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PubMed2007

Dual action on promoter demethylation and chromatin by an isothiocyanate restored GSTP1 silenced in prostate cancer.

Prostate carcinoma is characterized by the silencing of pi-class glutathione S-transferase gene (GSTP1), which encodes a detoxifying enzyme. The silencing of GSTP1, due to aberrant methylation at the CpG island in the promoter/5'-UTR, occurs in the vast majority of prostate tumors and precancerous lesions. It is a pathologic marker and probably an underlying cause of oxidative damage and inflammation at tumor initiation. Inhibition of the aberrant promoter methylation could therefore be an effective mean to prevent carcinogenesis. Several isothiocyanates, including phenethyl isothiocyanate (PEITC), found naturally in cruciferous vegetables, induced growth arrest and apoptosis in prostate cancer cells in culture and xenografts. The effects of PEITC to reactivate GSTP1 were investigated. Exposure of prostate cancer LNCaP cells to PEITC inhibited the activity and level of histone deacetylases (HDACs), and induced selective histone acetylation and methylation for chromatin unfolding. Concurrently PEITC demethylated the promoter and restored the unmethylated GSTP1 in both androgen-dependent and -independent LNCaP cancer cells to the level found in normal prostatic cells, as quantified by methylation-specific PCR and pyrosequencing. The dual action of PEITC on both the DNA and chromatin was more effective than 5'-Aza-2'-deoxycytidine, sodium butyrate, or trichostatin A (TSA), and may de-repress the methyl-binding domain (MBD) on gene transcription. The PEITC-mediated cross-talk between the DNA and chromatin in demethylating and reactivating GSTP1 genes, which is critically inactivated in prostate carcinogenesis, underlines a primary mechanism of cancer chemoprevention. Consequently, new approaches could be developed, with isothiocyanates to prevent and inhibit malignancies.

Acetylation↗
PubMed1997

Chemical carboxy-terminal sequence analysis of peptides using acetyl isothiocyanate.

A new derivatizing reagent, acetyl isothiocyanate (AITC), is applied for C-terminal peptide sequencing. It has been successfully used to sequence six C-terminal residues of a synthetic peptide at low nanomole levels. According to the mechanism study of the derivatization of C-terminal amino acid with various reagents, the derivatizing reagents (R-N=C=S or SCN-) were classified into three types: type I, the ionic compound (e.g., HSCN, NH4SCN, KSCN); type II, R is a good leaving group (e.g., TMS-ITC, TBSn-ITC); type III, R is reactive (e.g., AITC, BITC, DPP-ITC). Type III reagents are superior to other reagents because their double-function of activation and derivatization. Unlike type I and type II reagents, type III reagent chemistry does not require oxazolinone formation which can cause racemization. Compared with benzoyl isothiocyanate, diphenyl phosphoroisothiocyanatidate, trimethylsilyl isothiocyanate, and ammonium thiocyanate, AITC is the most effective derivatizing reagent. As a type III reagent, AITC possesses some features such as no need for oxazolinone formation, no requirement for separate activation step, high reactivity, easy preparation, and low absorption at 260-270 nm. Different reaction conditions were investigated for optimization and the chemical mechanism of AITC chemistry is illustrated. A convenient and efficient approach for synthesis of amino acid thiohydantoins as reference standards has also been developed.

Amino Acids↗
PubMed2001

Antibacterial and mutagenic activities of new isothiocyanate derivatives.

Nine newly synthesized isothiocyanate derivatives were demonstrated to posses antibacterial and genotoxic activities in vitro. 4-Hydroxybutyl isothiocyanate exhibited a broad antibacterial effect, with MIC values of 762 mumol/L for Staphylococcus aureus and Escherichia coli. Ethyl 4-methylsulfoxidobutanoate had the highest antibacterial activity in Gram-positive bacteria, the MIC value being 425 mumol/L for S. aureus. The highest tested concentrations of ethyl 4-isothiocyanatobutanoate and 4-hydroxybutyl isothiocyanate produced a bacteriocidal effect in Gram-positive bacteria. The compounds showed no mutagenic effects on Salmonella typhimurium tester strains TA 98 and TA 100, either in the absence or in the presence of a metabolically active microsomal S9 fraction from rat liver using standard Ames test.

Animals↗
PubMed2005

Pharmacokinetics of dietary phenethyl isothiocyanate in rats.

