Allyl Nitrile Research Articles

Copper-catalyzed enantioselective decarboxylative cyanation of β,γ-unsaturated carboxylic acids to access chiral allyl nitriles

Copper-catalyzed asymmetric radical cyanation reactions have emerged as a powerful platform for construction of a variety of enantioenriched cyano-containing compounds under mild conditions. Herein, we report a copper-catalyzed enantioselective decarboxylative cyanation of readily available β, γ -unsaturated carboxylic acids promoted by a hypervalent iodine(III) reagent. The key allyl radical can be efficiently formed through single-electron reduction of in-situ -generated phenyliodine(III) dicarboxylates by Cu(I) species. This protocol features mild conditions, wide substrate scope, and functional group tolerance, producing a diverse range of chiral allyl nitriles in moderate to good yields and with high regio- and enantioselectivities. The enantioenriched allyl nitrile products can be used for the preparation of various synthetically useful chiral intermediates through simple transformations. • Copper-catalyzed asymmetric radical cyanation reactions are developed • Enantioselective decarboxylative cyanation of β,γ -unsaturated carboxylic acids is shown • The reaction is promoted by a hypervalent iodine(III) reagent • Efficient generation of the highly reactive allyl radical powers the reaction Copper-catalyzed asymmetric radical cyanation reactions have emerged as a powerful platform for construction of enantioenriched cyano-containing compounds under mild conditions. Zhang and Huang et al. develop a copper-catalyzed enantioselective decarboxylative cyanation of readily available β,γ-unsaturated carboxylic acids promoted by a hypervalent iodine(III) reagent.

Assessing the Fate and Bioavailability of Glucosinolates in Kale (Brassica oleracea) Using Simulated Human Digestion and Caco-2 Cell Uptake Models.

Glucosinolates and their hydrolysis products were characterized in fresh and in in vitro gastric and intestinal digesta of Dinosaur kale (Brassica oleracea L var. palmifolia DC). In fresh kale, glucoraphanin, sinigrin, gluconapin, gluconasturtiin, glucoerucin, glucobrasscin, and 4-methoxylglucobrassicin were identified. After 120 min of gastric digestion, the levels of glucoraphanin, sinigrin, and gluconapin decreased, and no glucoerucin or glucobrasscin was detected. However, a concomitant increase in the glucosinolate hydrolysis products allyl nitrile, 3-butenyl isothiocyanate, phenylacetonitrile, and sulforaphane was observed. This trend continued through intestinal digestion. After 120 min, the levels of allyl nitrile, 3-butenyl isothiocyanate, phenylacetonitrile, and sulforaphane were 88.19 ± 5.85, 222.15 ± 30.26, 129.17 ± 17.57, and 13.71 ± 0.62 pmol/g fresh weight, respectively. Intestinal digesta were then applied to Caco-2 cell monolayers to assess the bioavailability. After 6 h of incubation, no glucosinolates were detected and the percentage of total cellular uptake of the glucosinolate hydrolysis products ranged from 29.35% (sulforaphane) to 46.60% (allyl nitrile).

Endophytic fungi from the roots of horseradish (Armoracia rusticana) and their interactions with the defensive metabolites of the glucosinolate - myrosinase - isothiocyanate system

BackgroundThe health of plants is heavily influenced by the intensively researched plant microbiome. The microbiome has to cope with the plant’s defensive secondary metabolites to survive and develop, but studies that describe this interaction are rare. In the current study, we describe interactions of endophytic fungi with a widely researched chemical defense system, the glucosinolate - myrosinase - isothiocyanate system. The antifungal isothiocyanates are also of special interest because of their beneficial effects on human consumers.ResultsSeven endophytic fungi were isolated from horseradish roots (Armoracia rusticana), from the genera Fusarium, Macrophomina, Setophoma, Paraphoma and Oidiodendron. LC-ESI-MS analysis of the horseradish extract incubated with these fungi showed that six of seven strains could decompose different classes of glucosinolates. Aliphatic, aromatic, thiomethylalkyl and indolic glucosinolates were decomposed by different strains at different rates. SPME-GC-MS measurements showed that two strains released significant amounts of allyl isothiocyanate into the surrounding air, but allyl nitrile was not detected. The LC-ESI-MS analysis of many strains’ media showed the presence of allyl isothiocyanate - glutathione conjugate during the decomposition of sinigrin. Four endophytic strains also accepted sinigrin as the sole carbon source. Isothiocyanates inhibited the growth of fungi at various concentrations, phenylethyl isothiocyanate was more potent than allyl isothiocyanate (mean IC50 was 2.30-fold lower).As a control group, ten soil fungi from the same soil were used. They decomposed glucosinolates with lower overall efficiency: six of ten strains had insignificant or weak activities and only three could use sinigrin as a carbon source. The soil fungi also showed lower AITC tolerance in the growth inhibition assay: the median IC50 values were 0.1925 mM for endophytes and 0.0899 mM for soil fungi.ConclusionsThe host’s glucosinolates can be used by the tested endophytic fungi as nutrients or to gain competitive advantage over less tolerant species. These activities were much less apparent among the soil fungi. This suggests that the endophytes show adaptation to the host plant’s secondary metabolites and that host metabolite specific activities are enriched in the root microbiome. The results present background mechanisms enabling an understanding of how plants shape their microbiome.

