Neuroprotective effects of (arylthio)cyclopentenone derivatives on manganese-induced apoptosis in PC12 cells

Parkinson's disease is characterized by degeneration of dopaminergic neurones in the substantia nigra. Chronic manganese poisoning shares many features of Parkinson's disease, and also induces extrapyramidal syndromes that resemble those of Parkinson's disease due to dopamine depletion in the central nervous system. This study was undertaken to develop novel neuroprotective drugs via the identification of compounds that inhibit manganese-induced apoptosis. Here, we report that (arylthio)cyclopentenone derivatives, which are synthetic analogs of cyclopentenone prostaglandins, prevent manganese-induced apoptosis in PC12 cells. A highly sensitive assay of caspase-3/7 activity was used for screening newly synthesized prostaglandin analogs. The results showed that some cyclopentenone derivatives (GIF-0642, GIF-0643, GIF-0644, GIF-0745, and GIF-0747) inhibit manganese-induced caspase-3/7 activation in a concentration-dependent manner. Effective compounds all have an arylthio group, indicating that this structure plays an important role in the anti-apoptotic effects of (arylthio)cyclopentenone derivatives. The anti-apoptotic effects of these compounds were confirmed by verifying their ability to inhibit the DNA fragmentation and caspase-9 activation induced by manganese. Furthermore, GIF-0747 prevented manganese-induced cytochrome c release from mitochondria. These results suggest that (arylthio)cyclopentenone derivatives may be good candidates for treating neurodegenerative diseases.