PURPOSE: Phenethyl isothiocyanate (PEITC) is a dietary component present in cruciferous vegetables and reported to have chemopreventive properties. Previous reports of PEITC pharmacokinetics have measured total ITC (PEITC and its metabolites) in plasma. Our objective was to examine the dose-dependent pharmacokinetics and oral bioavailability of unchanged PEITC, as well as its pH- and temperature-dependent stability and its serum protein binding. METHODS: Stability was studied at different pH values at room temperature and 4 degrees C. Protein binding was determined by equilibrium dialysis. For the pharmacokinetics study, male Sprague-Dawley rats were administered with PEITC at doses of 2, 10, 100, or 400 micromol/kg intravenously or 10 or 100 micromol/kg orally. Plasma samples were analyzed by liquid chromatography-tandem mass spectrometry. Pharmacokinetic analysis was conducted by WinNonlin and ADAPT II. RESULTS: Phenethyl isothiocyanate was stable in aqueous buffers at pH 7.4 with half-lives of 56.1 and 108 h at room temperature and 4 degrees C, respectively. The free fraction of PEITC in rat serum was 0.019. The clearance (Cl) at a low dose of PEITC (2 micromol/kg) was 0.70 +/- 0.17 L h(-1) kg(-1) with an apparent volume of distribution (Vss) of 1.94 +/- 0.42 L/kg. At higher doses, Cl tended to decrease, whereas Vss increased. Oral bioavailability of PEITC was 115 and 93% at doses of 10 and 100 micromol/kg, respectively. A three-compartment model with Michaelis-Menten elimination and distribution was found to best characterize the plasma concentration profiles. CONCLUSIONS: Phenethyl isothiocyanate is stable in biological samples, with increased stability under refrigerated conditions. It has high oral bioavailability, low clearance, and high protein binding in rats; nonlinear elimination and distribution occur following the administration of high doses. This investigation represents the first report of the pharmacokinetics of dietary PEITC.

Administration, Oral↗
PubMed1988

Differential induction of rat hepatic glutathione S-transferase isoenzymes by hexachlorobenzene and benzyl isothiocyanate. Comparison with induction by phenobarbital and 3-methylcholanthrene.

Male Wistar rats were treated with hexachlorobenzene, benzyl isothiocyanate, phenobarbital or 3-methylcholanthrene. Hepatic cytosolic glutathione S-transferase (GST) activity was determined with the substrates 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, ethacrynic acid and trans-4-phenyl-3-buten-2-one. Cytosolic glutathione peroxidase activity was measured with cumene hydroperoxide. GST activity toward 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene and ethacrynic acid was enhanced by all compounds, hexachlorobenzene and 3-methylcholanthrene causing the largest and the smallest increase respectively. Trans-4-phenyl-3-buten-2-one-conjugating activity exhibited only small changes, while peroxidase activity with cumeme hydroperoxide was not changed by any of the inducing agents. GST isoenzymes were purified on S-hexylglutathione Sepharose 6B and separated by means of FPLC-chromatofocusing, to evaluate effects on the GST isoenzyme pattern. Hexachlorobenzene and phenobarbital both caused an increase in the relative amounts of subunits 1 and 3 when compared with subunits 2 and 4 respectively. For 3-methylcholanthrene only induction of subunit 1 was observed, possibly due to the relatively low induction levels of total GST activity. In benzyl isothiocyanate-treated animals, an induction of subunit 3 was found as well as an increase in the relative amount of subunit 2. Thus, benzyl isothiocyanate behaves differently from hexachlorobenzene, phenobarbital and 3-methylcholanthrene as an inducing agent of rat hepatic glutathione S-transferases.

Animals↗
PubMed1995

On the cytotoxicity and genotoxicity of allyl and phenethyl isothiocyanates and their parent glucosinolates sinigrin and gluconasturtiin.

Four compounds commonly found in the human diet, allyl isothiocyanate (AITC), phenethyl isothiocyanate (PEITC) and their parent glucosinolates sinigrin and gluconasturtiin, were tested for cytotoxic and genotoxic effects in a Chinese hamster ovary cell line (CHO). The isothiocyanates were found to be more than one thousand times more cytotoxic than the glucosinolates, showing significant cytotoxic activity at concentrations below 1.0 microgram/ml. AITC was unable to induce either chromosome aberrations or sister chromatid exchanges (SCEs) even at highly cytotoxic doses. In contrast, PEITC was found to induce both aberrations and SCE at concentrations of 0.9-1.2 micrograms/ml whilst sinigrin and gluconasturtiin induced aberrations at concentrations above 2 mg/ml.

