Detailed profiles of 7-O-acyl esters in plankton and shellfish from the Portuguese coast

In bivalve mollusks from the Portuguese coast contaminated by diarrhetic shellfish poisoning (DSP), most of the parent toxins, okadaic acid (OA) or dinophysistoxin-2 (DTX2), are found esterified, and toxicity assessment is only performed after an alkaline hydrolysis step to recover the parent molecules in their free form. The presence of 7-O-acyl esters with fatty acids (FAs) has already been confirmed previously in Mytilus galloprovincialis and Donax trunculus samples. This paper reports the presence of acyl esters in a wider range of estuarine and offshore bivalve species found by direct analysis in LC-MS. The total of acyl esters found in each species represented the percentages commonly found by hydrolysis in those species in previous years, justifying the majority of the esters commonly found in shellfish. This implies that any diol esters remaining after digestion of toxic microalgae would represent only a minor contribution to the ester's contents. Esters with C14:0, C16:0, C16:1, C20:5 and C22:6 FAs were the most abundant, followed by esters with C18:0, C18:1, C18:2, C18:3 and C18:4. This is the first report of OA and DTX2 esters with odd FAs: C15:0, C17:0, C17:1, and probably a branched FA: iso-C16:0. Esters with iso-C16:0 where found in high percentages particularly in two species of estuarine clams, where they represented 13-34% of total esters found. Esters were also found in plankton, predominantly with C16:0. Total esters in plankton were not higher than 10%, not enough to justify per se the high levels found in bivalves.     

Thin-layer chromatography-pyrolysis-gas chromatography-mass spectrometry: a multidimensional approach to marine lipid class and molecular species analysis

A new multidimensional chromatographic method is described in which material separated into lipid-class bands on silica-coated quartz thin-layer chromatography (TLC) rods (Chromarods) is desorbed using a pyrolysis unit interface and introduced directly into a gas chromatograph-mass spectrometer for molecular species analysis. Steryl esters, wax esters, hydrocarbons, ketones, and fatty-acid methyl esters (FAMEs) are thermally desorbed without pretreatment. In order to desorb free sterols, monoacylglycerols (MAGs), aliphatic alcohols, and free fatty acids, the esters are converted to trimethylsilyl derivatives on the rod. Triacylglycerols and phospholipids are converted to FAMEs by thermochemolysis with tetramethylammonium hydroxide. The method's utility is demonstrated with lipids from seawater particulate matter by first confirming the identity of lipid bands with the appropriate standards. The wax ester-steryl ester TLC band contained no more than 8% steryl esters. Wax esters of up to C42 are detected. In six individual acyl lipid classes, C14-C22 fatty acids are detected with C16 acids predominant in all but wax esters. C16-C22 MAGs are identified in the complex acetone-mobile polar lipid band. The method successfully extends the scope of latroscan TLC-flame-ionization detection on Chromarods, which is a widely used technique for lipid-class analysis. Modification of the pyrolysis probe to handle intact TLC rods is a future objective.     

Wetting behavior of mixtures of water and nonionic polyoxyethylene alcohol

Five binary water + C4Ej mixtures, water + n-C4E0, water + 2-C4E0, water + iso-C4E0, water + n-C4E1, and water + iso-C4E1, were chosen to perform the surface/interfacial tension measurements over the experimental temperature range from 10 to 85 degrees C at the normal pressure by using a homemade pendent drop/bubble tensiometer. The symbol CiEj is the abbreviation of a nonionic polyoxyethylene alcohol CiH(2i+1)(OCH2CH2)jOH. The wetting behavior of the CiEj-rich phase at the interface separating gas and the aqueous phase is systematically examined according to the wetting coefficient resulting from the experimental data of surface/interfacial tensions measurements. For those systems with a lower critical solution temperature, for example, water + n-C6E2, water + n-C4E1, and water + iso-C4E1, a wetting transition from partial wetting to nonwetting is always observed when the system is brought to close to its lower critical solution temperature. On the other hand, to start with a partial wetting CiEj-rich phase, a wetting transition from partial wetting to complete wetting is always observed when the system is driven to approach its upper critical solution temperature. The effect of hydrophobicity of CiEj on the wetting behavior of the CiEj-rich phase at the interface separating gas and the aqueous phase was carefully investigated by using five sets of mixtures: (1) water + n-C4E0, water + n-C5E0, and water + n-C6E0; (2) water + 2-C4E0 and water + 2-C5E0; (3) water + 2-C4E0 and water + n-C4E0; (4) water + n-C4E1, water + n-C5E1, and water + n-C6E1; (5) water + n-C4E0 and water + n-C4E1. The CiEj-rich phase would tend to drive away from complete wetting (or nonwetting) to partial wetting with an increase in the hydrophobicity of CiEj in the binary water + CiEj system. All the wetting behavior observed in the water + CiEj mixtures is consistent with the prediction of the critical point wetting theory of Cahn.     

