Figure 6: Cytotoxic effect of tectorigenin. (a) Following 1,2-bis (2-aminophenoxy) ethane-N, N, N', N'-tetraacetic acid/acetoxy methyl (BAPTA/AM) treatment, cells were incubated with fura-2-acetoxy methyl as described in “Materials and methods.” Then, [Ca2+]i measurements were conducted in Ca2+-containing medium. Tectorigenin was added as indicated. (b) Cells were treated with 0–60 µM tectorigenin for 24 h, and cell viability assay was performed. Data are mean ± standard error of the mean of three independent experiments. Each treatment had six replicates (wells). Data are expressed as percentage of control response that is the increase in cell numbers in tectorigenin-free groups. Control had 10,545 ± 285 cells/well before experiments, and had 13852 ± 845 cells/well after incubation for 24 h. *P < 0.05 compared to control. In each group, the Ca2+ chelator BAPTA/AM (5 µM) was added to cells followed by treatment with tectorigenin in medium. Cell viability assay was subsequently performed.