Animals↗
PubMed1992

Reversed-phase high-performance liquid chromatographic separation of the stereoisomers of labetalol via derivatization with chiral and non-chiral isothiocyanate reagents.

The antihypertensive agent labetalol is a mixture of two racemates. We report reversed-phase high-performance liquid chromatographic (HPLC) methodology for the separation of the four stereoisomers of labetalol via derivatization with the chiral reagent (4S-cis)-2,2-dimethyl-5-isothiocyanato-4-phenyl-1,3-dioxane. The derivatives were separated on octadecylsilane columns with a methanol-ammonium phosphate buffer mixture as mobile phase. Separations of the diastereomeric forms of labetalol were achieved with the non-chiral derivatizing reagents benzyl isothiocyanate and 1-naphthalenemethyl isothiocyanate. In all cases the derivatives of the R,S/S,R forms eluted before those of the R,R/S,S forms. Isothiocyanates may have general utility in stereoisomer separations of amines by HPLC.

Chromatography, High Pressure Liquid↗
PubMed2006

Comparison of growth inhibition profiles and mechanisms of apoptosis induction in human colon cancer cell lines by isothiocyanates and indoles from Brassicaceae.

The isothiocyanates sulforaphane and PEITC (beta-phenethyl isothiocyanate) as well as the indoles indole-3-carbinol and its condensation product 3,3'-diindolylmethane are known to inhibit cancer cell proliferation and induce apoptosis. In this study, we compared the cell growth inhibitory potential of the four compounds on the p53 wild type human colon cancer cell line 40-16 (p53(+/+)) and its p53 knockout derivative 379.2 (p53(-/-)) (both derived from HCT116). Using sulforhodamin B staining to assess cell proliferation, we found that the isothiocyanates were strongly cytotoxic, whereas the indoles inhibited cell growth in a cytostatic manner. Half-maximal inhibitory concentrations of all four compounds in both cell lines ranged from 5-15 microM after 24, 48 and 72 h of treatment. Apoptosis induction was analyzed by immunoblotting of poly(ADP-ribose)polymerase (PARP). Treatment with sulforaphane (15 microM), PEITC (10 microM), indole-3-carbinol (10 microM) and 3,3'-diindolylmethane (10 microM) induced PARP cleavage after 24 and 48 h in both 40-16 and the 379.2 cell lines, suggestive of a p53-independent mechanism of apoptosis induction. In cultured 40-16 cells, activation of caspase-9 and -7 detected by Western blotting indicated involvement of the mitochondrial pathway. We detected time- and concentration-dependent changes in protein expression of anti-apoptotic Bcl-x(L) as well as pro-apoptotic Bax and Bak proteins. Of note is that for sulforaphane only, ratios of pro- to anti-apoptotic Bcl-2 family protein levels directly correlated with apoptosis induction measured by PARP cleavage. Taken together, we demonstrated that the glucosinolate breakdown products investigated in this study have distinct profiles of cell growth inhibition, potential to induce p53-independent apoptosis and to modulate Bcl-2 family protein expression in human colon cancer cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Beta-phenylethyl and 8-methylsulphinyloctyl isothiocyanates, constituents of watercress, suppress LPS induced production of nitric oxide and prostaglandin E2 in RAW 264.7 macrophages.

Beta-phenylethyl (PEITC) and 8-methylsulphinyloctyl isothiocyanates (MSO) represent two phytochemical constituents present in watercress Rorripa nasturtium aquaticum, with known chemopreventative properties. In the present investigation, we examined whether PEITC and MSO could modulate the inflammatory response of Raw 264.7 macrophages to bacterial lipopolysaccharide (LPS) by assessment of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression. Overproduction of both nitric oxide (NO) and prostaglandins (PGE) has been associated with numerous pathological conditions including chronic inflammation and cancer. Our results demonstrate that LPS (1 microg/ml approximately 24 h) induced nitrite and prostaglandin E2 (PGE-2) synthesis in Raw 264.7 cells was attenuated by both isothiocyanates (ITCs) in a concentration-dependent manner. Both PEITC and MSO decreased (iNOS) and (COX-2) protein expression levels leading to reduced secretion of both pro-inflammatory mediators. Interestingly, the reduction in both iNOS and COX-2 expression were associated with the inactivation of nuclear factor-kappaB and stabilization of IkappaBalpha. Taken together our data gives further insight into the possible chemopreventative properties of two dietary derived isothiocyanates from watercress.

