In situ observation of the generation of isothiocyanates from sinigrin in horseradish and wasabi

Sulfur K-edge X-ray absorption spectroscopy has been used to determine the chemical identity of the sulfur-containing species in horseradish (Armoraci a lapthifolia) and wasabi (Wasabia japonica) in situ, before and after cell disruption. The major sulfur-containing species in the intact root is sini grin (1-thio-beta -D-glucopyranose 1-N-(sulfoxy)-3-buteneimidate) and relat ed congeners. Disrupting the cells by applying local pressure allowed the c onversion of the sulfur moieties in sinigrin to isothiocyanates and sulfate in approximately equimolar amounts. In contrast to previous suggestions, n o detectable thiocyanates were formed, but an unusual thio intermediate may have been identified for the first time. (C) 2001 Elsevier Science B.V. Al l rights reserved.