467 DELIVERING SUSTAINABLE SOLUTIONS TO IMPROVE WELLBEING
Figure 13. Relative gene expression in HDFa cocultured with HEKa treated at different concentrations of S
rebaudiana extract for 24 hours. Data shown as MEAN ± SEM of the mean of six independent experiments
performed in duplicates. Statistical significance: *p 0.05, calculated using an unpaired student’s t test.
Figure 14. (A) Percentage of type I collagen synthesis and elastin in HDFa and HEKa cocultures treated
with S rebaudiana extract for 48 hours (for collagen) or 72 hours (for elastin) respect to control. Data shown
as MEAN ± SEM of the mean of four to five independent experiments performed in triplicates. Statistical
significance: **p 0.01, calculated using an unpaired Student’s t test. B) %MMPs synthesis in HDFa
and HEKa cocultures treated with stevia rebaudiana extract for 24 hours respect to control. Data shown as
MEAN ± SEM of the mean of 4 independent experiments performed in triplicates. Statistical significance:
**p 0.01, ****p 0.0001, calculated using an unpaired student’s t test.

468 JOURNAL OF COSMETIC SCIENCE
To evaluate the antioxidant capacity of stevia extract obtained through different extraction
methods, the samples were analyzed using the ORAC test (Figure 16). The stevia extract
obtained through subcritical water technology resulted in a much higher antioxidant
efficacy compared to the extract derived from common extraction processes with glycerin
or water, which suggests a higher recovery of antioxidant compounds with the subcritical
water technology.
Moreover, stevia extract was found to downregulate the expression of the cyclooxygenase-2
(COX-2) enzyme gene by 65% (data not shown) in HEKa treated with 0.37% S rebaudiana
extract for 24 hours. COX-2 encodes an enzyme responsible for producing inflammatory
prostaglandins and is a key player in the induction of inflammatory responses. The
Figure 15. Relative gene expression (fold change) in HDFa cultures treated with S rebaudiana extract at 1.1%
for 24 hours respect to control that is evaluated by microarray analysis.
Figure 16. Antioxidant capacity for stevia extract versus common extraction methodologies analyzed by
ORAC test.