Synthesis of Dithiolethiones and Identification of Potential Neuroprotective Agents via Activation of Nrf2-Driven Antioxidant Enzymes.

Oxidative stress is implicated in the pathogenesis of a wide variety of neurodegenerative disorders, and accordingly, dietary supplement of exogenous antioxidants or/and upregulation of the endogenous antioxidant defense system are promising for therapeutic intervention or chemoprevention of neurodegenerative diseases. Nrf2, a master regulator of the cellular antioxidant machinery, cardinally participates in the transcription of cytoprotective genes against oxidative/electrophilic stresses. Herein, we report the synthesis of 59 structurally diverse dithiolethiones and evaluation of their neuroprotection against 6-hydroxydopamine- or H2O2-induced oxidative damages in PC12 cells, a neuron-like rat pheochromocytoma cell line. Initial screening identified compounds 10 and 11 having low cytotoxicity but conferring remarkable protection on PC12 cells from oxidative-mediated damages. Further studies demonstrated that both compounds upregulated a battery of antioxidant genes as well as corresponding genes' products. Significantly, silence of Nrf2 expression abolishes cytoprotection of 10 and 11, indicating targeting Nrf2 activation is pivotal for their cellular functions. Taken together, the two lead compounds discovered here with potent neuroprotective functions against oxidative stress via Nrf2 activation merit further development as therapeutic or chemopreventive candidates for neurodegenerative disorders.