Disubstituted Dithiolethione ACDT Exerts Neuroprotective Effects Against 6-Hydroxydopamine-Induced Oxidative Stress in SH-SY5Y Cells

Abstract

Parkinson's disease (PD) is a prevalent, progressive, neurodegenerative disorder with no known cure. Oxidative stress has been found to play a significant role in its etiology, and the search for novel neuroprotective compounds that actively prevent disease progression is currently ongoing. Dithiolethiones are a group of sulfur-containing heterocyclic compounds found in cruciferous vegetables. Using the 6-hydroxydopamine (6-OHDA) model of PD, we tested a previously identified disubstituted dithiolethione 5-amino-3-thioxo-3H-(1,2) dithiole-4-carboxylic acid ethyl ester (ACDT) for its neuroprotective potential. Pretreatment of SH-SY5Y cells with ACDT led to a time- and concentration-dependent induction of the antioxidant glutathione (GSH). ACDT also diminished 6-OHDA-induced cell death, lactate dehydrogenase release, elevation of caspase 3/7 activity, and increase in levels of reactive oxygen species. Inhibition of the GSH-synthesizing enzyme glutamate-cysteine ligase catalytic subunit (GCLC) led a corresponding dissipation of ACDT's neuroprotective effects, hence underlining the importance of GSH in ACDT's neuroprotective response. ACDT caused the stabilization and nuclear translocation of nuclear factor erythroid-2 related factor (Nrf2), resulting in increased protein expression of the phase II enzyme NADPH:quinone oxidoreductase 1 (NQO1), and the excitatory amino acid cysteine membrane transporter (EAAT3). Interestingly, no changes in the levels of other Nrf2-dependent molecules including GCLC were observed, indicating the possible involvement of additional alternate mechanisms behind ACDT's GSH-inducing property. Collectively, the data demonstrated ACDT to be a promising new dithiolethione for the treatment of PD, with two modifiable functional groups offering additional avenues for enhanced pharmacological application.

Keywords: ACDT; Dithiolethione; Glutathione; Neuroprotection; Nrf2; Oxidative stress.