Neuroprotective effect of Sanguisorbae radix against oxidative stress-induced brain damage: in vitro and in vivo

Sanguisorbae radix (SR), the root of Sanguisorba officinalis L. (Rosaceae), has been traditionally used for its anti-inflammatory, anti-infectious and analgesic activities in Korea. Previous work has shown that SR prevents neuronal cell damage induced by Abeta (25--35) in cultured rat cortical neurons. The present study was carried out to further investigate the neuroprotective effect of SR on oxidative stress-induced toxicity in primary culture of rat cortical neurons, and on ischemia-induced brain damage in rats. SR, over a concentration range of 10--50 microg/ml, inhibited H2O2 (100 microM)-induced neuronal death, which was significantly inhibited by MK-801 (5 microM), an N-methyl-D-aspartate (NMDA) receptor antagonist, and verapamil (20 microM), an L-type Ca2+ channel blocker. Pretreatment of SR (10-50 microg/ml), MK-801 (5 microM), and verapamil (20 microM) inhibited H2O2-induced elevation of intracellular Ca2+ concentration ([Ca2+]i) measured by a fluorescent dye, Fluo-4 AM. SR (10-50 microg/ml) inhibited H2O2-induced glutamate release into medium measured by HPLC, and generation of reactive oxygen species (ROS) measured by 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA). In vivo, SR prevented cerebral ischemic injury induced by 2-h middle cerebral artery occlusion (MCAO) and 24-h reperfusion. The ischemic infarct and edema were significantly reduced in rats that received SR (10, 30 mg/kg, orally), with a corresponding improvement in neurological function. Catechin isolated from SR inhibited H2O2-induced neuronal death in cultures. Taken together, these results suggest that SR inhibits H2O2-induced neuronal death by interfering with the increase of [Ca2+]i, and inhibiting glutamate release and generation of ROS, and that the neuroprotective effect of SR against focal cerebral ischemic injury is due to its anti-oxidative effects. Thus SR might have therapeutic roles in neurodegenerative diseases such as stroke.