Osajin was administrated to rats orally in doses of 5, 10 and 20 mg/kg once a day

Three different types of human NPC cell lines: TW076 (type 1 NPC, squamous cell carcinoma, EBV negative) [49], CG1 (type 2 NPC, non-keratinizing carcinoma, EBV positive) and TW04 (type 3 NPC, undifferentiated carcinoma, EBV negative) were used for activity evaluation. y, NPC cells were seeded in 96-well plates (56103 /well) and allowed to adhere for 24 h. The medium was then substituted by a fresh one containing different concentrations (0.01–10 mM) of osajin for another 24 h. For the time-course assay, the incubation times with 5 mM of osajin were 6, 12, 24, 36 and 48 h. After incubation, 10 ml of 5 mg/ml of MTT was added to each well and incubated for 4 h at 37uC. Elution of the precipitate was performed with 100 ml of solubilization solution. Cell viability was calculated from absorption values obtained at 570 nm using an automated ELISA reader (Cape Code, UK). All experimental concentrations were performed in triplicate.