Various cytochrome P450 enzymes (e.g.
PGH2, particularly in the presence of ferrous iron (FeII), ferric iron (FeIII), or hemin, rearranges non-enzymatically to a mixture of 12-HHT and 12-HHT's 8-cis isomer, i,e, 12-(S)-hydroxy-5Z,8Z,10E-heptadecatrienoic acid [REF].