Animals↗
PubMed2006

Phenethyl isothiocyanate (PEITC) inhibits growth of ovarian cancer cells by inducing apoptosis: role of caspase and MAPK activation.

OBJECTIVE: Epithelial ovarian cancer has the highest mortality rate among gynecologic cancers. Chemotherapy is an essential component of its treatment. While isothiocyanates are known to possess chemopreventive effects against various cancers, yet little is known about their chemotherapeutic potential in ovarian cancer (OC). In the present study, we examined the antiproliferative and apoptotic effect of phenethyl isothiocyanate (PEITC), a naturally occurring isothiocyanate on OVCAR-3 cells. METHODS: Cytotoxic activity of PEITC on OVCAR-3 cells was determined using cell proliferation, apoptosis (DNA fragmentation and TUNEL assay) and caspase-activation studies. The role of PARP-1, Bax, and Bcl-2 in apoptosis was analyzed by Western blotting. Activation of JNK1/2, p38, Akt, ERK1/2, and c-Myc was examined by immunoblotting. Specific inhibitors of caspases, JNK1/2, p38, and MEK were used to corroborate these data. RESULTS: PEITC was cytotoxic to OVCAR-3 cells, and inhibited proliferation in a dose-dependent fashion (IC(50) = 23.2 microM). PEITC induced apoptosis by activating caspase-3 and -9, without capsase-8 activation. Anti-apoptotic Bcl-2 levels were suppressed while pro-apoptotic Bax levels were enhanced. PEITC suppressed activation of Akt, ERK1/2, and the expression of transcription factor c-Myc, while simultaneously activating pro-apoptotic p38 and JNK1/2. Specific inhibitors of caspase-3 and -9, JNK1/2, and p38 reversed the cytotoxic effect of PEITC. CONCLUSIONS: These findings demonstrate that PEITC exhibits cytotoxicity towards OVCAR-3 cells and induces apoptosis via caspase-9 and -3 pathways. PEITC inhibits Akt, ERK1/2 survival signaling, and c-Myc while simultaneously activating pro-apoptotic p38 and JNK1/2. Systematic preclinical and clinical trials with PEITC in ovarian cancer are indicated.

Apoptosis↗
PubMed2003

Effects of garden and water cress juices and their constituents, benzyl and phenethyl isothiocyanates, towards benzo(a)pyrene-induced DNA damage: a model study with the single cell gel electrophoresis/Hep G2 assay.

The aim of this study was to investigate the chemoprotective effects of water and garden cress juices towards benzo(a)pyrene (B(a)P)-induced DNA damage using the single cell gel electrophoresis (SCGE)/Hep G2 test system. This experimental model combines the advantages of the SCGE assay with that of human derived cells possessing inducible phase I and phase II enzymes. Treatment of Hep G2 cells with small amounts of water cress or garden cress juice (0.1-1.25 microl/ml) and B(a)P reduced the genotoxic effect of the latter in a dose-dependent manner. Contrary to the results with the juices, unexpected synergistic effects were observed with benzyl isothiocyanate (BITC, 0.6 microM), a breakdown product of glucotropaeolin contained abundantly in garden cress. Although these concentrations of BITC did not cause DNA damage per se, at higher concentrations (> or = 2.5 microM), the compound caused a pronounced dose-dependent DNA damage by itself. With phenethyl isothiocyanate (PEITC), the breakdown product of gluconasturtin contained in water cress, no synergistic effects with B(a)P were seen; however, significant induction of DNA damage was observed when the cells were exposed to the pure compound at concentrations > or = 5 microM. In experiments with (+/-)-anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE, 5.0 microM), the ultimate genotoxic metabolite of B(a)P, and the juices, only moderate protective effects were seen indicating that detoxification of BPDE is not the main mechanism behind the protective effect of the juices against B(a)P-induced DNA damage. In conclusion, our findings show that garden and water cress juices are highly protective against B(a)P-induced DNA damage in human derived cells and that their effects can not be explained by their isothiocyanate contents.

Benzo(a)pyrene↗
PubMed2003

Determination of aromatic primary amines at microg l(-1) level in environmental waters by gas chromatography-mass spectrometry involving N-allyl-n'-arylthiourea formation and their on-line pyrolysis to aryl isothiocyanates.

