Ethanol extract of Gynura bicolor (GB) protects against UVB-induced photodamage of skin by inhibiting P53-mediated Bcl-2/BAX/Caspase-3 apoptosis pathway

To investigate the protective effect of ethanol extract of Gynura bicolor (GB) against UVB-induced photodamage of skin and the possible mechanisms. DPPH (1,1-diphenyl-2-pico radical) test was used to detect the antioxidant capacity of ethanol extract of Gynura bicolor (GB). The protective effects of GB against UVB irritation were detected both in Hacat cells and photodamage rat models. UVB irradiation could inhibit viability and induce apoptosis of Hacat cells in a dose-dependent manner. The pretreatment of Hacat cells by GB could obviously reverse the effects in a dose-dependent manner. The mRNA and protein expressions of p53, Bax, caspase-3 were increased, while anti-apoptotic protein Bcl-2 was decreased and this effect could be reversed by GB pretreatment in a dose-dependent manner. In vivo, the application of GB could alleviate the skin damage of SD rats and improve the superficial inflammation of the dermis as well as inhibit the expressions of P53 and Caspase-3 induced by UVB irradiation. Ethanol extract of Gynura bicolor could protect the photodamage of human Hacat keratinocytes and SD rats against UVB irradiation by inhibiting P53-mediated Bcl-2/ BAX/Casaspe-3 apoptosis pathway.