Methods and compositions prolong life and increase stress resistance in cells and organisms

A compound of formula A: wherein R represents, independently for each occurrence, H, acetyl, benzoyl, acyl, phosphate, sulfate, (alkoxy) methyl, triarylmethyl, (trialkyl) silyl, (dialkyl) (aryl) silyl, (alkyl ) (diaryl) silyl or (triaryl) silyl; and X represents O or S, or a pharmaceutically acceptable salt thereof, for use in the treatment or prevention of a neurodegenerative disease.