Structures of polyunsaturated fatty acids (PUFAs). These are selected unsaturated fatty acids. Oleic acid (C18:1ω9; (9Z)-Octadec-9-enoic acid) is a ω9-monounsaturated fatty acid. Linoleic acid (C18:2ω6; (9Z,12Z)-octadeca-9,12-dienoic acid is a ω6-PUFA. α-Linolenic acid (C18:3ω3; (9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid) is a ω3-PUFA. Arachidonic acid (C20:4ω6; (5Z,8Z,11Z,14Z)-5,8,11,14-Eicosatetraenoic acid) is a ω6-PUFA. Eicosapentaenoic acid (C20:5ω3; (5Z,8Z,11Z,14Z,17Z)-5,8,11,14,17-eicosapentaenoic acid) is a ω3-PUFA. Docosahexaenoic acid (C22:6ω3; (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid) is a ω3-PUFA. All double bonds in these unsaturated fatty acids are in cis configuration. These fatty acids are either free or esterified in glycerides, lipoproteins, and phospholipids (PLs) of membranes) contributing to the structure and function of the cell and the whole system in general. The methylene-interrupted double bonds of PUFA are the targets of free radical-mediated oxidative attack