4.4. Sulforhodamine B (SRB) Cell Viability Assay

SRB assay was used to determine cell viability [49], which depended on the measured cellular protein content. The cells were seeded in 96-well plates in triplicate for each condition. After treatment with drugs for 96 h, the cells were fixed using 10% ice-cold trichloroacetic acid (TCA) (Sigma-Aldrich) at 4 °C for 1 h, rinsed four times with distilled water, and air-dried. The cells were then stained with 0.057% SRB (Sigma-Aldrich) in 1% acetic acid for 30 min at 24 °C. After washing four times with 1% acetic acid and being air-dried, 200 µL of 10 mM Tris-base (pH 10.5) was added into each well and incubated for 30 min at 24 °C. The colorimetric readings were performed using a microplate reader at 540 nm.