Abstract:

The study aimed to investigate the effect of Paulownia fortunei leaf extract （PFLE） on ultraviolet B （UVB）-induced skin photoaging in mice. The mice were divided into 5 groups: normal control group （NC）, model group （M）, low-dose PFLE group （L-PFLE）, medium-dose PFLE group （M-PFLE）, and high-dose PFLE group （H-PFLE）. Mice in NC group were not irradiated. Mice in the other groups were irradiated with UVB using ultraviolet photo-therapy equipment. On the day of UVB irradiation, mice in NC group and M group were smeared with cream on their backs, and mice in L-PFLE, M-PFLE and H-PFLE groups were smeared with 50, 100 and 200 mg/kg PFLE cream, respectively. The UVB irradiation and administration cycles were both 6 weeks. The body weight, skin moisture content, skin oxidative stress indicators （SOD, CAT, GSH-Px and MDA）, HYP and HA levels of the mice were detected. HE staining was used to observe skin morphology. The protein expression levels of Nrf2 （nucleus）, Keap1 and HO-1 in the skin were detected by Western blotting. The transcript levels of MMP-1 and MMP-3 in the skin were detected by RT-qPCR. The results show that compared with M group, the skin moisture content of the mice in L-PFLE group, M-PFLE group and H-PFLE group increases, the skin morphological changes are significantly improved, the levels of SOD, CAT and GSH-Px increase, the MDA level decreases, the relative expressions of Nrf2 （nucleus） and HO-1 protein increase, the relative expression of Keap1 protein decreases, the levels of HYP and HA increase, and the relative expressions of MMP-1 and MMP-3 mRNA decrease （P<0.05）. This study shows that transdermal administration of PELE has a good anti-skin photoaging effect.

Key words: Paulownia fortunei leaf extract, skin photoaging, antioxidant, hydroxyproline, hyaluronic acid