An analysis of the content changes in free and combinative forms of organic selenium in radish sprouts cultivated with solutions of selenoamino acids

Selenium (Se) is critical for human health, but human intake of Se is often inadequate. Organic forms of dietary Se are considered safe and more bioavailable than inorganic forms. Along with a generally high nutritional value, sprouts are sensitive to Se treatment. This study used selenomethionine and methylselenocysteine solutions to cultivate Se-enriched sprouts under an optimized hydroponic condition. Content change and transformations of the selenoamino acids were analyzed by a developed HPLC-ESI-MS/MS method. Uptake of both selenomethionine and methylselenocysteine was dose-dependent and involved active transport and passive diffusion, as demonstrated by the respiratory and aquaporin inhibition assays. Passive diffusion played a dominant role. Free methylselenocysteine was the predominant form in samples. Selenomethionine and methylselenocysteine were capable of mutual transformation. Moreover, the selenoprotein generation was associated with the increasing Se concentration of the culture solutions. The results provided scientific references for the efficient utilization of organic Se in sprouts.