1. Definition
Arachidonic acid (ARA), chemical name 5,8,11,14-eicosatetraenoic acid, relative molecular weight 304.5, molecular formula of C20H32O2. It belongs to the n-6 series of long chain polyunsaturated fatty acids (PUFA).
ARA is one of the most abundant, widely distributed, and active polyunsaturated fatty acid in mammals, mainly present in the form of phospholipids in mammalian organs, muscles, and blood, especially in brain and nerve tissues. In addition, ARA is also a direct precursor for many derivatives of eicosonic acid, such as prostaglandin E2 (PGE2), prostacycline (PGI2), thromboxane (TXA2), leukotriene B4 (LTB4), and C4 (LTC4). These bioactive substances have important regulatory effects on lipoprotein metabolism, hemorheology, vascular elasticity, leukocyte function, and platelet activation.
2. The source of ARA
(1) Internal transformation
ARA is mainly formed in or outside the liver by linoleic acid (LA) through dehydrogenation desaturation and carbon chain lengthening. Under normal dietary conditions, the endogenous (in vivo conversion) of ARA absorbed by the human body is higher than by exogenous (food intake).
(2) Food intake
ARA is widely distributed in the neutral fat of animals. It is a component of cow milk fat, pig fat, bovine fat, blood phospholipid, heparin, and cephalin, but in relatively small amounts. It is also a major component of adrenal phospholipid mixed fatty acids. Eggs contain a high amount of ARA in their fat. In addition, oil seeds also contain ARA.
(3) Specialty supplement
The traditional preparation of ARA is mainly extracted from deep-sea fish oil, but the content is low. It is not only affected by the season, origin and other factors, but also the content of ARA in fish oil is unstable and relatively scarce, so the price is very expensive. Nowadays, people use microbial fermentation to produce ARA, which overcomes the above shortcomings, has a short production cycle, simple cultivation, stable products, and can achieve large-scale industrial production.
