Abstract: The aim of the present study was to evaluate the important role of ginsenoside Re-arginine Maillard reaction products (MRPs) in the free radical scavenging and against Cu2+-induced oxidative stress in HepG2 cells.Ginsenoside Re with arginine was heated at 100 ℃ for 4 h to prepare the MRPs.The MRPs was analyzed by HPLC,the browning level was assayed at 420 nm,total phenol content was assayed by the Folin-Ciocalteu method and the result was illustrated as milligrams of GAE per gram of each sample tested.The change of Cu²⁺ chelating activities and the scavenging effect on DPPH radical were also evaluated.Meanwhile,the antioxidant ability was also assayed in HepG2 cells by using the Cu²⁺-induced oxidative stress model.The results indicate that the ginsenoside Re is transformed into less-polar ginsenosides such as Rg₂、Rg₆ and F₄ during Maillard reaction,and the glucose molecule at carbon-20 is separated,the browning level and the total phenol increase obviously,the Cu²⁺ chelating activity and DPPH radical scavenging activity are enhanced significantly.Comparing to the control,there is a 3.16-fold increase of oxidative stress of HepG2 cells under the influence of Cu²⁺.The oxidative stress induced by Cu²⁺ is only marginally inhibited by the treatment of ginsenoside Re or Re-arginine mixture (not significant,p>0.05) but significantly reduced by the treatment with Re-arginine MRPs in the concentration range of 100 to 300 μg/mL.Because of their high cell-membrane permeability,the ginsenoside Re-arginine MRPs increase the free radical-scavenging acivity in HepG2 cells,showing cellular antioxidant activity against Cu²⁺-induced oxidative stress higher than that of Re.

Key words: ginsenoside Re, arginine, Maillard reaction products, antioxidant