Compounds

VOSL was prepared as previously described [9]. Briefly, ten g of Saussurea lappa roots were crushed into powder, and extracted with 100 mL of hexane for 1h, The filtrates were evaporated to get VOSL, and then were analyzed by ultraperformance liquid chromatography coupled to quadrupole-time-of-flight mass spectrometer (Waters, Milford, MA, USA). Commercial Cos and Dehy were purchased from Shanghai Yuanye Biotech CO., Ltd and its purity is more than 98%. VOSL, Cos and Dehy were dissolved in dimethyl sulfoxide to 10 mg/mL, and then diluted to appropriate concentrations with cell culture medium.