Lipid composition of <Emphasis Type="Italic">Potamogeton pectinatus</Emphasis> as a function of water contamination

The lipid composition of Potamogeton pectinatus L. collected in different parts of the Sok River in the Lower Volga basin was studied. Differences were found in the quantitative lipid composition of the plant as a function of habitat. Plants inhabiting contaminated waters typically had a lower content of total lipids and glycolipids with an increased content of neutral lipids in addition to a lower content of polyunsaturated acids.     

Separation of Some Herbicides by Two Dimensional Thin Layer Chromatography on Calcium Sulphate

Abstract

Two dimensional thin layer chromatography is being used for the last forty years¹ and now it has became an important tool for the separations of varying complexity. Various coating materials such as alumina, cellulose, kieselgel G, silica gel, silufol and polyamide have been used and studied for the separation of organics such as alkaloids, amino acids, carbohydrates, fatty acids, glycopeptides, glycolipids, lipids, phospholipids, pigments, protiens, peptides, pesticides, steroids and inorganics such as oxy acids of phosphorus, metal ions. Our previous work^{2′3′4′5′6} shows that calcium sulphate coated paper and glass plates have a great separation potential for herbicides containing carboxyl group. Therefore now an attempt is made to test the separation potential of calcium sulphate alone and calcium sulphate containing aluminium oxide active neutral, calcium carbonate and p-dimethylaminobenzaldehyde for some nerbicides by two dimensional thin layer chromatography. The results obtained are discxissed in this paper.     

Lipids of Capsicum annuum Fruit Pulp

Lipids from fruit pulp of the sweet red pepper (Capsicum annuum, Solanaceae) were characterized. The principal components of the lipids from pepper fruit pulp were neutral lipids with predominance of triacylglycerines (55.8%). The polar lipids contained sulfoquinovosyldiacylglycerines and phosphotidylglycerines. The fatty-acid compositions of the neutral lipids, glycolipids, and phospholipids were determined.     

Comparison of four cholesterol‐based stationary phases for the separation of steroid hormones

The chromatographic behavior of steroid hormones on four cholesterol‐bonded stationary phases with different structures in binary methanol/water mobile phases was studied. Of the stationary phases tested, the commercially available stationary phases Cogent UDC cholesterol? and COSMOSIL cholester? provided better separations of steroid hormones in comparison to homemade aminocholesterol and diaminocholesterol stationary phases. The results show that the temperature has a significant influence on the retention and selectivity for steroid hormones separation. The temperature increase may cause changes in the elution order. From the dependences of the retention (ln k) on temperature (1/T), the standard partial molar enthalpy and standard partial molar entropy were calculated and their enthalpic and entropic contributions to the retention were compared. The enthalpic effects principally control the retention mechanism.     

Unsaponified Compounds and Unsaturated Fatty Acids of Lipids from Mediasia macrophylla Leaves

Unsaponified compounds of lipids from Mediasia macrophylla were investigated. They were found to contain about 50% essential oil. The content of petroselinic acid in the mixture of acids isolated from the neutral lipids and glycolipids of the leaves was determined by TLC, GC, and destructive oxidation.     

Glycolipids from Capsicum annuum

The component and fatty-acid compositions of glycolipids from seeds and pulp of Capsicum annuum (Solanaceae) were established. The dominant acid of seed galactolipids was found to be linoleic; of pulp, linolenic. The content of medium-chain acids 9:0-15:0 was greater in seed glycolipids than in the analgous component of pulp lipids.     

Preparation and Characterization of a New Quercetin‐bonded Stationary Phase for High Performance Liquid Chromatography

A quercetin‐bonded silica gel stationary phase (QUSP) containing natural flavonoid ligand was first prepared via γ‐glycidoxypropyltrimethoxysilane (KH‐560) as a coupling reagent for high‐performance liquid chromatography. Its chemical structure was characterized by Fourier infrared spectroscopy, elemental analysis, thermal thermogravimetry and ¹³C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR). The chromatographic property of QUSP was systematically evaluated by using neutral, basic and acidic aromatic compounds as probes. In order to clarify its retention mechanism, a comparative study of QUSP with conventional octadecylsilyl‐bonded stationary phase (ODS) was also carried out under the same conditions. The results showed that the new quercetin‐bonded phase exhibited an excellent reversed‐phase chromatographic property with relatively weak hydrophobicity. However, it has an advantage over ODS in the fast separation of polar aromatic compounds because the quercetin ligand could provide various sites besides hydrophobicity, such as hydrogen bonding, dipole‐dipole, π‐π staking and charge transfer interactions. QUSP was performed in the baseline separations of ionized polar basic or acidic compounds, including pyridines, anilines, pyrimidines, purines and phenols with symmetric peak shape in common mobile phases without buffer salt within relatively short time. The natural ligands from herbs are readily available and contain a variety of active sites, which facilitate the exploration of industrial chromatographic separation materials for green products.     

