Identification of unusual cyclopropane monounsaturated fatty acids from the deep-water lake invertebrate Acanthogammarus grewingkii

In the deep-lake invertebrate, Acanthogammarus grewingkii a number of unusual fatty acids such as cis-11,12-methylene-5-eicosenoate, cis,cis-11,12–14,15-bis-methylene-5-eicosenoate, and their homologues, were identified. The structures were determined from spectra (¹HNMR, ¹³CNMR, mass, IR) after their isolation and quantification by means of Ag⁺-TLC, semipreparative RP-HPLC and capillary GC-MS. The possibility of biosynthesis and function of these unusually fatty acids is discussed, e.g. they may represent a specific feature of animals dwelling in a deep lake or may also be metabolites that are formed in cellular membranes or be of dietary origin.