Identification of six species in the new genus Cronobacter (Enterobacter sakazakii) from culture using gas chromatographic analysis of fatty acid methyl esters

Capillary GC with flame ionization detection (FID) was used to determine the cellular fatty acid (CFA) profiles of six species in the new genus Cronobacter (Enterobacter sakazakii). The six different species are C. sakazakii, C. malonaticus, C. dublinensis, C. muytjensii, C. turicensis, and C. genomospecies. For GC-FID analysis, whole cell fatty acid methyl esters (FAMEs) from cells cultured on brain heart infusion (BHI) agar at 35 degrees C for 24 h were obtained by saponification, methylation, and extraction into hexane-methyl tert-butyl ether. A data set for 57 strains of Cronobacter species was prepared using fatty acid profiles from two or three replicates prepared on different days. Major fatty acids of the Cronobacter strains evaluated in this study were straight-chain C12:0, C14:0, C16:0, and unsaturated C18:1, omega7c, summed C16:1 omega7c/C16:1 omega6c, and summed C14:0 3-OH/iso-C16:1, and C17:0 omega cyclo 7-8. The CFA profiles for the Cronobacter species are similar, but there are several fatty acids-C12:0, C14:0, C16:0, C18:1 omega7c, and summed C16:1 omega7c/ C16:1 omega6c--that differ significantly among these six species. Analysis of FAMEs from Cronobacter strains grown on BHI agar by a rapid GC-FID method is a sensitive procedure for the identification of these organisms, and this analytical method provides a procedure for the differentiation of strains from closely related Cronobacter species.     

Identification and quantification of lipids from rabbit Harderian glands by gas chromatography/mass spectrometry

Lipids from hydrolysed extracts of Harderian glands from the rabbit were examined as trimethylsilyl, acetonide, nicotinate and picolinyl esters and shown to consist mainly of acylated glycerol ethers and acylated hydroxy-glycerol ethers. Constituents amounting to 98.8% of the recovered secretion were identified. Fatty acids were mainly normal, saturated compounds with chain lengths from 12 to 24 carbon atoms; n-16:0 and n-18:0 accounted for about 40% of the identified acids. Small concentrations of iso-17:0 and unsaturated acids with 18-carbon chains were also identified. Fatty alcohols were again mainly normal-unsaturated compounds; the chains varied from C18 to C25 with 20:0-OH and 22:0-OH being the most abundant. Three types of 1-alkyl glycerols were found. The major constituents had normal, saturated chains with from 14 to 23 carbon atoms with the even carbon chains predominating. These were accompanied by hydroxylated derivatives of the 16- and 18-carbon glycerol ethers with hydroxy groups in the 10, 11 and 12 positions. Branched-chain glycerol ethers were of low concentration and contained predominantly iso chains. Many of these compounds have not been reported before in this secretion. Low concentrations of the previously reported hydroxy acids with n-C14, -C15 and -C16 chains were also found. Nicotinate derivatives were applied to the structural determination of glycerol ethers for the first time and shown to reveal the position of methyl branch points in an analogous manner to that previously shown for mono- and di-hydric alcohols. Acids were identified as picolinyl esters.     

