Natural antioxidants may prevent posttraumatic epilepsy: a proposal based on experimental animal studies

Head injury or hemorrhagic cortical infarction results in extravasation of blood and breakdown of red blood cells and hemoglobin. Iron liberated from hemoglobin, and hemoglobin itself, are associated with the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS have been demonstrated to be involved in the mechanism of seizures induced by iron ions in the rat brain, an experimental animal model for posttraumatic epilepsy (PTE). ROS are responsible for the induction for peroxidation of neural lipids, i.e., an injury of neuronal membranes, and also could induce disorders in the excitatory and inhibitory neurotransmitters. Antioxidants, such as a phosphate diester of vitamin E and C (EPC-K1) and antiepileptic zonisamide, have been known to prevent the epileptogenic focus formation, or to attenuate seizure activities in the iron-injected rat brain. Natural antioxidants, such as alpha-tocopherol, and condensed tannins, including (-)-epigallocatechin and (-)-epigallocatechin-3-O-gallate, adenosine and its derivative, melatonin, uyaku (Lindera Strychnifolia), fermented papaya preparations, Gastrodia elata BI., and Guilingji, have been demonstrated to scavenge ROS and/or RNS and to be prophylactic for the occurrence of epileptic discharge in the iron-injected rat brain.