Neuroprotective effect of four flavonoids in the root of Scutellaria baicalensis Georgi

Scutellaria baicalensis Georgi has been used for the treatment of chronic inflammatory syndromes including respiratory disease, fever and gastric ulcer in traditional Eastern medicine and its major components; baicalin, baicalein and wogonin; were reported to have various biological effects. In this study, we compared the neuroprotective effect of four isolated flavones form the root of S. baicalensis on global ischemic model in rat by 4-vessel occlusion method. S. baicalensis methanol extract was administered at a dose of 100mg/kg whereas four flavones namely, wogonin, baicalein, wogonoside and baicalin were orally administered at a dose of 10mg/kg. The viable pyramidal neurons were counted in the CA1 portion of hippocampus approximately +3.3, 3.5 and 3.7mm caudal to the bregma. At a dose of 10mg/kg, isolated compounds, wogonin, baicalein, wogonoside and baicalin inhibited the hippocampal neuronal cell death by 78.6%, 91.0%, 81.0% and 41.0% respectively whereas S. baicalensis methanol extract inhibited the neuronal cell death by 92% (p<0.001). There was no significant difference in the neuroprotective effect of wogonin, wogonoside and baicalein with that of S. baicalensis methanol extract. Our study suggested that S. baicalensis and its isolated flavones have potential neuroprotective effect and these findings may be one of the alternative therapies for the management of stroke.