Figure 2.

Effect of EGCG on skin hydration via inhibition of NMF degradation. (a) under UVB irradiation, the viability of HaCaT cells with and without EGCG was measured by MTT assay; (b) mRNA expression of HYAL-1,2,3, and 4 was determined by RT-PCR in HaCaT cells after irradiation with UVB (30 mJ/cm²) for 24 h and treatment with EGCG (0–25 μM) or retinol (10 μg/mL). The relative density of HYAL expression was also measured. Statistical significance of results ((a) and bottom panel of (b)) was evaluated by Kruskal–Wallis/Mann–Whitney test. All data are expressed as means ± SD of an experiment. * p < 0.05 and ** p < 0.01 compared with control group.