Identification of ceramide 2-aminoethylphosphonate molecular species from different aquatic products by NPLC/Q-Exactive-MS.

Ceramide 2-aminoethylphosphonate (CAEP) is a type of phosphonosphingolipids with potential trophic activity. In this work, complicated CAEP species from different aquatic products were comprehensively identified and semi-quantified by utilizing normal phase liquid chromatography/Q-Exactive mass spectrometry (NPLC/Q-Exactive-MS). We elucidated the fragment schemes of CAEP molecules and found the presence of methylated CAEP (Me-CAEP) species. Remarkably, quantitative results revealed that Loligo chinensis had the highest CAEP content of 4.9 ±â€¯0.4 mg/g dry weight and the most complex molecular species composition, whereas Asterias amurenis had the lowest CAEP content of 1.9 ±â€¯0.6 mg/g dry weight. The most common molecule was CAEP (d19:3-16:0). Additionally, statistical analysis revealed that five aquatic products can be effectively distinguished from their CAEP species; thus, CAEP molecules can play an important role in identifying processed products from aquatic products.

High-performance liquid chromatographic determination of 2-aminoethylphosphonic acid and 2-amino-3-phosphonopropionic acid in seawater matrix using precolumn fluorescence derivatization with o-phthalaldehyde-ethanethiol.

2-Aminoethylphosphonic acid (2-AEP) and 2-amino-3-phosphonopropionic acid (2-AP3) are two types of abundant and ubiquitous naturally occurring phosphonates used as sources of phosphorus by many prokaryotic lineages. The potential utilization mechanism of 2-AEP and 2-AP3 in eukaryotic phytoplankton is currently under investigation. However, the lack of suitable analytical methods in saline samples are the limitation of such researches. Herein, a high-performance liquid chromatography (HPLC) method for monitoring 2-AEP and 2-AP3 using precolumn fluorescence derivatization with o-phthalaldehyde-ethanethiol (OPA-ET) in seawater matrix was developed. The derivatization procedure and HPLC conditions were carefully examined, which included optimization of the fluorescence excitation and emission wavelengths, the ammonium acetate concentration and pH of the mobile phase, the OPA-ET reagent content and composition and derivatization time. Because increasing salinity was observed to lower the derivatization efficiency, working standards were freshly prepared in artificial seawater with the same salinity as that of the samples for the quantification of 2-AEP and 2-AP3. The developed HPLC method showed a wide linear response with high linearity (R2 > 0.999) and high repeatability at three concentration levels. The relative standard deviation was less than 4.1% for 2-AEP and less than 1.7% for 2-AP3 (n = 7). The limits of detection for 2-AEP and 2-AP3 in artificial seawater matrix were both 12.0 µg/L. The recoveries were 83.0-104% for 2-AEP and 72.6-98.6% for 2-AP3 in different aqueous samples, including algal culture medium prepared with filtered seawater. These results indicated the matrix effect of this method was insignificant.

Detection of 2-aminoethylphosphonic acid in suspended particles in an ultraoligotrophic lake: a two-dimensional nuclear magnetic resonance (2D-NMR) study.

Particulate organic phosphorus (P) compounds were examined in ultraoligotrophic Lake Saiko, Japan. A cartridge filter was used to collect sufficient amount of suspended particles for analysis by a two-dimensional NMR (1H-31P heteronuclear multiple bond correlation). 2-Aminoethylphosphonic acid (2-AEP), a phosphonate, was detected in suspended particles in Lake Saiko. The identity of the phosphonate was confirmed by comparison with a commercially available compound. Because 2-AEP is bioavailable, microorganisms can store and use this compound under extremely P-limited conditions. This is the first study to detect 2-AEP in an ultra-oligotrophic environment.

The influence of salt matrices on the reversed-phase liquid chromatography behavior and electrospray ionization tandem mass spectrometry detection of glyphosate, glufosinate, aminomethylphosphonic acid and 2-aminoethylphosphonic acid in water.

