Increase in antioxidant and anticancer effects of ginsenoside Re-lysine mixture by Maillard reaction

Ginsenosides are the main active components of Panax ginseng. Structural changes in diol type ginsenosides along with generation of Maillard reaction products (MRPs) are strongly associated with increased free radical-scavenging activities. Ginsenoside Re, one of the major triol type ginsenosides of P. ginseng, possesses a hydrophobic four-ring steroid-like structure with hydrophilic sugar moieties at carbons-3 and -20. The aim of the present study was to identify changes in the structure, antioxidant and anticancer effects of ginsenoside Re upon Maillard reaction. Ginsenoside Re was transformed into less-polar ginsenosides, namely Rg(2), Rg(6) and F(4) by heat-processing. Free radical-scavenging activity of the ginsenoside Re-lysine mixture increased upon heat processing. This improved free radical-scavenging activity mediated by antioxidant MRPs, which were generated through Maillard reaction of a glucosyl moiety separated from carbon-20 of ginsenoside Re and lysine. The increased anticancer effect of ginsenoside Re-lysine mixture upon heat processing was mainly derived from the generation of less-polar ginsenosides through the regulation of Bcl-2 and Bax, as well as caspase-dependent apoptotic pathway. These results reported here have shed significant new lights on the mechanism of increased antioxidant and anticancer effects of P. ginseng upon heat processing.