Therapeutic efficacy of Kangen-karyu against H<SUB>2</SUB>O<SUB>2</SUB>-induced premature senescence

The anti-aging potential of Kangen-karyu extract was investigated using the mechanisms of the cellular aging model of stress-induced premature senescence (SIPS) in TIG-1 human fibroblasts. SIPS was induced by a sublethal dose of H2O2 and chronic oxidative stress with repeat treatment of low-dose H2O2. Reactive oxygen species generation, lipid peroxidation, and senescence-associated beta-galactosidase activity were elevated in TIG-1 cells under SIPS induced by H2O2. However, Kangen-karyu extract led to significant declines in these parameters, suggesting its role in ameliorating oxidative stress-related aging. It was also observed that SIPS due to H2O2 treatment led to the loss of cell viability, whereas Kangen-karyu extract improved cell viability by attenuating H2O2-induced oxidative damage. TIG-1 cells under the condition of SIPS caused by sublethal and chronic low doses of H2O2 showed nuclear factor-kappaB (NF-kappaB) translocation to the nucleus from the cytosol, while Kangen-karyu extract inhibited NF-kappaB nuclear translocation, implying that Kangen-karyu extract could exert an anti-aging effect through NF-kappaB modulation. In addition, treatment with Kangen-karyu extract under H2O2-induced chronic oxidative stress normalized the cell cycle by reducing the number of cells in the G0/G1 phase and elevating the proportion of those in the S phase, indicating the role of Kangen-karyu extract in cell cycle regulation. On the other hand, Kangen-karyu extract did not exert such an effect on cell cycle regulation under acute oxidative stress induced by sublethal H2O2. Furthermore, treatment with Kangen-karyu extract prolonged the lifespan of TIG-1 cells under SIPS. The present study suggests that Kangen-karyu might play a therapeutic role against the aging process caused by oxidative stress.