Protective Effect Of Cryptotanshinone Of Salvia Miltiorrhiza On Skin Cell Damage Induced By Ultraviolet Radiation

Ultraviolet radiation(UVR)is a causative factor for skin damage characterized by erythema,edema,pigmentation,telangiectasia,rough and wrinkles.UVR is also the most important and ubiquitous environmental threat that accelerates human skin aging.UVR-induced oxidative stress appears to be a critical factor in triggering the photodamage.As a commonly used traditional Chinese medicine,salvia miltiorrhiza possess wide range of pharmacological activities including antioxidant,anti-inflammation,improving microcirculation and anti-coagulation.The antioxidant effect of salvia miltiorrhiza has been considered as one of the important mechanisms for its beneficial pharmacological effects though the detailed underlying mechanism is not clear.This study was aimed to evaluate the antioxidant activities of the main active components of salvia miltiorrhiza,screen the components with the highest pharmacological activity and explore the underlying mechanism.This is of great significance for the application of salvia miltiorrhiza in photoprotection.In this study,we first compared the antioxidant activities of danshensu(DSS),salvianolic acid B(Sal B),tanshinone 2A(Tan-2A)and cryptotanshinone(CTS)to screen out the component with the strongest antioxidant activity,and then investigated the photoprotective effect this component on UVR-inflicted damage including mitochondrial dysfunction and aging,and futher explored its potential molecular mechanism.This study can be divided into three sections:(1)Screening the components with the strongest antioxidant activity: UVA and UVB were used to irradiate HFF-1 cells and Ha Ca T cells to induce oxidative damage,respectively.The cells were treated with different concentrations of DSS,Sal B,Tan-2A and CTS,the intracellular ROS level was detected by flow cytometry.It was found that all the four candidate components possess antioxidant activities.Further comparison of the antioxidant activities of DSS,Sal B,Tan-2A and CTS at the same concentration showed that CTS possessed the strongest activity.Therefore,the photoprotective effect of CTS on UVR-induced skin damage and its potential molecular mechanism was explored in the following study.(2)The photoprotective effect of CTS on UVA-induced oxidative stress in HFF-1cells: Pretreatment of the HFF-1 cells with CTS attenuated ROS production caused by UVA exposure,thereby ameliorated mitochondrial dysfunction through elevating the mitochondrial membrane potential as well as increasing the ATP production and the mitochondrial number.In addition,CTS could successfully prevent UVA-induced HFF-1 apoptosis and death as well as inhibit UVA-induced cell senescence.The result obtained from western blot revealed that the protective mechanism of CTS on UVA-induced skin damage might involve the activation of the AMPK/SIRT1/PGC-1α signaling pathway which participate in mitochondrial biosynthesis and the Nrf2 signaling pathway which is a classic antioxidant pathway.(3)The photoprotective effect of CTS on UVB-induced damage on Ha Ca T cells:Treatment with CTS for 0.5 h-12 h before UVB irradiation significantly reduced ROS production in a time-dependent manner.CTS could alleviate UVB-induced DNA damage,elevated mitochondrial membrane potential and up-regulate mitochondrial number and ATP production in UVB-irradiated Ha Ca T cells.CTS also inhibited cell senescence and reduced the death and apoptosis of Ha Ca T cells caused by UVB irradiation.Western blot results revealed that the protective mechanism of CTS on UVB-induced skin damage might involve the activation of the AMPK/SIRT1/PGC-1α signaling pathway and the Nrf2 signaling pathway.Taken together,in this study,CTS was detected to possess strong antioxidant activity through screen of DSS,Sal B,Tan-2A and CTS.CTS reduced the ROS production induced by UVR via activating Nrf2 antioxidant signaling pathway,thereby inhibited the oxidative damage caused by UV radiation,CTS ameliorated mitochondrial dysfunction through promoting the biosynthesis of mitochondria via activating AMPK/SIRT1/PGC-1α pathway,and further preventing the death,apoptosis and senescence of skin cells caused by UVR.These findings may further expand our understanding about the photoprotective effect and mechanism of CTS,also serve as an experimental basis for the application of CTS in protecting human skin against UVR.