Novel brominated phospholipid fatty acids from the Caribbean sponge Agelas sp

Secondary metabolites from marine sponges of the genus Agelas: a comprehensive update insight on structural diversity and bioactivity

As one of the most common marine sponges in tropical and subtropical oceans, the sponges of the genus Agelas, have emerged as unique and yet under-investigated pools for discovery of natural products with fabulous molecular diversity and myriad interesting biological activities. The present review highlights the chemical structure and biological activity of 355 compounds that have been isolated and characterized from the members of Agelas sponges, over the period of about five decades (from 1971 to November 2021). For a better understanding, these numerous compounds are firstly classified and presented according to their carbon skeleton as well as their biosynthetic origins. Relevant summaries focusing on the source organism and the associated bioactivity of these compounds belonging to different chemical classes are also provided. This review highlights sponges of the genus Agelas as exciting source for discovery of intriguing natural compounds.

The marine sponges of the genus Agelas, are unique and yet under-investigated pools for discovery of natural products with fabulous molecular diversity and myriad interesting biological activities.

Synthesis of a novel brominated vinylic fatty acid with antileishmanial activity that effectively inhibits the Leishmania topoisomerase IB enzyme mediated by halogen bond formation

Many marine derived fatty acids, mainly from sponges, possess vinylic halogenated moieties (bromine or iodine) but their assessment as antileishmanial candidates remains elusive. In this work, we undertook the first total synthesis of a novel series of 2-allyl-3-halo-2-nonadecenoic acids, which preferentially inhibit the Leishmania DNA topoisomerase IB enzyme (LTopIB) over the human topoisomerase IB enzyme (hTopIB). The synthesis of 2-allyl-3-bromo-2E-nonadecenoic acid (1a) and 2-allyl-3-chloro-2E-nonadecenoic acid (2a) was achieved through a palladium catalyzed haloallylation of 2-nonadecynoic acid (2-NDA) using either allyl bromide or allyl chloride in the presence of PdCl2(PhCN)2 in 57–83 % overall yields. Among the new halogenated synthetic compounds, 1a was the most inhibitory of LTopIB with an EC50 = 7 μM, while the shorter chain analogs 2-allyl-3-bromo-2E-dodecenoic acid (1b) and 2-allyl-3-chloro-2E-dodecenoic acid (2b), synthesized from 2-dodecynoic acid, were not inhibitory of LTopIB (EC50 > 100 μM) resulting in the overall order of inhibition 1a > 2-NDA > 2a > > 1b ≅ 2b. The acids 1a and 2a inhibit LTopIB by a Gimatecan-independent mechanism. The enhanced LTopIB inhibition of 1a was computationally rationalized in terms of a halogen bond between the bromine in 1a and a DNA phosphate (binding energy = − 4.85 kcal/mol). Acid 1a also displayed preferential cytotoxicity towards Leishmania infantum amastigotes (EC50 = 2.5 μM) over L. infantum promastigotes (EC50 > 25 μM).

Bioactive Secondary Metabolites from the Marine Sponge Genus Agelas

The marine sponge genus Agelas comprises a rich reservoir of species and natural products with diverse chemical structures and biological properties with potential application in new drug development. This review for the first time summarized secondary metabolites from Agelas sponges discovered in the past 47 years together with their bioactive effects.

The fatty acids of calcareous sponges (Calcarea, Porifera)

Twenty-nine specimens of calcareous sponges (Class Calcarea, Phylum Porifera), covering thirteen representative species of the families Soleneiscidae, Leucaltidae, Levinellidae, Leucettidae, Clathrinidae, Sycettidae, Grantiidae, Jenkinidae, and Heteropiidae were analysed for their fatty acids. The fatty acids of Calcarea generally comprise saturated and monounsaturated linear (n-), and terminally methylated (iso-, anteiso-) C(14)-C(20) homologues. Furthermore, polyunsaturated C(22) fatty acids and the isoprenoic 4,8,12-trimethyltridecanoic acid were found. The most prominent compounds are n-C(16), iso-C(17), iso-C(18), n-C(18), n-C(20). In addition, a high abundance of the exotic 16-methyloctadecanoic acid (anteiso-C(19)) appears to be a characteristic trait of Calcarea. Long-chain 'demospongic acids', typically found in Demospongiae and Hexactinellida, are absent in Calcarea. The completely different strategy of calcarean fatty acid synthesis supports their phylogenetic distinctiveness from a common Demospongiae/Hexactinellida taxon. Both intraspecific and intraclass patterns of Calcarea showed great similarity, suggesting a conserved fatty acid composition that already existed in the last common ancestor of Calcinea and Calcaronea, i.e. before subclasses diverged.

