The n-BuOH fraction of O. javanica significantly protected the primary cultures of rat cortical cells exposed to glutamate. Four flavonoids yielded from this fraction through bioactivity-guidance. The isolated compounds, identified as isorhamnetin (1), afzelin (2), hyperoside (3) and persicarin (4), were evaluated in vitro for their neuroprotective activity. Persicarin (4), the main constituent of O. javanica, showed significant neuroprotective activities in glutamate-injured rat cortical cells. Persicarin diminished calcium influx and inhibited the subsequent overproduction of nitric oxide and intracellular peroxide. In addition, persicarin significantly restored the reduced activities of glutathione (GSH) reductase and glutathione peroxidase, and the contents of GSH induced by glutamate. These results support a conclusion that persicarin greatly contributes to the neuroprotective activities of O. javanica.
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