Phase behavior of undecane-tetradecane mixtures confined in SBA-15

Phase behavior of undecane-tetradecane (n-C11H24-C14H30, C11-C14) mixtures in bulk and confined in SBA-15 have been studied using differential scanning calorimetry. The bulk C11-C14 system shows multiple phase regions due to rotator phase. Confined in the pores of SBA-15 (pore diameters 3.8-7.8 nm), the mixtures only show a melting boundary of a straight line and a curve, respectively. In SBA-15 (17.2 nm), phase behavior of themixtures has some similarity to that of the bulk. Under confinement, the phase diagrams of the mixtures vary with the pore size, temperature, and compositions.     

Lipidomics of the Edible Brown Alga Wakame (Undaria pinnatifida) by Liquid Chromatography Coupled to Electrospray Ionization and Tandem Mass Spectrometry

The lipidome of a brown seaweed commonly known as wakame (Undaria pinnatifida), which is grown and consumed around the world, including Western countries, as a healthy nutraceutical food or supplement, was here extensively examined. The study was focused on the characterization of phospholipids (PL) and glycolipids (GL) by liquid chromatography (LC), either hydrophilic interaction LC (HILIC) or reversed-phase LC (RPLC), coupled to electrospray ionization (ESI) and mass spectrometry (MS), operated both in high and in low-resolution mode. Through the acquisition of single (MS) and tandem (MS/MS) mass spectra more than 200 PL and GL of U. pinnatifida extracts were characterized in terms of lipid class, fatty acyl (FA) chain composition (length and number of unsaturations), and regiochemistry, namely 16 SQDG, 6 SQMG, 12 DGDG, 5 DGMG, 29 PG, 8 LPG, 19 PI, 14 PA, 19 PE, 8 PE, 38 PC, and 27 LPC. The FA (C16:0) was the most abundant saturated acyl chain, whereas the monounsaturated C18:1 and the polyunsaturated C18:2 and C20:4 chains were the prevailing ones. Odd-numbered acyl chains, iJ., C15:0, C17:0, C19:0, and C19:1, were also recognized. While SQDG exhibited the longest and most unsaturated acyl chains, C18:1, C18:2, and C18:3, in the sn-1 position of glycerol, they were preferentially located in the sn-2 position in the case of PL. The developed analytical approach might pave the way to extend lipidomic investigations also for other edible marine algae, thus emphasizing their potential role as a source of bioactive lipids.     

Synthesis and Crystal Structure of 2-Fluoro-4-methyl-3-oxo-4-aza-5α-androst-1-ene-17β-carboxylic Acid Methyl Ester

Synthesis and Crystal Structure of 2-Fluoro-4-methyl-3-oxo-4-aza-5α-androst-1-ene-17β-carboxylic Acid Methyl EsterAuthorJANG Yin-Zhi XIANG Zuo LIANG Da-Wei (Department of Applied Chemistry, Zhejiang Sci-Tech. University, Hangzhou 310018, China)AbstractThe title compound VII, 2-fluoro-4-methyl-3-oxo-4-aza-5α-androst-1-ene-17β-carboxylic acid methyl ester (C21H30FNO3, Mr = 363.46), was prepared through a seven-step reaction from pregnenolone, and characterized by elemental and single-crystal X-ray diffraction analyses as well as IR, MS and 1H-NMR spectra. It is of monoclinic system, space group P21/c with a = 6.3882(7), b = 9.9033(11), c = 15.4925(17) , β = 91.923(2)°, V = 979.57(19) 3, Z = 2, Dc = 1.232 mg/m3, μ = 0.088 mm-1, F(000)= 392, R = 0.0465, wR = 0.0989 and λ(MoKα) = 0.71073 . The structure indicates that the four cycles (A: C(1)-C(2)-C(3)-N(1)-C(5)-C(10), B: C(5)-C(6)-C(7)- C(8)-C(9)-C(10), C: C(8)-C(14)-C(13)-C(12)-C(11)-C(9), D: C(14)-C(15)-C(16)-C(17)-C(13)) are in chairand trans-configurations. The results of crystal structure determination show that there exist weak intra-molecular hydrogen bonds, resulting in a two-dimensional supramolecular frame-work of the title compound.Keywordsfluoro-sterol, synthesis, crystal structure, supramolecule     

