Neuroprotective and Cognition-Enhancing Effects of Compound K Isolated from Red Ginseng

The present study was aimed at elucidating the effect of compound K derived from red ginseng on memory function in mouse model and glutamate-induced cytotoxicity in mouse hippocampal HT22 cells. Compound K induced antioxidant enzymes in nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-mediated manner, and effectively attenuated cytotoxicity and mitochondrial damage induced by glutamate in HT22 cells. However, the cytoprotective effect by compound K was abolished by heme oxygenase-1 inhibitor, tin protophorphyrin IX, suggesting that neuroprotective effect of compound K was caused by its Nrf2-mediated induction of antioxidant enzymes. Further, memory deficit induced by scopolamine was restored by compound K, which did not inhibit acetylcholine esterase, in C57BL/6 mice but not in Nrf2 knockout mice as assessed by passive avoidance test, Y-maze and water maze tests, suggesting that scopolamine-induced memory impairment was overcome by the induction of Nrf2-mediated antioxidant enzymes by the compound K. Overall, our data indicate that compound K could be useful in prevention and treatment of reactive oxygen species-induced neurological disorders such as Alzheimer's disease.