Preparative Scale Separation of Xanthones and Iridoid Glycosides by Droplet Counter-Current Chromatography

Droplet counter-current chromatography (DCCC.) has been used for the preparative scale separation of pure constituents from crude medicinal plant extracts. Xanthones and the bitter principles have been isolated from North-American Gentiana species. From a crude extract of Ajuga pyramidalis L . (Labiatae), several hundred mg of iridoid glycosides were obtained within eight hours. The total volume of mobile phase employed for the elution was less than 150 ml. All the separations were achieved far more readily than by conventional chromatography. In addition, some general rules for solvent system selection are proposed.     

氮杂冠醚、环糊精混合功能基键合硅胶液相色谱固定相的合成与评价

冠醚键合固定相主要用于一些无机离子的分离,我们用连续固液相法合成了一系列冠醚键合硅胶固定相,并成功地用于有机化合物的分离［１～４］;β－ＣＤ的内腔疏水而外缘亲水,可以选择性地包结含苯环及萘环的化合物,且具有手性拆分能力,已被用于手性色谱固定相［５,...     

Cyclocholates as Chiral Selectors for Capillary Gas Chromatography – Effect of Temperature Conditioning on the Chromatographic Behavior of the Stationary Phase

The suitability of cyclocholates as chiral selectors in gas chromatography has been evaluated. We present the synthesis and characterization of two cyclocholates, viz. 3α,7α-diacetoxycyclo[3]cholate and 3α,7α-diacetoxycylo[4]cholate. Mixtures of these new selectors with polysiloxanes were tested as chiral stationary phases in capillary gas chromatography. Several enantiomer separations of common racemates were achieved with the 3α,7α-diacetoxycyclo[3]cholate at 10% in OV-1701 (w/w). It was shown that column efficiency was strongly dependent on temperature and that enantioselectivity was very sensitive to column conditioning. This chromatographic behavior suggested that cyclocholates were only dispersed in polysiloxane. Thus, it was assumed that chiral discrimination occurred via enantioselective adsorption interactions of enantiomers at the surface of the solid chiral selector dispersed in the polysiloxane matrix OV-1701.     

Zwitterionic Character and Lipid Composition Determine the Behaviour of Glycosylphosphatidylinositol Fragments in Monolayers

Glycosylphosphatidylinositols (GPIs) are complex glycolipids found in free form or anchoring proteins to the outer leaflet of the cell membrane in eukaryotes. GPIs have been associated with the formation of lipid rafts and protein sorting on membranes. The presence of a conserved glycan core with cell-specific modifications together with lipid remodelling during biosynthesis suggest that the properties of the glycolipids are being fine-tuned. We synthesized a series of GPI fragments and evaluated the interactions and arrangement of these glycolipids in monolayers as a 2-D membrane model. GIXD and IRRAS analyses showed the need of N-acetylglucosamine deacetylation for the formation of hydrogen bonds to obtain highly structured domains in the monolayers and an effect of the unsaturated lipids in formation and localization of the glycolipids within or between membrane microdomains. These results contribute to understand the role of these glycolipids and their modifications in the organization of membranes.     

Lipids ofGossypium mexicanum

The surface lipids of the coat and the lipids of the kernel of the seeds of a wild form of the medium-fibered cotton plantGossypium mexicanum var.nervosum have been studied in comparison with cultured species. Using the methods of CC, TLC, and GLC, and UV and mass spectrometry, in the cuticular lipids ofG. mexicanum three classes of neutral lipids have been detected, and in the kernel lipids 10 classes of neutral lipids, 2 classes of glycolipids, and 7 classes of phospholipids. The structures of the epoxyacyl-, hydroxyacyl-, and diacylglycerols of the kernel have been established. The greatest differences between the seeds of the wild form of the cotton plant and the cultured species are the greater weight of the seed coat, the presence in it of a considerable amount of the 18:1 and of medium-molecular-weight fatty acids, and a higher level in the kernel of gossypol pigments, polar lipids, and acylglycerols containing the 18:2 acid.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 57–62, January–February, 1987.     

Lipids of Some Lycopodiophyta Species

The fractional composition of neutral and polar lipids from four Lycopodiophyta species was studied. It has been established that the neutral lipids consist of esters of glycerin, alcohols, fatty acids, sterols, waxes, and hydrocarbons. The polar lipids contain glycolipids, phospholipids, and the betaine lipid of DGTS.     

