Distribuzione degli acidi grassi furanici e degli acidi grassi polinsaturi 3 nelle parti anatomiche della sarda (Sardina pilchardus) e dell’alice (Engraulis encrasicolus)

The high nutritional value of fish is generally ascribable to the presence of 3 polyunsaturated fatty acids (3 PUFA), such as eicosapentaenoic acid (C20:53, EPA), docosapentaenoic acid (C22:53, DPA) and docosahexaenoic acid (C22:6 3, DHA), which play a neuroprotective role and prevent the development of bowel inflammatory and cardiovascular diseases. Recent research have highlighted other minor fatty acids with beneficial health effects, such as Furan Fatty Acids (F-Acids). F-Acids are characterized by a furan ring, carrying an unbranched fatty acid chain with 9, 11 or 13 carbon atoms in one α-position and a short straight-chain alkyl group with 3 or 5 carbon atoms in the other α-position. The furan ring can be substituted with just one methyl group in the β-position adjacent to the aliphatic chain or with two methyl groups. Several studies have shown that F-acids prevent linoleic acid oxidation, have inhibitory effects on blood platelet aggregation on bacterial urease activity and play a crucial nutritional role synergistic to 3 PUFA, since they act as efficient radical scavengers during PUFAs oxidation. In a recent work carried out by our group, the fillet of six fish species harvested in the Adriatic sea (European hake, Merluccius merluccius; horse mackerel, Trachurus trachurus; common sole, Solea solea; European anchovy, Engralius encrasicolus; Atlantic mackerel, Scomber scombrus; European pilchard, Sardina pilchardus) had a content of F-acids, with a carbon skeleton of 20 atoms, such as 12,15-epoxy-13-methyleicosa-12,14-dienoic (MonoMeF11,5) and 12,15-epoxy-13,14-dimethyleicosa-12,14-dienoic (DiMeF11,5), which was positively correlated (R2 = 0.7041, P < 0.0001) with EPA, the 3 PUFA with 20 carbon atoms. Since EPA is a precursor of DPA and DHA, the biosynthesis of DPA and DHA is presumably competitive with that of F-acids. In order to better explain the synergic action of 3PUFA and F-acids, the aim of present study was to analyze the distribution of these fatty acids in different anatomical parts of European pilchard and European anchovy, in relation to their reproductive cycle. The fatty acid profile of liver, ovaries, testes, brain, eyes of each fish species harvested in different periods was determined with capillary gas chromatography coupled with mass spectrometry (GC/MS). The quantitation of fatty acids was carried out using GC/FID. The qualitative profile of both PUFA3 and F-acids fractions was neither affected by species, nor anatomical part or by the reproductive cycle of the species. In fact, no fatty acid could be used as a chemical marker for a peculiar fish species or for a specific organ. Conversely, the quantitative distribution of F-acids and PUFA3 changed according to the anatomical part. Moreover, the composition of the PUFA3 fraction was also affected by the reproductive cycle of the species. The brain presented the highest content of F-acids with respect to all the other organs in both species and during all the sampling period. On the contrary, the sexual organs resulted to be the poorest organs of F-acids. The amount of F-acids in European pilchard was 0.9 ± 0.2 % of total fatty acid in ovaries and 4.5 ± 0.4 % of total fatty acids in brain whereas in the European anchovy accounted for 0.5 ± 0.1 % in the testes and 5.5± 1.6 % in the brain. The furan fraction of all organs was mainly due to DiMeF11,5. The reproduction period strongly influenced the PUFAω3 distribution in the inner organs. In the samples collected during the sexual quiescence of both species, eyes and sexual organs had a similar PUFA ω3 content, but higher than the brain. During the reproduction period, the DHA content increased strongly in the sexual organs, which became the richest source of PUFA ω3. In European pilchard, the amount of PUFA ω3 increased during the reproduction period in the ovaries (44.4±0.9%, winter/spring; 31.1 ±4.0%, summer) and testes (50.2±0.2%, winter/spring; 32.3±5.7%, summer) significantly. The same trend was seen for European anchovy, which showed the highest content of PUFA ω3 in the testes (23.2±6.3%, winter; 35.9±7.3%, spring/summer) and ovaries (29.3±2.9%, winter; 44.1±3.8%, spring/summer) collected during the reproduction period.