scholarly journals Organic thiocyanates - glucosinolate enzymatic degradation products or artefacts of the isolation procedure?

2020 ◽  
Vol 18 (2) ◽  
pp. 77-87
Author(s):  
Milica Todorovska-Rasic ◽  
Niko Radulovic
Keyword(s):  
Aqueous Medium ◽  
Enzymatic Degradation ◽  
Degradation Products ◽  
Isolation Procedure ◽  
Present Review ◽  
Gas Chromatograph ◽  
Cationic Species ◽  
Hydrolysis Products ◽  
Enzymatic Formation ◽  
Heterolytic Dissociation

Glucosinolates are abundant in plants of the order Brassicales, and they are degraded by myrosinases into various organic breakdown products: isothiocyanates, thiocyanates, nitriles, etc., depending on their structure, conditions of hydrolysis, the presence of certain protein cofactors. Their most common hydrolysis products are isothiocyanates, while simple nitriles, epithionitriles, and thiocyanates are produced occasionally. Organic thiocyanates are described from a very limited number of Brassicales taxa. Up to now benzyl, (4-hydroxyphenyl)methyl, (4-methoxyphenyl)methyl, 4- methylthiobutyl, and allyl thiocyanates were reported as products of glucosinolates autolysis. The present review summarizes the knowledge on the mechanism of organic thiocyanate formation from the corresponding thioglucosides. The enzymatic formation of organic thiocyanates is believed to be enabled by thiocyanate-forming protein (TFP), but they could be formed via metabolic routes that do not involve TFP. All of the reported thiocyanates are produced from stable (carbo)cationic species that allow an isomerization of an isothiocyanate to thiocyanate, and vice versa. Although the possibility that thiocyanates can be biosynthesized in plats under certain conditions cannot be dismissed, allyl thiocyanate can be a thermal isomerization artefact of the original isothiocyanate that is formed in the heated zones of the gas chromatograph, while other thiocyanates could form in an aqueous medium via heterolytic dissociation to ambident nucleophilic SCN- and its recapture. One should always be aware of this analytical shortcoming when concluding on the presence and quantity of these specific (iso)thiocyanantes in the analyzed sample.

Fenton degradation of Cartap hydrochloride: identification of the main intermediates and the degradation pathway

2015 ◽  
Vol 72 (7) ◽  
pp. 1198-1205 ◽  
Author(s):  
Kaixun Tian ◽  
Cuixiang Ming ◽  
Youzhi Dai ◽  
Kouassi Marius Honore Ake
Keyword(s):  
Aqueous Medium ◽  
Flue Gas ◽  
High Performance ◽  
Oxygen Demand ◽  
Nitrogen Monoxide ◽  
Degradation Pathway ◽  
Gas Chromatograph ◽  
Gas Analyzer ◽  
Fenton System ◽  
Long Chain

The advanced oxidation of Cartap hydrochloride (Cartap) promoted by the Fenton system in an aqueous medium was investigated. Based on total organic carbon, chemical oxygen demand and high-performance liquid chromatography, the oxidation of Cartap is quite efficient by the Fenton system. Its long chain is easily destroyed, but the reaction does not proceed to complete mineralization. Ion chromatography detection indicated the formation of acetic acid, propionic acid, formic acid, nitrous acid and sulfuric acid in the reaction mixtures. Further evidence of nitrogen monoxide and sulfur dioxide formation was obtained by using a flue gas analyzer. Monitoring by gas chromatograph-mass spectrometer demonstrated the formation of oxalic acid, ethanol, carbon dioxide, and l-alanine ethylamide. Based on these experimental results, plausible degradation pathways for Cartap mineralization in an aqueous medium by the Fenton system are proposed.

Identification of tuliposide G, a novel glucoside ester-type tuliposide, and its distribution in tulip

2020 ◽  
Vol 75 (3-4) ◽  
pp. 75-86
Author(s):  
Taiji Nomura ◽  
Yasuo Kato
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Secondary Metabolites ◽  
High Performance ◽  
Enzymatic Degradation ◽  
Degradation Products ◽  
Tulipa Gesneriana ◽  
Tissue Extracts ◽  
Spectroscopic Analyses ◽  
Chemotaxonomic Marker

AbstractTuliposides (Pos) are major defensive secondary metabolites in tulip (genus Tulipa), having 4-hydroxy-2-methylenebutanoyl and/or (3S)-3,4-dihydroxy-2-methylenebutanoyl groups at the C-1 and/or C-6 positions of d-glucose. The acyl group at the C-6 position is converted to antimicrobial lactones, tulipalins, by tuliposide-converting enzymes (TCEs). In the course of a survey of tulip tissue extracts to identify novel Pos, we found a minute high-performance liquid chromatography peak that disappeared following the action of a TCE, and whose retention time differed from those of known Pos. Spectroscopic analyses of the purified compound, as well as its enzymatic degradation products, revealed its structure as 5″-O-(6-O-(4′-hydroxy-2′-methylenebutanoyl))-β-d-glucopyranosyl-(2″R)-2″-hydroxymethyl-4″-butyrolactone, which is a novel glucoside ester-type Pos. We gave this compound the trivial name ‘tuliposide G’ (PosG). PosG accumulated in bulbs, at markedly lower levels than 6-PosA (the major Pos in bulbs), but was not found in any other tissues. Quantification of PosG in bulbs of 52 types of tulip, including 30 cultivars (Tulipa gesneriana) and 22 wild Tulipa spp., resulted in the detection of PosG in 28 cultivars, while PosG was present only in three wild species belonging to the subgenus Tulipa, the same subgenus to which tulip cultivars belong, suggesting the potential usefulness of PosG as a chemotaxonomic marker in tulip.

