Cyclopropane fatty acid

• 8-( 2 - Octylcyclopropen -1-yl ) octanoic acid
• Sterculsäure
• Sterculinsäure
• Sterculasäure

Colorless oil

18.2 to 18.3 ° C

Template: Infobox chemical / molecular formula search available

The Sterculiasäure (English sterculic acid), scientifically 8-( 2 - Octylcyclopropen -1 -yl ) octanoic acid is a monocarboxylic acid with a cyclopropene ring in the carbon chain. The names Sterculsäure and Sterculinsäure are common. The salts hot Sterculate. The compound was in many mallow family ( Malvaceae ) proved it serves through its lipid metabolism interfering properties as natural protection against predators and pathogens. Although there are still some other known occurrences, but occurs Sterculiasäure total rarely in the fatty acid spectrum of living creatures on.

Name and History

1952, the compound was isolated from the seeds of Sterculia foetida Stinkbaumart and was in line with this, the ( English ) name sterculic acid. The German translation of this term is not uniform. The names Sterculiasäure, Sterculsäure and Sterculinsäure occur with similar frequency, rare one speaks of Sterculasäure.

When using the name Sterculinsäure, make sure that it is not the confusion comes with a different cyclopropenoiden fatty acid, which bears the English name sterculynic acid and was detected in the Stinkbaumart Sterculia alata. It differs from the Sterculiasäure mainly by a triple bond at the carboxy end facing away from the fatty acid chain.

Occurrence

Within the mallow ( Malvaceae ) Sterculiasäure is widely used as part of glycerides of seeds, leaves, stems and roots. Usually it is associated with the chemically very similar malvalic. Sterculiasäure example, it should contain

• 49-65 % in the seed oil of Sterculia foetida Stinkbaumes.
• 15 % in the seed oil of the kapok tree ( Ceiba pentandra ).
• 1-8 % in the seed oil of the African baobab tree ( Adansonia digitata ).
• 0.2 to 0.8 % in raw cotton seed oil.

But there are also some sites outside Mallow. The seed oil of those forming part of the legume Indigofera glabra, there are 10% Sterculiasäure. The belonging to the gymnosperms and used for human consumption, tree-like liana Gnetum gnemon contains the fat content of their seeds 13% Sterculiasäure (although at a relatively low total fat content of 4% in the dried seeds).

In addition Sterculiasäure was observed as a product of Verderbnisprozesses of nuts.

Biological Significance

It is believed that the Sterculiasäure as the other cyclopropenoiden fatty acids, the plant occupies a protective function against predators and pathogens, because the substance interferes with fat metabolism by inhibiting the body's own processes, which realize the insertion of a double bond in a fatty acid chain. Of these affected delta -5, delta -6 and delta -9 desaturation. The consequences are manifold and are partly the result in a reduction of growth and reproductive function; a feed ratio of 5% is lethal to rats. By inhibiting delta-9- desaturase, the body's synthesis of oleic acid, of stearic acid is inhibited. This results in a change in body fat composition, affects not only the storage of fat, but also the composition of the lipid membranes. Here, the melting point increased by the increased proportion of saturated fatty acids. For example, Sterculiasäure in the feed of laying hens even at a daily dose of 25 mg to a conspicuous discoloration of eggs, especially during cool storage. Here, the egg white takes on a pink color, while the yolk apricot appears. The reason is that an increased permeability membrane separating the yolk from the egg white to obtain a transfer of the protein conalbumin from egg white from the yolk is made possible. There is formed with the present in the yolk iron a pink complex, which in turn can diffuse into the egg whites again.

After tests on rainbow trout is Sterculiasäure suspected to have carcinogenic and co - carcinogenic properties.

Levels of Sterculiasäure in the human diet are considered a health risk, but can be removed by hydrogenation or by strong heating of the corresponding vegetable oils to 230 to 235 ° C in the deodorization.

Biosynthesis

Starting from the oleic acid is added to the double bond by a cyclopropane fatty acid synthase, a methyl group. The methyl group is derived from S-adenosylmethionine. This creates Dihydrosterculiasäure containing a cyclopropane ring. It is believed that a desaturase then the cyclopropane ring is converted into a cyclopropene ring, which provides Sterculiasäure.

Production and representation

From vegetable oils that are rich in Sterculiasäure as the seed oil of Sterculia foetida, can win this fatty acid. After the necessary splitting of the triglycerides, the actual cleaning procedure takes place. The difficulties lie in the simultaneous presence of the chemically very similar malvalic that differs only by one methylene group in the chain length as well as in the relative instability of the Cyclopropenringes. For application methods are coming urea extractive crystallization, column chromatography and vacuum distillation.

In the laboratory the Sterculiasäure can be represented by a Simmons-Smith reaction of 9- octadecinic acid ( stearolic acid ), and diiodomethane (4% yield).

Another synthetic approach with higher yield is based on 9- octadecinic acid and ethyl diazoacetate.

Analysis

To prove the Sterculiasäure example, gas chromatography -mass spectrometry (GC / MS ) is suitable.

Sterculiasäure shows due to the Cyclopropenrings the Halphen reaction.