Glutathione (GSH) is the major antioxidant within cells. It is an important component of the glutathione peroxidase antioxidant system, which includes glutathione peroxidase and glutathione reductase. As a vital antioxidant, glutathione peroxidase continues the job begun by superoxide dismutase (SOD). It transforms hydrogen peroxide (a reactive oxygen species) by donating an electron and is then replenished so it can keep working. The glutathione peroxide system scavenges lipid peroxides by donating an electron, and prevents other radicals from being produced as well.
Glutathione is a key component of glutathione S-transferase (GST). The inability to produce GST, a substance needed by the liver to detoxify harmful chemicals, has been linked to prostate cancer. Dr. William Nelson, of the Johns Hopkins University School of Medicine, discovered a genetic defect in prostate body cancer cells prevents the body from producing GST. The defect was not found in cells from healthy men.
Glutathione is composed of glutamic acid, cysteine, and aminoacetic acid. The compound must first be broken down into its components before it can pass through the cell membrane, and then reassembled in the cell. A third enzyme is needed to create glutathione from other amino acids and selenium.
Glutathione is able to lessen the side effects associated with chemotherapy and x-rays. Glutathione combats alcohol poisoning and protects against damage from cigarette smoking and radiation. It is used in the treatment of blood and liver disorders by detoxifying metals and drugs.
Given its role as an antioxidant, it is interesting to note that low levels of circulating glutathione have been found in low-birth-weight babies. This may be due to a limited intake of cysteine or an inability to synthesize cysteine. In rats, low levels can be restored simply by providing cysteine in the diet.
HIV infection is marked by the very low levels of intracellular glutathione. HIV-infected patients cannot import external GSH into their cells, and as a result, severe free- radical damage results which lead to the clinical symptoms of AIDS.