In Vitro Antiviral Activity of Marine Sponges Collected Off Brazilian Coast

This paper describes the in vitro antiviral evaluation of 27 different marine sponges (Porifera) collected off Brazilian coastline in the search for novel drug leads. With these sponges aqueous and organic extracts were prepared and tested for anti-herpetic (HSV-1, KOS strain), anti-adenovirus (human AdV serotype 5) and anti-rotavirus (simian RV SA11) activities. The evaluation of the cytotoxicity and potential antiviral activity of these extracts were performed by using MTT assay. Results were expressed as 50% cytotoxicity (CC50) and 50% effective (EC50) concentrations, respectively, in order to calculate the selectivity indices (SI=CC50/EC50) of each extract. From the 40 sponge extracts tested, 17 extracts showed antiviral action in different degrees. The results concerning the antiviral activity were obtained by using three different strategies: (1) simultaneous assay, when sponge extracts were added to the cells at the same time of the viruses; (2) pre treatment assay, when sponge extracts were added to the cells 15 h prior to the viruses infection; and (3) post treatment assay, when the viruses were added to the cells and remained during 2 h prior to the addition of sponge extracts. The antiviral assays with HSV-1/KOS and AdV-5 showed more promising results when the pre treatment test was employed. In relation to the RV-SA11 virus, only the simultaneous assay showed antiviral activity. The extracts presenting the most promising results were the aqueous extracts of Cliona sp., Agelas sp.2, Tethya sp., Axinella aff corrugata, Polymastia janeirensis and Protosuberites sp., and these extracts deserve special attention in further studies.

New fatty acid derivatives from Homaxinella sp., a marine sponge

Fractionation of the MeOH extract of Homaxinella sp., a marine sponge, led to the isolation of a sodium salt of a new brominated FA (1), two new MG (2 and 4), and a new lysoPC (6). The geometry of the double bonds in 1 and 2 was defined by comparison of the NMR chemical shifts of the allylic carbons, nuclear Overhauser effect spectroscopy correlations of the allylic protons, and coupling constants of the vinylic protons with those reported. Evidence mainly from NMR and MS analyses established the planar structures of the compounds. Compounds 1, 2, 4, and 6 were evaluated for cytotoxicity against a panel of five human solid tumor cell lines. Only compound 1 showed moderate activity.

Phospholipid fatty acids and sterols of two Cinachyrella sponges from the Saudi Arabian Red Sea: comparison with Cinachyrella species from other origins

Phospholipid class compositions, fatty acids and sterols of the sponges Cinachyrella alloclada and C. kükenthali from the Saudi Arabian Red Sea were studied and compared with previous results for other Cinachyrella spp. collected in Senegal (East Atlantic) and New Caledonia (West Pacific). More than 50 fatty acids were identified as methyl esters and N-acyl pyrrolidides in each phospholipid mixture by GC/MS. Six fatty acids not hitherto found in nature were identified, namely 17-methyltetracosanoic in C. kükenthali and 18-methyltetracosanoic, 18-methylpentacosanoic, 18-methylhexacosanoic, 18,24-dimethyl-hexacosanoic and 6-bromo-5,9-nonacosadienoic acids in C. alloclada. Approximately 20 Delta 5,9 unsaturated fatty acids were found, including three 6-brominated acids. The presence of bacteria was evidenced by the relatively high proportions of phosphatidylglycerol and high levels of branched short-chain fatty acids. A total of 20 free 3beta-hydroxysterols were found by GC/MS, including clerosterol in relatively high amounts and gorgosterol in low amounts. The latter sterol has not been reported to date in a sponge. Comparisons with Cinachyrella species from other geographical areas show marked differences for both phospholipid fatty acid and sterol compositions.

Natural halogenated fatty acids: their analogues and derivatives

A comprehensive survey has been made of all fatty acids containing halogen atoms covalently bonded to carbon and which are deemed as naturally occurring. Generally thought to be minor components produced by many different organisms, these interesting compounds now number more than 300. Recent research, especially in the marine area, indicates this number will increase in the future. Sources of halogenated fatty acids include microorganisms, algae, marine invertebrates, and higher plants and some animals. Their possible biological significance has also been discussed

Extractable organohalogens in tissues of beluga whales from the Canadian Arctic and the St. Lawrence estuary

