OBJECTIVE: Saikokeishito(TJ-10) is a Kampo(traditional Japanese herbal) medicine, clinically used for hundreds of years in East Asia. Among its various mechanisms elucidated so far, TJ-10 inhibits the production of transforming growth factor-β1(TGF-β1) and development of pancreatic fi brosis in vivo. Oxidative damage of normal human dermal fi broblasts(NHDFs) in the corium is a cause of human dermal senescence. Our aim was to determine whether TJ-10 protects NHDFs from premature senescence by hydrogen peroxide(H2O2). METHODS: Premature senescence was induced in NHDFs by 200 μmol/L H2O2 for 4 h. Cell viability and the expressions of p53, AMP-activated protein kinase α1(AMPKα1), AMPKα2, and 14-3-3 protein sigma(14-3-3 σ) were measured in NHDFs treated with TJ-10 for 48 h before exposure to H2O2 for 4 h. RESULTS: Cell viability after treatment with 200 μmol/L H2O2 for 4 h was similar(about 80%) to after pre-treatment with TJ-10. Ascorbic acid as a control did not protect NHDFs from damage by 200 μmol/L H2O2. Treatment with 200 μmol/L H2O2 tended to up-regulate p53 and to down-regulate SIRT1 and AMPKα1, but had no effect on AMPKα2 and 14-3-3 σ expression. Pretreatment with TJ-10 inhibited H2O2-induced up-regulation of p53 and enhanced AMPKα1 expression. CONCLUSION: It is suggested that Saikokeishito has a protective effect on oxidative stressinduced senescence of NHDFs. OBJECTIVE: Saikokeishito (TJ-10) is a Kampo (traditional Japanese herbal) medicine, clinically used for hundreds of years in East Asia. Among its various mechanisms elucidated so far, TJ-10 inhibits the production of transforming growth factor-β1 -β1) and development of pancreatic fi brosis in vivo. Oxidative damage of normal human dermal fi broblasts (NHDFs) in the corium is a cause of human dermal senescence. Our aim was to determine whether TJ-10 protects NHDFs from premature senescence by hydrogen METHODS: Premature senescence was induced in NHDFs by 200 μmol / L H2O2 for 4 h. Cell viability and the expressions of p53, AMP-activated protein kinase α1 (AMPKα1), AMPKα2, and 14-3-3 protein (14-3-3 σ) were measured in NHDFs treated with TJ-10 for 48 h before exposure to H2O2 for 4 h. RESULTS: Cell viability after treatment with 200 μmol / L H2O2 for 4 h was similar (about 80% ) to after pre-treatment with TJ-10. Ascorbic acid as a control did not protect NHDFs fro Treatment with 200 μmol / L H2O2 tended to up-regulate p53 and down-regulated SIRT1 and AMPKα1, but had no effect on AMPKα2 and 14-3-3 σ expression. Pretreatment with TJ- 10 inhibited H2O2-induced up-regulation of p53 and enhanced AMPKα1 expression. CONCLUSION: It is suggested that Saikokeishito has a protective effect on oxidative stress induced senescence of NHDFs.