[Glutathione: its biosynthesis, induction agents and concentrations in selected diseases].

Glutathione (GSH) is in a constant state of metabolic turnover. Because it is actively synthesized, it also must be degraded. In the first step of GSH synthesis, an amide linkage is formed between cysteine and glutamate catalyzed by gamma-glutamylcysteine synthetase. GSH synthetase catalyzes the reaction between amine residue of glycine and the cysteine carboxyl from gamma-glutamylcysteine dipeptide to form GSH. GSH is transported out of the cell and degraded by the membrane-bound enzyme gammaGT, which removes the gamma-glutamyl moiety, and by dipeptidases, which remove the glycine moiety. Glutathione is present in most of the plants and animals' tissues that constitute human diet. Thiol redox cycles play central roles in the antioxidant defense network. Lipoate and vitamins and other reducing factors affect the increase in glutathione concentrations in cells by the rise of the concentrations of reduced cysteine. The level of GSH in humans may be increased by taking different glutathione monoester (drug) or factors reducing cystyne to cysteine and increasing availability of this amino acid to GSH synthesis. GSH plays a critical role in cellular mechanisms that lead to cell death. The cancer cells resistant to apoptosis have higher intracellular GSH levels. The fact that numerous diseases are induced by RFT (that cause glutathione depletion) it seems that an in-depth study of the dietetic and pharmacological manners of manipulation of the GSH amount and availability may become in future a tool of great importance in the prevention of many illnesses.