2.7. Determination of intracellular reduced glutathione (GSH) levels

GSH levels were determined in Caco-2 cells, grown and differentiated in 6-well plates (5 ×10⁴ cells/ml in 2 ml). After preincubation with the phenolic extract, cells were treated with the oxysterol mixture for 1 h.

After treatment cells were scraped into 200 μl of ice-cold PBS and centrifuged at 10000 g for 20 min at 4 °C. The pellet was used to determine GSH levels through EC-HPLC quantification (Agilent 1260 infinity coupled with an electrochemical detector DECADE II Antec, Leyden, Netherlands) [29].