Malvalic acid is a

cyclopropene fatty acid Cyclopropane fatty acids (CPA) are a subgroup of fatty acids that contain a cyclopropane group. Although they are usually rare, the seed oil from lychee contains nearly 40% CPAs in the form of triglycerides. Biosynthesis CPAs are derived from un ...

found in

baobab ''Adansonia'' is a genus made up of eight species of medium-to-large deciduous trees known as baobabs ( or ). They are placed in the Malvaceae family, subfamily Bombacoideae. They are native to Madagascar, mainland Africa, and Australia.Tropic ...

seed oil and

cottonseed oil Cottonseed oil is cooking oil from the seeds of cotton plants of various species, mainly ''Gossypium hirsutum'' and ''Gossypium herbaceum'', that are grown for cotton fiber, animal feed, and oil. Cotton seed has a similar structure to other oi ...

. The

cyclopropene Cyclopropene is an organic compound with the formula . It is the simplest cycloalkene. Because the ring is highly strained, cyclopropene is difficult to prepare and highly reactive. This colorless gas has been the subject for many fundamental st ...

ring is thought to be one of the causes of abnormalities that develop in animals that ingest cottonseed oil. Refining processes, such as

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a Catalysis, catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or S ...

, can remove or destroy malvalic acid.

Biosynthesis

The

biosynthesis Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecules. ...

of malvalic acid starts with

oleic acid Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish. In chemical terms, oleic acid is classified as a monounsaturated omega ...

, an 18-carbon

monounsaturated fatty acid Monounsaturated fats are fatty acids that have one double bond in the fatty acid chain with all of the remainder carbon atoms being single-bonded. By contrast, polyunsaturated fats have more than one double bond. Molecular description Fatty aci ...

, leading to

sterculic acid Sterculic acid is a cyclopropene fatty acid. It is found in various plants of the genus ''Sterculia'', including being the main component of ''Sterculia foetida'' seed oil. Biosynthesis The biosynthesis of sterculic acid begins with the cycloprop ...

. An α-oxidation reaction removes one carbon from the chain to form the 17-carbon-chain structure of malvalic acid.

History

Wilson et al. demonstrated the co-occurrence of malvalic acid and the corresponding cyclopropane acids in several types of seeds. He suggested that methylene addition to oleic acid gave rise to dihydrosterculic acid, which was desaturated to sterculic acid, and that 8-heptadecenoic acid was similarly the precursor of dihydromalvalic acid and malvalic acid. Smith and Bu'Lock showed that in ''

Hibiscus ''Hibiscus'' is a genus of flowering plants in the mallow family, Malvaceae. The genus is quite large, comprising several hundred species that are native to warm temperate, subtropical and tropical regions throughout the world. Member species ...

'' seedlings the chains of sterculic and malvalic acids, but not the ring methylene carbon, were derived from acetate. They showed that the labeling pattern in malvalic acid was the same as that in sterculic acid minus the carboxyl carbon. They explained the shortening by α oxidation occurring during the biogenesis of malvalic acid. Hooper and Law demonstrated that the ring methylene carbon of both cyclopropane and cyclopropene acids was derived from the methyl group of methionine in ''Hibiscus'', and suggested from the distribution of label that the pathway was oleic → dihydrosterculic → sterculic acid.{{Cite journal , doi = 10.1007/BF02531267, title = The biosynthesis of cyclopropane and cyclopropene fatty acids in higher plants (Malvaceae), journal = Lipids, volume = 7, pages = 35–45, year = 1972, last1 = Yano , first1 = I., last2 = Morris , first2 = L. J., last3 = Nichols , first3 = B. W., last4 = Jams , first4 = A. T., s2cid = 35842195

References

Fatty acids Cyclopropenes Cotton