Diethylene glycol and its metabolites induce cell death in SH-SY5Y neuronal cells in vitro

Diglycolic acid inhibits succinate dehydrogenase activity, depletes mitochondrial membrane potential, and induces inflammation in an SH-SY5Y neuroblastoma model of neurotoxicity in vitro

Diethylene glycol is a toxic industrial solvent resulting in a well-defined toxidrome. Diglycolic acid (DGA) has been identified as the metabolite responsible for the nephrotoxicity and hepatotoxicity. These studies assess the mechanism of DGA-induced neurotoxicity, specifically addressing the known ability of DGA to chelate calcium (Ca²⁺) in solution and inhibit mitochondrial complex II. SH-SY5Y cells were seeded into 96-well plates to assess intracellular Ca²⁺ chelation, complex II activity, mitochondrial membrane potential (ΔΨm), ATP production, and release of inflammatory cytokines TNF-α and IL-1β with 2-, 4-, 6-, 24-, and 48-h DGA exposure. Peak Ca²⁺ chelation occurred at 4 h in cells treated with 6.25-50 mM DGA; however, effects were transient. Complex II activity was significantly decreased at all DGA concentrations tested, with 12.5 mM DGA causing 80% inhibition and 25 and 50 mM DGA causing 97 and 100% inhibition, respectively. Subsequently, 12.5-50 mM DGA concentrations significantly decreased ΔΨm at all time points. 50 mM DGA significantly increased release of TNF-α and IL-1β after 24 and 48 h with significantly decreased ATP production observed at the same time points and concentration. These studies demonstrate that the DGA-induced mechanism of SH-SY5Y cell death involves complex II inhibition leading to mitochondrial depolarization, and subsequent ATP depletion with accompanying inflammatory cytokine release. These results indicate a direct mechanism of DGA-induced neurotoxicity in vitro, similarly observed in other DEG-affected target organs.

Homotaurine and Curcumin Analogues as Potential Anti-Amyloidogenic Agents

Currently, there is neither a cure for Alzheimer’s disease (AD) nor a way to stop the progressive death of neuronal cells associated with this devastating aliment. To date, there are only medications that temporarily slow its progression, and do not interfere with its pathogenesis. One of the hallmarks of AD is the presence of amyloid-beta plaques derived from the metabolism of the amyloid precursor protein, via the cleavage by beta followed by gamma secretase. Homotaurine, a naturally occurring small molecule found in some seaweeds, and curcumin, a phenolic antioxidant found in Curcuma longa, have been extensively studied as potential compounds to prevent/reverse plaque formation. In this study, libraries of chalcones and extended chalcones based on curcumin, as well as aminopropylsulfonamides inspired by homotaurine, were synthesized. Using fluorescence spectroscopic analysis with Thioflavin T, the anti-aggregation effect on Aβ42 was determined. A select number of newly synthesized chalcones and extended chalcone analogs were revealed to be potential anti-amyloidogenic agents. These were further evaluated with regard to their neurotoxicity/neuroprotection. The extended chalcone analogs that displayed the most anti-aggregation effect on Aβ42 were further analyzed in an MTT assay. Although none of the compounds alone displayed any neurotoxicity, none were able to provide neuroprotection against Aβ42.