We previously found that sulfur fumigation, a commonly used controversial method for the post-harvest handling of ginger, induces the generation of a compound in ginger, which was speculated to be a sulfur-containing derivative of 6-shogaol based on its mass data. However, the chemical and biological properties of the compound remain unknown. As a follow-up study, here we report the chemical structure, systemic exposure, and anticancer activity of the compound. Chromatographic separation, nuclear magnetic resonance analysis, and chemical synthesis structurally elucidated the compound as 6-gingesulfonic acid. Pharmacokinetics in rats found that 6-gingesulfonic acid was more slowly absorbed and eliminated, with more prototypes existing in the blood than 6-shogaol. Metabolism profiling indicated that the two compounds produced qualitatively and quantitatively different metabolites. It was further found that 6-gingesulfonic acid exerted significantly weaker antiproliferative activity on tumor cells than 6-shogaol. The data provide chemical and biological evidence that sulfur fumigation may impair the healthcare functions of ginger.

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Dioscoreae Rhizoma (Chinese yam; derived from the rhizome of Dioscorea opposita Thunb.) (DR), commonly consumed as a food or supplement, is often sulfur-fumigated during post-harvest handling, but it remains largely unknown if and how sulfur fumigation impacts the chemistry of DR. In this study, we report the impact of sulfur fumigation on the chemical profile of DR and then the molecular and cellular mechanisms potentially involved in the chemical variations induced by sulfur fumigation. The results show that sulfur fumigation significantly and specifically changed the small metabolites (molecular weight lower than 1000 Da) and polysaccharides of DR at both qualitative and quantitative levels. Multifaceted molecular and cellular mechanisms involving chemical transformations (e.g., acidic hydrolysis, sulfonation, and esterification) and histological damage were found to be responsible for the chemical variations in sulfur-fumigated DR (S-DR). The research outcomes provide a chemical basis for further comprehensive and in-depth safety and functional evaluations of sulfur-fumigated DR.