Ginkgolide terpenoid lactones, including
ginkgolides and
bilobalide, are two crucial bioactive constituents of extract of Ginkgo biloba (EGb) which was used in the treatment of cardiovascular and
cerebrovascular diseases. The aims of this study were to investigate the
antioxidant effects and mechanism of
ginkgolides (
ginkgolide A (GA),
ginkgolide B (GB),
ginkgolide K (GK)) and
bilobalide (BB) against oxidative stress induced by transient focal
cerebral ischemia. In vitro, SH-SY5Y cells were exposed to
oxygen-
glucose deprivation (OGD) for 4 h followed by reoxygenation with
ginkgolides and BB treatments for 6 h, and then cell viability,
superoxide dismutase (SOD), and ROS were respectively detected using kit. Western blot was used to confirm the
protein levels of hemeoxygenase-1 (HO-1),
quinone oxidoreductase l (Nqo1), Akt, phosphorylated Akt (p-Akt), nuclear factor-E2-related factor2 (Nrf2), and phosphorylated Nrf2 (p-Nrf2). GB combined with different concentrations of
LY294002 (PI3K inhibitor) were administrated to SH-SY5Y cells for 1 h after OGD, and then p-Akt and p-Nrf2 levels were detected by western blot. In vivo, 2 h of
middle cerebral artery occlusion (MCAO) model was established, followed with reperfusion and GB treatments for 24 and 72 h. The
infarct volume ratios were confirmed by TTC staining. The
protein levels of HO-1, Nqo1, SOD1, Akt, p-Akt, Nrf2, and p-Nrf2 were detected using western blot and immunohistochemistry (IHC). Experimental data in vitro confirm that GA, GB, GK, and BB resulted in significant decrease of ROS and increase of SOD activities and
protein levels of HO-1 and Nqo1; however, GB group had a significant advantage in comparison with the GA and GK groups. Moreover, after
ginkgolides and BB treatments, p-Akt and p-Nrf2 were significantly upregulated, which could be inhibited by
LY294002 in a dose-dependent manner, meanwhile, GB exhibited more effective than GA and GK. In vivo, TTC staining indicated that the
infarct volume ratios in MCAO rats were dramatically decreased by GB in a dose-dependent manner. Furthermore, GB significantly upregulated the
protein levels of HO-1, Nqo1, SOD, p-Akt, p-Nrf2, and Nrf2. In conclusion, GA, GB, GK, and BB significantly inhibited oxidative stress damage caused by
cerebral ischemia reperfusion. Compared with GA, GK, and BB, GB exerts the strongest
antioxidant stress effects against
ischemic stroke. Moreover,
ginkgolides and BB upregulated the levels of
antioxidant proteins through mediating the Akt/Nrf2 signaling pathway to protect neurons from oxidative stress injury.