Study and Comparison of Fatty Acid Profile of Two Gorgonians of the Family Paramuriceidae

Abstract

Gorgonians are widely distributed in the coastal areas of the Indo-Pacific region. The Indian coast has abundant colonies of gorgonians, which are the largest single contributor to the total biomass of the reefs [1]. Gorgonians have acquired commercial importance as a source of raw materials for large quantities of prostaglandins, "wonder-drugs" for many systemic diseases in man and animals obtained from Plexaura homomalla (Esper), a Caribbean species [2]. The literature show the identification of some bioactive novel compounds such as steroids, terpenoids, glycosides, ceramides, etc. from different gorgonian species [3–6], but the literature on the fatty acid profile of the total lipid of marine gorgonians is very scarce. A few works have been carried out to study the fatty acid components of marine gorgonians [2, 7, 8]. The present study was carried out with the two gorgonians of the family Paramuriceidae Bayer collected from the Bay of Bengal of the Odisha coast. Extraction of Lipid, Preparation of Fatty Acid Methyl Esters (FAMEs), and FAME Analysis by GC. Gorgonian specimen Heterogorgia flabellum (class: Anthozoa, order: Gorgonacea Lamourex, family: Paramuriceidae Bayer) and Echinomuricea indica (class: Anthozoa, order: Gorgonacea Lamourex, family: Paramuriceidae Bayer) were collected from 25 m depth of the Bay of Bengal of Odisha coast during February–March 2007 from newly found ridge lineation [9, 10]. The two samples were identified by Dr. P. A. Thomas, Ex-Emeritus Scientist (ICAR), Trivandrum, Kerala. The gorgonians were thoroughly washed and air-dried. Ten grams of each species was homogenized and successively extracted three times with chloroform–methanol (2:1, v/v) to isolate lipids [11]. The crude lipid extracts were purified by a “Folch wash” to remove nonlipid contaminants [12]. The chloroform phase was separated from the combined extract, dried over anhydrous sodium sulfate, and concentrated under nitrogen atmosphere. Part of the lipophilic extract (100 mg) was taken in 5 mL of ethanolic KOH and then refluxed on a water bath at 70–80C for 4 h. After cooling, the free fatty acids were isolated and dried over sodium sulfate. The free fatty acids were dissolved in 4 mL of 5% HCl in methanol and 0.5 mL benzene, and the mixture was refluxed on a water bath at 70–80C for 2 h. After cooling, the methyl esters were extracted with petroleum ether and simultaneously neutralized and dried over anhydrous sodium sulfate. The solvent was evaporated to dryness at reduced pressure at 40C in a water bath. These fatty acid methyl esters (FAME) were then analyzed by GC for identification. FAME analyses were performed on an Agilent GC-MS equipped with FID, and a 25 m 0.25 mm, 0.25 m film thickness HP-1 column. Helium was used as the carrier gas at a flow rate of 1.2 mL/min, at a column pressure of 42 kPa. The column temperature was programmed for fatty acid methyl esters (FAMEs) from 120–280C at 2C/min, then 280C for 10 min, with a total run time of 100 min, using 70 eV ionization voltage (EI). Peak identification was carried out by comparison of their chromatographic retention times with those of authentic standards C4-C24 (Supelco standard FAME mixtures). A comparative study is made of the percent content of different fatty acids identified in the two gorgonian species of the same family (Table 1). Among the identified fatty acids, the % of saturated fatty acids is comparatively much higher than the other fatty acids in the two gorgonians. The percentages of saturated fatty acids in the two gorgonians, i.e., Heterogorgia flabellum and Echinomuricea indica, are 82.41% and 72.68%, respectively. Both species contain a high percentage of palmitic acid (16:0) and stearic acid (18:0) in comparison to other fatty acids. Both species contain more than 25% of palmitic acid and more than 20% of stearic acid, which is an important observation. As far as the saturated fatty acid lauric acid (12:0) is concerned, it is comparatively high in E. indica (3.04%). Myristic acid (14:0) and pentadecyclic acid (15:0) are also present in the two investigated species.