Oil for Life to Balance omega-3 polyunsaturated fatty acids ... - Oil4Life

4. FUNCTION OF PUFA IN CELL MEMBRANE PHOSPHOLIPIDS
Besides the structural role already described the long chain fatty acids incorporated in
membrane phospholipids has another important function, completely different.
After the release mediated by a specific phospholipase A2, AA and EPA are oxidized by
specific enzyme giving origin to cellular mediators, namely prostaglandins, leukotrienes,
thromboxane, prostacyclins.
However, several other classes can technically be termed eicosanoids, including the
hepoxilins, resolvins, isofurans, isoprostanes, lipoxins, epi-lipoxins, epoxyeicosatrienoic
acids (EETs) and endocannabinoids. LTs and prostanoids are sometimes termed 'classic
eicosanoids' (Van Dyke T.E. et al., 2003, Serhan C.N. et al., 2004, Anderle P. et al., 2004)
in contrast to the 'novel', 'eicosanoid-like' or 'nonclassic eicosanoids' (Evans A.R. et al., 2000,
O'Brien W.F. et al., 1993, Behrendt H. et al., 2001, Sarau H.M. et al., 1999) As already
reported above, eicosanoids are signaling molecules made by oxygenation of twenty-carbon
fatty acids. They exert complex control over many systems, mainly in inflammation or
immunity, and as messengers in the central nervous system. The networks of controls that
depend upon eicosanoids are among the most complex in the human body. Eicosanoids
derive from either omega-3 or omega-6. The n-6 eicosanoids are generally proinflammatory;
n-3's are much less so. The amounts and balance of fats in a diet will affect
the body's eicosanoid-controlled functions, with effects on cardiovascular disease,
triglycerides concentration, blood pressure, arthritis, inflammation and oxidative/nitrosative
conditions.
4.1 Biosynthesis
Two families of enzymes catalyze fatty acid oxygenation to produce the
eicosanoids:Cyclooxygenase, or COX, generates the prostanoids. Lipoxygenase, in several
forms, e.g. 5-lipoxygenase (5-LO) generates the leukotrienes. Eicosanoids are not stored
within cells, but are synthesized as required.
Eicosanoid biosynthesis begins when cell is activated by mechanical trauma, cytokines,
growth factors or other stimuli. (The stimulus may even be an eicosanoid from a neighboring
cell; the pathways are complex). Phospholipase is released at the cell membrane and travels
to the nuclear membrane. There, it frees 20-carbon fatty acids. This event appears to be the
rate-determining step for eicosanoid formation.
A schematic view of conversion of AA and EPA to prostanoids and leukotrienes through the
cyclo oxigenase and lipo oxigenase pathway are depicted in the following figure:
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