5(S)-Hydroperoxyeicosatetraenoic acid (5(S)-HpETE) is a monohydroperoxy polyunsaturated fatty acid (PUFA) generated by the enzymatic conversion of arachidonic acid via 5-lipoxygenase (5-LO). Subsequently, 5(S)-HpETE undergoes metabolism to form leukotriene A4 (LTA4), which serves as a pivotal intermediate in the synthesis of leukotrienes (LTs).

15(S)-HpETE is a monohydroperoxy polyunsaturated fatty acid (PUFA) produced by the action of 15-lipoxygenase (15-LO) on arachidonic acid. It is either metabolized to 14,15-leukotriene A4 [1] or reduced to 15(S)-HETE by peroxidases.[2] [1] 15(S)-HpETE mediates a number of biological functions including the induction of c-fos and c-jun, and activation of AP-1. [3] 15(S)-HpETE inhibits prostacyclin synthesis in porcine aortic microsomes and bovine endothelial cells, and can cause the suicide inactivation of porcine 12-LO.[2][4][5]

12(S)-HpETE is a monohydroperoxy polyunsaturated fatty acid (PUFA) produced by the action of platelet or leukocyte 12-lipoxygenase (12-LO) on arachidonic acid. It activates human blood leukocyte 5-LO, resulting in the synthesis of 5(S)-HETE, leukotriene B4 (LTB4), and 5(S),12(S)-DiHETE. Rat lung metabolizes 12(S)-HpETE to 8,11,12- and 10,11,12-trihydroxyeicostrienoic acids. 12(S)-HpETE is the mediator of many biological functions, including induction of c-fos and c-jun, activation of AP-1, and endothelium-dependent vasoconstriction. It mediates the inhibitory synaptic response to FMRF-amide in Aplysia sensory neurons and inhibits Ca2+/calmodulin-dependent protein kinase II from rat brain cortex.