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Many physiopathological conditions (aging, degenerative diseases, etc.) are characterized by oxidative stress and glutathione (GSH) depletion; in these states it can be advantageous to restore the physiological levels of glutathione in tissues.

GSH, however, is poorly bioavailable to humans. The introduction of GSH into the body using external sources is in fact scarcely effective to increasing the plasma and / or intracellular concentration. On the other hand, when glutathione is parenterally administered an increase in the plasma concentration is observed, followed by a return to baseline levels within a few minutes; this cannot be attributed to the spread in the intracellular compartment.

Two main causes explaining its poor bioavailability are known: i) glutathione is a peptide and, as such, it is the substrate of peptidase and protease of the alimentary canal. Therefore, only a small percentage of GSH taken orally, if any, reaches the plasmatic compartment; ii) cell membrane lacks a specific carrier for glutathione; the peptide cannot therefore enter inside cells.

Derivatives or associations of GSH credited with higher bioavailability

 * Glutathione-liposome. GSH is encapsulated inside a liposomal micelle which favors its absorption into the intestine.


 * N-acetylcysteine (NAC). It is a cysteine derivative, one of the three amino acids required for the biosynthesis of GSH.


 * Amide derivatives of GSH, such as the N-acetyl-glutathione. These compounds are characterized by better bioavailability, though easily undergo to oxidation of the sulfhydryl group.


 * Thioesters of the glutathione, such as S-acetyl glutathione and S-acyl-glutathione derivatives. The latter, in particular, constitute a family of glutathione thioesters with saturated or unsaturated, long-chain fatty acids. These novel compounds have been recently designed by a group of biochemists at the University of Florence . The presence of the hydrocarbon chain confers amphiphilic character to the molecule, which enables it to overcome the intestinal barrier and penetrate into the cells of the peripheral tissues. These compounds are therefore effective in fighting cellular damage caused by free radicals,.