Acteoside and its aglycones protect primary cultures of rat cortical cells from glutamate-induced excitotoxicity

We have previously reported that acteoside isolated from the leaves of Callicarpa dichotoma has significant neuroprotective activity against glutamate-induced neurotoxicity in primary cultured rat cortical cells. To determine the essential structural moiety within this phenylethanoid glycoside needed to exert neuroprotective activity, acteoside was hydrolyzed with acid into its aglycones, caffeic acid and 3',4'-dihydroxylphenylethanol. Caffeic acid and 3',4'-dihydroxylphenylethanol also showed significant neuroprotective activities. Acteoside and its aglycones inhibited glutamate-induced intracellular Ca2+ influx resulting in overproduction of nitric oxide and reduced the formation of reactive oxygen species. These compounds preserved the mitochondrial membrane potential and the activities of antioxidative enzymes, such as superoxide dismutase, glutathione reductase and glutathione peroxidase reduced by glutamate. It was followed by the preservation of the level of glutathione and finally the inhibition of membrane lipid peroxidation.