JOURNAL OF COSMETIC SCIENCE 26 effects on the amelioration of cytotoxicity, sacran gave a signifi cantly higher reduction in cytotoxicity than HA (Figure 5). Regarding levels of intracellular oxidation, tobacco smoke strongly elevated intracellular ROS levels associated with intracellular CPs. Sacran signifi cantly suppressed the eleva- tion of intracellular ROS levels (Figure 6) and intracellular CPs (Figure 7). Although HA reduced levels of intracellular ROS, it failed to signifi cantly suppress levels of intracel- lular CPs. BARRIER FUNCTION OF POLYSACCHARIDES AGAINST TOBACCO SMOKE In the ex vivo study, corneocytes exposed to tobacco smoke for 2 h had increased levels of CPs. Polysaccharide-treated corneocytes showed signifi cantly lower levels of CPs af- ter exposure to tobacco smoke than nontreated corneocytes. In addition, when exposed to tobacco smoke, sacran gave signifi cantly lower CP levels in corneocytes than HA (Figure 8). Figure 5. Amelioration of the cytotoxicity induced by tobacco smoke on HaCaT keratinocytes. HaCaT ke- ratinocytes were cultured in DMEM containing PBS diffused with tobacco smoke through fi lters treated with or without sacran or HA for 24 h at 37°C. Cell viability was measured using the neutral red assay and is ex- pressed as a percentage against sham-treated cells (Control(-)). Each value represents the mean ± SD of six experiments. Wilcoxon rank-sum test, ***p 0.001.

SACRAN PROTECTS SKIN AGAINST POLLUTANTS 27 DISCUSSION This study aimed to investigate the antipollution effects of sacran using tobacco smoke as a representative air pollutant. In a previous study, we identifi ed the unique characteristics of sacran that result in the formation of a gel-like sheet. That gel-like sheet suppresses water evaporation and penetration by chemicals (23). The application of a sacran solution improves itching and facial rashes in patients with atopic dermatitis based on a question- naire survey (24). In addition, sacran showed improvement of corneocyte maturation in healthy volunteers who had a history of atopic dermatitis (24). These effects have been considered to be based on the shielding effects of the skin against external stimuli due to the physicochemically unique properties of sacran. Thus, sacran is also expected to have protective effects against air pollutants. To identify the potential effects of sacran against air pollutants, we conducted various examinations focusing on oxidative stress using tobacco smoke as a representative air pollutant. Furthermore, to demonstrate whether sacran ex- hibits specifi c effects, we also examined the effects of HA, which is commonly formulated as an anionic polysaccharide in cosmetic products. In this study, to evaluate the effects of sacran, the effects of HA were compared as a representative polysaccharide. Figure 6. Amelioration of ROS generation induced by tobacco smoke in HaCaT keratinocytes. HaCaT kerati- nocytes were cultured in DMEM containing PBS diffused with tobacco smoke through fi lters treated with or without sacran or HA for 24 h at 37°C. Intracellular ROS levels were measured using H2DCFDA. Each value represents the mean ± SD of six experiments. Wilcoxon rank-sum test, ***p 0.001. Control(-) denotes sham-treated cells and Control(+) denotes cells treated with tobacco smoke diffused through a nontreated fi lter.