Coffee improves rat redox status by enhancing GSH biosynthesis

Coffee consumption is very popular throughout the world and apart from its stimulating effect, various beneficial health effects have been attributed to it. However, most studies are either observational, or do not analyze the majority of tissues. In the current work, a lightly roasted coffee extract was administered for two weeks in the water of rats to examine whether its previously observed in vitro antioxidant properties correspond to in vivo results. The administered dose corresponded to a moderate human daily consumption of 3-4 cups. According to the results, coffee had beneficial effects in the blood and all eleven tissues tested, mainly by increasing reduced glutathione (GSH) levels, an important endogenous antioxidant tripeptide. In addition, protein and lipid oxidation was reduced in several tissues in the coffee group. Interestingly, the brain was the most significantly affected tissue. The observed increase in GSH was attributed to increased levels of the rate-limiting enzyme in its biosynthetic pathway, namely γ-glutamylcysteine ligase, as demonstrated by both Real-time PCR and Western blot analysis. Overall, moderate coffee consumption showed beneficial short term effects in all tissues by stimulating the endogenous antioxidant mechanisms, in agreement with previous in vitro cell culture findings.