Cyclopropane fatty acid

Examples of mycolic acids, a class of mono- and dicyclopropane fatty acids found in the cell wall of the bacterium Mycobacterium tuberculosis

Cyclopropane fatty acids (CPA) are a subgroup of fatty acids that contain a cyclopropane group.[1] Although they are usually rare, the seed oil from lychee contains nearly 40% CPAs in the form of triglycerides.[2]

## Biosynthesis

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CPAs are derived from unsaturated fatty acids by cyclopropanation. The methylene donor is a methyl group on S-adenosylmethionine (SAM). The conversion is catalyzed by cyclopropane-fatty-acyl-phospholipid synthase.[3] The mechanism is proposed to involve transfer of a CH3+ group from SAM to the alkene, followed by deprotonation of the newly attached methyl group and ring closure.[4]

## Cyclopropene fatty acids

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malvalic acid, a cyclopropene fatty acid

Cyclopropene fatty acids are even rarer than CPAs. The best-known examples are malvalic acid and sterculic acid. A triglyceride made of 3 sterculic acid molecules esterified with glycerol is present in Sterculia foetida seed oil (in amounts greater than 60%) and at low levels in the seed oil of other species of Malvaceae[a] (~12%), cottonseed oil (~1%). The cyclopropene ring is destroyed during refining and hydrogenation of the oils. They have attracted interest because they reduce levels of the enzyme stearoyl-CoA 9-desaturase (SCD), which catalyzes the biodesaturation of stearic acid to oleic acid.[7]

At least one review indicates that CPFA's are carcinogenic.[8]

## Notes

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1. ^ A number of species in several genera of the Malvaceae family are known as 'Kapok trees'. For example: Ceiba pentandra, Bombax ceiba and B. costatum are all widely and ambiguously called "the kapok tree".[5][6]

## References

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1. ^ "Natural alicyclic fatty acids, cyclopropane, cyclopropene, cyclopentene - structure, composition, analysis, biosynthesis". Archived from the original on 2014-12-17. Retrieved 2015-02-02.
2. ^ Gaydou, E. M.; Ralaimanarivo, A.; Bianchini, J. P. "Cyclopropanoic Fatty-Acids of Litchi (Litchi-Chinensis) Seed Oil - a Reinvestigation" J. Agr. Food Chem. 1993, vol. 41, pp. 886-890. doi:10.1021/jf00030a009
3. ^ Grogan DW, Cronan JE Jr: Cyclopropane ring formation in membrane lipids of bacteria" Microbiol Mol Biol Rev 1997, vol. 61, pp. 429-441. http://mmbr.asm.org/content/61/4/429.full.pdf+html
4. ^ Ludger A. Wessjohann and Wolfgang Brandt, Thies Thiemann "Biosynthesis and Metabolism of Cyclopropane Rings in Natural Compounds" Chem. Rev., 2003, volume 103, pp 1625–1648. doi:10.1021/cr0100188
5. ^ Bohannon, M. B.; Kleiman, R. (April 1978). "Cyclopropene fatty acids of selected seed oils from bombacaceae, malvaceae, and sterculiaceae". Lipids. 13 (4): 270–273\. doi:10.1007/BF02533669. PMID 661511. S2CID 4017359.270-273&rft.date=1978-04&rft_id=https://api.semanticscholar.org/CorpusID:4017359#id-name=S2CID&rft_id=info:pmid/661511&rft_id=info:doi/10.1007/BF02533669&rft.aulast=Bohannon&rft.aufirst=M.+B.&rft.au=Kleiman,+R.&rfr_id=info:sid/en.wikipedia.org:Cyclopropane+fatty+acid" class="Z3988">
6. ^ Yu, Xiao-Hong; Rawat, Richa; Shanklin, John (December 2011). "Characterization and analysis of the cotton cyclopropane fatty acid synthase family and their contribution to cyclopropane fatty acid synthesis". BMC Plant Biology. 11 (1): 97. doi:10.1186/1471-2229-11-97. PMC 3132707. PMID 21612656.
7. ^ Abraham, Samuel (1975). International encyclopedia of pharmacology and therapeutics: Pharmacology of lipid transport and atherosclerotic processes, Volume 1. Pergamon Press. p. 108\. ISBN 9780080177625.
8. ^ L. O. Hanus, P. Goldshlag, V. M. Dembitsky (2008). IDENTIFICATION OF CYCLOPROPYL FATTY ACIDS IN WALNUT (JUGLANS REGIA L.) OIL. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2008, 152(1):41–45.

## Further reading

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* Bao, X.; Katz, S.; Pollard, M.; Ohlrogge, J. (2002). "Carbocyclic fatty acids in plants: Biochemical and molecular genetic characterization of cyclopropane fatty acid synthesis of Sterculia foetida" (PDF). Proceedings of the National Academy of Sciences. 99 (10): 7172–7177\. Bibcode:2002PNAS...99.7172B. doi:10.1073/pnas.092152999. PMC 124547. PMID 11997456.7172-7177&rft.date=2002&rft_id=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC124547#id-name=PMC&rft_id=info:pmid/11997456&rft_id=info:doi/10.1073/pnas.092152999&rft_id=info:bibcode/2002PNAS...99.7172B&rft.aulast=Bao&rft.aufirst=X.&rft.au=Katz,+S.&rft.au=Pollard,+M.&rft.au=Ohlrogge,+J.&rft_id=http://www.pnas.org/cgi/reprint/99/10/7172.pdf&rfr_id=info:sid/en.wikipedia.org:Cyclopropane+fatty+acid" class="Z3988">