A superoxide anion generator, pyrogallol induces apoptosis in As4.1 cells through the depletion of intracellular GSH content

We investigated the involvement of ROS such as H₂O₂ and O₂{radical dot}^-, and GSH in As4.1 cell death induced by pyrogallol. The intracellular H₂O₂ levels were decreased or increased depending on the concentration and incubation time of pyrogallol. The levels of O₂{radical dot}^- were significantly increased. Pyrogallol reduced the intracellular GSH content. And ROS scavengers, Tempol, Tiron, Trimetazidine and NAC could not significantly down-regulate the production of H₂O₂ and O₂{radical dot}^-. However, these ROS scavengers slightly inhibited apoptosis. Interestingly, Tempol showing the recovery of GSH depletion induced by pyrogallol significantly decreased apoptosis without the significant reduction of intracellular O₂{radical dot}^- levels. SOD and catalase did not change the level of H₂O₂ but decreased the level of O₂{radical dot}^-. The inhibition of GSH depletion by these was accompanied with the decrease of apoptosis, as evidenced by sub-G1 DNA content, annexin V staining, mitochondria membrane potential (ΔΨ_m) and Western data. In addition, ROS scavengers and SOD did not alter a G2 phase accumulation of the cell cycle induced by pyrogallol. However, catalase changed the cell cycle distributions of pyrogallol-treated cells to those of pyrogallol-untreated cells. In summary, we have demonstrated that pyrogallol potently generates ROS, especially O₂{radical dot}^-, in As4.1 JG cells, and Tempol, SOD and catalase could rescue to a lesser or greater extent cells from pyrogallol-induced apoptosis through the up-regulation of intracellular GSH content.