In a previous study, we reported that ginseng extract has anxiolytic-like effects in the elevated plus-maze model and that the ginseng saponin fraction plays an important role. This experiment was performed to investigate the anxiolytic-like effects of ginsenosides Rb1, Rg1, Rg3-R, and Rg3-S, and the Rg5 and Rk mixture isolated from the ginseng saponin fraction in the elevated plus-maze. Furthermore, the anxiolytic-effects of Rb1, Rg1, Rg3-R, Rg3-S, and the Rg5 and Rk mixture were compared with those of a well-known active anxiolytic drug (diazepam). The oral administration of ginsenoside Rb1 significantly increased the number of open arm entries and the time spent on the open arm compared with those in the vehicle-treated group. Ginsenoside Rg1 and the Rg5 and Rk mixture also significantly increased the number of open arm entries and the time spent on the open arm. However, ginsenosides Rg3-R and Rg3-S did not increase the number of open arm entries or the time spent on the open arm. On the other hand, ginsenoside Rb1 and the Rg5 and Rk mixture decreased locomotor activity in a manner similar to diazepam. These data indicate that ginsenosides Rb1, Rg1, and the Rg5 and Rk mixture have anxiolytic-like effects, but ginsenosides Rg3-R and Rg3-S do not in this model. We provide evidence that some ginsenosides may be useful for the treatment of anxiety.
2005 The Pharmaceutical Society of Japan