Phospholipid studies of marine organisms: III. New phospholipid fatty acids fromPetrosia ficiformis

The fatty acyl components of the phospholipids from the spongePetrosia ficiformis consisted predominantly of branched, especially iso and anteiso acids. The two major components of the complex mixture are the hitherto unknown Z,Z-25-methyl-5,9-hexacosadienoic and Z,Z-24-methyl-5,9-hexacosadienoic acids. Other unknown acids are: 7,13,16-docosatrienoic acid, 15-methyldocosanoic acid, 15-methyltricosanoic acid and 24-methyl-5,9-pentacosadienoic acid. Short branched-chain fatty acids, presumably of bacterial origin, are considered to be the possible bioprecursors of these novel phospholipid constituents. The major phospholipids were PE, PC, PG, PS and PI. The distribution of fatty acids among the phospholipid classes was also studied.     

Phospholipid studies of marine organisms: New branched fatty acids fromStrongylophora durissima

The phospholipids of the spongeStrongylophora durissima were analyzed. The major phospholipids present were phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylglycerol (PG) and phosphatidylinositol (PI). The major fatty acid components of the phospholipids consisted of short chain (C₁₄−C₁₉) and very long chain (C₂₅−C₃₀) “Demospongic” acids. Three novel branched Δ⁵ monounsaturated acids,Z-19-methyl-5-pentacosenoic,Z-19-methyl-5-hexacosenoic andZ-19-methyl-5-heptacosenoic acids were encountered in the sponge. The 3-saturated counterparts of these compounds, 19-methylpentacosanoic, 19-methylhexacosanoic and 19-methylheptacosanoic acids, as well as 19-methylpentacosanoic and 20-methyloctacosanoic acids also are hitherto undescribed acids present in the sponge. Trace amounts of 2 very long chain acids also were detected and their structures tentatively assigned as 19,21-dimethylheptacosanoic and 20,22-dimethyloctacosanoic acids. The distribution of these fatty acids according to phospholipid head groups also was described.     

Phospholipid studies of marine organisms: V1 new α-methoxy acids fromHigginsia tethyoides

The phospholipids of the demospongeHigginsia tethyoides are shown to have at least 16 long-chain α-methoxy acids, which represent a new class of fatty acids. Among them are the saturated α-methoxy acids containing 19–24 carbon atoms. The monounsaturated compounds are 2-OMe-Δ¹⁷-24:1, 2-OMe-Δ¹⁸-25:1, 2-OMeΔ¹⁹-26:1 and 2-OMe-Δ²¹-28:1. The major diunsatured ones were shown to be 2-OMe-Δ^{5, 19}-26:2 and 2-OMe-Δ^{7, 21}-28:2. Small amounts of 2-OMe-23∶1, 2-OMe-26∶3; 2-OMe-27∶1 and 2-OMe-28∶3 were also encountered. Structures of the minor monounsaturated compounds were tentatively assigned as 2-methoxy-16-tricosenoic acid and 2-methoxy-20-heptacosenoic acids. The double bonds of the fatty acids show all-cis configuration. Circular dichroism measurements indicate an R-configuration for the α-methoxy acids. The major component of the total phospholipid acid mixture is 5,9,23-triacontatrienoic acid. Possible biosynthetic routes to these unusual phospholipid acids are discussed. The major phospholipids were phosphatidylethanolamine, phosphatidylglycerol and phosphatidylserine. The distribution of fatty acids among the phospholipids was also investigated.     

Bromine content of lipids of marine organisms

Lipids were extracted from a number of organisms taken in the northern Pacific ocean and the bromine content measured by neutron activation analysis. The lipids of each species studied were found to contain bromine with concentrations ranging from ten to several hundred μg/g. The major portion of the bromine was associated with the fatty acids in Chromatographic separations; however, the presence of a number of different brominated compounds was indicated. When the fatty acids were prepared from the crude lipids by acid hydrolysis, partitioned into base, and then esterified, 60% of the initial bromine was recovered in the ester fraction. This would indicate the presence of brominated acids in marine lipids.     

Chemical ecology of marine organisms: An overview

An overview of marine chemical ecology is presented. Emphasis is placed on antipredation, invertebrate-toxic host relationships, antifouling, competition for space, species dominance, and the chemistry of ecological interactions.     

The docosahexaenoic acid of marine organisms

Preparative gas chromatography has been used for the purification of the highly unsaturated C₂₂ acid present in cod liver. Confirmation that this acid is Δ^{4,7,10,13,16,19} docosahexaenoic acid has been obtained by purely physicochemical means using NMR and mass spectrometry.     

