The lipoxins. Stereochemical identification and determination of their biosynthesis

The stereochemistry and double bond geometry of a novel series of leukocyte-derived arachidonic acid metabolites, the lipoxins, was determined by comparison to pure unambiguous synthetic standards. The lipoxins were found to be a mixture of four lipoxin A isomers and two lipoxin B isomers. In determining the biosynthesis of these compounds, they were shown to be formed via a tetraene epoxide. In addition, it was shown that all of the lipoxin isomers formed by the incubation of 15-hydroperoxyeicosatetraenoic acid with human leukocytes were also formed by nonenzymatic hydrolysis of this tetraene epoxide.