The analysis of highly polar and amphoteric compounds in seawater is a continuing challenge in analytical chemistry due to the possible formation of complexes with the metal cations present in salt-based matrices. Here we provide information for the development of analytical methods for glyphosate, glufosinate, AMPA, and 2-AEP in salt water, based on studies of the effects of salt matrices on reversed-phase liquid chromatography-heated electrospray ionization-tandem mass spectrometry (RP-LC-HESI-MS/MS) after derivatization of the target compounds with FMOC-Cl. The results showed that glyphosate was the only analyte with a strong tendency to form glyphosate-metal complexes (GMC), which clearly influenced the analysis. The retention times (RTs) of GMC and free glyphosate differed by approximately 7.00min, reflecting their distinct RP-LC behaviors. Divalent cations, but not monovalent (Na+, K+) or trivalent (Al3+, Fe3+) cations, contributed to this effect and their influence was concentration-dependent. In addition, Cu2+, Co2+, Zn2+, and Mn2+ prevented glyphosate detection whereas Ca2+, Mg2+, and Sr2+ altered the retention time. At certain tested concentrations of Ca2+ and Sr2+ glyphosate yielded two peaks, which violated the fundamental rule of LC, that under the same analytical conditions a single substance yields only one LC-peak with a specific RT. Salt-matrix-induced ion suppression was observed for all analytes, especially under high salt concentrations. For glyphosate and AMPA, the use of isotopically labeled internal standards well-corrected the salt-matrix effects, with better results achieved for glufosinate and 2-AEP with the AMPA internal standard than with the glyphosate internal standard. Thus, our study demonstrated that Ca2+, Mg2+, and Sr2+ can be used together with FMOC-Cl to form GMC-FMOC which is suitable for RP-LC-HESI-MS/MS analysis.

Lipid Profile in Different Parts of Edible Jellyfish Rhopilema esculentum.

Jellyfish Rhopilema esculentum has been exploited commercially as a delicious food for a long time. Although the edible and medicinal values of R. esculentum have gained extensive attention, the effects of lipids on its nutritional value have rarely been reported. In the present of study, the lipid profile including lipid classes, fatty acyl compositions, and fatty acid (FA) positions in lipids from different parts (oral arms, umbrella, and mouth stalk) of R. esculentum was explored by ultraperformance liquid chromatography--electrospray ionization--quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS). More than 87 species from 10 major lipid classes including phosphatidylcholine (PC), lysophosphatidylcholine (LPC), phosphatidylethanolamine (PE), lysophosphatidylethanolamine (LPE), phosphatidylinositol (PI), lysophosphatidylinositol (LPI), phosphatidylserine (PS), ceramide (Cer), ceramide 2-aminoethylphosphonate (CAEP), and triacylglycerol (TAG) were separated and characterized. Semiquantification of individual lipid species in different parts of R. esculentum was also conducted. Results showed that glycerophospholipids (GPLs) enriched in highly unsaturated fatty acids (HUFAs) were the major compenents in all parts of R. esculentum, which accounted for 54-63% of total lipids (TLs). Considering the high level of GPLs and the FA compositions in GPLs, jellyfish R. esculentum might have great potential as a health-promoting food for humans and as a growth-promoting diet for some commercial fish and crustaceans. Meanwhile, LPC, LPE, and LPI showed high levels in oral arms when compared with umbrella and mouth stalk, which may be due to the high proportion of phospholipase A2 (PLA2) in oral arms. Moreover, a high CAEP level was detected in oral arms, which may render cell membranes with resistance to chemical hydrolysis by PLA2. The relatively low TAG content could be associated with specific functions of oral arms.

Membrane phospholipid composition of hemocytes in the Pacific oyster Crassostrea gigas and the Manila clam Ruditapes philippinarum.

The detailed sterol (free sterol proportions and compositions) and phospholipid (PL) compositions (relative proportions of PL classes and subclasses and their respective fatty acid (FA) compositions) of hemocyte membranes were investigated in two bivalve mollusks: the Pacific oyster Crassostrea gigas and the Manila clam Ruditapes philippinarum. Hemocyte membrane lipids of both species revealed similar general composition: i) their free sterol/PL ratio was above 0.4 and ii) their PL were predominated by the diacyl+alkyl forms of glycerophosphatidylcholine (PC), the plasmalogen form of glycerophosphatidylethanolamine (PE) and ceramide aminoethylphosphonate (CAEP). Free sterols were predominated by cholesterol in both species. Plasmalogen forms of PE and glycerophosphatidylserine (PS) represented 82-83% and 46-55% of total PE and PS, respectively. When compared to their respective diacyl+alkyl forms, plasmalogen forms of PE and PS were specifically enriched in non-methylene-interrupted (NMI) FA and 20:1n-11, suggesting a functional significance of these PL molecular species in bivalve hemocytes. Lysoglycerophosphatidylcholine (LysoPC) levels were found to be fairly high in hemocytes, accounting for about 8% of the PL. Some species-specific features were also found. LysoPC and glycerophosphatidylinositol (PI) FA compositions differed between Ruditapes philippinarum and Crassostrea gigas. CAEP proportion was higher in R. philippinarum than in C. gigas (14.5% and 27.9% of the PL, respectively). Hemolymph cell monolayer observations and flow-cytometric analyses revealed species-specific hemocyte morphology and sub-populations which could account for some of the observed species-specific membrane lipid compositions.

