Abstract

Background

Phytol is a component of chlorophyll with demonstrated anticancer and immune-enhancing effects. In particular, it has been reported that phytol enhances the activity of natural killer cells that detect and remove cancer cells and promotes macrophage functions in immunity. In this study, based on the recently published precedent articles, we examined whether phytol can also inhibit cellular senescence to provide evidence for its possible use as a base material for cosmetics.

Methods

HaCaT keratinocytes were pretreated with phytol for 24 h and then treated with oxidative stress-inducing hydrogen peroxide (H₂O₂) for 6 h before the analysis; anti-inflammation analysis, cell cycle analysis, cytoprotection analysis, caspase 3 (CASP3) activity analysis, and senescence-associated β-galactosidase (SA-β-gal) assay were performed to examine the cell potency of phytol.

Results

In this study, HaCaT keratinocytes, treated with 750 μM H₂O₂, were tested with a phytol concentration below 10 μM to obtain the following results. First, phytol pretreatment suppressed H₂O₂-induced inflammation in a concentration-dependent manner, as indicated by the reduced expression of the mRNA levels of TNF-α (tumor necrosis factor-alpha), IL6 (interleukin 6), IL8 (interleukin 8), and COX2 (cyclooxygenase 2). Second, the quantitative analysis of cell cycle, NRF2 (nuclear factor erythroid 2-related factor 2), HO-1 (heme oxygenase 1), 14-3-3σ (Stratifin), cyclin B mRNA, and CASP3 was performed to examine the cytoprotective effects of phytol, as evidenced by increased mRNA expression of the cytoprotective genes NRF2 and HO-1 and decreased mRNA expression of the G2 cell cycle arrest-inducing genes 14-3-3σ and Cyclin B. CASP3, a protein that induces apoptosis, was reduced in a concentration-dependent manner, confirming that phytol protected cells from apoptosis. Third, the SA-β-gal assay revealed that phytol reduced H₂O₂-induced senescence in a concentration-dependent manner, and the cellular senescence was delayed on treatment using phytol.

Conclusions

This study verifies that phytol can inhibit oxidative stress-induced senescence of HaCaT keratinocytes. The results suggest the use of phytol as a base material for cosmetics to inhibit cellular senescence.