Glutathione promotes prostaglandin H synthase (cyclooxygenase)-dependent formation of malondialdehyde and 15(S)-8-iso-prostaglandin F2α

► Cyclooxygenases (COX) convert arachidonic acid to MDA and 15(S)-8-iso-PGF2α. ► Glutathione (GSH) promotes COX-dependent MDA and 15(S)-8-iso-PGF2α formation. ► Mechanisms are proposed for the formation of MDA and 15(S)-8-iso-PGF2α. ► The utility of MDA and 15(S)-8-iso-PGF2α as oxidative stress biomarkers is challenged.