scholarly journals Fungal Sensitivity to and Enzymatic Degradation of the Phytoanticipin α-Tomatine

1998 ◽  
Vol 88 (2) ◽  
pp. 137-143 ◽  
Author(s):  
Robert W. Sandrock ◽  
Hans D. VanEtten
Keyword(s):  
Phytophthora Infestans ◽  
Effective Dose ◽  
Verticillium Dahliae ◽  
Strong Correlation ◽  
Fungal Pathogens ◽  
Enzymatic Degradation ◽  
Degradation Products ◽  
Solanum Species ◽  
Tolerance Mechanisms ◽  
Multiple Tolerance

α-Tomatine, synthesized by Lycopersicon and some Solanum species, is toxic to a broad range of fungi, presumably because it binds to 3β-hydroxy sterols in fungal membranes. Several fungal pathogens of tomato have previously been shown to be tolerant of this glycoalkaloid and to possess enzymes thought to be involved in its detoxification. In the current study, 23 fungal strains were examined for their ability to degrade α-tomatine and for their sensitivity to this compound and two breakdown products, β2-tomatine and tomatidine. Both saprophytes and all five non-pathogens of tomato tested were sensitive, while all but two tomato pathogens (Stemphylium solani and Verticillium dahliae) were tolerant of α-to-matine (50% effective dose > 300 μM). Except for an isolate of Botrytis cinerea isolated from grape, no degradation products were detected when saprophytes and nonpathogens were grown in the presence of α-tomatine. All tomato pathogens except Phytophthora infestans and Pythium aphani-dermatum degraded α-tomatine. There was a strong correlation between tolerance to α-tomatine, the ability to degrade this compound, and pathogenicity on tomato. However, while β2-tomatine and tomatidine were less toxic to most tomato pathogens, these breakdown products were inhibitory to some of the saprophytes and nonpathogens of tomato, suggesting that tomato pathogens may have multiple tolerance mechanisms to α-tomatine.

Brown rot gene expression and regulation in acetylated and furfurylated wood: a complex picture

Holzforschung ◽  
2020 ◽  
Vol 74 (4) ◽  
pp. 391-399 ◽  
Author(s):  
Rebecka Ringman ◽  
Annica Pilgård ◽  
Klaus Richter
Keyword(s):  
Enzymatic Degradation ◽  
Degradation Products ◽  
Expression Patterns ◽  
Alcohol Oxidase ◽  
Untreated Wood ◽  
Brown Rot ◽  
Degradation Process ◽  
Quinone Reductase ◽  
Complex Picture ◽  
Modified Wood

AbstractThe aim of this study was to investigate Rhodonia placenta expression patterns of genes involved in the depolymerisation during the non-enzymatic phase in acetylated (WAc) and furfurylated wood (WFA). During the 98-day-long exposure, WAc [22.6% weight per cent gain (WPG) on average] and WFA (69% WPG on average) lost no more than 3% mass while the untreated wood (WUn) reached 41% mass loss (ML) in 55 days. Expression of six genes putatively involved in the non-enzymatic degradation process were investigated. In conclusion, expression levels of alcohol oxidase Ppl118723 (AlOx1) and laccase Ppl111314 (Lac) were significantly higher in the modified wood materials (WMod) than in WUn, which is in accordance with previous results and may be explained by the absence of the degradation products that have been proposed to down-regulate the non-enzymatic degradation process. However, copper radical oxidase Ppl156703 (CRO1) and a putative quinate transporter Ppl44553 (PQT) were expressed at significantly lower levels in WMod than in WUn while quinone reductase Ppl124517 (QRD) and glucose oxidase Ppl108489 (GOx) were expressed at similar levels as in WUn. These results suggest that gene regulation in WMod is more complex than a general up-regulation of genes involved in the non-enzymatic degradation phase.

scholarly journals STUDIES ON ANTIGENICITY

1964 ◽  
Vol 120 (5) ◽  
pp. 955-965 ◽  
Author(s):  
Bernard B. Levine ◽  
Baruj Benacerraf
Keyword(s):  
Immune Responses ◽  
Guinea Pigs ◽  
Enzymatic Degradation ◽  
Degradation Products ◽  
Antigenic Determinants ◽  
Low Molecular Weight ◽  
Aqueous Extracts ◽  
Molecular Fragments ◽  
In Vivo Degradation

The enzymatic degradation of fluorescein conjugates of poly-L-lysine, poly-D-lysine, and exhaustively succinylated poly-L-lysine by aqueous extracts of spleens from "responder" (guinea pigs which can develop immune responses to hapten-poly-L-lysine conjugates) and "non-responder" guinea pigs was investigated. The in vivo degradation of H3-tagged dinitrophenyl conjugates of these synthetic polyamino acids was also studied by measuring urinary excretion of radioactive low molecular weight degradation products of these conjugates after their intraperitoneal injection. It was found that both responder and non-responder guinea pigs can degrade succinylated and unsuccinylated poly-L-lysine conjugates into small molecular fragments, but they cannot degrade hapten-poly-D-lysine conjugates. These studies demonstrate that in addition to the known requirements for antigenicity of macromolecules, i.e. the presence of antigenic determinants, and their capacity to be degraded by immunological tissues, the resulting degradation products must undergo certain additional, as yet unidentified, specific metabolic steps in order to induce an immune response.

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