Indian Journal of Geo Marine Sciences Vol. 48 (08), August 2019, pp. 1232-1237 Fatty acid composition of select sea anemones from Mandapam Coast, Tamil Nadu S. Thangaraj 1* , S. Bragadeeswaran 2 , & V. Gokula 1 1 PG & Research Department of Zoology, National College, Tiruchirappalli, Tamil Nadu, India 2 Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences,Annamalai University, Parangipettai, Tamil Nadu, India * [E-mail: thangamjayam@gmail.com] Sea anemones, such as Heteractis magnifica, H. aurora, Stichodactyla haddoni, and S. gigantea, were collected from Mandapam coast, south-east coast of India. The tissue samples were extracted and analyzed by gas chromatography–flame ionization detection using a one-step extraction–methylation method. Totally, 40 fatty acids were identified and confirmed. Among them, palmitic acid (C16:0) was found in all the sea anemones. It was higher in H. aurora (60.53%) than in S. gigantea (23.62%). The highest saturated fatty acid (SFA) content was observed in S. gigantea extract followed by H. magnifica, H. aurora, and S. haddoni. The predominant SFA C16:0N alcohol was present in H. magnifica (22.24%) and S. haddoni (27.79%). Monounsaturated fatty acid (MUFA) C16:1ω-7 was found in H. magnifica (3.88%) and S. haddoni (8.12%) and saturated fatty acid (SFA) C18:1ω-9 was found in H. aurora extract (3.87%). Polyunsaturated fatty acid (PUFA) C18:3ω-6 was found in H. magnifica (3.88%) and C20:4ω-6 was found in S. haddoni (9.49%), H. aurora (12.26%), and S. gigantea (3.47%). The percentage of total fatty acids and SFA was higher in S. gigantea extract, the MUFA was high in H. magnifica, and PUFA was higher in H. aurora than in other sea anemone species. It is presumed that the chief fatty acids present in a particular organ are related to the specific functions of the organ. In all the tissues that were analyzed, SFA levels were higher than MUFA and PUFA. To the best of our knowledge, this is the first report on the fatty acid composition in sea anemones from Indian waters. [Keywords: Sea anemone; Palmitic acid; Saturated fatty acid; GC–flame ionization] Introduction In metabolism, lipids as one of the most elemental nutrients generate many bioactive lipid molecules, which are fundamental mediators of multiple signaling pathways. Any kind of changes in lipid metabolism can lead to the disruption of signaling networks and could be associated with some pathological states, such as cancer, cardiovascular and neurodegenerative disorder, metabolic diseases, and inflammatory complications. Lipids consist of fatty acids that are classified mostly according to the presence or absence of double bonds as follows: (i) Saturated fatty acids (SFAs—without double bonds), (ii) Monounsaturated fatty acids (MUFAs—with one double bond), and (iii) Polyunsaturated fatty acids (PUFAs—with two or up to six double bonds). They are also classified further as cis or trans based on the configuration of the double bonds and as n-3 or n-6 PUFAs depending on the position of the first double bond from the fatty acid methyl-end. The study of total fatty acid composition, especially PUFAs and ω-3 in marine organism is of great interest due to their beneficial effects on coronary diseases 1,2 . The chemical composition of species may change depending on the species, location, diet, and seasonality. Hence, the chemical compositions of marine invertebrate species are of interest for scientists since some of them are known as sources of methylene-interrupted PUFA, in particular of the (n-3) and (n-6) series, and also their toxic levels are directly proportional to their protein levels 3,4 . Sea anemones as member of Phylum: Cnidaria are common organisms in many benthic marine communities. They are known as omnivorous marine organisms that consume everything they can catch and they can live by adhering to hard substrates, such as rocks, corals, other animals, or ship bottoms. Researches on the chemical composition are limited to a few species and regions 5,9 . Hence, an attempt was made to determine the fatty acid composition of four species of sea anemones, namely, Heteractis magnifica, H. aurora, Stichodactyla haddoni, and S. gigantea. Materials and Methods Sea anemones, H. magnifica (n=6), S. haddoni (n=8), H. aurora (n=10), and S. gigantea (n=10),