glucobrassicin and indole-3-acetonitrile

A systematic investigation was carried out on the influence of fermentation on glucosinolates and their degradation products from fresh raw cabbage, throughout fermentation at 20 °C and storage at 4 °C. Glucosinolates were degraded dramatically between Day 2 and 5 of fermentation and by Day 7 there was no detectable amount of glucosinolates left. Fermentation led to formation of potential bioactive compounds ascorbigen (13.0 μmol/100 g FW) and indole-3-carbinol (4.52 μmol/100g FW) with their higher concentrations from Day 5 to Day 9. However, during storage indole-3-carbinol slowly degraded to 0.68 μmol/100 g FW, while ascorbigen was relatively stable from Week 4 until Week 8 at 6.78 μmol/100 g FW. In contrast, the content of indole-3-acetonitrile decreased rapidly during fermentation from 3.6 to 0.14 μmol/100 g FW. The results imply a maximum of health beneficial compounds after fermentation (7-9 days) in contrast to raw cabbage or stored sauerkraut.

Topics: Brassica; Fermentation; Glucosinolates; Indoles

The aim of the study was to investigate the effect of storage on the contents of glucosinolates (GLS) and their degradation products in a boiled white cabbage. A 24h storage at 4 °C resulted in a decrease in GLS content (20-40%, depending on the cooking time applied) in the edible parts. The most significant losses were observed for sinigrin (20-45%), and the least for glucobrassicin (12-32%). Storage had a diversified effect on GLS breakdown products (indole-3-acetonitrile, indole-3-carbinol, ascorbigen and 3,3'-diindolylmethane released from glucobrassicin and 4-methylsulfinylbutanenitrile released from glucoiberin) in the boiled cabbage. The increase in the content of indole-3-acetonitrile, especially considerable within the first 24h of storage (and a simultaneous decrease in glucobrassicin) clearly indicates that degradation of GLS may occur during storage or cooling to 4 °C.

Topics: Ascorbic Acid; Brassica; Drug Stability; Fermentation; Food Handling; Food Preservation; Glucosinolates; Hot Temperature; Indoles

Turnip (Brassica rapa ssp. rapa) and rape (Brassica napus ssp. biennis) and other brassica forage crops are regarded as "safe" feed for cattle during late summer and fall in the North Island of New Zealand when high Pithomyces chartarum spore counts in pastures frequently lead to sporidesmin toxicity (facial eczema). Sporadic acute severe cases of turnip photosensitization in dairy cows characteristically exhibit high γ-glutamyl transferase and glutamate dehydrogenase serum enzyme activities that mimic those seen in facial eczema. The two diseases can, however, be distinguished by histopathology of the liver, where lesions, in particular those affecting small bile ducts, differ. To date, the hepato-/cholangiotoxic phytochemical causing liver damage in turnip photosensitization in cattle is unknown. Of the hydrolysis products of the various glucosinolate secondary compounds found in high concentrations in turnip and rape, work has shown that nitriles and epithionitriles can be hepatotoxic (and nephro- or pancreatotoxic) in rats. These derivatives include β-hydroxy-thiiranepropanenitrile and 3-hydroxy-4-pentenenitrile from progoitrin; thiiranepropanenitrile and 4-pentenenitrile from gluconapin; thiiranebutanenitrile and 5-hexenenitrile from glucobrassicanapin; phenyl-3-propanenitrile from gluconasturtiin; and indole-3-acetonitrile from glucobrassicin. This perspective explores the possibility of the preferential formation of such derivatives, especially the epithionitriles, in acidic conditions in the bovine rumen, followed by absorption, hepatotoxicity, and secondary photosensitization.

Topics: Animals; Brassica napus; Brassica rapa; Cattle; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Glucosinolates; Indoles; Liver; Mice; New Zealand; Nitriles; Rats

The aim of the study was to investigate the effect of the pasteurization process on the content of ascorbigen, indole-3-carbinol, indole-3-acetonitrile, and 3,3'-diindolylmethane in fermented cabbage. Pasteurization was run at a temperature of 80 °C for 5-30 min. Significant changes were only observed in contents of ascorbigen and 3,3'-diindolylmethane. The total content of the compounds analyzed in cabbage pasteurized for 10-30 min was found to be decreased by ca. 20%, and the losses were due to thermal degradation of the predominating ascorbigen. Pasteurization was found not to exert any considerable effect on contents of indole-3-acetonitrile and indole-3-carbinol in cabbage nor did it affect contents of the compounds analyzed in juice.

Topics: Ascorbic Acid; Brassica; Fermentation; Glucosinolates; Hot Temperature; Indoles; Pasteurization

Glucosinolates are plant secondary metabolites that act as direct defenses against insect herbivores and various pathogens. Recent analysis has shown that methionine-derived glucosinolates are hydrolyzed/activated into either nitriles or isothiocyanates depending upon the plants genotype at multiple loci. While it has been hypothesized that tryptophan-derived glucosinolates can be a source of indole-acetonitriles, it has not been explicitly shown if the same proteins control nitrile production from tryptophan-derived glucosinolates as from methionine-derived glucosinolates. In this report, we formally test if the proteins involved in controlling aliphatic glucosinolate hydrolysis during tissue disruption can control production of nitriles during indolic glucosinolate hydrolysis. We show that myrosinase is not sufficient for indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate and requires the presence of functional epithospecifier protein in planta and in vitro to produce significant levels of indol-3-acetonitrile. This reaction is also controlled by the Epithiospecifier modifier 1 gene. Thus, like formation of nitriles from aliphatic glucosinolates, indol-3-acetonitrile production following tissue disruption is controlled by multiple loci raising the potential for complex regulation and fine tuning of indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate.