碱催化法衍生化气相色谱/质谱法分析青海湖裸鲤鱼油中的脂肪酸

用碱催化法将青海湖裸鲤鱼油甲酯化,以气相色谱/质谱法分析鱼油中的脂肪酸。青海湖裸鲤可食用部分中鱼油含量为25.13%。从鱼油中共鉴定出47种脂肪酸,包括直链、单支链、多支链饱和脂肪酸,单不饱和、多不饱和脂肪酸,环丙烷基、呋喃基脂肪酸等。不饱和脂肪酸含量为73.6%,其中多不饱和脂肪酸含量为25.4%,以C18∶2(4.9%),C18∶3(3.1%),C20∶4(1.3%),C20∶5(二十碳五烯酸（EPA）, 9.4%)和C22∶6(二十二碳六烯酸（DHA）, 6.7%)为主。单不饱和脂肪酸含量为48.2%,主要由C16∶1(20.3%),C18∶1(25.9%)构成。饱和脂肪酸含量为25.7%,主要有C14∶0(3.4%),C16∶0 (19.4%)和C18∶0(1.1%)。青海湖裸鲤鱼油中还存在不常见的环丙烷基和呋喃基脂肪酸及多种奇数碳链和支链脂肪酸。因此,青海湖裸鲤是功能性脂肪酸的重要膳食来源。     

Determination of the acyl moieties of the antibiotic complex A40926 and their relation with the membrane lipids of the producer strain.

Structures of the fatty acid residues characterizing the various components of A40926 were determined by gas chromatography/mass spectrometry on the methyl esters obtained by methanolysis of the complex. The results confirm the residues previously assigned to Factor A (n-undecanoic acid) and B (10-methyl-undecanoic acid) and establish the residues of Factor A1 (9-methyl-decanoic acid), B1 (n-dodecanoic acid), RS1 (8-methyl-nonanoic acid), RS2 (n-decanoic acid), and RS3 (n-tridecanoic acid). As the Actinomadura species contain in their mycelia large quantities of C15-C17 fatty acid residues as membrane phospholipids, these mycelia were saponified and the fatty acids obtained were analyzed as above. There is a close correlation between the fatty acid content of A40926 complex and that of the longer homologues in the producer mycelia.     

Biocontrol efficacy of Cestrum diurnum L. (Solanaceae: Solanales) against the larval forms of Anopheles stephensi

Cestrum diurnum L. (Solanaceae: Solanales) is a multistemmed shrub that is also known as 'Day Jasmine'. The efficacy of the plant as a strong biocontrol agent of the larval anopheline mosquito was evaluated in the laboratory and bioactive ingredients were characterized by thin layer chromatography (TLC) and infrared (IR) analysis. Thin layer chromatographic analysis revealed the presence of steroidal compound as a bioactive ingredient and IR analysis reported the presence of O-H group, C-S bond as a -CH2S group, H bonded -C=O group and carbonyl stress of esters. The LC50 value of the active ingredient was determined as 0.70, 0.89, 0.90 and 1.03 mg/100 mL-1, for 1st, 2nd, 3rd and 4th instar larva respectively in 24 h study period. The active component was analyzed by GLC and GLC-MS and altogether 14 components were detected.     

Determination of the fatty acyl profiles of phosphatidylethanolamines by tandem mass spectrometry of sodium adducts

