Arachidonic acid physiological role

Elucidation of the physiological role of arachidonic acid 13 and other polyunsaturated fatty acids, particularly the role of all Z-4,7,10,13,16,19-decosahexaenoic acid 14, found in brain, required the corresponding stable-isotope labelled material1011. The deuteriated phosphonium salt 15, the key intermediate used in the synthesis of title compound 16 (equation 8), has been prepared in 19% overall yield12 starting with ethanol-D6 (equation 7). 

Emphasis is placed on the physiological role of the two essential fatty acids, linoleic acid (n-6) and linolenic acid (n-3) and their metabolites—arachidonic acid (n-6), docosahexaenoic acid (n-3), and eicosapentaenoic acid (n-3). The uninitiated reader is... 

Prostaglandin H synthase is the first enzyme involved in the arachidonic acid cascade . The prostaglandins can cause both relaxation and tension in smooth muscle and so have vital physiological roles. Prostaglandin H synthase acts as both a peroxidase and an oxygenase its so-called cyclooxygenase activity involves addition of two equivalents of oxygen to a free radical derived from arachidonic acid to form an endoperoxide... 

A third mechanism for the oxygenation of arachidonic acid involves the cytochrome P450 pathway. The activity of the monooxygenases in this microsomal system yields epoxides, certain forms of HETEs (e.g., w-hydroxy derivatives), and diol forms (diHETEs) (Fig. 35.13). The biologic activities of these compounds include actions in ocular, vascular, endocrine, and renal systems. Some of these actions are attributed to inhibition of Na, K -ATPase. The physiologic role of these compounds remains to be fully characterized. 

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