Topics: Arabidopsis; Arabidopsis Proteins; Enzymes; Glucosinolates; Hydrolysis; Indoles; Sensitivity and Specificity; Time Factors

The metabolism of the cruciferous phytoalexins brassinin and cyclobrassinin, and the related compounds indole-3-carboxaldehyde, glucobrassicin, and indole-3-acetaldoxime was investigated in various plant tissues of Brassica juncea and B. rapa. Metabolic studies with brassinin showed that stems of B. juncea metabolized radiolabeled brassinin to indole-3-acetic acid, via indole-3-carboxaldehyde, a detoxification pathway similar to that followed by the "blackleg" fungus (Phoma lingam/Leptosphaeria maculans). In addition, it was established that tetradeuterated brassinin was incorporated into the phytoalexin brassilexin in B. juncea and B. rapa. On the other hand, the tetradeuterated indole glucosinolate glucobrassicin was not incorporated into brassinin, although the chemical structures of brassinins and indole glucosinolates suggest an interconnected biogenesis. Importantly, tetradeuterated indole-3-acetaldoxime was an efficient precursor of phytoalexins brassinin, brassilexin, and spirobrassinin. Elicitation experiments in tissues of Brassica juncea and B. rapa showed that indole-3-acetonitrile was an inducible metabolite produced in leaves and stems of B. juncea but not in B. rapa. Indole-3-acetonitrile displayed antifungal activity similar to that of brassilexin, was metabolized by the blackleg fungus at slower rates than brassinin, cyclobrassinin, or brassilexin, and appeared to be involved in defense responses of B. juncea.

Topics: Anti-Infective Agents; Brassicaceae; Cells, Cultured; Glucosinolates; Indoles; Isotope Labeling; Phytoalexins; Plant Extracts; Plant Leaves; Plant Roots; Plant Stems; Sesquiterpenes; Terpenes; Thiocarbamates

Arabidopsis thaliana expresses four nitrilases, three of which (NIT1, NIT2 and NIT3) are able to convert indole-3-acetonitrile to indole-3-acetic acid (IAA), the plant growth hormone, while the isozyme NIT4 is a beta-cyano-l-alanine hydratase/nitrilase. NIT3 promoter activity is marginal in leaves or roots of vegetative plants and undetectable in bolting and flowering plants, but its level increases strongly when plants experience sulphur deprivation. No other nitrilase genes respond to sulphur supply/deficiency. Neither N- nor P-deprivation cause detectable changes in NIT3 promoter activity. In transgenic plants expressing uidA under the control of the NIT3 promoter (NIT3p::uidA), sulphate deprivation leads to the appearance of beta-glucuronidase activity in shoots and particularly in roots, most strongly in the conductive tissues and lateral root primordia. Deletion analysis allowed localization of the sulphur-responsive element to a 317 bp segment of the NIT3 promoter encompassing nt -2151 to -1834 upstream of the transcriptional start point. Both nitrilase polypeptide and nitrilase activity were also induced by sulphur starvation. NIT3 promoter activity was strongly induced by O-acetylserine, suggesting that, as is the case with enzymes of sulphate assimilation, sulphate deficiency may be communicated to NIT3 via an increase in the level of the cysteine precursor, O-acetylserine. During sulphur deprivation, a preferential depletion of the pool of the indole-3-acetonitrile precursor glucobrassicin compared with that of total glucosinolates was noticed. In the absence of an external sulphate supply, plants developed longer roots with a higher number of lateral roots. The increased growth of the root system occurred at the expense of shoot growth which was retarded under conditions of sulphur starvation. Taken together, these results suggest that a regulatory loop appears to exist by which sulphate deficiency, through an increase in glucobrassicin turnover and nitrilase 3 accumulation, initiates the production of extra auxin leading to increased root growth and branching, thus allowing the root system to penetrate new areas of soil effectively to gain access to fresh supplies of sulphur.

Topics: Aminohydrolases; Arabidopsis; Gene Expression Regulation, Plant; Glucosinolates; Glucuronidase; Indoleacetic Acids; Indoles; Plant Leaves; Plant Roots; Plants, Genetically Modified; Promoter Regions, Genetic; Serine; Sulfur

In this study we investigated the role of indole-3-acetonitrile, indole-3-carbinol, indole and tryptophan in the formation of N-nitroso compounds in green cabbage extracts. Green cabbage extracts were separated by gel permeation chromatography. Fractions were treated with nitrite, tested for mutagenicity and analysed for total N-nitroso content. Fractions in which spiked indole-3-acetonitrile, indole-3-carbinol, indole and tryptophan eluted appeared to be low in mutagenic activity and contained relatively small amounts of N-nitroso compounds. To detect indole compounds other than the ones used in the gel permeation chromatography experiments, high-performance liquid chromatography and gas chromatography-mass spectrometry analyses were performed of green cabbage extracts. Indole-3-carboxaldehyde was found to be the most commonly occurring indole compound, but it did not show direct mutagenic activity upon nitrite treatment. Indole-3-acetonitrile was the second most common compound; although it was mutagenic after nitrite treatment, its contribution to the mutagenicity of nitrite-treated green cabbage was roughly estimated to be only 2%. No other indole compounds were detected. From this study we conclude that neither the tested indole compounds nor indole-3-carboxaldehyde play a significant role in the formation of direct mutagenic N-nitroso compounds in nitrite-treated green cabbage extracts.

Topics: Brassica; Chromatography, Gel; Chromatography, High Pressure Liquid; Gas Chromatography-Mass Spectrometry; Glucosinolates; Indoles; Mutagens; Nitroso Compounds; Salmonella typhimurium; Tryptophan