Phosphatidylethanolamines (PEs) are one of the major constituents of cellular membranes, and, along with other phospholipid classes, have an essential role in the physiology of cells. Profiling of phospholipids in biological samples is currently done using mass spectrometry (MS). In this work we describe the MS fragmentation of sodium adducts of 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphatidylethanolamine (POPE) and 2-linoleoyl-1-palmitoyl-sn-glycero-3-phosphatidylethanolamine (PLPE). This study was performed by electrospray ionization tandem mass spectrometry (ESI-MS/MS) using three different instruments and also by matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS). All MS/MS spectra show product ions related to the polar head fragmentation and product ions related to the loss of acyl chains. In ESI-MS/MS spectra, the product ions [M+Na-R1COOH-43]+ and [M+Na-R2COOH-43]+ show different relative abundance, as well as [M+Na-R1COOH]+ and [M+Na-R2COOH]+ product ions, allowing identification of both fatty acyl residues of PEs, and their specific location. MALDI-MS/MS shows the same product ions reported before and other ions generated by charge-remote fragmentation of the C3-C4 bond (gamma-cleavage) of fatty acyl residues combined with loss of 163 Da. These fragment ions, [M+Na-(R2-C2H3)-163]+ and [M+Na-(R1-C2H3)-163]+, show different relative abundances, and the product ion formed by the gamma-cleavage of sn-2 is the most abundant. Overall, differences noted that are important for identification and location of fatty acyl residues in the glycerol backbone are: relative abundance between the product ions [M+Na-R1COOH-43]+ > [M+Na-R2COOH-43]+ in ESI-MS/MS spectra; and relative abundance between the product ions [M+Na-(R2-C2H3)-163]+ > [M+Na-(R1-C2H3)-163]+ in MALDI-MS/MS spectra.     

Deuteration as an aid to the high-temperature gas chromatography—mass spectrometry of steryl fatty acyl esters

A method is presented for reducing degradative losses of steryl fatty acyl esters bearing polyunsaturated fatty acyl moieties during high-temperature gas chromatography (GC) and combined high-temperature GC—mass spectrometry (MS). The method employs selective deuteration of the double bonds in the fatty acyl moiety using a homogeneous catalyst (Wilkinson's catalyst). The Δ⁵ double bond, which occurs in the most commonly occurring plant and animal sterols, is not deuterated under the conditions described. In addition to improving GC behaviour, the method has the advantage of preserving structure information by labelling each double bond present in the original unsaturated fatty acyl moiety. The carbon number and degree of unsaturation of the labelled fatty acyl moiety are readily revealed by combined GC—MS employing negative-ion ammonia chemical ionisation. Two applications of the method are demonstrated in the analysis of steryl fatty acyl esters isolated from a rape seed oil and ovary tissue of the marine prawn Penaeus monodon.     

Analysis of naturally occurring α-acetotriacylglycerides by gas chromatography — chemical ionization mass spectrometry

The seed oils of three Maytenus species have been examined by high temperature GLC using SOP-50 (methoxy-terminated) and OV-225-OH (OH-terminated) glasscapillary columns. The main compounds (71–76%) could be identified as α-mono-acetotriacylglycerols by a combination of high temperature GLC-MS in negative chemical ionization mode with a CH₄/N₂O mixture as reactant gas and other spectroscopical methods (infrared, ¹H- and ¹³C-nuclear magnetic resonance spectroscopy). The OV-225-OH phase demonstrated better separation properties that the SOP-50 phase for this substance class and up to eight species of α-monoacetotriacylglycerols could be separated. The content of usual triacyclglycerols was below 1%. The results of the analysis of the individual fatty acids as their methyl esters by GC and GC-MS are also presented.     

Unambiguous detection of astaxanthin and astaxanthin fatty acid esters in krill (Euphausia superba Dana)

