Structural Elucidation and Storage Stability of Novel Dietary Sulfur Compounds from Radish

Radishes (Raphanus sativus L.) have attracted interest as functional foods containing various bioactive components. Among them, sulforaphane (SFN), an isothiocyanate compound, is known for its potent antioxidant and anticancer properties. This study aimed to extract, purify, and identify SFN and SFN-derived compound X (SFN-DX), a dietary sulfur-containing bioactive compound, from freeze-dried radishes. High-performance liquid chromatography analysis revealed that the freeze-dried radish extract contained 13.262 mg/g SFN-DX. A major peak was detected with a f of 12.713 min, closely matching that of the SFN standard (RT = 12.883 min). SFN-DX was subsequently isolated with 99% purity through preparative liquid chromatography. Structural elucidation confirmed that SFN-DX is a derivative of SFN and shares characteristic features with isothiocyanates. The storage stability of purified SFN-DX was evaluated under various temperatures (-18 °C, 4 °C, 20 °C, and 40 °C) and storage durations (1 week and 1 month). A significant reduction in compound purity was observed at elevated temperatures and during prolonged storage. Accordingly, -18 °C was identified as the optimal storage temperature for preserving the stability of SFN-DX. Collectively, these findings provide a scientific basis for the efficient extraction, structural analysis, and storage of dietary sulfur-containing compounds derived from radishes.