Sterculate

Sterculic acid and related substances are the subject of an article in the July 1982 is sue of Journal of Chemical Education (pp 539-543)... 

Double bonds are accommodated by rings of all sizes The smallest cycloalkene cyclo propene was first synthesized m 1922 A cyclopropene nng is present m sterculic acid a substance derived from one of the components of the oil present m the seeds of a tree (Sterculia foelida) that grows m the Philippines and Indonesia... 

Sterculiagum Sterculic acid Sterculic acid [738-87-4] Sterculic acids Stereolithography Stereon... 

Step-shear test, 21 708-709 Sterculic acid(s), 5 28, 36t Stereochemistry... 

Malvaceae). Malvalic acid is produced from sterculic acid by chain shortening from the carboxyl end (Figure 3.14). Sterculic acid is an inhibitor of the A9-desaturase which converts stearic acid into oleic acid and is potentially harmful to humans in that it can alter membrane permeability and inhibit reproduction. 

In other cases cyclopropenes have been obtained by direct reaction of an alkyne with a diazo-compound in. the presence of a suitable catalyst. Typical of these is the reaction of ethyl diazoacetate with alkynes in the presence of copper, which is reported to lead to about 40-50 % conversion to cyclopropene per equivalent of diazo-compound. This has been applied to the synthesis of the important naturally occurring cyclopropene, sterculic acid, (66) 56) ... 

However, the elimination may be achieved in high yield from either cis- or trans-, 2-di-iodo-1,2-dibutylcyclopropanes using one molecular equivalent of butyllithium at low temperature. Since no reaction occurred at the ester group under these conditions, this has been applied in synthesis esters as of sterculic acid, a-hydroxysterculic acid (55)108 and 56, a potential inhibitor of mycolic acid synthesis109 ... 

Bickerstaffe, R., Johnson, A.R. 1972. The effect of intravenous infusions of sterculic acid on milk fat synthesis. Br. J. Nutr. 27, 561-570. 

Sterculic acid is a potent inhibitor of several desaturases, which are the enzymes responsible for the formation of double bonds in long-chain acids used as fuels, membrane components, and other critical biological molecules. Consequently, vegetable oils containing sterculic acid must be hydrogenated or processed at high temperatures to reduce or destroy the cyclopropene ring. 

Many chemists once believed that a cyclopropene could never be made because it would snap open (or polymerize) immediately from the large ring strain. Cyclopropene was eventually synthesized, however, and it can be stored in the cold. Cyclopropenes were still considered to be strange, highly unusual compounds. Natural-product chemists were surprised when they found that the kernel oil of Sterculia foelida, a tropical tree, contains sterculic acid, a carboxylic acid with a cyclopropene ring. 

Halphen Test for Detecting Cottonseed Oil (Cb 1-25) estimates the presence of cottonseed oil in vegetable or animal fats or oils as the result of a pink color formed between the reagent and cyclopropenoic fatty acids (sterculic and malvalic) normally present in cottonseed oil. 

Glanded cottonseed kernels contain 1.1-1.3% gossypol (19) plus related pigments that affect nutritional properties and color of the oil and meal. Cottonseed also contains the cydoptopenoid acids, malvahc and sterculic acids, which exist as glycerides and are concentrated in the seed axis (32). 

The involvement of desaturase-type enzymes in the biosynthesis of some important lipidic antifeedants now has been firmly established (Fig. Ic) (7). An instructive example of this phenomenon is the production of ricinoleate (a purgative) by a desaturase homolog found in the castor plant. Here, a subtle variation in mechanistic pathway is responsible for the introduction of a C-12 hydroxyl group rather than a 12,13-double bond (7). Another interesting case features the putative dehydrogenation of a cyclopropyl fatty acid to produce sterculate, a potent inhibitor of the mammalian but not the plant A desaturase (8). Finally, the biosynthesis of polyacetylenes with antifungal properties such as falcarindiol is thought to involve a sequence of unique desaturase-mediated oxidations (9). 

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