Inhibitory effects of HTNs 1-3, and PBN on ROS (superoxide) production in SHSY5Y human neuroblastoma cell cultures exposed to oxygen glucose deprivation (4 h) and ischemic reperfusion (3 h). Bars shows % ROS formed after OGD and IR alone (IR 3 h) or after treatment with HTNs 1-3 and PBN, at the indicated concentration concentrations. Values are then mean ± SEM of three experiments, each one performed in triplicate. Values for ROS in IR were calculated as 1.98 ± 0.25 UAF/min/150,000 cells. The statistics compare the effect of IR against the corresponding control (red ***) or the effect of the different compounds respect to IR alone (red dotted line), (black ***) at * p < 0.05, ** p < 0.01, *** p < 0.001 (one-way ANOVA followed by Holm–Sidak analysis post hoc).