Extract of Padina pavonica (EPP) and Opuntia ficus-indica (EOFI) investigated. EOFI or EPP improved viability of a yeast model of Alzheimer’s disease (AD). EOFI or EPP treatment ameliorated lifespan and mobility defects in AD flies. Survival of Parkinson’s disease but not wild-type flies is enhanced by EOFI or EPP. Either extract mitigates toxicity of Amyloid-β and α-synuclein aggregates.