Tocopherol, heavy metals (Cd, Pb, Cu, Fe, Mn, Zn), and fatty acid contents of thornback ray (Raja clavata Linnaeus, 1758) liver oil in relation to gender and origin in the Mediterranean and Black seas)

Abstract

The study objective was to investigate the profiles of tocopherol, heavy metals, and fatty acids in the liver oil of female and male thornback ray Raja clavata from the Black and Mediterranean seas. The fish liver oil analyses were carried out by using a spectrophotometer (Hitachi U-1900), ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry, and a GC-MS (gas chromatography-mass spectrometry), respectively. Results showed that the tocopherol content differed between the sample origin and gender (range of 42.3–134.5 mg kg−1). Pb, Cd, and Mn contents in livers of all R. clavata were lower than for Cu, Fe, and Zn. Levels of 7.6 and 8.9% in the eicosapentaenoic acid (EPA) were found to be higher in Black Sea thornback rays than in Mediterranean specimens (4.5 and 5.8%) (P < 0.05). All thornback ray liver oils contained large amounts of docosahexaenoic acid (DHA) in the range of 19.9–26.1%.