Glutathione–enriched baker’s yeast: production, bioaccessibility and intestinal transport assays

AIMS: a glutathione (GSH) yeast-based biomass (S. cerevisiae) was used to investigate GSH stability, solubilization during gastrointestinal digestion and GSH intestinal transport. METHODS AND RESULTS: a post-growing procedure was applied to improve intracellular GSH yeast content. The presence of adenine (ADE) in the biotransformation solution (CYS-GLY-GLU mixture) and alternatively, a glucose shot after 4 h incubation, allowed to obtain cells containing about GSH 1.6-1.7% dcw (dry cell weight) (control 0.5%). Yeast samples were subjected to in vitro gastro-intestinal digestion and absorption assays employing Caco-2 and HT29-MTX cell lines in different proportions (100/0, 70/30 and 50/50). Trials were also performed to verify intestinal cell viability. CONCLUSIONS: at least 87% of ingested GSH is available in reduced form for intestinal absorption. In vitro GSH transport assays indicated that GSH is poorly absorbed (<20%). Nevertheless, studies in response to oxidative stress induced by H2 O2 demonstrated a protective role of the GSH-enriched biomass towards intestinal cell viability. SIGNIFICANCE AND IMPACT OF STUDY: an enriched GSH yeast-based biomass has been obtained using a post-growing procedure. Although GSH present in enriched yeasts is poorly absorbed by intestinal cells, this biomass showed an intestinal local protective effect, improving cells viability when a simulated oxidative stress was applied.