MTT assay

MTT colorimetric assay was used to detect cell viability. HGC-27 and AGS cells were cultured into 96-well plates at a density of 5×10³ cells/well. MTT (5 mg/ml) was then added to each well at four time points (0, 24, 48 and 72 h). After 4 h incubation at 37°C, acid isopropanol was added to each well. The cell samples were then mixed until the dark blue crystals dissolved completely. A microplate reader was used to read the absorbance at 570 nm. The triplicate repeated readings for each sample were averaged, and the medium background was subtracted from the analytical readings to correct the absorbance.