(a) Comparison of the cytotoxic effect of 2 against
HT29 and A549 cells in the absence and presence of light (λ
= 400–700 nm, 23 mW cm–2, 28 J cm–2). Comparison of the cytotoxic effect of 2, 4, and 11 against (b) HT29 and (c) A549 cells. For the
treatment with 2 and 4, light irradiation
(λ = 400–700 nm, 23 mW cm–2, 28 J cm–2) was also applied. The concentrations for 4 and 11 were multiplied by 3 in the figures. For (a)–(c),
data are expressed as the mean ± SEM of three independent experiments,
each performed in quadruplicate. (d) Variation of the combination
index with the IC value determined from the dose-dependent survival
curves of 2, 4, and 11 against
HT29 and A549 cells.