Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Mead acid is an omega-9 fatty acid, first characterized by James F. Mead. Like some other omega-9 polyunsaturated fatty acids animals can make Mead acid de novo. Its elevated presence in the blood is an indication of essential fatty acid deficiency. Mead acid is found in large quantities in cartilage.
Mead acid, also referred to as eicosatrienoic acid, is chemically a carboxylic acid with a 20-carbon chain and three methylene-interrupted cis double bonds. The first double bond is located at the ninth carbon from the omega end. In physiological literature, it is given the name 20:3(n-9). See Fatty Acid#Nomenclature for an explanation of the naming system. In the presence of lipoxygenase, cytochrome p450 or cyclooxygenase Mead acid can form various hydroxy (HETE) and hydoperoxy (HpETE) products .
Two fatty acids, linoleic acid and alpha-linolenic acid, are considered essential fatty acids (EFAs) in humans and other mammals. Both are 18 carbon fatty acids unlike mead acid, which has 20 carbons. Linoleic is an ω-6 fatty acid whereas linolenic is ω-3 and mead is ω-9. One study examined patients with intestinal fat malabsorption and suspected EFA deficiency. They were found to have blood-levels of Mead acid 1263% higher than reference subjects. Under severe conditions of essential fatty acid deprivation, mammals will elongate and desaturate oleic acid to make mead acid, (20:3, n−9). This has been documented to a lesser extent in vegetarians and semi-vegetarians following an unbalanced diet.
Role in inflammation
Prostaglandin H synthases (also known as COX) are enzymes known to play a large role in inflammatory processes through oxidation of unsaturated fatty acids. Most notably, the formation of Prostaglandin H2 from arachidonic acid which is very similar in structure to mead acid. When physiological levels of arachidonic acid are low, other unsaturated fatty acids including mead and linoleic acid are oxidized by COX.
- Polyunsaturated fatty acid – lists of ω-3, −6 and −9 fatty acids; some others.
- Siegel, George J.; Albers, R. Wayne (2006). Basic neurochemistry: molecular, cellular, and medical aspects, Volume 1 (7th ed.). p. 40.
One of these is 20:3ω9, termed 'Mead acid' after its discovery by James Mead....
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- Hornstra, Gerard (September 2007). "Essential Polyunsaturated Fatty Acids and Early Human Development". Fats of Life Newsletter. Archived from the original on June 7, 2008. Retrieved 2007-10-23.
- Hamazaki, Tomohito; Suzuki, Nobuo; Widyowati, Retno; Miyahara, Tatsuro; Kadota, Shigetoshi; Ochiai, Hiroshi; Hamazaki, Kei (October 22, 2008). "The Depressive Effects of 5,8,11-Eicosatrienoic Acid (20:3n-9) on Osteoblasts". Lipids 44 (2): 97–102. doi:10.1007/s11745-008-3252-8. Retrieved October 19, 2012. Check date values in:
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- , Conversion of 5,8,11-Eicosatrienoic Acidt o Leukotrienes C3 and D3 Journal of Biological Chemistry (1981) vol. 256, p. 2275