Mulberrofuran G Protects Ischemic Injury-induced Cell Death via Inhibition of NOX4-mediated ROS Generation and ER Stress

The aim of this study was to investigate the neuroprotective effect of mulberrofuran G (MG) in in vitro and in vivo models of cerebral ischemia. MG was isolated from the root bark of Morus bombycis. MG inhibited nicotinamide adenine dinucleotide phosphate oxidase (NOX) enzyme activity and oxygen–glucose deprivation/reoxygenation (OGD/R)-induced NOX4 protein expression in SH-SY5Y cells. MG inhibited the expression of activated caspase-3 and caspase-9 and cleaved poly adenine dinucleotide phosphate-ribose polymerase in OGD/R-induced SH-SY5Y cells. In addition, MG protected OGD/R-induced neuronal cell death and inhibited OGD/R-induced reactive oxygen species generation in SH-SY5Y cells. In in vivo model, MG-treated groups (0.2, 1, and 5 mg/kg) reduced the infarct volume in middle cerebral artery occlusion/reperfusion-induced ischemic rats. The MG-treated groups also reduced NOX4 protein expression in middle cerebral artery occlusion/reperfusion-induced ischemic rats. Furthermore, protein expression of 78-kDa glucose-regulated protein/binding immunoglobulin protein, phosphorylated IRE1α, X-box-binding protein 1, and cytosine enhancer binding protein homologous protein, mediators of endoplasmic reticulum stress, were inhibited in MG-treated groups. Taken together, MG showed protective effect in in vitro and in vivo models of cerebral ischemia through inhibition of NOX4-mediated reactive oxygen species generation and endoplasmic reticulum stress. This finding will give an insight that inhibition of NOX enzyme activity and NOX4 protein expression could be a new potential therapeutic strategy for cerebral ischemia.