Location: Bio-oils Research Unit
Title: Synthesis of lesquerella a-hydroxy phosphonates Authors
Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 24, 2013
Publication Date: January 21, 2014
Citation: Cusimano, J.S., Hart, M.M., Cermak, D.M., Cermak, S.C., Durham, A.L. 2014. Synthesis of lesquerella a-hydroxy phosphonates. Industrial Crops and Products. 53:236-243. Interpretive Summary: Castor oil, which is obtained from castor seeds usually imported from India, serves as the main U.S. source of hydroxy fatty acids (HFA) or ricinoleic acid. HFA has been isolated and modified extensively for a number of applications ranging from industrial materials to pharmaceuticals. Unfortunately, castor seeds also contain several undesirable compounds which pose severe health risks, including ricin, an unusually stable, deadly protein; ricinine, a poisonous alkaloid; and several other allergens. The structural and chemical similarity of the primary HFA found in lesquerella, a U.S. crop, suggests that lesquerella oil and its derivatives may function as a competitive alternative to castor oil. Unfortunately, there is a significant difference in desired HFA abundance in lesquerella oil (50%) than castor oil (90%), requiring more extensive purification measures and careful identification of the correct components of lesquerella. In this research, we report the purification and synthesis, in high yields and high purity, of the desired HFA in lesquerella. This work is significant because it opens the potential for HFA from lesquerella to function effectively and replace the use of castor oil in a wide variety of biological activities as enzyme inhibitors, pesticides, antibiotics, and anti-cancer therapeutics.
Technical Abstract: Hydroxy fatty acids (HFAs) have found a number of uses in today’s market, with uses ranging from industrial materials to pharmaceuticals. Castor oil, which is obtained from castor seeds, has served as a source of a versatile HFA; its principle component, ricinoleic acid, can be isolated from castor oil and has been modified extensively for a number of applications. Unfortunately, castor seeds also contain several undesirable compounds which pose severe health risks, including ricin, an unusually stable, deadly protein; ricinine, a poisonous alkaloid; and several allergens. Lesquerella oil, obtained from seeds of the Lesquerella fendleri species, has been identified as the most promising alternative source of HFAs. Lesquerolic acid, the primary HFA found in lesquerella oil, is also most homologous to ricinoleic acid; the only structural difference between the two is that lesquerolic acid possesses two additional methylene groups on the carboxyl end of the molecule. This structural and chemical similarity further suggests lesquerella oil and its derivatives may function as a competitive alternative to castor oil. Unfortunately, the desired HFA, lesquerolic acid, constitutes approximately 50% of lesquerella oil, where castor oil contains approximately 90% of the desired HFA. This difference in desired HFA abundance in lesquerella oil required more extensive purification measures and careful identification of the correct component. Additionally, alpha-hydroxy phosphonates and their corresponding phosphonic acids are functional moieties that have been shown to display a wide variety of biological activities, as enzyme inhibitors, pesticides, antibiotics, and anti-cancer therapeutics. We previously reported the synthesis of two families of alpha-hydroxy phosphonic acids based on ricinoleic acid: a family that retains the cis alkene found in ricinoleic acid and one where the alkene has undergone hydrogenation to produce a saturated alpha-hydroxy phosphonic acid. We now report the purification of the desired lesquerolic acid component of lesquerella oil and synthesis of lesquerolic acid-derived alpha-hydroxy phosphonates, both the unsaturated and saturated families. As with the ricinoleic acid-based compounds, the lesquerolic acid-based compounds have been produced in high yields and high purity, and the synthesis of these compounds is reported in this manuscript.