Glutathione Powder Antiaging Glutathione (GSH) is an important antioxidant in plants, animals, fungi and some bacteria and archaea.
Glutathione prevents damage to important cellular components caused by
reactive oxygen species such as free radicals, peroxides, lipid
peroxides and heavy metals. It is a tripeptide having a gamma peptide
bond between the carboxyl group of glutamic acid side chain and the
amine group of cysteine, and the carboxyl group of cysteine is linked to
glycine through a normal peptide bond.
L(+)-Arginine The thiol group is a reducing agent and is present in animal cells at a
concentration of about 5 mM. Glutathione reduces disulfide bonds formed
in the cytoplasm to cysteines by acting as electron donors. In this
process, glutathione is converted to its oxidized form, glutathione
disulfide (GSSG), also known as L - (-) - glutathione. Once oxidized,
glutathione can be reduced by glutathione reductase, using NADPH as the
electron donor. The ratio of reduced intracellular glutathione to
oxidized glutathione is commonly used as a measure of cellular oxidative
stress. Functions and Usages Glutathione exists in both reduced (GSH)
and oxidized (GSSG) states. In the reduced state, the sulfhydryl group
of cysteine is capable of providing reducing equivalents (H ++ e-) to
other molecules, such as reactive oxygen species to neutralize them, or
to maintain their reduced form for the protein cysteine. By donating
electrons, glutathione itself becomes reactive and easily reacts with
another active glutathione to form glutathione disulfide (GSSG). This
reaction is most likely due to the relatively high concentration of
glutathione in cells (up to 7 mM in the liver). In general, the
interaction between GSH and other molecules with higher relative
electrophilicity depletes intracellular GSH levels. An exception to this
situation relates to the sensitivity of GSH to the relative
concentration of electrophilic compounds. At high concentrations, the
organic molecule diethyl maleate completely depletes the GSH levels in
the cells. However, at low concentrations, cellular GSH levels decreased
slightly and then tripled. GSH can be regenerated from GSSG by
glutathione reductase (GSR): NADPH decreases the FAD present in GSR to
produce transient FADH anions. This anion then rapidly disrupts the
disulfide bond (Cys58-Cys63) and causes Cys63 to nucleophilic attack the
nearest sulfide unit in the GSSG molecule (promoted by His467),
resulting in a mixed disulfide bond (GS-Cys58) and GS- anion . His467 of
GSR then protons the GS- anion to form the first GSH. Next, Cys63
nucleophile attacks the sulfide of Cys58, releasing the GS-anion, which
in turn extracts solvent protons and releases it from the enzyme,
resulting in a second GSH. Thus, for each GSSG and NADPH, two reduced
GSH molecules are obtained that can again act as antioxidants to
scavenge reactive oxygen species in the cells. In healthy cells and
tissues, more than 90% of the total glutathione pool is reduced (GSH)
and less than 10% exists as disulfide (GSSG). Increased GSSG to GSH
ratio is considered an indicator of oxidative stress.
