Planta medica
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The involvement of ginsenosides in the signal cascade that stimulates cellular growth was investigated. It was found that ginsenosides Rh1 and Rh2 extracted from the root of Panax ginseng inhibited cellular proliferation in NIH 3T3 fibroblasts. ⋯ We also observed that the phosphorylation of myristoylated alanine-rich C kinase substrate, one of the major substrates of protein kinase C in cells, was inhibited by the ginsenosides. Data suggest that the ginsenoside Rh1 or Rh2 exerts antiproliferative effects by inhibiting phospholipase C, which produces second messengers necessary for the activation of protein kinase C.
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The potential of intestinal bacteria to hydrolyze ginsenoside Rb1 to 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (I) was found in 79% of the fecal specimens from 58 human subjects whose age ranged from 1 to 64 years. Following a ginsenoside-Rb1-hydrolyzing activity assay, Prevotella oris strains were then isolated as a major bacterial species possessing the potential. ⋯ These results suggest that the metabolism of protopanaxadiol saponins to metabolites I-III in the intestines seems most partly due to intestinal P.oris. In addition, the fact that neither intact ginsenoside Rb1 nor its middle metabolic derivatives but only the final metabolite I was detected at 1.0-7.3 micrograms/ml in blood after oral administration of mice with ginsenoside Rb1 (125 mg/kg) allows us to speculate that metabolites I-III are the most likely forms of protopanaxadiol saponins absorbed from the intestines.