Protective effect of astragaloside Ⅳ against ultraviolet B-induced photodamage to human HaCaT keratinocytes and its mechanisms / 中华皮肤科杂志

ABSTRACT

Objective To evaluate the protective effect of astragaloside Ⅳ against ultraviolet B (UVB)-induced photodamage to human HaCaT keratinocytes,and to investigate its mechanisms.Methods Culturedimmortalized human HaCaT keratinocytes were divided into four groupsblank control group receiving untreated,UVB group irradiated with 50 mJ/cm2 UVB,astragaloside Ⅳ group treated with astragaloside Ⅳ,UVB + astragalosideⅣ group treated with astragaloside Ⅳ for 24 hours before and after 50 mJ/cm2 of UVB radiation.The concentration ofastragaloside Ⅳ ranged from 10 to 200 mg/L in cell proliferation assay,and according to the results of proliferationassay,20 mg/L was determined as the optimal concentration in the other assays.At 24 hours after UVB radiation,cellcounting kit-8 (CCK8) assay was performed to evaluate cellular proliferative activity,flow cytometry to determineintracellular reactive oxygen species (ROS) levels,and Western blot to measure the expression levels of p53,p38,matrix metalloproteinase-9 (MMP-9) and high mobility group Al (HMGA-1) protein in HaCaT cells.ResultsCompared with the control group,astragaloside Ⅳ at 10 and 20 mg/L had no inhibitory effect (F =1.32,P ＞ 0.05),while astragaloside Ⅳ at 50,100 and 200 mg/L showed significantly inhibitory effect (F =20.20,P ＜ 0.05),on theproliferation of HaCaT cells.In addition,cellular proliferative activity in the UVB group was significantly lower thanthat in the control group (F =99.00,P ＜ 0.01).Compared with the UVB group,cellular proliferative activityincreased to different degrees in HaCaT cells treated with both UVB and astragaloside Ⅳ of 10-200 mg/L (F =19.08,P ＜ 0.01),with the strongest increase observed in those treated with UVB and astragaloside Ⅳ of 20 mg/L.Further experiments revealed reduced intracellular ROS levels in the UVB + astragaloside Ⅳ (20 mg/L) groupcompared with the UVB group (t =21.12,P ＜ 0.01).Western blot assay showed that the expression levels of p53,p38,MMP-9 and HMGA-1 protein were significantly higher in the UVB group than in the control group (all P ＜0.01),but significantly lower in the UVB + astragaloside Ⅳ (20 mg/L) group than in the UVB group (all P ＜ 0.01).Conclusion Astragaloside Ⅳ can effectively protect keratinocytes from UVB-induced photodamage.