ligands for the study of IN. As an initial approach toward irreversible ligand design directed against IN, we appended isothiocyanate functionality onto caffeic acid phenethyl ester (CAPE), a known HIV integrase inhibitor. The choice of isothiocyanate as the reactive functionality, was based on its demonstrated utility in the preparation of affinity ligands directed against a number of other protein targets. Several isomeric CAPE isothiocyanates were prepared to explore the enzyme topography for reactive nitrogen and sulfur nucleophiles vicinal to the enzyme-bound CAPE. The preparation of these CAPE isothiocyanates, required development of new synthetic methodology which employed phenyl thiocarbamates as latent isothiocyanates which could be unmasked near the end of the synthetic sequence. When it was observed that beta-mercaptoethanol (beta-ME), which is required to maintain the catalytic activity of soluble IN (a F185KC280S mutant), reacted with CAPE isothiocyanate functionality to form the corresponding hydroxyethylthiocarbamate, a variety of mutant IN were examined which did not require the presence of beta-ME for catalytic activity. Although in these latter enzymes, CAPE isothiocyanate functionality was presumed to be present and available for acylation by IN nucleophiles, they were equally effective against Cys to Ser mutants. One conclusion of these studies, is that upon binding of CAPE to the integrase, nitrogen or sulfur nucleophiles may not be properly situated in the vicinity of the phenethyl aryl ring to allow reaction with and covalent modification of reactive functionality, such as isothiocyanate groups. The fact that introduction of the isothiocyanate group onto various positions of the phenethyl ring or replacement of the phenyl ring with naphthyl rings, failed to significantly affect inhibitory potency, indicates a degree of insensitivity of this region of the molecule toward structural modification. These findings may be useful in future studies concerned with the development and use of HIV-1 integrase affinity ligands.     

Mitochondrial peroxiredoxin 3 is rapidly oxidized in cells treated with isothiocyanates

Isothiocyanates are phytochemicals with anti-cancer properties that include the ability to trigger apoptosis. A substantial body of evidence suggests that reaction of the electrophilic isothiocyanate moiety with cysteine residues in cellular proteins and glutathione accounts for their biological activity. In this study we investigated the effect of several different isothiocyanates on the redox states of the cysteine-dependent peroxiredoxins (Prx) in Jurkat T lymphoma cells, and compared this to known effects on the selenoprotein thioredoxin reductase, glutathione reductase and intracellular GSH levels. Interestingly, oxidation of mitochondrial Prx3 could be detected as early as 5 min after exposure of cells to phenethyl isothiocyanate, with complete oxidation occurring at doses that only had small inhibitory effects on total cellular thioredoxin reductase and glutathione reductase activities. Peroxiredoxin oxidation was specific to the mitochondrial isoform with cytoplasmic Prx1 and Prx2 maintained in their reduced forms at all analyzed time points and concentrations of isothiocyanate. Phenethyl isothiocyanate could react with purified Prx3 directly, but it did not oxidize Prx3 or promote its oxidation by hydrogen peroxide. A selection of aromatic and alkyl isothiocyanates were tested and while all lowered cellular GSH levels, only the isothiocyanates that caused Prx3 oxidation were able to trigger cell death. We propose that pro-apoptotic isothiocyanates selectively disrupt mitochondrial redox homeostasis, as indicated by Prx3 oxidation, and that this contributes to their pro-apoptotic activity.     

Selection of Heterodera glycines chorismate mutase-1 alleles on nematode-resistant soybean

The soybean cyst nematode Heterodera glycines is the most destructive pathogen of soybean in the Unites States. Diversity in the parasitic ability of the nematode allows it to reproduce on nematode-resistant soybean. H. glycines chorismate mutase-1 (Hg-CM-1) is a nematode enzyme with the potential to suppress host plant defense compounds; therefore, it has the potential to enhance the parasitic ability of nematodes expressing the gene. Hg-cm-1 is a member of a gene family where two alleles, Hg-cm-1A and Hg-cm-1B, have been identified. Analysis of the Hg-cm-1 gene copy number revealed that there are multiple copies of Hg-cm-1 alleles in the H. glycines genome. H. glycines inbred lines were crossed to ultimately generate three F2 populations of second-stage juveniles (J2s) segregating for Hg-cm-1A and Hg-cm-1B. Segregation of Hg-cm-1A and 1B approximated a 1:2:1 ratio, which suggested that Hg-cm-1 is organized in a cluster of genes that segregate roughly as a single locus. The F2 H. glycines J2 populations were used to infect nematode-resistant (Hartwig, PI88788, and PI90763) and susceptible (Lee 74) soybean plants. H. glycines grown on Hartwig, Lee 74, and PI90763 showed allelic frequencies similar to Hg-cm-1A/B, but nematodes grown on PI88788 contained predominately Hg-cm-1A allele as a result of a statistically significant drop of Hg-cm-1B in the population. This result suggests that specific Hg-cm-1 alleles, or a closely linked gene, may aid H. glycines in adapting to particular soybean hosts.     

