Extraction of the active compound of Nrf2-ARE pathway derived from Panax ginseng C. A. Meyer
Oxidative stress induced by reactive oxygen species (ROS) generated in the human body is considered as a risk factor of various neurodegenerative diseases. Nrf2-ARE pathway is well-known as biological defensive system against the oxidative stress. In this study, we isolated and identified the Nrf2-ARE activator from Panax ginseng C. A. Meyer and then evaluated its actions against PC12 cells. First, the extract of Panax ginseng C. A. Meyer exhibited high ARE activity by luciferase reporter assay using PC12 cells. Dividing the extract into 9 fractions by reversed-phase HPLC, we determined the ARE activities of each fraction by reporter assay. Based on LC/TOF-MS, the active ingredient responsible for the ARE activity was identified as panaxytriol ((3R,9S,10S)-Heptadec-1-en-4,6-diyne-3,9,10-triol). Importantly, the pretreatment of panaxytriol significantly protected native PC12 cells from 6-OHDA toxicity. Additionally, NQO1 assay revealed that panaxytriol raised NQO1 activity in native PC12 cells. These results suggest that the extract of Panax ginseng C. A. Meyer contains panaxytriol as a Nrf2-ARE activator and has the cytoprotective effect against oxidative stress by inducing some antioxidant enzymes.