Answer to Question #169810 in Biochemistry for Reena

Question

Arachidonic acid is an important omega 3 fatty acid present in fish. Consumption of arachidonic acid has been linked to decreased incidence of heart disease and cancer, but unfortunately it oxidizes very rapidly to produce very potent off-flavors and aromas (often metallic or fishy). Draw out the mechanism showing the formation of the shortest possible aldehyde that can form from the autoxidation of arachidonic acid. Show the initiation step (not including double bond migration), hydroperoxide formation and breakdown to a product including an aldehyde

Answer 1

 Peroxynitrite, the product of the diffusion-limited reaction between nitric oxide and superoxide anion, mediates oxidative modifications in lipid systems including cell membranes and lipoproteins. Peroxynitrite diverts the metabolic fates of arachidonic acid. Enzymatic oxidation of AA leads to the formation of both prostaglandins and leukotrienes. Peroxynitritemediated nitration of AA should divert AA from its normal metabolic pathways leading to the formation of novel products with unknown biological properties: image below.

Possible nonenzymatic pathways for oxidation of arachidonic acid (AA) as a lipid-oxidation example. The pathways are suggested based on the radical reaction of 1,4- pentadiene with the hydroxyl radical. The pattern of 1,4- pentadiene is indicated by thick lines. Described on an image below