Oral Prodrug of a Novel Glutathione Surrogate Reverses Metabolic Dysregulation and Attenuates Neurodegenerative Process in Transgenic Alzheimer’s Mice

Glycation-induced oxidative stress underlies the numerous metabolic ravages of Alzheimer's disease (AD). Reduced glutathione levels in AD lead to increased oxidative stress, including glycation-induced pathology. Previously, we showed that the accumulation of reactive 1,2-dicarbonyls such as methylglyoxal, the major precursor of nonenzymatic glycation products, was reduced by the increased function of GSH-dependent glyoxalase-1 enzyme in the brain. In this two-pronged study, we evaluate the therapeutic efficacy of an orally bioavailable prodrug of our lead glyoxalase substrate, pro-ψ-GSH, for the first time in a transgenic Alzheimer's disease mouse model. This prodrug delivers pharmacodynamically relevant brain concentrations of ψ-GSH upon oral delivery. Chronic oral dosing of pro-ψ-GSH effectively reversed the cognitive decline observed in the APP/PS1 mouse model. The prodrug successfully mirrors the robust effects of the parent drug, i.e., reducing amyloid pathology, glycation stress, neuroinflammation, and the resultant neurodegeneration, in these mice. We also report the first metabolomics study of such a treatment that yields key biomarkers linked to the reversal of AD-related metabolic dysregulation. Collectively, this study demonstrates the neuroprotective effect of pro-ψ-GSH in a symptomatic preclinical model of AD and paves the way for further preclinical advancement of such therapeutics. Metabolomic signatures identified could prove beneficial in the development of treatment-specific, clinically translatable biomarkers.