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Komarova, E. L.; Толкачев, О. Н.

doi:10.1023/a:1014050926916

Cited by 76 publications

(36 citation statements)

References 57 publications

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“…The chromatographic method enables the [7]. For evaluation of extraction efficiency, both extraction solvents (acetonitrile/water with and without adding ammonium carbonate) were compared by extracting a sclerotia-contaminated rye flour.…”

Section: Methods Developmentmentioning

confidence: 99%

“…The (R)-configured EAs (suffix: -in) show high toxicity, whereas the (S)-configured EAs (suffix: -inin) are biologically inactive [5,6]. Bidirectional isomerization occurs under both acidic and alkaline conditions [7]. Therefore, both epimers have to be taken into consideration in sample analysis, making epimer-specific analytical techniques very important.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, a proper sample isolation protocol is crucial in allowing the measurement without further isomerization during sample preparation. In addition to epimerization, other degradation pathways for EAs are known [7].…”

Section: Introductionmentioning

confidence: 99%

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Degradation and epimerization of ergot alkaloids after baking and in vitro digestion

et al. 2012

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The degradation and epimerization of ergot alkaloids (EAs) in rye flour were investigated after baking cookies and subsequently subjecting them to an in vitro digestion model. Different steps of digestion were analyzed using salivary, gastric, and duodenal juices. The degradation and bidirectional conversion of the toxicologically relevant (R)-epimers and the biologically inactive (S)-epimers for seven pairs of EAs were determined by a HPLC method coupled with fluorescence detection. Baking cookies resulted in degradation of EAs (2-30 %) and a shift in the epimeric ratio toward the (S)-epimer for all EAs. The applied digestion model led to a selective toxification of ergotamine and ergosine, two ergotamine-type EAs. The initial percentage of the toxic (R)-epimer in relation to the total toxin content was considerably increased after digestion of cookies. Ergotamine and ergosine increased from 32 to 51 % and 35 to 55 %, respectively. In contrast, EAs of the ergotoxine type (ergocornine, α- and β-ergocryptine, and ergocristine) showed an epimeric shift toward their biologically inactive (S)-epimers. Further experiments indicated that the selective epimerization of ergotamine EAs occurs in the duodenal juice only. These results demonstrate that toxification of EAs in the intestinal tract should be taken into consideration.

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Section: Methods Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Degradation and epimerization of ergot alkaloids after baking and in vitro digestion

et al. 2012

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“…This suggests that, for the ergot alkaloids examined, the products from the photoreactor were less fluorescent than the native alkaloids. This is not altogether surprising, as ergot alkaloids have been reported to degrade upon UV irradiation (Komarova and Tolkachev 2001). Therefore, unlike the case with PAX, PEN-A, and VER, the photoreactor would not be expected to enhance the detection of these compounds.…”

Section: Resultsmentioning

confidence: 99%

Photoreaction of indole-containing mycotoxins to fluorescent products

Maragos

2009

Mycotox Res

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Photochemical reaction of the non-fluorescent mycotoxin cyclopiazonic acid (CPA) to fluorescent products was recently reported. Because CPA contains an indole moiety, believed to contribute to the fluorescence, it was of interest to determine whether the effect might be more generally applicable to indole-containing mycotoxins. Three indole-containing tremorgens (penitrem A, paxilline, verruculogen) that have not previously been reported to be fluorescent were rendered fluorescent by exposure to ultraviolet light in a photoreactor. Naturally fluorescent ergot alkaloids, which also contain an indole-moiety, exhibited a diminished response after exposure. This suggests that the phenomenon may be most useful for detection of indole-containing tremorgens that are non-fluorescent, rather than for the enhancement of materials that are already fluorescent, such as the ergot alkaloids. The extent to which fluorescence enhancement was seen was strongly influenced by the reaction environment, in particular the solvent used and whether cyclodextrins were present. In an HPLC format, placement of the photoreactor post-column allowed for the fluorescence detection of penitrem A, paxilline, and verruculogen. The ability to photoreact indole-containing tremorgens and detect them by fluorescence may open up new avenues for detection of these mycotoxins alone or in combination.

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“…1). 1, 2 This class of highly pharmocologically active compounds is found in largest amounts in the Clavicipitaceae. These include various ergot fungi in the genus Claviceps , and several fungi in the genera Epichloë / Neotyphodium , of which the latter two live as endophytic symbionts in grasses 2.…”

mentioning

confidence: 99%

Competitive Decay Pathways of the Radical Ions Formed by Photoinduced Electron Transfer between Quinones and 4,4′-Dimethoxydiphenylmethane in Acetonitrile

Giacco¹,

Baciocchi²,

Lanzalunga³

et al. 2001

Chem. Eur. J.

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The reactivity of the cation radical of (4-MeOC6H4)2CH2 photosensitized by 1,4-benzoquinone (BQ), 2,5-dichloro-1,4-benzoquinone (Cl2BQ), and tetrachloro-1,4-benzoquinone (chloranil, CA) was investigated in acetonitrile. The main photoreaction products obtained by steady-state irradiation were identified to be: (4-MeOC6H4)2-CHOC6H4OH, sensitized by BQ; (4-MeOC6H4)2CHCl, sensitized by Cl2BQ; (4-MeOC6H4)2CHOH, sensitized by CA. The mechanism of their formation was investigated by nanosecond laser flash photolysis that allowed transient species (radical ions, neutral radicals, and ions) to be detected and characterized in terms of absorption spectra, formation quantum yields, and decay rate constants. For all systems, the interaction between the triplet quinone (Q) and (4-MeOC6H4)2CH2 produced the corresponding radical ions (quantum yield phi > or = 0.72) which mainly decay by back electron transfer processes. Less efficient reaction routes for the radical ions Q*- and (4-MeOC6H4)2CH2*+ were also: i) the proton-transfer process with the formation of the radical (4-MeOC6H4)2CH* by use of Cl2BQ; ii) the hydrogen-transfer process with the formation of the cation (4-MeOC6H4)2CH+ in the case of CA. Instead. BQ sensitized a much higher yield of BOH* and (4-MeOC6H4)2CH*, mainly by the direct interaction of triplet BQ with (4-MeOC6H4)2CH2. It was also shown that the presence of salts decreases significantly the rate of the back electron transfer process and enhances the quantum yields of formation of the neutral radicals and ions when Cl2BQ and CA are used, respectively. The behavior of BQ*-, Cl2BQ*-, and CA*- appears to be mainly determined by the Mulliken charges on the oxygen atom obtained from quantum mechanical calculations with the model B3LYP/6-311G(d,p). Spin densities seem to be much less important.

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Cited by 76 publications

References 57 publications

Degradation and epimerization of ergot alkaloids after baking and in vitro digestion

Degradation and epimerization of ergot alkaloids after baking and in vitro digestion

Photoreaction of indole-containing mycotoxins to fluorescent products

Competitive Decay Pathways of the Radical Ions Formed by Photoinduced Electron Transfer between Quinones and 4,4′-Dimethoxydiphenylmethane in Acetonitrile

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