1-Methyl 4-phenylpyridinium Ion (MPP+) a neurotoxin selective to dopaminergic neurons and an inhibitor of mitochondrial complex I has been widely used as an etiologic model of Parkinson s disease In this study we investigated the protective effects of a novel synthetic compound 8-Phenyl-6a,7 89 9a,10-hexahydro-6H-isoindolo [5 6-g]quinoxaline-7 9-dione (PHID) on MPP+ induced cytotoxioty in SH-SY5Y cells MPP+ induced apoptosis characterized by generation of reactive oxygen species caspase-3 activation poly ADP ribose polymerase proteolysis and increase in Bax/Bcl 2 ratio were blocked by PHID in a dose dependent fashion Furthermore MPP+ mediated activation of stress-activated protein kinase/c-Jun N-terminal kinase (JNK) was also inhibited by PHID in a dose-dependent manner The results indicate that PHID protects against MPP+-Induced apoptosis by blocking reactive oxygen species stimulation and JNK signaling pathways in SH-SY5Y cells implicating the novel compound in the prevention of progressive neurodegenerative diseases such as Parkinson s disease (C) 2010 Elsevier B V All nghts reserved