Divalent salts of S-allylmercapto-N-acetylcysteine and related compositions are disclosed which can be administered in order to provide protection from the formation of aldehyde-protein adducts, protein carbonylation, protein aggregation, and the resulting neuroinflammation. Various neurodegenerative diseases which are suitable for treatment using these compositions include Alzheimer's disease, senile dementia, Parkinson's disease, multiple sclerosis, Lewy body disease, peripheral neuropathy, spinal cord injury, stroke and cerebral ischemia.