Brassica vegetables as sources of epithionitriles: Novel secondary products formed during cooking
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.
Hanschen, F. S., Kaufmann, M., Kupke, F., Hackl, T., Kroh, L. W., Rohn, S., Schreiner, M. 2018. Brassica vegetables as sources of epithionitriles: Novel secondary products formed during cooking. Food Chemistry, 245, 564-569.