Allyl nitrile: Toxicity and health effects

Allyl nitrile (3-butenenitrile) occurs naturally in the environment, in particular, in cruciferous vegetables, indicating a possible daily intake of the compound. There is no report on actual health effects of allyl nitrile in humans, although it is possible that individuals in the environment are at a risk of exposure to allyl nitrile. However, little is known about its quantitative assessment for the environment and bioactivity in the body. This study provides a review of previous accumulated studies on allyl nitrile. Published literature on allyl nitrile was examined for findings on toxicity, metabolism, risk of various cancers, generation, intake estimates, and low-dose effects in the body. High doses of allyl nitrile produce toxicity characterized by behavioral abnormalities, which are considered to be produced by an active metabolite, 3,4-epoxybutyronitrile. Cruciferous vegetables have been shown to have a potential role in reducing various cancers. Hydrolysis of the glucosinolate sinigrin, rich in cruciferous vegetables, results in the generation of allyl nitrile. An intake of allyl nitrile is estimated at 0.12 μmol/kg body weight in Japan. Repeated exposure to low doses of allyl nitrile upregulates antioxidant/phase II enzymes in various tissues; this may contribute to a reduction in neurotoxicity and skin inflammation. These high and low doses are far more than the intake estimate. Allyl nitrile in the environment is a compound with diverse bioactivities in the body, characterized by inducing behavioral abnormalities at high doses and some antioxidant/phase II enzymes at low doses.

Anti-Inflammatory and Antioxidant Effects of Repeated Exposure to Cruciferous Allyl Nitrile in Sensitizer-Induced Ear Edema in Mice.

BackgroundSkin sensitizers induce allergic reactions through the induction of reactive oxygen species. Allyl nitrile from cruciferous vegetables has been reported to induce antioxidants and phase II detoxification enzymes in various tissues. We assessed the effects of repeated exposure to allyl nitrile on sensitizer-induced allergic reactions.Material/MethodsMice were dosed with allyl nitrile (0–200 μmol/kg), and then received a dermal application of 1 of 3 sensitizers on the left ear or 1 of 2 vehicles on the right ear. Quantitative assessment of edema was carried out by measuring the difference in weight between the portions taken from the right and left ears. We tested enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and thiobarbituric acid reactive substances (TBARS) in ears.ResultsRepeated exposure to allyl nitrile reduced edemas induced by glutaraldehyde and by 2, 4-dinitrochlorobenzene (DNCB), but not by formaldehyde. The repeated exposure decreased levels of TBARS, a marker of oxidative stress, induced by glutaraldehyde and by DNCB, but not by formaldehyde. Allyl nitrile elevated SOD levels for the 3 sensitizers, and CAT levels for formaldehyde and DNCB. Allyl nitrile also increased GPx levels for formaldehyde and DNCB, but not for glutaraldehyde. The reduced edemas were associated with changes in oxidative stress levels and antioxidant enzymes.ConclusionsRepeated exposure to allyl nitrile reduced allergic reactions induced by glutaraldehyde and by DNCB, but not by formaldehyde. This reduction was associated with changes in ROS levels and antioxidant enzyme activities.

Identification of Proteins Possibly Involved in Glucosinolate Metabolism in L. agilis R16 and E. coli VL8.

