Cyclopropyl Fatty Acids and Methyl Esters

Cyclopropanoid fatty acids are major constituents of some seed oils and also occur in bacterial membranes, but are not synthesized or used by humans.1 Cyclopropenoids, such as sterculic acid, inhibit the enzyme Δ9-desaturase preventing the conversion of stearic acid to oleic acid and potentially causing significant health problems for organisms which consume them. Cyclopropenoid fatty acids have been reported to have several deleterious effects on mammals, such as carcinogenicity and acute and chronic toxicity.2,3 Because of the harmful effects of cyclopropenoids, cottonseed oil (a major world-wide edible oil which contains around 1% of these fatty acids) is required to be heat treated and hydrogenated before consumption.


  1. G. Knothe “NMR Characterization of Dihydrosterculic Acid and Its Methyl Ester” Lipids, Vol. 41(4) pp. 393-396, 2006
  2. X. Bao et al., Characterization of cyclopropane fatty-acid synthase from Sterculia foetida, J Biol Chem., Vol. 278(15) pp. 12846-12853, 2003
  3. E. Fehling et al., Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils, JAOCS, Vol. 75(12), pp. 1757–1760, 1998