Lipid classes and fatty acid composition of the tropical nudibranch mollusks Chromodoris sp. and Phyllidia coelestis.

Two nudibranch mollusks, Chromodoris sp. and Phyllidia coelestis, collected from tropical waters of the Northwestern Pacific, were analyzed for lipids. The aim of this study was to fill the gap in knowledge of lipid biochemistry of mollusks. Phospholipids (PL) were the dominating lipid class followed by sterols (13%). Neutral lipids were not detected in Chromodoris sp. By contrast, P. coelestis contained TAG, diacylglyceryl ether, long chain alcohol and esters of sterols. Among PL, PC was predominant (about 50%); PE, PS and CAEP were almost in equal proportions. Sixty five FA were identified as methyl esters and N-acyl pyrrolidides by GC-MS. The sea slugs exhibited a wide diversity of FA. The common marine n-3 PUFA, 20:5n-6 and 22:6n-3, constituted 0.6-1.3% of the total FA, whereas n-6 PUFA, 22:4n-6, 20:4n-6, and 18:2n-6, were the main (25%). Among monounsaturated FA, 7-21:1 was the main (up to 6.2%). The non-methylene-interrupted (NMI) FA were found (9.4 and 12.4%), including the known 5,11-20:2, 5,13-20:2, 7,13-22:2, 7,15-22:2 and a novel isomer 7,13-21:2 (up to 3.9%). The pathway of its biosynthesis was suggested. A series of very long chain FA (VLC FA), with the main 5,9-25:2 and 5,9-26:2, were identified. High level of VLC FA (8.7 and 11.7%) in sea slugs is apparently the result of predation on sponges. Another unique feature concerned a high abundance of various odd and branched FA (16.7 and 34%), which could have originated from the dietary origin or symbiotic bacteria. This is the first report on lipid and FA composition of nudibranchs.

Residue determination of glyphosate, glufosinate and aminomethylphosphonic acid in water and soil samples by liquid chromatography coupled to electrospray tandem mass spectrometry.

This paper describes a method for the sensitive and selective determination of glyphosate, glufosinate and aminomethylphosphonic acid (AMPA) residues in water and soil samples. The method involves a derivatization step with 9-fluorenylmethylchloroformate (FMOC) in borate buffer and detection based on liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS). In the case of water samples a volume of 10 mL was derivatized and then 4.3 mL of the derivatized mixture was directly injected in an on-line solid phase extraction (SPE)-LC-MS/MS system using an OASIS HLB cartridge column and a Discovery chromatographic column. Soil samples were firstly extracted with potassium hydroxide. After that, the aqueous extract was 10-fold diluted with water and 2 mL were derivatized. Then, 50 microL of the derivatized 10-fold diluted extract were injected into the LC-MS/MS system without pre-concentration into the SPE cartridge. The method has been validated in both ground and surface water by recovery studies with samples spiked at 50 and 500 ng/L, and also in soil samples, spiked at 0.05 and 0.5 mg/kg. In water samples, the mean recovery values ranged from 89 to 106% for glyphosate (RSD <9%), from 97 to 116% for AMPA (RSD < 10%), and from 72 to 88% in the case of glufosinate (RSD < 12%). Regarding soil samples, the mean recovery values ranged from 90 to 92% for glyphosate (RSD <7%), from 88 to 89% for AMPA (RSD <5%) and from 83 to 86% for glufosinate (RSD <6%). Limits of quantification for all the three compounds were 50 ng/L and 0.05 mg/kg in water and soil, respectively, with limits of detection as low as 5 ng/L, in water, and 5 microg/kg, in soil. The use of labelled glyphosate as internal standard allowed improving the recovery and precision for glyphosate and AMPA, while it was not efficient for glufosinate, that was quantified by external standards calibration. The method developed has been applied to the determination of these compounds in real water and soil samples from different areas. All the detections were confirmed by acquiring two transitions for each compound.

