L-Cysteine & N-Acetyl-L Cysteine

dietary supplementation of Cys is complicated because its free
38 sulfhydryl group is capable of spontaneous oxidation, resulting in product instability.
39 Moreover, the oxidized form, cystine (Cys-Cys), is relatively insoluble, making both
40 forms poor candidates for enteral or parenteral nutrition formulas. Recent studies suggest
41 excess dietary Cys may be deleterious to animal growth and feed consumption in various
42 species (Dilger et al., 2007). Therefore, safe and functional alternative Cys precursor
43 products have been sought.
44 N-Acetyl-L-cysteine (NAC) serves as a precursor for Cys because the
-amino
45 nitrogen is protected by an acetyl group, and most tissues in the animal body possess the
46 ability to remove this acetyl group and, thus, furnish Cys. For this reason, NAC has been
47 extensively studied as both a therapeutic agent and direct Cys precursor.