Unknown

Leukemia cells (CCRF–CEM and HL-60), colon cancer cells (HCT116) and human glioblastoma multiforme U87MG cells were used for activity evaluation. Adherent cells were detached by treatment with 0.25% trypsin/EDTA (Invitrogen) and an aliquot of 1 x 10^4 cells was placed in each well of a 96-well cell culture plate (Thermo Scientific, Germany) in a total volume of 200 mkl. Cells were allowed to attach overnight and then were treated with different concentrations of compounds. For suspension cells, aliquots of 2 x 10^4 cells per well were seeded in 96-well-plates in a total volume of 100 mkl. The studied sample was immediately added in varying concentrations in an additional 100 mkl of culture medium to obtain a total volume of 200 mkl/well. After 24 h or 48 h, 20 mkl resazurin (Sigma–Aldrich, Germany) 0.01% w/v in ddH2O was added to each well and the plates were incubated at 37 ◦C for 4 h. Fluorescence was measured on an Infinite M2000 ProTM plate reader (Tecan, Germany) using an excitation wavelength of 544 nm and an emission wavelength of 590 nm.