Antioxidative Effects of Polyphenol‐Enriched Red Ginseng Extracts on Hydrogen Peroxide‐Induced Oxidative Stress in C2C12 Cells

Abstract

Excessive generation of reactive oxygen species (ROS) in skeletal muscle is known to cause muscle fatigue and damage, which can be countered by endogenous antioxidant enzyme systems and dietary antioxidants. Although the medicinal efficacy of red ginseng extract (RGE) have been largely attributed to ginsenosides, the effects of phenolic compounds in RGE on ROS scavenging activity are not well known. We assessed the changes in total contents of saponins and phenolic compounds and examined the antioxidative effects of polyphenol‐enriched RGE (PRGE) on hydrogen peroxide (HP)‐induced oxidative stress in differentiated C2C12 muscle cells. Cells treated with 100 μM HP caused a marked increase of ROS within 6 hr, peaking at 24 hrs and remained high till 48 hrs. Compared to controls, both RGE and PRGE at 1.0 mg/ml concentration caused a marked decrease of ROS levels during the time course of 24 hr. The inhibitory effect of PRGE was significantly higher compared with RGE, consistent with ~2.6‐fold increase of total phenolic contents and major phenolic compounds in PRGE. Moreover, PRGE at 1.0 mg/ml increased the expression of catalase and glutathione reductase mRNAs. These results indicate that the superior antioxidant effect of PRGE relative to RGE can be accounted for the higher phenolic contents that directly scavenges ROS and/or through activation of antioxidant enzymes.