The effect of cafestol and kahweol on cell viability in MSTO-211H cells. (A) Chemical structure of cafestol and kahweol. The cell viability effect of cafestol and kahweol on MSTO-211H (B) or H28 (C) cells. MSTO-211H cells or H28 were treated with cafestol and kahweol in FBS-RPMI 1640 for various time. The viability of cells were determined with the MTS assay kit, as described under “Material and Methods”. Results are indicated as cell viability relative to untreated controls with cafestol and kahweol, as determined from three independent experiments. Data are represented as the mean ± SD. The asterisk indicated a significant difference compared with the negative control (p < 0.05). (D) The cell morphological changes of MSTO-211H cells treated or untreated with cafestol and kahweol for 48 hours.