Suppression of Fas-mediated apoptosis of keratinocyte cells by chikusetsusaponins isolated from the roots of Panax japonicus

Fas-mediated apoptotic cell death of a human keratinocyte cell line, HaCaT cells, and of a murine keratinocyte cell line, Pam212 cells, was suppressed by pre-treatment with a methanol extract from the roots of Panax japonicus C.A. Meyer. Activity-guided fractionation led to the isolation of chikusetsusaponins IV, IVa, V and polysciasaponin P5 as the active ingredients. Of these compounds, chikusetsusaponin IV, was most active when applied at a concentration of 12.5 mu g/mL. The intracellular hallmark events of apoptosis such as DNA fragmentation and chromatin condensation were significantly reduced by the treatment with chikusetsusaponin IV. The apoptotic cell death of Jurkat cells was also suppressed by treatment with the active saponins. These results suggest that the use of chikusetsusaponins IV, IVa, V, polysciasaponin P5, or a crude extract of P.japonicus containing these saponins is expected to relieve cutaneous symptoms caused by excessive apoptotic cell death in the skin through the Fas/FasL pathway.