Responses of Heterodera glycines and Meloidogyne incognita to exogenously applied neuromodulators

Biogenic amines regulate important behaviours in nematodes and are associated with pharyngeal activity in plant-parasitic nematodes. A robust behavioural assay based upon nematode body movements was developed to expand the study of these and other neuroregulators in plant-parasitic nematodes. Dopamine, octopamine and serotonin each had significant but differing effects on the behaviour of soybean cyst nematode Heterodera glycines and root-knot nematode Meloidogyne incognita juveniles. Body movement frequency was increased twofold in H. glycines by 5 mM dopamine (P = 0.0001), but decreased by 50 mM dopamine in H. glycines (88%) and M. incognita (53%) (P < 0.0001). Movement frequency in both species was increased by 50-70% (P < 0.0001) by 50 mM octopamine, and 5 mM octopamine increased M. incognita movement frequency more than twofold (P < 0.0001). Movement frequency in each species was reduced by more than 90% by 5 mM serotonin (P < 0.0001). While amplitude of body movement in H. glycines was unaffected by any amine, it was significantly reduced in M. incognita by all amines (P < 0.0006). Stylet pulsing frequencies in either species were unaffected by dopamine or octopamine, but 5 mM serotonin stimulated pulsing in H. glycines by nearly 13-fold (P < 0.0001) and in M. incognita by more than 14-fold (P < 0.0001). The invertebrate neuropeptide FLRFamide (N-Phe-Leu-Arg-Phe) increased M. incognita body movement frequency 45% (P = 0.02) at 1 mM but did not affect stylet activity. Finally, H. glycines egg hatch was completely suppressed by 50 mM serotonin, and partially suppressed by 50 mM dopamine (75%; P < 0.0001) and 50 mM octopamine (55%; P < 0.0001).     

A mixture of isothiocyanates induces cyclin B1- and p53-mediated cell-cycle arrest and apoptosis of human T lymphoblastoid cells

As with other candidate chemopreventive agents, most of our knowledge on the biological effects of isothiocyanates (the many sulfur-containing metabolites found in cruciferous vegetables) comes from studies of single natural or synthetic compounds. To investigate whether the biological/chemopreventive effects of administration of single isothiocyanates can differ from those of a mixture of isothiocyanates, we tested the effects of a mixture of four different isothiocyanates on cell-cycle progression and apoptosis in human T leukemia Jurkat cells, and identified some of the molecular pathways triggered by the mixture. The mixture affected critical points of the cell cycle via modulation of the expression of cyclin B1. Moreover, it induced apoptosis, mediated by an increase in p53 and bax (expression of bcl-2 was unaffected). Comparison of the data with those previously obtained with the single isothiocyanates under identical experimental conditions provides evidence that the quantitative effects of a single, specific isothiocyanate can be significantly different from those of an isothiocyanate mixture at realistic doses.     

Natural isothiocyanates: genotoxic potential versus chemoprevention

Isothiocyanates, occurring in many dietary cruciferous vegetables, show interesting chemopreventive activities against several chronic-degenerative diseases, including cancer, cardiovascular diseases, neurodegeneration, diabetes. The electrophilic carbon residue in the isothiocyanate moiety reacts with biological nucleophiles and modification of proteins is recognized as a key mechanism underlying the biological activity of isothiocyanates. The nuclear factor-erythroid-2-related factor 2 system, which orchestrates the expression of a wide array of antioxidant genes, plays a role in the protective effect of isothiocyanates against almost all the pathological conditions reported above. Recent emerging findings suggest a further common mechanism. Chronic inflammation plays a central role in many human diseases and isothiocyanates inhibit the activity of many inflammation components, suppress cyclooxygenase 2, and irreversibly inactivate the macrophage migration inhibitory factor. Due to their electrophilic reactivity, some isothiocyanates are able to form adducts with DNA and induce gene mutations and chromosomal aberrations. DNA damage has been demonstrated to be involved in the pathogenesis of various chronic-degenerative diseases of epidemiological relevance. Thus, the genotoxicity of the isothiocyanates should be carefully considered. In addition, the dose-response relationship for genotoxic compounds does not suggest evidence of a threshold. Thus, chemicals that are genotoxic pose a greater potential risk to humans than non-genotoxic compounds. Dietary consumption levels of isothiocyanates appear to be several orders of magnitude lower than the doses used in the genotoxicity studies and thus it is highly unlikely that such toxicities would occur in humans. However, the beneficial properties of isothiocyanates stimulated an increase of dietary supplements and functional foods with highly enriched isothiocyanate concentrations on the market. Whether such concentrations may exert a potential health risk cannot be excluded with certainty and an accurate evaluation of the toxicological profile of isothiocyanates should be prompted before any major increase in their consumption be recommended or their clinical use suggested.