Effects and mechanism of metal ions on the stability of glucosinolates in aqueous solution

Glucosinolates (GLs) are important precursors of anticancer isothiocyanates in cruciferous plants. However, GLs in aqueous solution have been found to decompose under certain conditions, and the effect of metal ions remains unclear. In this study, high-purity glucoraphanin and glucoraphenin were used to explore the effects of metal ions with thermal treatment. The degree of GLs decomposition was affected by the type and concentration of metal ions, temperature, and duration of heating. Fe 3+ (1 mM) was found to cause the decomposition of 78.1 % of glucoraphanin and 94.7 % of glucoraphenin in 12 h at 100 °C, while Cu 2+ completely decomposed both GLs. The decomposition products were all the corresponding nitriles, and decomposition dynamic curves were first-order. In addition to accelerating hydrolysis, metal ions may promote the generation of nitriles as catalysts. The exploration of GLs decomposition could help to adopt more effective methods to avoid the formation of toxic compounds.