The occurrence and distribution of furan fatty acids in spawning male freshwater fish.

Furan fatty acids (F acids) have been found in the livers and/or testes of 20 species, representing 9 families, of male freshwater fish. In 9 species they are major components of the lipids while in the remaining 11 species they occur to a much lesser extent. The F acids in some species reach a maximum concentation in the testes lipids, and minimum liver lipid concentration, at spawning. In all species in the testes, the F acids are confined almost exclusively to the triglyceride fraction while, in the liver lipids, they are found, in order of decreasing concentration, in the cholesteryl esters, the triglycerides, and the phospholipids. In the lipids of many individuals F6, 12,15-epoxy-13,14-dimethyleicosa-12,14-dienoic acid, is the major fatty acid present. It is presumed that these acids perform some as yet unidentified metabolic function. Isolation technology and identification of F acids by a specific thin layer chromatographic spray reagent are discussed.