Ether lipids inhibit the effects of phorbol diester tumor promoters

Recent studies have shown that the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) stimulates protein kinase C (PKC), whereas the ether-linked phospholipid 1-O-octadecyl-2-O-methyl-rac-glycerol-3-phosphocholine (ET-18-OCH₃) inhibits PKC activity in vitro. Therefore, the antitumor effects of ET-18-OCH₃ could be due to its inhibition of PKC activity and the effects of tumor promotion. TPA stimulates arachidonic acid release, prostaglandin synthesis, phosphatidylcholine synthesis and the degradation of phosphatidylcholine by phospholipase C in Madin Darby canine kidney (MDCK) cells. Therefore, we have determined the effects of ET-18-OCH₃ on these consequences of TPA stimulation. Preliminary experiments determined that ET-18-OCH₃ inhibited PKC partially purified from MDCK cells by ion-exchange chromatography on DEAE-cellulose. In addition, ET-18-OCH₃, inhibited the TPA-stimulated phosphorylation of a 40,000-dalton protein in intact MDCK cells. These data indicate that ET-18-OCH₃ is an effective inhibitor of PKC activity in MDCK cells. In addition, ET-18-OCH₃ was found to inhibit arachidonic acid release and prostaglandin synthesis. The inhibition of prostaglandin synthesis appears to be secondary to inhibition of arachidonic acid release, since ET-18-OCH₃ does not inhibit TPA-stimulated synthesis of prostaglandin H synthase or the activity of the enzyme directly (Parker, J., Daniel, L. W., and Waite, M. [1987]J. Biol. Chem. 262, 5385–5393). ET-18-OCH₃ also inhibits TPA-stimulated phosphatidylcholine synthesis and phosphatidylcholine degradation by phospholipase C. These data provide evidence that the antineoplastic ether lipids inhibit the biochemical effects of the tumor promoter TPA in intact cells and indicate that this inhibition may have a role in their biological activities.     

Ether lipids based on the glyceryl ether skeleton: Present state,future potential

Lipids from natural sources consist mainly of saponifiable substances, such as glycerides, along with some unsaponifiable lipids, some of which are ether lipids. Typical ether lipids are monoalkyl ethers of glycerin, also called alkyl/alkenyl glyceryl ethers. Alkyl/alkenyl glyceryl ethers have also been reported in marine organisms and in human feces. Several chemical syntheses of such ether lipids have been reported. Typical examples are alkyl glyceryl ether formation by the addition reaction of alkyl glycidyl ether and the telomerization reaction of butadiene with glycerin and a transition metal catalyst. Characteristic chemical structures, such as terpene alkyl glyceryl ethers, archaebacterial macrocyclic ether lipids, and glyceryl ethers of condensed cyclic planar molecules, have been obtained as well. Over the past few decades, industry has shown much interest in the chemistry and application of highly branched fatty acids. For example, isostearyl glyceryl ether (GE-IS) with methyl branching in the middle chain was already known, but it is now prepared at an industrial scale by proprietary alkyl glycidyl ether methods. The characteristic behavior of GE-IS toward water, such as formation of water-in-oil emulsions containing large amounts of water and of liquid crystals, has made it applicable for use in hair and skin-care cosmetics. Based on these studies and considerations, glyceryl ether lipids, which are rarely investigated, may become one of the most important and useful lipids in the industry.     

Ether lipids and analogs in experimental cancer therapy. A brief review of the munich experience

This review covers the work of our laboratory on the antineoplastic activity of some ethei lipids and derivatives that are related to platelet-activating factor (PAF). Various 1-O-alkyl lysophospholipid derivatives (ALP) show therapeutic activity in mouse transplant tumor models and in metastatic 3-Lewis lung carcinoma in vivo. However, certain autochthonous mouse leukemias and radiation-induced lymphomas are resistant to ALP treatment. The therapeutic effects of these compounds are partially due to the activation of cytotoxic macrophages and direct cytotoxicity. Approximately 20 ether lipids and derivatives were tested for direct cytotoxicity in cells from human solid tumors and leukemias using [³H]thymidine uptake, trypan blue dye exclusion, human tumor clonogenic assays (HTCA) and cell morphology as criteria. Certain ALP, thioether lysophospholipid-derivatives (TLP), ether0linked lipoidal amines,sn-2 analogs of PAF, and conjugates of ether lipids and cytosine arabinoside were found cytotoxic in a dose- and time-dependent fashion. Cytotoxicity of some of the ether lipids tested is based on destruction of cell membranes. Structure-activity studies were performed to better understand the mechanisms leading to accumulation and cytotoxicity of ALP. Comparative studies with normal bone marrow cells and leukemic blasts from humans revealed preferential antileukemic cytotoxity of three ether lipids.     