Samples of blubber, brain, kidney, liver, and muscle of individual beluga whales were extracted and analyzed for extractable organic Cl (EOCl), Br (EOBr), and I (EOI) by neutron activation analysis. The highest levels of EOCl (554 microg g(-1) lipid) were found in the kidney of Arctic beluga and the lowest (24 microg g(-1) lipid) in the blubber. Levels in brain and liver lipids were on average of equal magnitude. The unequal distribution of EOCl in tissue lipids is in marked contrast to the equal distribution, in lipid, demonstrated for organochlorines such as DDTs and PCBs by a number of investigations. The distribution of brominated (EOBr) and iodinated (EOI) compounds was similar and markedly different from that of EOCl. The tissue distribution of EOCl seems to be related to the proportion to polar lipids in the tissues. Beluga from St. Lawrence had significantly higher brain EOCl levels than the Arctic samples whereas the levels of EOCl in liver and kidney were higher in the Arctic whales.

Unusually high levels of eicosatetraenoic, eicosapentaenoic, and docosahexaenoic fatty acids in Palestinian freshwater sponges

The fatty acid compositioin of three freshwater sponges-Ephydatia syriaca, Nudospongilla sp., and Cortispongilla barroisi-were studied. Twenty principal fatty acids, and unusually high levels of eicosatetraenoic (5,8,11,14-20:4 up to 10.1% of the total acid mixture), eicosapentaenoic (5,8,11,14,17-20:5 up to 11.6%), and docosahexaenoic acids (4,7,10,13,16,19-22:6 up to 11.8%) were detected. The only demospongic acid found was 5,9,17-hexacosatrienoic acid (1.8-3.7%).

The distribution of brominated long-chain fatty acids in sponge and symbiont cell types from the tropical marine sponge Amphimedon terpenensis

The tropical marine sponge Amphimedon terpenensis (family Niphatidae, order Haplosclerida) has previously been shown to possess unusual lipids, including unusual fatty acids. The biosynthetic origin of these fatty acids is of interest as the sponge supports a significant population of eubacterial and cyanobacterial symbionts. The total fatty acid composition of the sponge was analyzed by gas chromatography/mass spectrometry of the methyl esters. Among the most abundant of the fatty acids in intact tissue were 16:0, 18:0 and 3,7,11,15-tetramethyl-hexadecanoic (phytanic) acid. In addition, three brominated fatty acids, (5E,9Z)-6-bromo-5,9-tetracosadienoic acid (24:2Br), (5E,9Z)-6-bromo-5,9-pentacosadienoic acid (25:2Br) and (5E,9Z)-6-bromo-5,9-hexacosadienoic acid (26:2Br) were also present. The three brominated fatty acids, together with phytanic acid, were isolated from both ectosomal (superficial) and choanosomal (internal) regions of the sponge. Analysis of extracts prepared from sponge/symbiont cells, partitioned by density gradient centrifugation on Ficoll, indicated that phytanic acid and the three brominated fatty acids were associated with sponge cells only. Further, a fatty acid methyl ester sample from intact tissue of A. terpenensis was partitioned according to phospholipid class, and the brominated fatty acids were shown to be associated with the phosphatidylserine and phosphatidylethanolamine fractions that are commonly present in marine sponge lipids. The phosphatidylcholine and phosphatidylglycerol fractions were rich in the relatively shorter chain fatty acids (16:0 and 18:0). The association of brominated long-chain fatty acids (LCFA) with sponge cells has been confirmed. The findings allow comment on the use of fatty acid profiles in chemotaxonomy and permit further interpretation of LCFA biosynthetic pathways in sponges.(ABSTRACT TRUNCATED AT 250 WORDS)

Positional distribution of octadecadienoic acids in sponge phosphatidylethanolamines

The distribution of C14-C22 fatty acids in the phosphatidylethanolamines isolated from the sponges Agelas sp. and Spongia tampa was investigated. Selective changes with phospholipase A2 (from Agkistrodon halys blomhoffii) followed by thin-layer chromatographic separation of the resulting lysophosphatidylethanolamines and free fatty acids and subsequent methylation with HCl/MeOH and diazomethane, respectively, revealed that the 5,9-octadecadienoic acid and the 9,12-octadecadienoic acid present showed no preference for either position sn-1 or sn-2 in these phosphatidylethanolamines. The other saturated and unsaturated fatty acids with chains between 14 and 22 carbons long were also found to be equally distributed between positions sn-1 and sn-2 in the phosphatidylethanolamines in these sponges. The results contrast with what is known about the distribution in most mammalian phospholipids, such as the phosphatidylcholines from human erythrocytes, where octadecadienoic acid typically occupies the sn-2 position.