Growth characteristics and selenium status changes of yeast cells with inorganic and organic selenium supplementation: selenium, a chemopreventive agent.

We attempted to determine the level and form of selenium (Se) that yielded the maximum Se status of yeast cells, for their evaluation as a source of Se for chemopreventive action. The influence of various Se concentrations from organic (selenomethionine) and inorganic (sodium selenite) Se compounds on growth pattern and cell viability and the alterations in the antioxidant enzyme system of yeast were evaluated. A continuous decrease in cell and colony-forming units counts was observed with increasing concentrations of Se from either source. Increasing Se status of yeast cells was found with increasing concentrations of Se with both forms, with much greater uptake for organic Se at maximum Se concentrations. A continuous increase in glutathione peroxidase (GSH-Px) activity with increasing Se concentrations in both forms revealed an active Se response in terms of antioxidant activity, with a more pronounced percentage increase with selenomethionine. A highly significant increase in total glutathione was observed with selenomethionine supplementation, compared with sodium selenite. A decreasing trend in reduced glutathione was observed with increasing organic or inorganic Se concentrations. An increasing trend in glutathione-S-transferase activity was observed with increasing Se concentrations for both forms. Significantly higher values of glutathione-S-transferase were associated with the organic form at higher Se concentrations. There was normal activity of Se in mammalian cells. The results showed that an organic Se source more greatly enhances the Se status of yeast cells and hence could help in chemoprevention if consumed by the population.