Fatty Acids of the Medusae Aureliaaurita (Linnaeus, 1758) and Rhopilemaesculentum (Kishinouye, 1891): The Presence of Families of Polyenoic Acids with 24 and 26 Carbon Atoms

It was found that lipids of scyphoid jellyfishes of the Sea of Japan, Aurelia aurita (Linnaeus, 1758) and Rhopilema esculentum (Kishinouye, 1891) contain, along with the common fatty acids (FAs) that are characteristic of marine organisms, notable concentrations of polyunsaturated fatty acids (PUFAs) with 24 and 26 carbon atoms. The main PUFAs in A. aurita and Rh. esculentum were 20:5(n–3), 22:6(n–3), 24:6(n–3), and 22:5(n–3). In addition, it was found for the first time that Rh. esculentum contains 1.6% C26 PUFAs: C26:7(n–3), C26:6(n–3), and C26:5(n–3). In spite of similar PUFA levels in A. aurita and Rh. esculentum (65.95 and 58.79%, respectively), the ratio of the FA (n–3)/(n–6) families was in A. aurita 7 times higher than in Rh. esculentum. Saturated acids (26.57% in A. aurita and 31.75% in Rh. esculentum) were represented by palmitic and stearic acids. The level of monounsaturated FAs, including C16:1 and C18:1 isomers, was low and did not exceed 10% in both species. The presence of unusual families of PUFAs with 24 and 26 carbon atoms and the difference in the contents of FAs (n–3) and (n–6) in species that live under similar conditions is of great interest.