Protective Effect of Paeonia anomala Extracts and Constituents against tert-Butylhydroperoxide-Induced Oxidative Stress in HepG2 Cells

The fruit and root parts of Paeonia anomala L. are used for the treatment of many kinds of disorders in Mongolian traditional medicine. The protective effect of a fruit extract from P. anomala against tert-butylhydroperoxide-induced cell damage was evaluated in human hepatoma HepG2 cells and compared to that of a root extract from P. anomala on the basis of cell viability, generation of intracellular reactive oxygen species, cellular total glutathione concentration, and anti-genotoxicity. The fruit extract of P. anomala showed excellent protection against the oxidative stress when compared to the root extract, through free radical scavenging, enhancing cellular glutathione concentration, and inhibiting DNA damage. Chemical constituents in the fruit extract of P. anomala were investigated and two novel compounds, 2-hydroxy-6-methoxy-4-O-(6'-O-alpha-Larabinofuranosyl- beta-D-glucopyranosyl) acetophenone (1) and 3,3'-di-O-methyl-4-O-(3''-O-galloyl-beta-D-glucopyranosyl) ellagic acid ( 2), along with 18 other known compounds were identified. Compound 2 showed better cytoprotection against tert-butylhydroperoxide than compound 1. Among other compounds isolated from the fruit extract, ellagic acid, methyl gallate, ethyl gallate, fischeroside B, and quercetin derivatives showed potent protective effects against tert-butylhydroperoxide-induced oxidative stress via inhibiting reactive oxygen species generation and increasing total glutathione levels in HepG2 cells.