HPLC atmospheric pressure chemical ionization (APCI)/MS, GC MS, HPLC diode array detection (DAD), and NMR were used for the identification of astaxanthin and astaxanthin fatty acid esters in krill (Euphausia superba Dana). Matrix solid phase dispersion was applied for the extraction of the carotenoids. This gentle and expeditious extraction technique for solid and viscous samples leads to distinct higher enrichment rates than the conventional liquid-liquid extraction. The chromatographic separation was achieved employing a C30 RP column that allows the separation of shape-constrained geometrical isomers. A methanol/tert-butylmethyl ether/water gradient was applied. (all-E) Astaxanthin and the geometrical isomers were identified by HPLC APCI/MS, by coelution with isomerized authentical standard, by UV spectroscopy (DAD), and three isomers were unambiguously assigned by microcoil NMR spectroscopy. In this method, microcoils are transversally aligned to the magnetic field and have an increased sensitivity compared to the conventional double-saddle Helmholtz coils, thus enabling the measurement on small samples. The carotenol fatty acid esters were saponified enzymatically with Lipase type VII from Candida rugosa. The fatty acids were detected by GC MS after transesterification, but also without previous derivatization by HPLC APCI/MS. C14:0, C16:0, C16:1, C18:1, C20:0, C20:5, and C22:6 were found in astaxanthin monoesters and in astaxanthin diesters. (all-E) Astaxanthin was identified as the main isomer in six fatty acid ester fractions by NMR. Quantitation was carried out by the method of internal standard. (13-cis) Astaxanthin (70 microg/g), 542 microg/g (all-E) astaxanthin, 36 microg/g unidentified astaxanthin isomer, 62 microg/g (9-cis) astaxanthin, and 7842 microg/g astaxanthin fatty acid esters were found.     

Contribution to the analysis of the essential oil of Helichrysum italicum (Roth) G. Don. Determination of ester bonded acids and phenols

The essential oil of Helichrysum italicum (Roth) G. Don (everlasting or Immortelle essential oil) was isolated by hydrodistillation and analysed by GC and GCMS. Forty four compounds were identified. The main components were alpha-pinene(12.8%), 2-methyl-cyclohexyl pentanoate (11.1 %), neryl acetate (10.4%), 1,7-di-epi-alpha-cedrene (6.8%) and other compounds. The oil was fractionated and ester-containing fraction was hydrolysed with KOH/H(2)SO(4). The liberated volatiles were analysed by GC and GC-MS: three phenols and twenty seven volatile carboxylic acids were identified[70% low fatty acids (C(2)-C(5)), 15% C(10)-C(12) acids and 15% other acids]. The main acids were acetic acid (24.3%) propanoic acid (17.2%), 2-methylpropanoic acid (11.4%),dodecanoic acid (8.7%), 2-methylbutanoic acid (8.3%), (Z)-2-methylbutenoic acid(5.1%) and decanoic acid (4.6%). With respect to the identified bonded carboxylic acids,the minimal number of esters in the oil was twenty seven, but their overall quantity was probably larger due to different possible combinations of alcohols with acids to form esters. On the other hand, only six main esters were identified in the oil before fractionation and hydrolysis.     

Novel superstructure of nondiscoid mesogens: uneven-parallel association of half-disk molecules, 3,4,5-trialkoxybenzoic anhydrides, to a columnar structure and its one-directionally geared interdigitation

Compact and simple nondiscoid mesogens, trialkoxybenzoic anhydrides 2-11 ((RO)(3)C(6)H(2)-CO-O-CO-C(6)H(2)(OR)(3), R = C(2)H(5), n-C(3)H(7), n-C(4)H(9), n-C(6)H(13), n-C(8)H(17), n-C(10)H(21), n-C(12)H(25), n-C(14)H(29), n-C(16)H(33), and (S)- and (R)-3,7-dimethyloctyl) were designed and synthesized, and their superstructures were investigated by polarized light microscopy, differential scanning calorimetry, calculation (MM2 and AM1), circular dichroism spectroscopy, and X-ray diffraction. As the result, in the cases of 5-9 and 11, the half-disk molecules in the liquid crystal phases were self-assembled by the dipole-dipole interaction between their carbonyl groups to a column in which the molecules were piled up in an alternately antiparallel manner, and the columns were interdigitated each other. The observed interdigitations were highly directional in the perpendicular direction to the column axis. In the case of compound 11 which has (S)- or (R)-3,7-dimethyloctyl groups, a helical organization of the molecules in the column was estimated from the peaks in the circular dichroism spectra. This is the first report of a one-directionally interdigitated columnar phase, and these compounds are the first liquid crystalline acid anhydrides. It was demonstrated that a -CO-O-CO- moiety is useful as a polar junction in liquid crystalline compounds.     