Enantiomeric Separation of Non-Protein Amino Acids by Chiral Ligand-Exchange High-Performance Liquid Chromatography

Abstract

The enantiomeric separation by high-performance liquid chromatography of underivatized non-protein amino acids was investigated by using a column packed with octadecylsilanized silica coated with N,S-dioctyl-D-penicillamine as a chiral ligand-exchange phase (Sumichiral OA-5000). Excellent to good separations of enantiomers were achieved with a variety of nonprotein amino acids carrying aliphatic or aromatic side-chains by optimizing the amount (0-20%, v/v) of the organic component (2-propanol) and the concentration (1-5 mM) of the complexing metal ion (Cu²⁺) in the hydro-organic eluent.     

Separation of polycyclic aromatic hydrocarbons with a C60 bonded silica phase in microcolumn liquid chromatography

A chemically bonded C₆₀ silica phase was synthesized as a stationary phase for liquid chromatography (LC) and its retention behavior evaluated for various polycyclic aromatic hydrocarbons (PAHs) using microcolumn LC. The results indicate that the C₆₀ bonded phase offers selectivity different from that of octadecylsilica (ODS) bonded phases in the separation of isomeric PAHs. With the C₆₀ phase, PAH molecules having a partial structure similar to that of the C₆₀ molecule, e.g. triphenylene and perylene, were retained longer than with ordinary ODS stationary phases. The results also show that good correlation exists between the retention data with this C₆₀ bonded phase and with C₆₀ itself as the stationary phase.     

Comparative characteristics of bud meristem lipids from <Emphasis Type="Italic">Picea obovata</Emphasis> and <Emphasis Type="Italic">Pinus sylvestris</Emphasis>

It was shown that the lipid content of Pinus sylvestris L. was greater than that of Picea obovata L. The difference was 43–45% of total lipids in winter. Polar fractions dominated the lipid composition of both conifers. The phospholipid content was greater than the glycolipid content in winter. A significant amount of glycolipids that was equal to that of phospholipids was present simultaneously in meristem of wintering pine buds. Swelling buds of both species showed in spring an elevated content of glycolipids.     

Lipids ofOriganum tytthanthum

The composition of lipids and fatty acids from the above-ground part ofOriganum tytthanthum Gontsch. (Lamiaceae) is studied. Lipids from the air-dried plant material are enriched in glycolipids, essential fatty acids, and biologically active lipophilic substances. The free fatty acids include 15-methylhexadecanoic acid (0.5 % by GLC).Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 100–102, March–April, 2000.     

Tubing modifications for countercurrent chromatography: Investigation of geometrical parameters

Countercurrent chromatography (CCC) is a separation technique which may be described as a combination of a great number of liquid–liquid distributions of analytes in a two-phase solvent system with liquid chromatography (LC) features. Even optimized CCC separations currently provide a lower number of theoretical plates when compared to LC. For this reason, instrumental advancements are indispensable to, at least partly, overcome this drawback. Recently, we found that improvement of the classic CCC coil, that is using a long hollow tubing, may be achieved by the introduction of tubing crimpings which increase the stationary phase retention. In this study, we systematically investigated the effects of three geometrical parameters (crimping depth, distance between two crimpings as well as partial or complete crimping of the tubing) on the stationary phase retention by a factorial design of experiments approach. Separation efficiency tests were performed with two groups of analytes: fatty acid methyl esters (FAME) in the n-hexane/acetonitrile (HAcn) and alkyl p-hydroxybenzoates in the n-hexane/tert-butylmethylether/methanol/water solvent system. The most narrow crimping distance and the deepest crimping of the tubing were the best configurations in the examined flow rate range.     

Lipids of cottonseed kernels

The free, bound, and strongly bound lipids of the seed kernels of the cotton plant of variety 108-F have been studied. It has been shown that the free and bound lipids include 97.3% and 47.6% of neutral lipids, respectively. The polar lipids consist mainly of phospholipids and glycolipids. Two groups of glycolipids — sterol glycosides and glycosylglycerides — have been isolated and their compositions have been determined.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 435–438, July–August, 1983.     

Use of beta-cyclodextrin bonded phase with s-triazine moiety in the spacer for separation of aromatic carboxylic acid isomers by high-performance liquid chromatography

The separation and retention behavior of five aromatic carboxylic acid isomers was investigated by means of high-performance liquid chromatography (HPLC) using a β-cyclodextrin bonded phase with s-triazine ring in the spacer. The influence of mobile phase pH on the retention was examined. The presence of s-triazine moiety in the spacer enhances greatly the selectivity of the isomers of aromatic carboxylic acids. Baseline separations of the five aromatic carboxylic acid isomers were achieved. In particular, the isomers of toluic, aminobenzoic, nitrobenzoic and hydroxybenzoic acid were successfully and effectively separated. The chromatographic results indicate that, in addition to inclusion complexation, π-π interaction and hydrogen bonding interaction between the bonded phase and analytes play significant roles in the retention of these acid isomers. Different elution orders were observed for these acidic solutes with different substituents. Possible retention mechanisms are discussed.