Elevation of glutathione levels by coffee components and its potential mechanisms.

The tripeptide glutathione (L-γ-glutamyl-L-cysteinylglycine) is found ubiquitous in microorganisms, plants and animals. In mammalian cells, where the tripeptide fulfils numerous functions, concentrations range from 0.5 to 10 mM (Meister & Tate, 1976; Meister, 1984; Redegeld et al., 1990). Glutahione is involved, for example, in the synthesis of proteins and DNA, in the regulation of enzyme activity, in the transport and reservoir of amino acids. A very important function of glutathione is the protection of cells, for instance as an antioxidant or as a co-factor in the conjugation of xenobiotics (Meister & Anderson, 1983; Redegeld et al., 1990).