Inhibitory Effects of Ginsenosides from the Root of Panax ginseng on Stimulus-Induced Superoxide Generation, Tyrosyl or Serine/Threonine Phosphorylation, and Translocation of Cytosolic Compounds to Plasma Membrane in Human Neutrophils

The effects of five ginsenosides (G-Rh₂, -Rd, -Rb₁, -Rb₂, -Rh₁) isolated from the root of Panax gingseng on stimulus-induced superoxide generation in human neutrophils were evaluated by measuring the reduction of ferricytochrome c. The tyrosyl or serine/threonine phosphorylation of neutrophil proteins and translocation of p47^phox, p67^phox, and Rac to the plasma membrane were detected using specific monoclonal antibodies. G-Rh₂ significantly suppressed superoxide generation induced by N-formylmethionyl-leucylphenylalanine (fMLP), phorbol 12-myristate 13-acetate (PMA), and arachidonic acid (AA) in a concentration-dependent manner. G-Rh₁ showed a comparably lower suppression on fMLP-induced superoxide generation. G-Rd, -Rb₁, and -Rb₂ also suppressed AA-induced superoxide generation in high concentrations. G-Rd and G-Rb₁ showed no effect on fMLP- and PMA-induced superoxide generation. FMLP-, PMA-, and AA-induced tyrosyl or serine/threonine phosphorylation and translocation of p47^phox, p67^phox, and Rac to the plasma membrane were in parallel with the suppression of the stimulus-induced superoxide generation.