Brassica vegetables as sources of epithionitriles: Novel secondary products formed during cooking. (15th April 2018) - Hanschen, Franziska S.
Highlights: Epithionitriles are major hydrolysis products from Brassica vegetables. Reactivity of three Brassica epithionitriles was investigated. Cooking degrades especially 1-cyano-2, 3-epithiopropane (CETP) from white cabbage. CETP degrades to 2-aminothiophene and 1, 4-dithiane-2, 5-diacetonitrile. Three novel compounds were identified using NMR. Abstract: The epithionitriles, 1-cyano-2, 3-epithiopropane, in particular, and 1-cyano-3, 4-epithiobutane, are important, but yet underestimated glucosinolate hydrolysis products that are released instead of the cancer preventative isothiocyanates in Brassica vegetables, such as cabbage, broccoli, or pak choi. Here, we characterized the reactivity of 1-cyano-2, 3-epithiopropane under aqueous heat treatment conditions and compared our findings to those of the related epithionitriles 1-cyano-3, 4-epithiobutane and 1-cyano-4, 5-epithiopentane. In contrast to the other epithionitriles, 1-cyano-2, 3-epithiopropane is highly reactive. As a result, 2-aminothiophene and dimeric 1, 4-dithiane-2, 5-diacetonitrile were identified as main products and a reaction mechanism is proposed. Formation of 2-aminothiophene was also observed in cooked white cabbage samples. Moreover, three novel compounds were identified as derivatives of the related epithionitriles. The results imply that apart from isothiocyanates, process-derived compounds should be considered in regards to cancer preventative Brassica vegetable related bioactivity.