Abstract (eng)
Isothiocyanates (ITCs), also known as mustard oils, are breakdown products of glucosinolates (GLs) as they are found in wasabi, lat. Eutrema japonicum, but also in many other Brassicaceae (cruciferous plants). The ITCs formed under the action of the enzyme myrosinase serve as protection against predators and pathogens. They are of interest to humans because of their antioxidant, anti-inflammatory, antimicrobial and anti-cancer effects. Wasabi has already been examined in various scientific papers and its ingredients have been quantified. Here, the ITCs in E. japonicum have been quantified in the form of their n-acetylcysteine (NAC) derivatives using supercritical liquid chromatography (SFC). A UHPSFC system (UPC²) was used, which enabled the separation with supercritical CO2 and methanol as the mobile phase. For detection a photodiode array and a mass detector were used. The derivatization with NAC should make the ITCs easier to handle and facilitate their detection, especially using a mass detector. For this purpose, the UPC² method was optimized and the most important ITC-NAC derivatives were semi-sythesized as standards. These were used to generate calibration functions to test whether an indirect quantification of ITCs in wasabi materials was possible. For this purpose, fresh ITC extracts were obtained from the different organs of E. japonicum, derivatized to ITC-NACs. In this way the most important ITCs were quantified in the form of their NAC derivatives. In addition, as a comparison method, the total ITC content was determined by derivatization using benzene-1,2-dithiol and detection with a UV-Vis spectrometer.