Metabolism of actinic skin tumors: Incorporation of14C-acetate into lipids

Biochemical parameters of normal and actinically induced tumorous skin were compared. Similar respiratory rates and respiratory quotients were observed. However, both quantitative and qualitative differences occur in these tissue's ability to incorporate¹⁴C-acetate into lipids.     

Occurrence,function and biosynthesis of wax esters in marine organisms

Wax esters occur as a major lipid-type in at least 30 species of marine animals, distributed among 17 orders and 3 phyla. They are of limited usefulness as a chemotaxonomic character, since only in two suborders, the calanoid copepods, Calanoidei, and the toothed whales, Odontoceti, do the wax esters occur in all members so far examined. In bony fishes their occurrence in muscle correlates better with mesopelagic habitat and vertical migration patterns than with taxonomy. Homologs with 21 to 44 total carbon atoms have been reported, but the usual range for the wax esters in copepods and fish is C₃₀–C₄₂. In fishes the muscle wax esters contain predominantly one and two double bonds per molecule, while in roe lipids up to 65% of the homologs contain three or more double bonds. The component alcohols are saturated and monounsaturated, with 16∶0 and 18∶1 as the usual major constituents. The fatty acids are more diverse, but 18∶1 is most often the main component, and 16∶1 and 20∶1 are frequent major constituents; polyunsaturated acids make up 1–12% in fish muscle and whale oils and up to 45% in fish roe wax esters. Possible functions of the wax esters are for buoyancy, as energy reserves and for thermal insulation. In vitro, various tissues of marine bony fishes synthesize wax esters from long chain alcohols and fatty acids, without activation. A competing pathway for the long chain alcohols in vivo is their catabolic oxidation to the corresponding fatty acids. The key to the accumulation of wax esters is to be sought in the metabolism of the long chain alcohols, their biosynthesis and esterification vs. their catabolism. Presented at the 60th AOCS Annual Meeting, San Francisco, April 1969, as part of a Symposium on Natural Waxes.     

Variation of the lipids and fatty acids in marine shrimps consumed in Venezuela

There are three marine shrimp species in the Venezuelan internal market, two of them are native species, from fisheries, Farfantapenaeus brasiliensis and Litopenaeus schmitti, and one is an exotic species and farmed, L. vannamei. The objectives of this paper were to determine the possible variation of lipid content and fatty acid composition of these species, even under different culture conditions (e.g. feed used). The lipid content in all the species are higher (5 to 10 times) that the data from previous papers deal with marine shrimps, ranged from 4.8 to 10.9%, suggesting that its impact in the human health should be reviewed. At the same time, there were detected differences between the lipid content and fatty acids composition of the species. Wild L. schmitti had the highest lipid content (10.9%), following by wild F. brasiliensis (9.0%), cultured L. schmitti (4.8% to 7.1%) and cultured L. vannamei (5.1% to 6.2%). On the other hand, L. schmitti fed on commercial feed had the highest proportion of EPA and/or DHA, following by L. vannamei fed on the experimental feed, wild L. schmitti and fed with the experimental feed and wild F. brasiliensis.     

Metabolism of 1-14C linolenic acid in developing brain: II. Incorporation of radioactivity from 1-14C linolenate into brain lipids

Metabolism of 1-¹⁴C linolenic acid was studied in growing animals by injecting the tracer intraperitoneally into 12–13 day old suckling rats and following up the results by sacrificing groups of animals at 8 hr, 48 hr, 15 day, and 45 day intervals. In the first 15 days, there was a greater decrease in radioactivity of brain total lipids compared to the later period, although the earlier age period is characterized by lipid deposition rather than breakdown. Since the 18∶3 ω3 family of fatty acids occurs largely in the brain total phosphatidyl ethanolamine fraction, we expected that, in the initial period, total phosphatidyl ethanolamine would be the most highly radioactive component. However, results showed that 8 hr after the tracer phosphatidyl choline had the highest specific radioactivity. When the total phosphatidyl ethanolamine fraction was resolved into diacyl and alk-1-enyl species, it was found that radioactivity was not distributed evenly between the two species. There was a progressive increase in radioactivity of the alkenyl and a decrease in the diacyl species. Forty-eight hr after the tracer, however, the radioactivity of phosphatidyl ethanolamine increased and at 45 days remained slightly higher than phosphatidyl choline. Radioactivity of cholesterol, a result of synthesis from acetate undoubtedly derived from the breakdown of tracer linolenate, was also high 48 hr after tracer and remained high until 45 days.     

