Polyunsaturated fatty acids (PUFAs) are essential nutrients that show distinct deficiency syndromes when not present in adequate amounts in the diet.[1][2] Virtually all cellular arachidonic acid is esterified in membrane phospholipids where its presence is tightly regulated through multiple interconnected pathways [3]. Free arachidonic acid is a transient, critical substrate for the biosynthesis of eicosanoid second messengers. Receptor-stimulated release, metabolism, and re-uptake of free arachidonate are all important aspects of cell signalling and inflammation.[4]
多不饱和脂肪酸（PUFAs）是必需营养素，在饮食中摄入不足时会表现出明显的缺乏综合症。几乎所有的细胞花生四烯酸都被酯化在膜磷脂中，其存在通过多个相互连接的途径进行严密调控。游离花生四烯酸是二级信使类前体，是瞬态的重要底物。受体刺激后的游离花生四烯酸的释放、代谢和重新摄取都是细胞信号传递和炎症的重要方面。
Reference:
[1]. Simopoulos, A.P. Omega-3 Fatty acids in health and disease and in growth and development. American Journal of Clinical Nutrition 54, 438-463 (1991).
[2]. Holman, R.T. Control of polyunsaturated acids in tissue lipids. J. Am. Coll. Nutr. 5(2), 183-211 (1986).
[3]. Nixon, A.B., Greene, D.G., and Wykle, R.L. Comparison of acceptor and donor substrates in the CoA-independent transacylase reaction in human neutrophils. Biochim. Biophys. Acta. 1300(3), 187-196 (1996).
[4]. Burgoyne, R.D., and Morgan, A. The control of free arachidonic acid levels. Trends Biochem. Sci. 15(10), 365-366 (1990).