Similarities in the lipid class profiles of oils from Atlantic and Pacific dogfish livers

Abstract

Liver oils from Atlantic and Pacific dogfish (Squalus acanthias) have been compared for lipid classes, fatty acids of the total oil and of important lipid classes, and details of the alkyl chains in the 1‐O‐alkyl‐2,3‐diacylglycerol ethers (DAGE). In general there were few striking differences, confirming the view of biologists that these sharks are one species. The Pacific dogfish liver oil had a higher content (41.2%) of DAGE than the oil from Atlantic dogfish (18.2%). Both oils had all common and expected fatty acids in the proportions usual for marine oils, but they differed in the eicosenoic chains of the glycerol ethers (GE). The Pacific oil was unusual in having low but similar proportions of two alkyl chain isomers, 20:1n‐11 and 20:1n‐9. The Atlantic oil was very high in the 20:1n‐11 isomer, which is usually lower than 20:1n‐9 in the fatty acids of most regional marine oils. Unexpectedly, the DAGE of both oils had further unusual 20:1 isomer proportion in the GE chain, with 20:1n‐7 >20:1n‐9. Minor oddities in the fatty acids may reflect different basic food sources.

Ether lipids

“…In all these cartilaginous fish the levels of chimyl alcohol (C16:0) and C16:1n-7 alkylglycerol made up about 20% of the alkylglycerols and the remaining was made up of batyl alcohol, C20:1 and C22:1 alkylglycerols. It is noteworthy, to point out that high levels of C20:1 alkylglycerol have been reported in Squalus acanthias and a Centrophorus species, 18 and 13%, respectively, showing fluctuations in the levels of certain alkylglycerol types in the liver oil of elasmobranch fish (Kang et al, 1998;Kayama et al, 1971). The 1-O-alkyl chain composition of the liver oil of the basking shark (Cetorhinus maximus) is similar to that of other chondrichthyans mentioned before although there, the most prevalent alkylglycerols are chimyl and selachyl alcohols found at similar levels.…”

“…Hitherto, the highest DAGE amount reported in the liver oil of a chondrichthyan is from the Squaliforme Scymnodon plunketi, which contained 89% DAGE, 10% triacylglycerol and none squalene in its liver oil (Wetherbee and Nichols, 2000). Table 1 DAGE and TAG % in the liver oil of S. acanthias from different places: (a) Kang et al (1998), (b) Malins et al (1965), (c) Wetherbee and Nichols (2000 The lipid compositions of some deep-sea Squaliformes from Australian, New Zealand and Tasmaninan waters are well documented and a compilation of the major lipids in their liver oils shows the mean percentages of DAGE (24 ± 7%), squalene (65 ± 11%) and TAG (10 ± 5%) for the following species: Centroscymnus crepidater, Centroscymnus owstoni, Dalatias licha, Deania calcea, Etmopterus granulosus, Centrophorus crepidater, Centrophorus scalpratus, Centroscymnus coelolepis, and Etmopterus baxteri (Bakes and Nichols, 1995;Deprez et al, 1990;Wetherbee and Nichols, 2000). High DAGE:TAG ratios are relevant for industry since in the process of DAGE extraction and refinement for health supplements DAGE and TAG are usually not separated.…”

Natural antioxidants in the stability of ray liver oil

“…Dissected livers were placed on polyethylene bags and frozen at -20°C for their transportation to the Aquaculture Nutrition Laboratory at the Department of Scientific and Technological Research of the University of Sonora (DICTUS). The oil was extracted by the procedure described by KANG et al (1998).…”

Canned cod liver as a source of n-3 polyunsaturated fatty acids, with a reference to contamination

“…The interest in fish liver has been growing in recent years, as many authors have reported n-3 polyunsaturated fatty acids to be beneficial for human health [1][2][3]. The presence of diacylglycerol ethers (DAGE) in the dogfish liver has promoted interest in the latter as well [4].…”