Figure 1.

Evaluation of the effect of the Southern (A,C) and Northern (B,D) medium-polar (mp) and polar (p) leaves fractions on cell viability of HEK293 cells. Cell viability was assessed by MTT assay at two time points, 6 h (A,B) and 48 h (C,D). Relative cell viability is expressed as cell viability of the fractions at the indicated concentrations compared to control vehicle-treated cells. Cell viability of control cells was set at 1. Data are expressed as the mean ± SD, (n = 5–9), ** p < 0.01; *** p < 0.001.