cells were treated with various concentrations
of these compounds for 48 h. The cultures were fixed
at 4 °C for 1 h by addition of ice cold 50% trichloroacetic acid
(TCA), to give a final concentration of 10%. Fixed cells were
rinsed five times with deionised water and stained for 10 min
with 0.4% sulforhodamine B dissolved in 1% acetic acid. The
wellswerewashed five timeswith 1% acetic acid and left to dry
overnight. The absorbed sulforhodamine B dissolved in 150 μL
unbuffered 1% Tris base solution in water. The absorbance of
extracted sulforhodamine B at 515 nm was measured on a
microplate reader (Bio-rad, iMark). The experiments were