Fatty Acid Profile, Sterol Composition of Lipids, and Antibacterial Study of the Marine Sponge Psammaplysilla purpurea Collected from the Bay of Bengal (Odisha Coast)

Abstract

Marine sponges are the most primitive multicellular sedentary animals that produce bioactive metabolites. Among the aquatic animals, sponges are characterized by the greatest diversity of fatty acids (FA), sterols, etc. Fatty acids and sterols as lipid components of sponges have been elaborately studied by a number of investigators [1][2][3][4][5][6]. Some lipids of sponges are characterized as biologically active [7][8][9].The sponge Psammaplysilla purpurea (order Verongida, family Aplysinellidae) is a well-known source of several bromotyrosine alkaloids of unique structural features and exhibiting promising biological activities such as cytotoxicity, antimicrobial properties, etc. [10][11][12][13]. The methanol and dichloromethane extracts of this species have shown broad-spectrum larvicidal and insecticidal activity [14]. However there has been no report on the FA profile of the lipid composition of P. purpurea. This is the first report on the analysis of the FA and sterol composition of the sponge P. purpurea collected from the Bay of Bengal region of the Odisha coast. The search for FAs and sterols of the lipophilic extract of P. purpurea can give valuable information on its chemotaxonomy. Thus, these minor components appear as biomarkers for such organisms.Forty-nine fatty acids were identified in the mixture of total lipids of P. purpurea by GC-MS analysis (Table 1). Peak identification was carried out by comparison of the mass spectra with those available in the NIST and WILEY libraries and also confirmed by comparison of their chromatographic retention times as well as mass fragmentations with those of authentic standards C-4-C-24 (Supelco standard FAME mixtures). Among the identified fatty acids, saturated linear FAs account for more than 50% of the total FA content, which is an important observation. All of the acids from 12:0 to 27:0 were found except 13:0. Generally, among saturated fatty acids, 16:0 and C18:0 dominated in most of the sponges. But in the present investigation, the acids 19:0 and 16:0 were dominant. Long-chain saturated fatty acids like 22:0 to 27:0 are present, among which 26:0 is present in good amount (6.04%).In sponges, branched saturated iso/anteiso acids with a total number of carbon atoms from C-14 to C-29 were found, among which C-15-C-20 acids were the most widespread [15]. In the present investigation, 24 saturated monobranched FAs were identified (29.92%), br-16:0 and br-14:0 being the major ones. It is considered that saturated iso and anteiso C-15-C-20 acids have a bacterial origin [16]. The ratio of iso and anteiso FAs is much higher in sponges, a significant part of whose biomass is compounded by bacterial symbionts. Thus, in the sponge P. purpurea the content of iso and anteiso may be due to symbiotic bacteria. Only one polybranched FA was identified, i.e., 3,7,11,15-tetramethylhexadecanoic acid (br-16:0, 4.38%), which is very often found in marine sponges [17]. The identification of 3,7,11,15-tetramethyl-16:0 was finally confirmed by comparing its key mass fragments (...