Sphingophosphonolipid molecular species from edible mollusks and a jellyfish.

The goal of this study is to supplement the composition and nature of sphingophosphonolipids diversity from edible mollusks (Mytilus galloprovincialis, Eobania vermiculata) and from jellyfish Pelagia noctiluca, organisms rich in phosphonolipids. M. galloprovincialis contained a major ceramide 2-aminoethylphosphonate (CAEP-IM) and a minor ceramide that was detected chromatographically as the methyl analog (CAEP-IIM). In CAEP-IM, saturated fatty acids (FA) of 14, 16 and 18 carbons amounted to 68.8%; also 52.5% dihydroxy bases were detected. On thin layer chromatography, the Rf for CAEP-IIM was smaller than the Rf for CAEP-IM because of an increase of 22.0% in 2OH-16:0 FA, plus 29.2% trihydroxy bases (phytosphingosine). Similarly, a ceramide 2-methylaminoethylphosphonate (CAEP-IIE, 1.5% of phospholipids) was quantitated in Eobania (apart from the previously reported major CAEP, 7.6%). In CAEP-IIE, saturated and hydroxy FA of 14, 16 and 18 carbons amounted to 37.0 and 37.8%; 29.1% dihydroxy and 23.0% trihydroxy bases were detected in the same molecule. Eobania's unsaturated FA percentages (total lipids: 66.3, polar: 47.5, neutral: 59.0) were similar to those previously found for other land snails. A suite of two minor CAEP (CAEP-IIP, CAEP-IIIP) was quantitated in Pelagia at 2.0 and 1.3% of phospholipids (apart from the previously reported major CAEP, 21.0%) identified chromatographically as methyl analogs. In CAEP-IIP, saturated FA of 14, 16, 18 and 19 carbons amounted to 56.0%; 12.6% dihydroxy and 34.1% trihydroxy bases were also detected in CAEP-IIP. The Rf CAEP-IIIP

Aminomethylphosphonate and 2-aminoethylphosphonate as (31)P-NMR pH markers for extracellular and cytosolic spaces in the isolated perfused rat liver.

Aminomethylphosphonate (NMePo) and 2-aminoethylphosphonate (NEthPo) were evaluated as alternative pH indicators in the isolated perfused rat liver using (31)P-nuclear magnetic resonance (NMR). NMePo did not distribute within cells and remained in the extracellular space. It exhibited pH titration with a low pK(a) value (5.35). This behaviour makes NMePo useful for extracellular volume or acidic pH determination. In contrast, NEthPo accumulated within cells without altering liver energetic steady state, evaluated from nucleosides triphosphates resonances, even for prolonged (100 min) experiments. Withdrawal of NEthPo from perfusate revealed a residual resonance corresponding to the internalized amount of this phosphonate. This fraction was almost stable vs time and allowed determination of spin-lattice relaxation time constant T(1) within the liver (2.2 +/- 0.3 s; n = 6). Comparison of the titration curves for NEthPo and inorganic phosphate revealed that the accuracy of pH determination within physiologic or acidic range in both cases was comparable. Finally, when extracellular pH was decreased, the NEthPo resonance frequency was found to undergo the same chemical shift variations as observed for cytosolic P(i) signal, which was in good agreement with a cytosolic accumulation of this phosphonate. Therefore, NEthPo could be considered as an interesting cytosolic pH probe suitable for (31)P-NMR measurements, especially when experimental conditions prevent reliable observation of cytosolic Pi resonance.

Structural variation in the glycoinositolphospholipids of different strains of Trypanosoma cruzi.

The structures of the glycoinositolphospholipids (GIPLs) from five strains of the protozoan parasite Trypanosoma cruzi have been determined. Two series of structures were identified, all but one containing the same Man4(AEP)GlcN-Ins-PO4 core. Series 1 oligosaccharides are substituted at the third mannose distal to inositol (Man 3) by ethanolamine-phosphate or 2-aminoethylphosphonic acid, as are some glycosyl-phosphatidylinositol-protein anchors of T. cruzi. The core can be further substituted by terminal (1-3)-linked beta-galactofuranose units. In contrast, Series 2 oligosaccharides do not have additional phosphorus-containing groups attached to Man 3, the latter being substituted instead by a single side chain unit of beta-galactofuranose. Series 1 oligosaccharides are present in all strains (G, G-645, Tulahuen CL, and Y) whereas Series 2 structures are present mainly in CL and Y strains. The lipid moiety in the GIPLs from the G, G-645 and Tulahuen strains is predominantly ceramide, as reported for the Y strain, whilst that from the CL strain is a mixture of ceramide and alkylacylglycerol species. The lipid moiety of the GIPLs, and probably also the phosphoinositol-oligosaccharide structures may play an important immunomodulatory role in infection by T. cruzi.

