Dibenzocyclooctadiene Lignans from Schisandra chinensis Protect Primary Cultures of Rat Cortical Cells from Glutamate-Induced Toxicity

A methanolic extract of dried Schisandra fruit (Schisandra chinensis Baill.; Schisandraceae) significantly attenuated the neurotoxicity induced by L-glutamate in primary cultures of rat cortical cells. Five dibenzocyclooctadiene lignans (deoxyschisandrin, gomisin N, gomisin A, schisandrin, and wuweizisu C) were isolated from the methanolic extract; their protective effects against glutamate-induced neurotoxicity were then evaluated. Among the five lignans, deoxyschisandrin, gomisin N, and wuweizisu C significantly attenuated glutamate-induced neurotoxicity as measured by 1) an inhibition in the increase of intracellular [Ca²⁺]; 2) an improvement in the glutathione defense system, the level of glutathione, and the activity of glutathione peroxidase; and 3) an inhibition in the formation of cellular peroxide. These results suggest that dibenzocyclooctadiene lignans from Schisandra chinensis may possess therapeutic potential against oxidative neuronal damage induced by excitotoxin.