What is glutathione, the peptide you (and most living beings) can’t do without
Remember: All protective mechanisms in the skin are interconnected and regulated by redox-dependent processes.
What is glutathione?
Figure: glutathione (a.k.a. γ-L-Glutamyl-L-cysteinylglycine), with that all-important SH group. When oxidized, two glutathione molecules are joined together to make a S-S bridge.
L-Glutathione (gamma-L-Glutamyl-L-cysteinyl-glycine) is a tripeptide composed of the amino acids L-glutamine, L-cysteine, and glycine. Glutathione is part of the antioxidant defense system of the cell, together with superoxide dismutase, catalase, glutharedoxin, thioredoxin, alpha-D-tocopherol (vitamin E), ascorbic acid (vitamin C), and others.
GSH protects cells by neutralizing (i.e., reducing) Reactive Oxygen Radicals (ROS*). This conversion is illustrated by the reduction of peroxides:
- 2 GSH + R2O2 → GSSG + 2 ROH (R = H, alkyl)
and with free radicals:
- GSH + R. → 0.5 GSSG + RH
And, as if detoxifying ROS* wasn’t enough…
GSH not only detoxifies ROS*, but can also regenerate oxidized Vitamin E and retinoids. In aged skin the concentration of anti-oxidants is strongly decreased, including Vitamin E, Vitamin C and glutathione. The function and interaction of all anti-oxidants is deeply interwoven to keep the redox state in the skin tissue in balance. Glutathione is an imporatnt part of this system, on which skin physiology and health depend.
Beside its role as an anti-oxidant, GSH is also a cofactor for enzymatic reactions. The glutathione peroxidase is an enzyme that fulfills two tasks: reduce hydrogen peroxide to water and stop lipid peroxidation. In humans, eight glutathione peroxidases are known, five of them containing selenium as a co-factor. It may also work to keep a balance of iron in the cell, as iron is a micronurient, essential but poisonous if it is not regulated carefully.
Glutathione is crucial to cell life, and impairment of the glutathione system results in damage to the cell membrane and cell death.
Why is glutathione so important? It is key to a finely adjusted redox state that allows for life to go on. It circulates in the cell as a wild card that re-reduces molecules that were oxidized by Reactive Oxygen Species (ROS*) that came into the cell or were produced by its mitochondria or enzymes like NAD.
Because of its involvement in eiminating ROS*, glutathione is very useful in skin care. It can help prevent damage by UV, and it is used to deal with hyperpigmentation and melasma. Glutathione ia also needed for proteins like glutaredoxin and thioredoxin to do their jobs.
What not to do
Glutathione is not something you want to take orally (it would not nothing for you). Your body is pretty good at regulating its own redox state. Besides, oxidation is one of the defensive mechanisms the skin has against bacteria, fungus and even cancer cells. It is your skin that is subjected to a continuous bombarding of UV (and the ROS* it originates), ROS* from the environment and more.
Skin Actives products that contain glutathione
How long can this list get? Very long, because redox status affects skin aging, both endogenous and photoaging, inflammation, redness, hyperpigmentation, depigmentation. Everything!
Ready to use
Moisturizing Antioxidant Day Cream
Ingredients for DIY (do it yourself) Add any of these to a cream or lotion base
References:
Rinnerthaler, M., Bischof J., Streubel MK, Trost, A., Richter, K. (2015) Oxidative Stress in Aging Human Skin, Biomolecules, 5 545-589.
Farage, M.A.; Miller, K.W.; Elsner, P.; Maibach, H.I. (2013) Characteristics of the aging skin. Adv. Wound care, 2:5–10.
Passi, S.; Grandinetti, M.; Maggio, F.; Stancato, A.; de Luca, C. Epidermal oxidative stress in vitiligo. Pigment Cell Res. 1998, 11, 81–85.
Weber, S.U.; Thiele, J.J.; Cross, C.E.; Packer, L. (1999) Vitamin C, uric acid, and glutathione gradients in murine stratum corneum and their susceptibility to ozone exposure. J. Investig. Dermatol. 113, 1128–1132. 115.
Schafer, M.; Werner, S. (2011) The cornified envelope: A first line of defense against reactive oxygen species. J. Investig. Dermatol., 131, 1409–1411.
Schafer, M.; Dutsch, S.; Keller, U.A.D.; Navid, F.; Schwarz, A.; Johnson, D.A.; Johnson, J.A.; Werner, S. (2010) Nrf2 establishes a glutathione-mediated gradient of UVB cytoprotection in the epidermis. Gene Dev. 24, 1045–1058.