Impact of Ginkgo Biloba Extract EGb 761 on ischemia/reperfusion - induced oxidative stress products formation in rat forebrain

Abstract

Dysbalance in reactive oxygen/nitrogen species is involved in the pathogenesis of cerebral ischemia/reperfusion injury (IRI). Ginkgo biloba extract (Egb 761) pre-treatment was used to observe potential antioxidant/neuroprotective effect after global ischemia/reperfusion. Egb 761 significantly decreased the level of lipoperoxidation (LPO) in rat forebrain total membrane fraction (homogenate) induced by in vitro oxidative stress (Fe(2+)+H(2)O(2)). In animals subjected to four-vessel global ischemia for 15 min and 2-24 h reperfusion the EGb pretreatment slightly decreased LPO in forebrain homogenate. However, as detected in EGb treated group, the LPO-induced lysine conjugates are attenuated in comparison to non-treated IRI animals. EGb significantly improved parameters which indicate forebrain protein oxidative damage after IRI. The intensity of tryptophane fluorescence was increased by the 18.2% comparing to non-treated IRI group and bityrosine fluorescence was significantly decreased in ischemic (21%) and 24 h reperfused (15.9%) group in comparison non-treated IRI group. In addition, the level of total free SH- groups in pre-treated animals was significantly higher comparing to non-treated animals. Our results indicate that extract of EGb 761 has potent antioxidant activity and could play a role to attenuate the IRI-induced oxidative protein modification and lipoperoxidation in the neuroprotective process.

Fig. 1.

Effect of 15 min ischemia (ISCH) and 24 h reperfusion (REP) on fluorescence intensity of tryptophan (Trp) in rat forebrain homogenate (4-vessel occlusion model). The results are expressed as ±SEM of 6 experiments.^*** p<0.001; significantly different as compared to corresponding control.⁺⁺⁺ p<0.001; significantly different as compared to corresponding ischemia.^## p<0.01; significantly different in comparison between I/R groups with and without EGb pre-treatment. Fluorescence intensity of Trp is represented in arbitrary units (a.u.).

Fig. 2.

Effect of 15 min ischemia (ISCH) and 24 h reperfusion (REP) on fluorescence intensity of bityrosine (biTyr) in rat forebrain homogenate (4-vessel occlusion model). The results are expressed as ±SEM of 6 experiments.^*** p<0.001; significantly different as compared to corresponding control.⁺ p<0.05; significantly different as compared to corresponding ischemia.^#<0.05,^### p<0.001; significantly different in comparison between control, 15 min ISCH, 24 h REP groups with and without EGb pre-treatment. Fluorescence intensity of biTyr is represented in arbitrary units (a.u.).