Fig. 3.

Effect of treatment of LS-180 cells with increasing concentrations of (A) oleocanthal, (B) cembratriene, (C) γ-tocotrienol, (D) asiatic acid, and (E) rifampicin on P-gp expression and activity. Cells were treated for 48 h followed by Western blot analysis for P-gp expression (shown as column bars) and uptake study for P-gp activity (shown as lines). P-gp activity was measured as the ratio of intracellular rhodamine 123 fluorescence in the presence and absence of 100 μM verapamil as P-gp inhibitor. The data is expressed as mean ± SD for P-gp activity (n=3). P-gp expression was determined for n=2. *P < 0.05 compared P-gp activity in untreated and treated cells.