Synthesis of novel organic selenium compounds and speciation of their metabolites in biofortified kale sprouts

Sprouts enriched with selenium offer increased nutritional value and chemopreventive properties raising interest in their contribution to the human diet. The effect of selenium depends on its concentration and the chemical forms. The aims of this study were: to synthesize several novel organic selenium compounds (selenoesters), to examine how effectively they can deliver selenium to Brassica sprouts, and investigate their metabolism in sprouts. We revealed that selenium content in the fortified sprouts was several orders of magnitude higher than in the unfortified ones. There were significant differences between doses of selenium delivered to sprouts by different selenium compounds. A small percentage of supplemented selenium (<10%) was incorporated into the sprouts as seleno-L-methionine, Se(IV) and Se-methylselenocysteine, while several other low molecular weight selenium species were also identified, in different proportions, depending on the compound used in the fortification procedure. In conclusion: novel selenorganic compounds were successfully applied to fortify kale sprouts in selenium. The detection, screening, and characterization (including structure elucidation) of their low molecular weight metabolites and derivatives have previously been unreported in Brassica genus.