[Studies on the pharmacodynamics of ginsenoside-Rg1, -Rb1 and -Rb2 in rats]

The pharmacodynamics of ginsenoside-Rg1 (Rg1), -Rb1 (Rb1) and -Rb2 (Rb2) in rats were studied. In these studies, obvious differences were found in their pharmacodynamics. That is, Rg1 was easily hydrated to the same prospogenins in both rat stomach and 0.1 N HCl solution, but Rb1 and Rb2 were little decomposed (metabolised) in rat stomach and a small quantity of their hydroperoxide derivatives were found, but they were easily hydrated to their prosapogenins by 0.1 N HCl. These ginsenosides were decomposed (metabolised) to several prosapogenins by enteric bacteria and enteric enzymes. The modes of their decomposition (metabolism) were respectively different. In particular, the terminal sugar moiety at the C-20 hydroxy group was noted to affect the rates of their decomposition. The amount of Rg1 and Rb1 absorbed from the gastrointestinal tract of rat were 1.9% and 0.1% of the dose, respectively. And that of Rb2 was determined to be 3.7% of the dose by using 3H-labeled Rb2. Rg1 was excreted into the urine and bile in a 2:5 ratio. Rb1 and Rb2 were mainly excreted into the urine.