Derivatization of aromatic primary amines to N-allyl-N'-arylthioureas by reaction with allyl isothiocyanate and GC-MS of the derivatives, when pyrolysis to aryl isothiocyanates occurs in the heated injector, has been used to determine aromatic amines in the range 0.5-50 microg l(-1) with a correlation coefficient, r, in the range 0.9902-0.9992. The limit of detection ranged 8 to 30 ng l(-1) when 60 ml of sample were preconcentrated, after derivatization, on a styrene-divinylbenzene copolymer sorbent. The pyrolytic cleavage of sym- and unsym-diaryl or alkyl-/arylthioureas has been rationalized. The chromatography of isothiocyanates is much superior to that of aryl amines and the specific mass fragmentation permits positive identification of amines. The method has been applied to spiked drinking water, groundwater and river water samples, when the recovery ranged from 84 to 109% with RSD of 5-9%, and to detect aromatic amines formed by reductive cleavage of azo dyes in effluents when the recovery of amine was in the range 81-95% with RSD 8-15%. The method is not applicable to nitroanilines.

Amines↗
PubMed2000

A glutathione S-transferase inducer from papaya: rapid screening, identification and structure-activity relationship of isothiocyanates.

We have developed a simple system for rapid detection and measurement of glutathione S-transferase placental form (GSTP1) that detoxify polycyclic aromatic hydrocarbons using the cultured rat normal liver epithelial cell line, (RL34) cells. Survey of fruit extracts for GST inducing ability identified both papaya and avocado as significant sources. Benzyl isothiocyanate (BITC) was isolated from papaya methanol extract as a principal inducer of GST activity. Further, the GST inducing ability of a total of 20 isothiocyanates (ITCs) and their derivatives was investigated. Some ITCs showed significant induction, and BITC was one of the most potent inducers among all compounds tested in the present study. The modification of isothiocyanate group (-NCS) or introduction of substituent group to the alpha-carbon modifies GST induction. Moreover, a significant correlation (P<0.01, r=0.913) between the GST activity enrichment and GSTP1 protein induction by ITCs was observed. We also indicated that phenethyl ITC and nitrophenyl ITC, potently inducing GST activity, but not inactive benzyl isocyanate, are potential inducers of intracellular reactive oxygen intermediates (ROIs). Our system of GSTP1 induction is appropriate for the chemical research such as screening and identification of novel type of inducers as well as the structure-activity relationship studies, providing mechanistic insight into essential structural elements for GSTP1 induction.

Animals↗
PubMed2001

Investigation of the enhancement of N-nitrosomethylbenzylamine-induced esophageal tumorigenesis by 6-phenylhexyl isothiocyanate.

Previous studies in our laboratory have shown that 6-phenylhexyl isothiocyanate (PHITC), enhances N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in F344 rats while the shorter chain analogs, phenylethyl isothiocyanate (PEITC), and 3-phenylpropyl isothiocyanate (PPITC), inhibit NMBA-induced esophageal tumorigenesis. To test the hypothesis that PHITC influences the promotional stage of esophageal tumorigenesis, groups of 22-27 rats were dosed with vehicle or NMBA three times a week for 5 week, and fed a modified AIN-76A diet containing PHITC at concentrations of 0.0, 1.0, and 2.5 micromol/g. At the 25th week, the rats were killed, esophagi harvested and tumors counted. In the groups that received NMBA+PHITC, apparent but statistically insignificant increases in tumor multiplicity of 32 and 42% were found in comparison to rats treated with NMBA alone. A higher frequency of dysplastic lesions was found in rats treated with NMBA+2.5 micromol/g PHITC (71%) when compared to rats treated with NMBA only (12%). To test whether PHITC increased cellular proliferation, we evaluated proliferating cell nuclear antigen (PCNA) expression by immunohistochemistry. While there were no significant increases in PCNA staining in rats treated with NMBA+PHITC compared to rats treated with NMBA only, rats treated with PHITC only had a significantly higher PCNA index compared to untreated controls. Expression of cyclin D1, another biomarker of proliferation, was analyzed by semi-quantitative reverse transcription-polymerase chain reaction. There were no significant increases in cyclin D1 expression in groups treated with NMBA+PHITC compared to the group treated with NMBA only. Thus, while the data suggest a promotional effect by PHITC as manifested by a significant increase in dysplastic leukoplakia by the high dose of PHITC and an increase in the PCNA index by PHITC alone, PHITC does not appear to have a significant effect on esophageal cell proliferation.

Animals↗
PubMed2000

Advantageous attributes of larval whitefringed weevil, Naupactus leucoloma (Coleoptera: Curculionidae) for bioassaying soil fumigants, and responses to pure and plant-derived isothiocyanates.

