Neuroprotective effect of liquiritin against focal cerebral ischemia/reperfusion in mice via its antioxidant and antiapoptosis properties

Our present study was conducted to investigate whether liquiritin (7-hydroxy-2-[4-[3,4,5-trihydroxy-6-(hydroxymethyl) oxan-2-yl] oxyphenyl]-chroman-4-one, 1), an active component of Glycyrrhiza uralensis Fisch., exerts a neuroprotective effect against focal cerebral ischemia/reperfusion (I/R) in male Institute of Cancer Research (ICR) mice. On the establishment of mice with middle cerebral artery occlusion (MCAO) for 2 h and reperfusion for 22 h, liquiritin at the doses of 40, 20, and 10 mg/kg was administered before MCAO once a day intragastrically for a subsequent 3 days. Neurological deficits and infarct volume were measured, respectively. The levels of malondialdehyde (MDA) and carbonyl, activities of superoxide anion (SOD), catalase (CAT) and glutathion peroxidase (GSH-Px) and reduced glutathione/oxidized disulfide (GSH/GSSG) ratio in brain were estimated spectrophotometrically. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) and terminal deoxynucleotidyl transferase-mediated DuTP-biotin nick end labeling (TUNEL)-positive cells were detected by immunohistochemical analysis. Our results showed that the neurological deficits, infarct volume, and the levels of MDA and carbonyl decreased, the ratio of GSH/GSSG and the activities of SOD, CAT, and GSH-Px were compensatorily up-regulated, and 8-OHdG and TUNEL-positive cells decreased after 22 h of reperfusion in liquiritin-treated groups. These findings suggest that liquiritin might be a potential agent against cerebral I/R injury in mice by its antioxidant and antiapoptosis properties.