Figure 2.

(a) Effect of the C. sinensis extract (CsEx) on the expressions of Sirtuins 1, 3, and 6 in keratinocytes. The keratinocytes were stimulated with 0.0006% CsEx or with resveratrol as a positive control for 6 h and then processed for RT-PCR analysis. (b) The NAD/NADH ratio was determined in HaCaT cells after 24 h of treatment with CsEx or resveratrol. The reported values represent the averages of three independent experiments; the control was set to 100%. The bars represent the standard deviations, and the asterisks indicate the p-value according to Student’s t test (* p < 0.05, ** p < 0.01, *** p < 0.001).