SIH - A novel lipophilic iron chelator - Protects H9c2 cardiomyoblasts from oxidative stress-induced mitochondrial injury and cell death

Recent evidence suggests that oxidative stress is a common denominator in many aspects of cardiovascular pathogenesis. Free cellular iron plays a crucial catalytic role in the formation of highly toxic hydroxyl radicals, and thereby it may aggravate the contribution of oxidative stress to cardiovascular disease. Therefore, iron chelation may be an effective therapeutic approach, but the progress in this area is hindered by the lack of effective agents. In this study, using the rat heart myoblast-derived cell line H9c2, we aimed to investigate whether the novel lipophilic iron chelator salicylaldehyde isonicotinoyl hydrazone (SIH) protects the cells against hydrogen peroxide (H₂O₂)-induced cytotoxicity. Exposure of cells to 100 μmol/l H₂O₂ has within 4 h induced a complete dissipation of their mitochondrial membrane potential (ΔΨ_m) . Co-treatment with SIH dose-dependently reduced (EC₅₀ = 0.8 μmol/l) or even completely abolished (3 μmol/l) this collapse. Furthermore, the latter SIH concentration was capable to fully prevent alterations in cell morphology, and inhibited both apoptosis (annexin-V staining, nuclear chromatin shrinkage, TUNEL positivity) and necrosis (propidium iodide staining), even 24 h after the H₂O₂ exposure. In comparison, deferoxamin (a commercially available hydrophilic iron chelator used in clinical practice and most previous studies) was cytoprotective only at three-order higher and clinically unachievable concentrations (EC₅₀ = 1300 μmol/l). Thus, in this study, we present iron chelation as a very powerful tool by which oxidative stress-induced myocardial damage can be prevented.