Structure of the asn-linked oligosaccharides of apolipophorin III from the insect Locusta migratoria. Carbohydrate-linked 2-aminoethylphosphonate as a constituent of a glycoprotein.

The primary structures of the N-linked carbohydrate chains of apolipophorin III from the insect Locusta migratoria have been determined. The glycoprotein was completely deglycosylated with peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase F. Released oligosaccharides were separated from the remaining protein using gel-permeation chromatography on Bio-Gel P-100. Purification of the carbohydrate chains was achieved by a combination of FPLC anion-exchange chromatography on Mono-Q and amine adsorption HPLC on Lichrosorb-NH2. The structures of the carbohydrate chains were deduced with a combination of fast atom bombardment mass spectrometry, 1H- and 31P-NMR spectroscopy, and methylation analysis. The majority of the carbohydrate chains contains 2-aminoethylphosphonate (AEP), which is linked to the 6-position of Man and/or GlcNAc. L. migratoria apolipophorin III is the first example of a glycoprotein containing carbohydrate-linked 2-aminoethylphosphonate. The structures of the major oligosaccharides were established to be the following: [formula: see text]

Kinetics of endosomal acidification in Dictyostelium discoideum amoebae. 31P-NMR evidence for a very acidic early endosomal compartment.

We have examined the pH of the various endosomal compartments in the amoebae of the cellular slime mould Dictyostelium discoideum. This was accomplished both by fluorescence and by in vivo 31P-NMR methods. The fluid-phase marker, fluorescein-labeled dextran, was fed to the amoebae to report the average pH of their endocytic vesicles. During the progressive loading of successive endosomal compartments, we observed an early acidification down to a minimum value of pH < or = 5.3 after 30 min at 20 degrees C followed by an increase to an average pH of 5.8 when all the endosomal compartments were loaded by the fluid-phase marker. The weak fluorescence intensity of FITC-dextran at acidic pH precluded a more detailed investigation and we checked various phosphonate compounds as potential 31P-NMR pH probes for the endosomal compartments. Two molecules, aminomethylphosphonate and 2-aminoethylphosphonate, were selected for this study because of the large amplitudes of their chemical shift variation with pH (2 and 2.5 ppm, respectively) and their acidic pKs of 5.5 and 6.3, respectively. They were only moderately toxic (IC50% approximately 10 mM) towards both the axenic growth and the differentiation program of Dictyostelium amoebae. Internalization of the two aminophosphonates occurred only through the fluid-phase pinocytosis pathway as revealed by the full inhibition of their entry with 1 mM vanadate or 7.5 mM caffeine, two previously characterized inhibitors of endocytosis in Dictyostelium. We found that in vivo 31P-NMR of amoebae suspensions incubated with the aminophosphonates allowed the detection of three distinct intracellular compartments at pH 4.3, 5.8-6.0 and 7.3. Kinetics of aminophosphonate entry were analyzed and the results allowed us to reconstruct the time course for the acidification sequence during endocytosis. The data are consistent with the hypothesis that in Dictyostelium amoebae phosphonates occupy a highly acidic early endosomal compartment (t1/2 = 18 min; pH 4.3) before reaching a less acidic late endosomal/prelysosomal compartment (pH 5.8-6.0) from where they are immediately transported to, and trapped in, the cytoplasm (pH 7.3).

Determination of the presence of ceramide aminoethylphosphonate and ceramide N-methylaminoethylphosphonate in marine animals by fast atom bombardment mass spectrometry.

Phosphonosphingolipids from 15 kinds of shellfish were analyzed by fast atom bombardment mass spectrometry to determine the contents of ceramide aminoethylphosphonate (CAEPn) and ceramide N-methylaminoethylphosphonate (CMAEPn). Two pairs of ions, at m/z 126 and 140 in the positive ion mode and at m/z 124 and 138 in the negative ion mode, were used to distinguish between aminoethylphosphonic acid and N-methylaminoethylphosphonic acid in CAEPn and CMAEPn. Interestingly, mollusca in the early stage of evolution have both CAEPn and CMAEPn, while most in the middle stage have only CMAEPn and those in the highest stage have only CAEPn.

