光甘草定的美白作用及其机制OA

This study aimed to investigate the whitening effect of glabridin(GLA)and its mechanism.A mouse model of ultraviolet B(UVB)-induced skin photoaging(SP)mice was used.The mice were randomly assigned to 6 treatment groups(n=12),which were control group(C group),UVB group,low,medium and high dose glabridin group(L,M,H-GLA),and high dose glabridin+nuclear factor E2-related factor 2(Nrf2)inhibitor ML385 group(H-GLA+ML385).Group C was conventionally fed without UVB irradiation,while the other groups were subjected to UVB irradiation.Each group received percutaneous administration 1 h before UV exposure once daily for 8 weeks.The skin was analyzed by hematoxylin and eosin(HE)staining and Masson's trichrome staining.Melanin content was determined by the NaOH dissolution method.Tyrosinase activity was detected by ELISA.The activities of superoxide dismutase(SOD),catalase(CAT),and glutathione peroxidase(GSH-Px)and the content of malondialdehyde(MDA)were determined using commercial kits.Reactive oxygen species(ROS)were detected by dihydroethidium(DHE)staining.The levels of interleukin-6,tumor necrosis factor-α(TNF-α)and IL-1β in skin tissue were detected by ELISA.mRNA levels of type I collagen α1 chain(COL1A1),matrix metalloproteinase-1(MMP-1),tyrosinase-associated protein(TRP)-1,TRP-2,heme oxygenase-1(HO-1)and NAD(P)H:quinone oxidoreductase-1(NQO-1)were detected by RT-qPCT.Western blot was used to analyze protein expression of α-MSH,Nrf2(nuclear)and Keap1 in the skin.The results show that compared with the UVB group,the three doses of glabridin(L,M and H-GLA groups)alleviate UVB-induced skin damage and collagen degeneration in the skin photoaging mice,decrease the level of MMP-1 mRNA and increase the level of COL1A1 mRNA.decrease skin melanin content,tyrosinase activity,the levels of TRP-1 and TRP-2 mRNA,the relative expression level of α-MSH protein,increase the skin SOD,CAT and GSH-Px activities,decrease MDA content and ROS relative fluorescence intensity,and decrease skin IL-6,TNF-α and IL-1β contents,increase the expression level of Nrf2(nuclear)protein,and HO-1 and NQO-1 mRNA,and decrease the relative expression level of Keap1 protein(P<0.05).However,the Nrf2 inhibitor ML385 attenuates the above effects of glabridin(P<0.05).These results indicate that glabridin alleviates UVB-induced skin damage and collagen degeneration,inhibits melanin production,and reduces oxidative stress and inflammation in mice with skin photoaging by activating Nrf2.