The major glucosinolate hydrolysis product in rocket (Eruca sativa L.), sativin, is 1,3-thiazepane-2-thione: Elucidation of structure, bioactivity, and stability compared to other rocket isothiocyanates

•The major glucosinolate hydrolysis product from rocket was identified by NMR.•This product from 4-mercaptobutyl glucosinolate is 1,3-thiazepane-2-thione.•This hydrolysis product has a 7-membered ring structure.•Stability of 1,3-thiazepane-2-thione during thermal heat treatments was evaluated.•1,3-T...

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Bibliographic Details
Published in:Food chemistry 2018-09, Vol.261, p.57-65
Main Authors: Fechner, Jana, Kaufmann, Martin, Herz, Corinna, Eisenschmidt, Daniela, Lamy, Evelyn, Kroh, Lothar W., Hanschen, Franziska S.
Format: Article
Language:English
Subjects:
1,3-Thiazepane-2-thione
4-Mercaptobutyl isothiocyanate
Brassicaceae - chemistry
Cooking
Cyclization
Drug Stability
Glucosinolates
Glucosinolates - chemistry
Hydrolysis
Isothiocyanates - chemistry
Nuclear magnetic resonance (NMR)
Reactivity
Rocket
Thiones - chemistry
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Summary:•The major glucosinolate hydrolysis product from rocket was identified by NMR.•This product from 4-mercaptobutyl glucosinolate is 1,3-thiazepane-2-thione.•This hydrolysis product has a 7-membered ring structure.•Stability of 1,3-thiazepane-2-thione during thermal heat treatments was evaluated.•1,3-Thiazepane-2-thione is stable compared to isothiocyanates. Rocket is rich in glucosinolates and valued for its hot and spicy taste. Here we report the structure elucidation, bioactivity, and stability of the mainly formed glucosinolate hydrolysis product, namely sativin, which was formerly thought to be 4-mercaptobutyl isothiocyanate. However, by NMR characterization we revealed that sativin is in fact 1,3-thiazepane-2-thione, a tautomer of 4-mercaptobutyl isothiocyanate with 7-membered ring structure and so far unknown. This finding was further substantiated by conformation sampling using molecular modeling and total enthalpy calculation with density functional theory. During aqueous heat treatment sativin in general was quite stable, while the isothiocyanates erucin and sulforaphane were labile, having half-lives of 132 min and 56 min (pH 5, 100 °C), respectively. Moreover, using a WST-1 assay, we found that sativin did not reduce cell viability of HepG2 cells in a range of 0.3–30 µM, and, therefore, exhibited no cytotoxic effects in this cell line.
ISSN:0308-8146
1873-7072
DOI:10.1016/j.foodchem.2018.04.023