Fig 4. Protective effect of 9-Phe against H₂O₂-induced death in H9c2 cardiomyocytes.

(A) Dose-dependent impact of H₂O₂ on cell viability. Cultures of H9c2 cells were exposed 4 h to DMEM medium containing 0, 100, 200, 300, 400, or 500 μM H₂O₂, then viability was measured by MTT assay. Asterisks indicate significantly lower viability (absorbance) than for the control (0 μM H₂O₂). n = 4 for each concentration. (B) Impact of 9-Phe on the H₂O₂ challenge. Cultures were incubated 4 h with 200 μM H₂O₂ in the presence of DMSO or 20 μM 9-Phe. The 9-Phe completely prevented the damage caused by H₂O₂. n = 5 for each condition. * p < 0.05, ** p < 0.01, N.S.: p > 0.05.