Structural requirements of aldehydes produced in LPO for the activation of the heat-shock genes in Hela cells

The ability of various aldehydes, some of which are produced in lipid peroxidation, to effect heat-shock gene expression and heat-shock proteins synthesis was evaluated in HeLa cells. Only (E)-4-hydroxyalk-2-enals were active both in racemic and homochiral form. Between the reported primary metabolic products of (E)-4-hydroxynon-2-enal, only the glutathione conjugates were active, whereas (E)-4-hydroxynon-2-enoic acid and 2-nonen-1,4-diol were inactive. Also, unnatural (E)-5-hydroxynon-2-enal and (E)-5-hydroxyhex-2-enal were active, whereas (E)-6-hydroxynon-2-enal was inactive. Thus, it was established that the active aldehydic compounds must possess an (E)-2 double bond and an hydroxy group in a position suitable for the formation of a cyclic hemiacetal in a possible adduct of these aldehydes with proteins. An irreversible binding to proteins could be the first step of the mechanism by which these compounds exert their biological activity.