This study was aimed to identify sinigrin-induced bacterial proteins potentially involved in the metabolism of glucosinolate in two glucosinolate-metabolising bacteria Lactobacillus agilis R16 and Escherichia coli VL8. Sinigrin (2 mM) was used to induce the proteins in both bacteria under anaerobic incubation for 8 h at 30 °C for L. agilis R16 and 37 °C for E. coli VL8 and the controls without sinigrin were performed. Allyl isothiocyanate and allyl nitrile as two degradation products of sinigrin were detected in sinigrin-induced cultures of L. agilis R16 (27% total products) and E. coli VL8 (38% total products) from a complete sinigrin degradation in 8 h for both bacteria. 2D gel electrophoresis was conducted to identify induced proteins with at least twofold increased abundance. Sinigrin-induced L. agilis R16 and the control produced 1561 and 1543 protein spots, respectively. For E. coli VL8, 1363 spots were detected in sinigrin-induced and 1354 spots in the control. A combination of distinct proteins and upregulated proteins of 32 and 35 spots in L. agilis R16 and E. coli VL8, respectively were detected upon sinigrin induction. Of these, 12 and 16 spots from each bacterium respectively were identified by LC-MS/MS. In both bacteria most of the identified proteins are involved in carbohydrate metabolism, oxidoreduction system and sugar transport while the minority belong to purine metabolism, hydrolysis, and proteolysis. This indicated that sinigrin induction led to the expressions of proteins with similar functions in both bacteria and these proteins may play a role in bacterial glucosinolate metabolism.

Repeated Exposure to Cruciferous Allyl Nitrile Protects against Chemically Induced Skin Inflammation in the Mouse

Repeated exposure to cruciferous allyl nitrile can induce antioxidant and phase 2 detoxification enzymes in various tissues. In the present study, we examined the effect of five days repeated exposure to allyl nitrile at subtoxic levels (0 - 400 μmol/kg/day) on the mouse ear. There was an increase in catalase activity in the ear at 100 - 400 μmol/kg/day, while elevated quinone reductase activity was observed at 400 μmol/kg/day only. Next, after repeated allyl nitrile exposure (0 - 400 μmol/kg/day), the skin irritant croton oil was applied to the ear to induce skin acute inflammation (oedema). Compared with the 0 μmol/kg/day group, animals in the 100 and 400 μmol/kg/day pre-treatment groups showed reduced oedematous response to croton oil. The reduced oedematous response was inversely associated with enhanced myeloperoxidase activity used as index of the presence of neutrophils. These data suggest that repeated exposure to allyl nitrile at subtoxic levels contributes to protection against croton oil-induced ear dermatitis, potentially through decreasing reactive oxygen species and through infiltration of neutrophils.

Preconditioning with subneurotoxic allyl nitrile: Protection against allyl nitrile neurotoxicity

High-dose cruciferous allyl nitrile can induce behavioral abnormalities in rodents, while repeated exposure to allyl nitrile at subneurotoxic levels can increase phase 2 detoxification enzymes in many tissues, although the brain has not been investigated yet. In the present study, we examined the effect of 5 days repeated exposure to subneurotoxic allyl nitrile (0–400 μmol/kg/day) on the brain. Elevated glutathione S-transferase activity was recorded in the striatum, hippocampus, medulla oblongata plus pons, and cortex. Enhancement of quinone reductase activity was observed in the medulla oblongata plus pons, hippocampus, and cortex. In the medulla oblongata plus pons, elevated glutathione levels were recorded. Following repeated subneurotoxic allyl nitrile exposure (0–400 μmol/kg/day), mice were administered a high-dose allyl nitrile (1.2 mmol/kg) which alone led to appearance of behavioral abnormalities. Compared with the 0 μmol/kg/day group, animals in the 200 and 400 μmol/kg/day pre-treatment groups exhibited decreased behavioral abnormalities and elevated GABA-positive cell counts in the substantia nigra pars reticulata and the interpeduncular nucleus. These data suggest that repeated exposure to subneurotoxic levels of allyl nitrile can induce phase 2 enzymes in the brain, which together with induction in other tissues, may contribute to protection against allyl nitrile neurotoxicity.

Induction of Detoxication Enzymes in Mice by Naturally Occurring Allyl Nitrile

Little is known about whether glucosinolate-derived nitriles have the ability to increase phase 2 detoxication enzymes and glutathione (GSH) in vivo. In this study, the ability of allyl nitrile, a hydrolysis product of the glucosinolate sinigrin, to increase tissue levels of the phase 2 detoxication enzymes glutathione S-transferase and quinone reductase and GSH in a variety of mouse tissues was examined. At the lowest dose level (11.8 mg/kg/day), allyl nitrile showed inductive ability in the stomach and lungs. At 23.6 mg/kg/day, the inductive effect was observed in the stomach, rectum, urinary bladder, and lungs, whereas at 47.2 mg/kg/day, it was recorded in the stomach, rectum, urinary bladder, kidneys, and lungs. These results show that allyl nitrile displays its maximum potency in the stomach and lungs, which is of interest in light of epidemiological studies demonstrating an inverse association between crucifer intake and the incidence of stomach and lung cancers.