First instars of the soil-inhabiting whitefringed weevil, Naupactus leucoloma (Boheman), are a particularly good bioassay model for assessing volatile soil fumigants and biofumigants. Eggs are readily obtained and can be stored for long periods with larvae hatched on demand and the first instar is non-feeding, surviving without food or shelter. Longevity varies with temperature, but readily accommodates the period required to conduct bioassays without appreciable mortality of untreated controls. In vitro bioassays of pure methyl isothiocyanate, the active ingredient from metham sodium soil fumigant, and the less volatile 2-phenylethyl isothiocyanate, sensitively detected differences in toxicity and effects of temperature. Bioassay of volatiles emitted from hydrolysed tissue of various isothiocyanate-producing Brassica plants revealed widely varying toxicity effects, indicating that bioassays with N. leucoloma are a sensitive and relevant indicator of the potential of different plants for biofumigation of soil-borne pest organisms.

Animals↗
PubMed1993

Time resolution of fluorescence changes observed in titrations of fluorescein 5'-isothiocyanate-modified Na,K-ATPase with monovalent cations.

Equilibrium fluorometric titrations of fluorescein 5'-isothiocyanate-modified Na,K-ATPase with cations have usually been interpreted by assuming that an enhancement reports the conformational change from E2 to E1. We report time resolution of the fluorescence change into three phases when fluorophore-modified enzyme is mixed with the chloride salt of either sodium or choline in a stopped-flow instrument. The first phase is an increase in fluorescence within the dead time of the instrument that is also observed when fluorescein 5'-isothiocyanate (FITC) reacted with lysine is substituted for fluorescein-labeled enzyme. The other two phases occur on millisecond and second time scales. Three phases are also observed when fluorophore-modified enzyme preincubated in KCl is mixed with NaCl, but in this case the slowest phase is absent when choline chloride replaces NaCl. The two faster effects in phases one and two can be eliminated either by controlling the ionic strength or by anti-fluorescein antibody. Labeling the enzyme with fluorescein 5'-isothiocyanate in the presence of its substrate, adenosine 5'-triphosphate, practically eliminates the slowest effect. These results demonstrate that fluorescein reports three events that occur on three different time scales. The fastest phase reports the ionic strength jump of unbound fluorophore. The intermediate phase reports the ionic strength jump of fluorescein at "antibody-accessible" sites [Abbott, A. J., Amler, E., & Ball, W. J., Jr. (1991) Biochemistry 30, 1692-1701]. Only the slowest phase reports the enzyme conformational change implicated in transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Effect of methyl jasmonate on phenolics, isothiocyanate, and metabolic enzymes in radish sprout (Raphanus sativus L.).

The effect of spraying exogenous plant hormone methyl jasmonate (MeJA) upon radish sprout (Raphanus sativus L.) was investigated in aspects of total phenolic content (TPC), isothiocyanate content, antioxidant activity of the radish extract, and enzymatic activities of phenylalanine ammonia lyase (PAL) and myrosinase. The MeJA treatment significantly increased the TPC that resulted in the increased DPPH* (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging capacity. In addition, the PAL activity also increased by 60% at 24 h after MeJA treatment. However, the same treatment decreased the amount of 4-methylthio-3-butenylisothiocyanate (MTBITC), a major isothiocyanate in radish sprout and the activity of myrosinase, an enzyme related to produce isothiocyanates.

Acetates↗
PubMed1999

High-performance liquid phase separation of glycosides. 5. Determination of individual glucosinolates in cabbage and rapeseed by laser-induced fluorescene capillary electrophoresis via the enzymatically released isothiocyanate aglycon.

A capillary electrophoresis (CE) method was developed for the profiling and determination of individual glucosinolates (GSs) via their isothiocyanate degradation products upon myrosinase digestion. The resulting isothiocyanates, the structures of which are reflective of the parent GS's, were then converted to their corresponding amines via base hydrolysis or reaction with 1, 2-benzenedithiol. Subsequently, the amines were fluorescently labeled to allow their sensitive detection by laser-induced fluorescence (LIF). The CE method involved the use of in situ charged micelles for the separation of isothiocyanates and their corresponding fluorescently labeled amines by micellar electrokinetic capillary chromatography (MECC). The term "in situ charged micelles" refers to micelles formed by complexing the polar hydroxyl groups of glycosidic surfactants with borate. The MECC method with on-column LIF detection was applied to the determination of GSs in white cabbage, rapeseed leaves, and rapeseed roots.

Brassica↗