Pharmacological actions of ginseng saponin in stress mice.

Abstract

P. ginseng is an important role in Oriental medicine. Some pharmacological experiments were carried out with pure saponins [ginsenoside (GS)-Rb1, Rb2, Rc, Re and Rg1] isolated from the P. ginseng root, a mixture of ginseng saponins [ginsenoside mixture B (GMB) obtained from the lateral root (Hakumo) and crude ginsenoside K (GSK) obtained from the main root (Hakusan)] and prosapogenins (PSG), partial hydrolysates of Rb1, Rb2, Rc and Rd [20R-PSG, 20S-PSG and .DELTA.20-PSG], by using specific repeatedly cold stressed (SART stressed) mice and in restraint and water immersion-stressed (RWIS) mice. A single i.p. administration of 10 mg/kg of GS or PSG gave no influence on pentobarbital-induced sleeping in non-stressed mice. The inhibition of a natural increase in body weight in SART stressed mice was markedly counteracted by administration with a daily dose of 2.5 mg/kg of Rb1, Rc, Re, 20S-PSG or GSK for 5 consecutive days during SART stressing. A single i.p. administration of 10 mg/kg of Rb2, Rc, Re, 20R-PSG or 20S-PSG increased the analgesic index by the modified Randall-Selitto method and that of 20R-PSG or 20S-PSG decreased the writhing syndrome by the method of acetic acid in non-stressed mice. When SART stressed mice were used as test animals in place of non-stressed mice, the analgesic effect was augmented. Prolonged actions were observed in SART stressed mice administered daily with 5-10 mg/kg of Rb2, Rc, Re, 20R-PSG or 20S-PSG. When analgesic effect was tested 60 min after the last administration by the modified method of Randall-Selitto, almost the same effect as the single administration was obtained. The inhibitory effect on acetic acid writhing of Rb1, Rb2, Re, .DELTA.20-PSG, and GMB, which was ineffective by a single administration, in addition to Rg1, 20R-PSG and 20S-PSG, was observed. The decrease in ACh [acetylcholine] response of the isolated SART stressed mouse duodenum was inhibited by daily administration of Rb1, Rb2, Rc, Re, 20S-PSG, GMB, and GSK. The increase in ACh response of the isolated RWIS mouse duodenum was inhibited by 3 pretreatments with Rb1, Re, Rg1, 20S-PSG and GMB, but not with Rb2, Rc, or GSK. The effects of ginseng saponins may be different from those of saikosaponins. The former compounds have a weak analgesic action, and may improve some symptoms of vegetative stigmatism due to SART stress and RWIS. The classification of GS and PSG based on their actions was attempted.