Figure 3. Molecular mechanisms responsible for cytotoxicity.

(A) sGC/cGMP involvement was evaluated by the use of 10 µM ODQ (30 min pretreatment) in survival assay of A549 cells treated with 0.5 mM Ni(SalPipNONO). Cell survival was evaluated by MTT. ^*p < 0.05, ^***p < 0.001 vs untreated cells. (B) Oxidative stress involvement was assessed by measuring ROS levels in A549 cells treated with Ni(SalPipNONO) and Ni(SalPip)Cl in the presence of different serum concentrations. NAC pretreatment (5 mM, 30 min) was used as a ROS scavenger. ^***p < 0.001 vs untreated cells. (C) The contribution of NONO or salicylaldehyde moiety was evaluated by testing the cytotoxicity of molecules devoid of the NONO or salicylaldehyde group (each at 0.5 mM). Data are reported as relative absorbance of the MTT assay after 72 h incubation. ^**p < 0.01 and ^***p < 0.001 vs untreated cells.