alpha-Guanidinoglutaric acid as a free radical generator.

alpha-Guanidinoglutaric acid (alpha-GGA) was first isolated from the cobalt-induced epileptic focus of cat cerebral cortex by us in 1980. alpha-GGA could induce behavioral convulsion as well as electroencephalography-documented epileptic seizures, when it was administered into the brain. alpha-GGA was also found to be a potent nitric oxide synthase inhibitor, suggesting that suppression of this activity may result in epileptic seizures. It is now observed that alpha-GGA generates reactive oxygen species as superoxide and hydroxyl radicals in aqueous solution. These findings suggest that reactive oxygen species may damage cell membranes, thus leading to neuronal depolarization, which is closely related to epileptogenesity.