Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 5, 2007
Publication Date: May 1, 2007
Citation: Zerkowski, J.A., Solaiman, D. 2007. Polyhydroxy Fatty Acids Derived from Sophorolipids. Journal of the American Oil Chemists' Society. 84(5):463-471. Interpretive Summary: Fatty acids that contain reactive oxygen groups are used in large quantities to prepare polymers, lubricants, and other materials. Unfortunately, these starting materials are primarily obtained from toxic plants. Furthermore, only a small number of variants are produced by these plants, limiting the applications where the resultant polymers can be used. We are addressing this problem by using fermentation by yeasts to convert inexpensive biorenewable agricultural coproducts such as soy molasses and tallow into sophorolipids (a type of biological surfactant). Sophorolipids contain oxygenated fatty acids that are easily purified, obviating the need to process materials from toxic plants. To enhance their utility, we now have modified them using well-established methods of organic chemistry. Specifically, we have added between one and four extra oxygen groups into the fatty acid molecule in a variety of locations and orientations. The added oxygens can be introduced in a "masked" fashion, that is, they remain unreactive until needed, when they can be selectively activated for use with specific and mild conditions. These reactive oxygens will allow the modified fatty acid to find application in a wider range of technological situations, from building blocks for polymers or detergents to coatings, lubricants, or slow-release polymers for drug delivery.
Technical Abstract: Starting from 17-hydroxyoleic acid, which is readily available from acid alcoholysis of sophorolipids, several new polyhydroxy fatty acids have been synthesized. These compounds contain from 2 to 5 hydroxy groups, in some instances combined with other functional groups. The added hydroxy groups can be incorporated in the C18 chain in a variety of geometries, for example spaced widely throughout the chain at C1, C8, and C17. This regiochemical control will be of use in structure/function studies involving materials constructed from these hydroxy fatty acids. A further benefit is that the hydroxy groups can be present in protected or free states. The principal reactions used to introduce extra hydroxy groups are selenium oxide-mediated allylic hydroxylation, osmium-catalyzed dihydroxylation, and borohydride reduction of a carboxylic ester. These new compounds are expected to be of use in a number of areas, but particularly as building blocks for polymers or components of lubricant formulations.