高效液相色谱法同时测定化妆品中的3种苯扎氯铵同系物

建立了采用高效液相色谱-二极管阵列检测器(HPLC-DAD)同时检测化妆品中3种苯扎氯铵同系物(n-C12H25-C9H13NCl、n-C14H29-C9H13NCl、n-C16H33-C9H13NCl)的方法。采用含0.5%甲酸的甲醇超声提取样品,以CAPCELL PAK SCX色谱柱(250 mm×4.6 mm, 5 μm)分离,流动相为40 mmol/L乙酸铵水溶液(含0.1%三乙胺,pH 4.0)和乙腈,梯度洗脱,流速1.0 mL/min,检测波长260 nm,柱温25 ℃,进样量20 μL。该方法的检出限50.0 mg/kg,定量限200.0 mg/kg,线性范围5.0～3000.0 mg/L,加标回收率92.5%～102.1%,相对标准偏差为3.81%～6.66%。结果表明,该方法快速、准确,能够同时测定化妆品中3种苯扎氯铵同系物。     

Phytochemical investigation and biological studies of Bombax malabaricum flowers

In this study, extracts of the flowers of the folk medicinal plant Bombax malabaricum DC were biologically and chemically screened. Chemical constituents in the n-hexane fraction from the flowers of B. malabaricum DC were investigated using gas-liquid chromatography (GLC) analysis, affording 14 compounds, including cholesterol, stigmasterol, campesterol and α-amyrin, while the residual 10 compounds are hydrocarbons. GLC analysis of the fatty acid (FA) esters established the majority abundance of the saturated FA over their unsaturated analogues. The polar methanol fraction afforded seven flavones: vicenin 2 (1), linarin (2), saponarin (3), cosmetin (4), isovitexin (5), xanthomicrol (6) and apigenin (7). Structures 1-7 were established by intensive studies of various spectral data (H-NMR, mass spectroscopy and UV) and comparison with authentic samples. Compounds 1-7 are described here for the first time from this plant. Extracts of n-hexane and methanol exhibited significant antioxidant and antimicrobial activities.     

A matrix-assisted laser desorption/ionization mass spectrometry approach to the lipid A from Mesorhizobium loti

The isolation, purification and analysis of the lipid A obtained from Mesorhizobium loti Ayac 1 BII strain is presented. Analysis of the carbohydrate moiety after acid hydrolysis by high-pH anion-exchange chromatography with pulse amperometric detection (HPAEC-PAD) showed the presence of glucosamine and galacturonic acid as the only sugar components. Gas chromatographic (GC) and GC/mass spectrometric (MS) analysis of the fatty acids revealed the presence of 3-OH-C12:0; 3-OH-C13:0; 3-OH-C20:0 and 27-OH-C28:0 among the major hydroxylated species. In addition, C16:0, C17:0, C18:0 and C 20:0 were shown as main saturated fatty acids. Different polyacylated species were evidenced by thin layer chromatography of lipid A, allowing the purification of two fractions. Ultraviolet matrix-assisted laser desorption/ionization time-of-flight (UV-MALDI-TOF) MS analysis with different matrices, in the positive- and negative-ion mode, was performed. The fast moving component revealed the presence of hexa-acylated species, varying in the fatty acid composition. Species containing three 3-OH fatty acids and a 27-OH-C28:0 fatty acid were observed. Individual ions within this family differ by +/-14 mass units. The slow moving component was enriched mainly in penta-acylated species. Among them, three subgroups were detected: the major one compatible with the sugar core bearing two 3-OH 20:0 fatty acids, a 3-OH 13:0 or a 3-OH 12:0 fatty acid, a 27-OH 28:0 fatty acid and one saturated fatty acid. Each signal differs in a C18:0 acyl unit from the corresponding hexa-acylated family. On the other hand, a subgroup bearing one 3-OH 20:0 fatty acid, one 27-OH 28:0 fatty acid and two non-polar fatty acids was shown. A minor subgroup compatible with structures containing two hydroxylated and three non-polar fatty acids was also detected. The results obtained showed that nor-harmane was an excellent matrix for charged lipid A structural studies in both, positive and negative ion modes.