GSH is an antioxidant
Glutathione, a tripeptide ( a short protein chain) composed of glutamate, cysteine and glycine, is found in plant and animal tissues. It is an important compound. It works intra and extra-cellularly in its reduced form, L-glutathione (abbreviated as “GSH”) and is the body’s key antioxidant and protectant. GSH has multiple disease preventing functions and is involved in the detoxification of chemicals and drugs. The depletion of L-glutathione is associated with increased risks of toxicity, disease and disorders of the body. GSH works synergistically with the other cellular antioxidants to neutralise and scavenge oxygen and other free radical species and thereby prevent or diminish “oxidative stress” (Hersh, 1998).
The liver produces GSH and so controls blood levels, but dietary GSH also raises tissue levels. A deficiency of hepatic GSH and other antioxidants and/or an increase in oxidative stress, may contribute to the progression of liver disease. Glutathione is important in the management of patients with alcoholic liver disease and viral hepatitis, particularly those with hepatitis C.
The role of antioxidants, particularly L-glutathione, in chronic liver diseases s shown in a study that reported on the levels of glutathione in liver, blood and lymphocytes of patients with chronic hepatitis C (some of these patients were also HIV positive) . GSH levels in these three sites was significantly reduced in patients with hepatitis C and correlated with the severity of their liver disease as well as with the ability of the hepatitis C virus to replicate (Hersh, 1998).
Those who were also HIV positive had even lower levels. The lowest GSH levels were in those patients addicted to drugs. Low GSH levels make both diseases are more resistant to anti-viral therapy - interferon for those with chronic hepatitis and antiretroviral drugs for those with HIV. Repletion of glutathione levels improves the response to interferon treatment in hepatitis cases. DeMaria and co-investigators at the Oklahoma Medical Research Foundation also confirmed that oxidative stress occurs in patients with chronic hepatitis (Hersh, 1998). They showed that the levels of free radicals correlated with the activity of the hepatitis. Another study showed that by increasing glutathione levels with high intravenous doses in patients with fatty livers (steatosis) (caused by alcoholic hepatitis or viral hepatitis (B or C)), there was a marked improvement in patients’ liver tests that lasted for several months after GSH treatment.
Hersh (1998) reports that Charles Lieber at Mt. Sinai in New York also showed that free radicals from the oxidation of lipids developed in patients with alcoholic liver disease and that Fitzgerald and co-workers in Philadelphia concluded that oxidant stress contributes to the deterioration of the liver disease.
Conclusions on the role of L-glutathione
L-glutathione has an important antioxidant role in maintaining a healthy liver. There is clear evidence that oxygen and other toxic free radicals caused by oxidative stress are found in chronic liver disease, contributing to liver damage in various common types of chronic hepatitis. Blood and liver antioxidant levels, especially those of L-glutathione, are found to be reduced in these patients. Liver cell damage can be reduced by repletion of L-glutathione. In chronic hepatitis C, repletion of glutathione not only impairs Virus C replication but also renders interferon anti-viral therapy more efficacious.