Alpha-Linolenic acid

• (all- cis) -9 ,12,15 - octadeca - trienoic acid,
• 9c, 12c, 15c - octadecatrienoic
• Linolenic acid
• ALA (alpha- linolenic acid)
• 18:3 ( ω -3) ( lipid Name )

Colorless liquid

Liquid

0.92 g · cm -3

-11 ° C

232 ° C (23 hPa)

• Insoluble in water
• Readily soluble in many organic solvents

1.480 at 20 ° C.

Template: Infobox chemical / molecular formula search available

α -linolenic acid ( alpha-linolenic acid, often called only linolenic acid or ALA) is a tri-unsaturated fatty acid having 18 carbon atoms. She is a (all- cis) -9 ,12,15 - octadeca - trienoic acid, short- term C18: 3 (9c, 12c, 15c ) and belongs to the group of omega-3 fatty acids.

Several other fatty acids but also bear the word linolenic acid in their name, but differ chemically. So are approximately gamma-linolenic acid [( all-cis ) -6 ,9,12 - octadeca - trienoic acid, GLA ] as well as the dihomogammalinolenic [( all-cis ) - 8 ,11,14 eicosa - trienoic acid, DGLA ] to group of the omega-6 fatty acids, the latter also consists of only 20 instead of 18 carbon atoms. The name of linolenic acid similar linoleic finally, also an omega- 6 fatty acid that has one double bond less than the linolenic acid, is merely an octadeca -9 ,12- dienoic acid.

The name linolenic acid is derived from the Greek word linos for flax ( flax).

Occurrence

Linolenic acid is a chemical component of many triglycerides, which form the major part of the natural fats and oils. A number of course derived vegetable oils rich in linoleic acid. These include the oil from the Iberian dragon head (up to 70 %), Chiaöl (approx. 60%), perilla oil ( 31-42 %), linseed oil ( 56-71 %), hemp oil ( 28%), walnut oil (about. of 15% ), rapeseed oil ( 5-16 %) and soya oil (4-11 %). Some plant oils contain only small quantities (up to 1.5 %); these include sunflower oil, olive oil and grape seed oil ( less than 1% linolenic acid, 72% linoleic acid). Animal sources are Pferdemett (approx. 30%) and lard (< 1.5%).

Production and representation

The fatty acid can be obtained by alkaline hydrolysis of the corresponding triglycerides by the corresponding fats or oils are boiled with alkalis. As the natural fats and oils contain many different fatty acids always includes in the control separation of the resulting mixture of. Commercially it is derived primarily from linseed oil.

Properties

Physical Properties

Carefully cleaned and stored under exclusion of air linolenic acid is a colorless, oily and almost odorless liquid. The molar mass is 278.43 g mol -1, and the density of 0.92 g · cm - 3 having a melting point of -11 ° C and a boiling point of 232 ° C (at 23 mbar). The fatty acid is insoluble in water, but well soluble in many organic solvents.

Chemical Properties

Linolenic acid is very sensitive to oxidation and aging in the air under rapid yellowing, which is due to the formation of hydroperoxides. In the further course of the oxidation occurs to form resinification of varnish, this operation is also referred to as drying.

Biological Significance

α -linolenic acid (ALA ) is an essential nutrient (DHA ) and eicosapentaenoic acid (EPA ) is used to form the omega -3 fatty acids docosahexaenoic acid needed. ALA also plays an important role in inflammatory processes. It is processed by the same enzymes to EPA, which also produce acid from linoleic acid dihomogammalinolenic ( DGLA ) and arachidonic acid ( AA). From DGLA and EPA in turn anti-inflammatory eicosanoids are formed (series 1 and series 3), while from the arachidonic acid inflammatory series -2 eicosanoids are formed. ALA thus acts anti-inflammatory, as they

Studies show that about 5-10% of the recorded α -linolenic acid to EPA and 2-5 % is converted to DHA. Other studies speak of conversion rate to EPA and DHA is less than 5 %. One study concludes that the conversion rate is ALA to DHA is less than 1 %. A study by the Royal Adelaide Hospital in Australia concludes that α - Linolensäurereiches vegetable oil (along with a linoleic acid diet), similar to the EPO levels can rise in the tissue, such as supplementation with fish oil. An increase in DHA levels in the blood by additional supplementation of ALA is - except in infants - by the International Society for the Study of Fatty Acids and Lipids ( ISSFAL ) denied.

Proof

The detection and determination of content of linolenic acid is usually done by gas chromatography of the methyl esters; supplement can be a separation of the unsaturated isomers with silver nitrate thin layer chromatography.

Use

Acylglycerols of linolenic acid and linoleic acid are ( inter alia paints) used as an additive to varnish and other drying oils for coatings.