2.4. Cell viability assays
Cell viability assay was performed using the MTT photometric
analysis and trypan blue dye exclusion method. Briefly, cells
were plated in wells of 12-well plates and incubated for 24 h
at 37 C. Cells were treated with or without the extracts. At
the end of the treatment, the medium was removed and cells
were incubated with 20 ll of MTT (5 mg/ml in phosphate buffered
saline; PBS) in fresh medium for 4 h at 37 C. After 4 h,
formazan crystals, formed by mitochondrial reduction of
MTT, were solubilized in DMSO (150 ll/well). After mixing,
the absorbance of the cells was measured at 540 nm nm after
10 min incubation on the iMark Microplate Reader BioRad
(Hercules, CA, USA). The dye exclusion method was performed
by calculating the number of died cells over the
control.