3.4.4. Alamar Blue Assay

To assess the cytotoxicity of GCE, KTE and EAE extracts and evaluate their effect on cell viability, the Alamar Blue (AB) test (Sigma, R7017, Life Tecnologies, Bleiswijk, Netherlands) was used. Test were performed in accordance with the procedure previously described by Nizioł-Łukaszewska et al. [80,81]. After 24 h exposure of HaCaT and BJ cells to analyzed extracts in the concentration range of 10–1000 μg/mL, a solution of resazurin (60 μM) was added to each well. The plates were then incubated at 37 °C for 2 h. After incubation, fluorescence measurements were carried out at λ = 570 nm using a FilterMax F5microplate reader (Thermo Fisher Scientific, Waltham, MA, USA). Three independent experiments were performed to assess cytotoxicity using the AB assay. Results are expressed in graphs as a percentage of cell viability compared to controls (100%).