Instability and Structural Change of 4-Methylsulfinyl-3-butenyl Isothiocyanate in the Hydrolytic Process

Sulforaphene (4-methylsulfinyl-3-butenyl isothiocyanate), which has significant chemopreventive activities, is an important phytochemical ingredient produced by myrosinase hydrolysis of glucoraphenin (4-methylsulfinyl-3-butenyl glucosinolate) found in radish seeds. In this research, we found that sulforaphene was unstable and converted rapidly to a water-soluble degradation product in the hydrolytic process. The degradation product was successfully purified by preparative high-performance liquid chromatography on a C18 column using 10% methanol in water as the mobile phase. On the basis of MS and NMR spectroscopy data, the degradation product was identified to be 6-[(methylsulfinyl)methyl]-1,3-thiazinan-2-thione. The degradation pathway of sulforaphene was proposed in our study. Furthermore, low pH and metal ions were also found to have an effective inhibition to the degradation reaction of sulforaphene. Through adjusting the pH value of the system or adding metal ions after the content of sulforaphene has reached its maximum, the yield of sulforaphene increased significantly compared with that of the control.