KR 31378, a Potent Antioxidant, Inhibits Apoptotic Death of A7r5 Cells

This work describes the pharmacological inhibition by KR 31378 and its acetyl metabolite, KR 31612, of the apoptotic cell death induced by $H_2O_2$ in the A7r5 cells. Exposure of A7r5 cells to $H_2O_2$ (0.5 mM) induced a concentration-dependent cytotoxicity in association with oligonucleosomal DNA fragmentation. $H_2O_2-induced$ cell death was potently suppressed by KR 31378, KR 31612, ${\alpha}-tocopherol$ or trolox. Additionally, the apoptotic death of A7r5 cells (DNA ladders on electrophoresis) was also strongly suppressed by KR 31378 and KR 31612, but to a less degree by ${\alpha}-tocopherol$ and trolox. As a mechanistic study, incubation with $H_2O_2$ markedly showed a decreased Bcl-2 level and, in contrast, increased Bax protein and cytochrome C release, which were significantly and concentration-dependently reversed by KR 31378 and KR 31612 as well as by ${\alpha}-tocopherol$ and trolox. KR 31378 and ${\alpha}-tocopherol$ significantly reduced lipid peroxidation in accordance with reduced intracellular ROS and peroxyl radical. These results suggest that KR 31378 has a therapeutic potential against the apoptotic injury via mediation of anti- oxidative stress.