Occurrence of 2-aminoethylphosphonic acid in feeds, ruminal bacteria and duodenal digesta from defaunated sheep.

A quantitative method of analysis for 2-aminoethylphosphonic acid (AEP) was developed using reverse-phase HPLC. The detection limit for AEP was 15 nM, and the detector response (peak area) was linear from AEP levels up to 100 microM (R = .99). Mean recovery of AEP added to strained ruminal fluid from faunated sheep was 98.2%. When AEP was added to a fermentation mixture at a concentration of 22.6 micrograms/ml, 78% disappeared during a 24-h incubation. 2-Aminoethylphosphonic acid was readily detected in preparations of mixed ruminal ciliate protozoa as well as in mixed and pure strains of ruminal bacteria, feedstuffs, and ruminal fluid and duodenal digesta from defaunated sheep. The occurrence of AEP in feed and bacterial hydrolysates was confirmed by organic phosphorus analyses. The concentration of AEP in mixed ruminal protozoa was three times greater than its concentration in mixed ruminal bacteria (4,304 vs 1,383 micrograms/g DM, respectively). The AEP values for pure ruminal bacterial cultures ranged from 733 micrograms/g DM in Bacteroides succinogenes B21a to 1,166 micrograms/g DM in Butyrivibrio fibrisolvens H17c. Ruminal fluid and duodenal digesta from defaunated sheep contained AEP concentrations of 30 micrograms/ml and 90 micrograms/g DM, respectively. The concentration of AEP in feedstuffs ranged from 25 micrograms/g DM in wheat straw to 263 micrograms/g DM in oats. Because AEP occurrence is not limited to ruminal ciliate protozoa, it is of little value as a marker for protozoal presence in or passage out of the rumen.

Distribution of ciliatine (2-aminoethylphosphonic acid) and phosphonoalanine (2-amino-3-phosphonopropionic acid) in human tissues.

Ciliatine (2-aminoethylphosphonic acid) was detected in the human brain, heart, kidney, liver, intestine, spleen, adrenal glands, and aorta. Phosphonoalanine (2-amino-3-phosphonopropionic acid) was found in the human liver, intestine and spleen. Tissue homogenates were extracted with trichloroacetic acid and a chloroform-methanol mixture. After hydrolysis, each fraction was subfractionated by ion-exchange chromatography and examined by paper chromatography and electrophoresis using a specific ninhydrin-molybdate staining procedure to detect the phosphonic acids. The acids were found bound either to lipid or to protein; no free phosphonic acid was detected.

Alkylphosphonates as unique compounds in the metabolism of the schistosomal vector Biomphalaria glabrata.

Examination of intact freshly laid egg masses of the schistosomal snail vector Biomphalaria glabrata by both 31P nuclear magnetic resonance spectroscopy and colorimetric phosphorus analysis indicated that 98% of the phosphorus in the egg masses was present in the form of alkylphosphonic acids. At least 87% of the total phosphorus originally present was comprised of 2-aminoethylphosphonic acid. During 11 days of embryonic development, alkylphosphonate-phosphorus decreased from 98% to 50% of the total phosphorus, indicating a possible role for phosphonate-phosphorus in the embryonic nutrition of these snails. Considering the relative uniqueness of the alkylphosphonates in nature, the very high concentration of these compounds in freshly laid eggs, and the reduction in their amount during embryonic development, the anabolic and catabolic pathways of alkylphosphonates may serve as sites for highly specific analogues in the control of these schistosomal vectors.

Structure of a novel diphosphonoglycosphingolipid isolated from the skin of Aplysia kurodai.

A new phosphonoglycosphingolipid containing two 2-aminoethylphosphonate residues was isolated from the skin of Aplysia kurodai, a marine gastropod, using two systems of silicic acid chromatography. By methanolysis, permethylation, mild acid hydrolysis and hydrogen fluoride treatment combined with thin layer chromatography and gas chromatography-mass spectrometry, the new phosphonoglycosphingolipid was shown to be 3-O-MeGal (1----3) GalNAc (1----3) [6'-O-(2-aminoethylphosphonyl) Gal (1----2)] [2-aminoethylphosphonyl (----6)] Gal (1----4) Glc (1----1) ceramide. Most of the fatty acid (90 per cent) was palmitic acid. Octadeca-4-sphingenine and anteiso-nonadeca-4-sphingenine were the major sphingosine bases of the new glycolipid.