Inosine is a naturally occurring nucleoside which serves as an intermediate in purine metabolism. The metabolism of purines in humans generates a potent antioxidant compound, uric acid, which is known to be a natural scavenger of both oxygen and nitrogen reactive species as well as having chelator properties. Inosine, as a precursor of uric acid, was shown to have neuroprotective effect in vitro and is being tested in phase III of clinical trials for the treatment of Parkinson disease. The treatment with inosine is belived to prevent or slow the disease.