The presence of volatile,nonpolar bromo organic compounds synthesized by marine organisms

The presence of volatile, nonpolar bromine-containing compounds in marine organisms is demonstrated. These compounds represent, especially in tissue containing a high fat content, ca. 0.1–1.0% of the total amount of bromo organic compounds present in marine oils. In tissue with a low fat content, a higher concentration of bromo organic compounds is found. It is concluded that these compounds are probably synthesized in one or more stages in the marine food chain. These compounds may follow and disturb the analyses when isolating and determining chlorinated hydrocarbons originating from industrial and other sources of pollution.     

Pressurized limonene as an alternative bio-solvent for the extraction of lipids from marine microorganisms

A fast and green process for the isolation of high value lipids from different marine microorganisms is presented involving the use of limonene, a green biodegradable solvent, as an alternative to traditional hexane extraction. The optimized process is based on pressurized liquid extraction (PLE) at 200 °C for 15 min using limonene:ethanol (1:1, v/v) as extracting solvent. Under these conditions, lipids were extracted from different microalgae such as Spirulina, Phormidium, Anabaena and Stigeoclonium and their composition in terms of fatty acids were studied by using a Fast-GC–MS method and compared with the original content in the raw material. The extraction method provided the best results in terms of extraction yield for Spirulina, meanwhile the highest amount of ω-3 fatty acids were obtained from Stigeoclonium.     

The distribution of lipids and sterols in cell types from the marine spongePseudaxinyssa sp

The sponge Pseudaxinyssa sp., unique in sterol and fatty acid composition, was cellularly dissected into fractions enriched in each of the major cell types present in the sponge: microbial symbionts (cyanobacteria), small sponge cells (pinacocytes and choanocytes), and large sponge cells (archeocytes and cyanophytes). Three phototrophic microbial symbionts were also isolated from the cell fractions and grown in culture. An unsymmetrical distribution of fatty acids and sterols was observed for the sponge cells: small cells contained larger quantities of long chain fatty acids (greater than C24) and smaller quantities of sterols than were present in the larger sponge cells. Moreover, the rare sterols 24-isopropylcholesterol predominated in the smaller sponge cells, whereas its 22-dehydro analog predominated in the larger sponge cells. Long chain fatty acids and sterols were not detected in the cultured microbial symbionts. This constitutes the first report of lipid variability according to cell type for this most primitive group of Metazoa.     

Role of membrane lipids in the immunological killing of tumor cells: I. Target cell lipids

The metabolic and physical properties of tumor cells that are associated with their ability to resist or escape from immune attack have been investigated. The susceptibility of P815 murine-mastocytoma cells to immune killing can be modulated. Culturing the cells with adriamicin or with hydrocortisone increases or decreases, respectively, the sensitivity of the cells to killing by antibody (Ab) plus complement (C); in addition, culturing the cells with mitomycin C or hydrocortisone increases or decreases, respectively, the sensitivity of the cells to killing by cytotoxic T lymphocytes (CTL). The susceptibility of the cells to Ab-C killing correlates with the ability of the cells to synthesize complex cellular lipids, but not DNA, RNA, protein, or carbohydrate. Further, tumor cells rendered sensitive to Ab-C killing by adriamycin are decreased in total lipid content and in their cholesterol/phospholipid mole ratio; hydrocortisone-treated resistant cells showed the opposite effects. The ability of tumor cells to resist CTL killing did not correlate with their total cellular lipid synthesis, but did correlate with the synthesis and composition of specific cellular phospholipids. In addition, tumor cells increased in sensitivity to Ab-C killing exhibited an increase in cell surface membrane fluidity, whereas cells increased in suceptibility to CTL attack showed an increase in their net negative cell surface charge density. These data show certain unique chemical and physical properties of tumor cells to be of fundamental importance for their ability to resist either humoral or cell-mediated immunologic attack; modulation of one or another of these cellular properties results in a change in the cells' susceptibility to immune killing by antibody plus C or by cytotoxic T lymphocytes. Presented at the 73rd Annual Meeting of the American Oil Chemists' Society in Toronto, Canada, May 1982.