Lipophilic Constituents of the Blubber from Blue Whale, Balaenoptera musculus, Washed Ashore at Pakistan Coast

Abstract

The blue whale, Balaenoptera musculus (Linnaeus, 1758), is the biggest animal recognized to exist today throughout world’s oceans. High commercial value of lipids has made this species vulnerable. Blubber, a crucial adaptation for mammals living in water, serves as energy reservoir. Surplus energy is deposited in the form of fatty acids (FA) and therefore have been analysed. The compositional analysis also helps in understanding the dietary and structural role of FAs in blubber. Lipid analysis of blubber from stranded, dead blue whale through Thin layer chromatography (TLC) has resulted in identifying 6 constituents. These constituents are a triacyl glyceride (TAG), 2 steroids, and 3 FAs. Approximate analysis of waxy constituents has also been attempted exploiting TLC. Gas chromatography-mass spectrometry (GC-MS) analyses has resulted in identification of 86 compounds, which were further confirmed through the Retention Indices. Altogether 17 SFAs including 4 Branched FAs, 5 MUFAs, and a PUFA were identified. These accounted to a total concentration of 85.7, 86.1, 84.8, and 89.7 % in jaw, abdomen, peduncle, and fluke, respectively. The main reasons for the low quantitative and qualitative content of PUFAs were susceptibility of PUFAs towards oxidation. Thus 8 FAlds, 4 FAlcs, and 3 other oxygenated FAs, which made a total of 2.7, 0.9, 1.3, and 5.2% in jaw, abdomen, peduncle, and fluke, respectively were justified. Further the chromatographic region where PUFAs are expected to resolve has been found masked with significant concentration of anthropogenic compounds, which accounted to 43.4, 35.6, 34.6, and 30.7% in jaw, abdomen, peduncle, and fluke, respectively. These pollutants included 25 hydrocarbons, 4 phthalates, 2 siloxanes, 2 bisphenols, and diphenyl carbonate. 4 natural Prenols were also identified. Altogether 16 constituents with concentration of 14.2, 8.0, 15.7, and 10.8% in jaw, abdomen, peduncle, and fluke, respectively, were remained unidentified. Few constituents were justified through food chain.