Figure 3.

Metabolic pathways of arachidonic acid hydrolysis and oxidation. Phospholipids in the cell membranes commonly have a SFA esterified to sn1 position and a PUFA, such as arachidonic acid (AA) esterified to sn2 position. Activation of different phospholipases releases AA from phospholipids, either in one enzymatic step (PLA₂) or through several enzymatic steps (PLA₁, PLC, PLD). Unesterified AA can be further metabolized to various eicosanoid metabolites by different COX, LOX, and CYP enzymes. Abbreviations: 2-AG, 2-arachidonoylglycerol; AA, arachidonic acid; COX, cyclooxygenase; CYP, cytochrome P450 enzyme; DAG, 1,2-diacylglycerol; DGL, DAG lipase; EET, epoxyeicosatrienoic acid; HETE, hydroxyeicosatrienoic acid; IP₃, inositol 1,4,5-trisphosphate; LOX, lipooxygenase; LTC₄, leucotriene C₄; Lyso-GPL, lyso-glycerolphospholipid; Lyso-PLC, lysophospholipase C; MGL, monoacylglycerol lipase; PA, phosphatidic acid; PAP, PA phosphatase; PGD₂, prostaglandin D₂; PLA₁, phospholipase A₁; PLA₂, phospholipase A₂; PLC, phospholipase C; PLD, phospholipase D; SFA, saturated fatty acid; TXA₂, thromboxane A₂.