Inhibition of equine cyathostomes to glucosinolate hydrolysis products

Cyathostome nematodes have become the central focus of concerns related to internal parasites of horses due to their pathological and persistent effects on the growing and mature horse (Murphy and Love, 1997). Current anthelmintic treatments have, however, led to resistance and alternative control measures are required. Glucosinolate hydrolysis derivatives have a wide range of biological activities, and have previously been shown to inhibit root nematodes (Brown and Morra, 1997). The aim of the study was to examine whether cyathostome nematode eggs could be inhibited by glucosinolate hydrolysis products.An in vitro egg hatch assay was set up using eggs extracted from the faeces of naturally infected horses (Kassai, 1999). The egg suspension (containing approximately 100 eggs) were incubated with nine different concentrations (range: 20-10,000 ppm) of the glucosinolate hydrolysis products (allyl isothiocyanate (C), allyl nitrile (N) and phenethyl isothiocyanate (P). A control was set up in which water replaced the hydrolysis product. The number of eggs and larvae were counted using an inverted microscope. Statistical differences between treatments were assessed using General Linear Model, ANOVA.

P2A47 - The influence of alcohol on allylnitrile (ALN) metabolism in male sprague-dawley rats

P2A47 - The influence of alcohol on allylnitrile (ALN) metabolism in male sprague-dawley rats

Transformation of the Glucosinolate-Derived Allelochemicals Allyl Isothiocyanate and Allylnitrile in Soil

Hydrolysis of glucosinolates in Brassica tissues results in formation of allelochemicals potentially useful in controlling soil-borne plant pests. Major degradation products of glucosinolates in soil are organic isothiocyanates and nitriles ; however, a clear understanding of allelochemical persistence in soil is lacking. Half-lives of allyl isothiocyanate (AI) and allylnitrile (AN) in six soils were determined using gas chromatographic analysis of ethyl acetate extracts. The half-lives for AI ranged from 20 to 60 h, whereas AN had longer half-lives of 80-120 h. AI transformation increased with reduced soil moisture and higher temperatures and occurred more rapidly in soils containing greater concentrations of organic carbon. AN transformation increased under wetter conditions and lower temperatures and occurred more rapidly in soils having higher inorganic carbon concentrations. Although different mechanisms contribute to substrate disappearance, the relatively rapid dissipation of AI and AN in soil has important implications in the control of soil-borne plant pests with Brassica tissues.

Alterations in the metabolism of serotonin and dopamine in the mouse brain following a single administration of allylnitrile, which induces long-term dyskinesia

The effects of allylnitrile (ALN), which induces a long-term dyskinesia in mice, on the metabolism of serotonin (5-HT) and dopamine (DA) were studied after a single administration. One day after injection, ALN produced a significant increase in the levels of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA): 5-HT in the brain cortex, medulla oblongata plus pons, hypothalamus and midbrain; 5-HIAA in the cortex, medulla oblongata plus pons, striatum, hypothalamus and midbrain; the ratio of 5-HIAA/5-HT in the medulla oblongata plus pons, striatum and midbrain; HVA in the cortex and midbrain. These changes were not seen 10 and 35 days after injection when the animals were showing behavioral abnormalities. The present findings suggest that changes in 5-HT and DA metabolism are involved in the appearance of the dyskinetic syndrome.

Allylnitrile: A compound which induces long-term dyskinesia in mice following a single administration

A single oral dose of allylnitrile (ALN) in mice pretreated with CCl 4 induced behavioral abnormalities such as circling, hyperactivity, and head twitching, which lasted for a 4-month observation period. Histopathologically hemorrhage, demyelinated fibers and necrotic neurons were observed in the midbrain and pons 40 to 50 days after the administration of ALN. The head twitching was either reduced by treatment with serotonin and dopamine antagonists or enhanced by a serotonin releaser, suggesting that both serotonin and dopamine systems are involved in the behavioral abnormalities by ALN. These disorders by ALN may be used as an animal model of the dyskinetic syndrome.