Background
Existing literature on anti-oxidant capacity of ginseng has been inconsistent due to variance in the profile of ginseng steroids (Ginsenosides) that is because of differences in seasons and species.
Conclusion
The results of this study provide an explanation for the inconsistent findings on anti-oxidative property among previous ginseng studies. For optimizing the anti-oxidant outcome, ginseng supplementation at high dose should be avoided.
Methods
We used various doses of ginseng steroids to determine its effect on oxidative stress and anti-oxidant capacity of rat skeletal muscle against exercise.
Results
Under non-exercise conditions, we found increased thiobarbituric acid reactive substance (TBARS) levels and decreased reduced/oxidized glutathione ratio (GSH/GSSG) in rat skeletal muscle as dose increases (p < 0.05), which indicates the pro-oxidant property of ginseng steroids at baseline. Intriguingly, exhaustive exercise-induced increased TBARS and decreased GSH/GSSG ratio were attenuated with low and medium doses of ginseng steroids (20 and 40 mg per kg), but not with high dose (120 mg per kg). At rest, anti-oxidant enzyme activities, including catalase (CAT), glutathione reductase (GR) and glutathione S-transferase (GST) were increased above vehicle-treated level, but not with the high dose, suggesting a hormetic dose-response of ginseng steroids.