Synthesis of monoglycosyl diglycerides and their derivatives

Conclusions The Koenigs-Knorr condensation of 1,2- and 2,3-di-O-benzyl-sn-glycerols with acetobromohexapyranoses results in the formation of practically only 1,2-trans-glycosides. The latter have been used for the synthesis of a number of monoglycosyl diglycerides with diglyeride moieties with L and D configurations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 643–649, March, 1976.     

Chromatographic resolution of molecular species of phosphatidylethanolamine as n-acyl-o-methyl derivatives

Phosphatidylethanolamines were converted into the N-acetyl-O-methyl or N-benzoyl-O-methyl derivatives by treatment with acetic anhydride/benzoyl chloride and diazomethane. Methods for the separation of these derivatives by argentation thin-layer chromatography and reversed-phase partition thin-layer chromatography are described. The procedure is especially advantageous for the analysis of phosphatidylethanolamines that are radioactively labelled in the ethanolamine moiety.     

Conformational analysis of polymethylated derivatives of piperidine by the method of molecular mechanics

The conformational (steric) energies of different conformers and thus the type of dominant conformation were determined by the method of molecular mechanics for polysubstituted derivatives of piperidine. The chair conformation dominates for polymethylated 4-piperidines. The half-chair conformation is preferred for 1-methyl-3-methylene-4-piperidone, and the sofa conformation is preferred for analogous polymethylated enones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 91–97, January, 1991.     

New method for the synthesis of thioglycidic acids and their derivatives

Conclusions A new method was described for the preparation of thioglycidic acids and their derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1788–1794, August, 1973.     

Selective gas chromatographic analysis of monohydroxysteroids as their cyanosyl derivatives

A new silylating reagent that forms cyanosyl (cyanoethyldimethylsilyl) derivatives with monohydroxysteroids is introduced and its usefulness for the gas chromatographic analysis of these compounds evaluated. The reactivity of the new reagent, N-methyl-N-cyanoethyldimethylsilyltrifluoroacetamide, has been studied using a series of monohydroxysteroids and compared to that of other reagents forming cyanosyl or alkylsilyl derivatives. The results obtained indicate that at room temperature, in polar solvents, the reagent reacts rapidly and selectively with most hydroxyl groups found in steroids. The cyanosyl derivatives formed have retention properties that are comparable to those of the corresponding alkylsilyl derivatives. However, the former offer advantageous properties for detection since they can be analyzed with a nitrogen-phosphorus detector, and they exhibit mass spectral features that are suitable for identification and quantitation at low levels using selected ion monitoring mass spectrometry. The detection limits for all the monohydroxysteroids studied in this work, as cyanosyl derivatives, are typically on the order of 30-50 pg and the relative response factors are unity within a range of 25 percent.     

High-performance liquid chromatographic analysis of bile pigments as their native tetrapyrroles and as their dipyrrolic azosulfanilate derivatives

A reversed-phase high-performance liquid chromatographic (HPLC) analysis of bile pigments is described that provides baseline separation of the major bilirubin conjugates found in bile. The advantage of the technique is that the bile pigments can be analyzed directly as their native tetrapyrroles without prior solvent extractions or derivatization. The use of ammonium acetate in place of sodium salts permits preparative isolation and lyophilization of the pigments for mass spectroscopy. The derivatization of the pigments as their dipyrrolic azosulfanilates with subsequent HPLC analysis demonstrates baseline separation of the endo- and exovinyl azodipyrroles and allows identification of that half of the tetrapyrrole which contains the conjugate in the instances of monoglycosides.     

Incorporation of glycoconjugated porphyrin derivatives into phospholipid monolayers: a screening method for the evaluation of their interaction with a cell membrane

The use of porphyrin derivatives in photodynamic therapy is of excellent prospect for the treatment of superficial or easily reachable tumors. The selection of porphyrin derivatives by tumor cells depends to a large extent of their ability to interact with the biological membrane. The evaluation of porphyrin interaction with phospholipids can thus be used as a screening method. In this work we report on the assessment of the interaction of three new porphyrin derivatives with various phospholipids forming Langmuir films by surface tension and surface pressure measurements, grazing incidence X-ray diffraction, and liquid chromatography on an IAM stationary phase. The results show that the hydroxylated phenylporphyrin (m-THPP) is able to interact with all studied phospholipids and to significantly disorganize the structure of their monolayers. Obviously, the interaction occurs at the level of the hydrophobic chains of a phospholipid. A triglucoconjugated phenylporphyrin (m-TPP(Glu)3) also interacts with the phospholipids though to a lesser extent. Conversely, the tetraglucoconjugated derivative (m-TPP(Glu)4) exhibits both a weak surface activity and a poor affinity for the studied phospholipids. Thus, whereas m-THPP and m-TPP(Glu)3 are expected to penetrate into a biological membrane, m-TPP(Glu)4 seems unlikely to do so.     

Collection of alpha1-acid glycoprotein molecular species by capillary electrophoresis and the analysis of their molecular masses and carbohydrate chains. Basic studies on the analysis of glycoprotein glycoforms

A highly heterogeneous glycoprotein, alpha1-acid glycoprotein, was resolved into their glycoforms by capillary electrophoresis using a surface-modified capillary in 20 mM acetate buffer (pH 4.2) containing 0.5% (w/v) hydroxypropylmethylcellulose. We collected the fractions containing each glycoform as nearly pure state by capillary electrophoresis, and examined the molecular masses of these glycoforms by matrix assisted laser desorption time-of-flight mass spectrometry. We also analyzed carbohydrate chains after releasing them with N-glycosidase F followed by fluorescent labeling with 8-aminopyrene-1,3,6-trisulfonate. We found that the separation of glycoforms was mostly due to the presence of multiantennary carbohydrate chains. We propose that the present technique is useful for the analysis of post translational modification of proteins with carbohydrate chains.     

Carbon-13 NMR spectra and the method for their calculation for long-chain polybranched carboxylic acids and their derivatives

Carbon-13 NMR spectra of 56 long-chain polybranched carboxylic acids their esters, including chloroand acetoxy-substituted derivatives, have been studied. An empirical linear two-parameter equation, relating carbon chemical shifts in α-branched carboxylic acids and their derivatives to the chemical shifts of the corresponding carbon atoms in analogous hydrocarbons, and to the degree of branching at the α-carbon atom, is suggested for the assignment of the signals, where δ_X is the shift in the acid (ester), δ_H the shift in its hydrocarbon counterpart and n the degree of branching. The regression coefficients, A, B and C, are given for X=COOH, COOMe and COOEt. It is shown that with polysubstituted derivatives, the equation may be applied sequentially. The secondary coefficients for the α-substituent then depend on the nature of the substituent X entering the primary equation. The equation may, if necessary, be applied in combination with the additive and structural increments of halogen atoms.     

Sensitive method for the determination of different S(IV) species in cloud and fog water

Suppressed ion chromatography has been applied to the determination of S(IV) species in cloud and fog water in the range 0.012–2.4 mg S(IV)-S/L. The samples have been preserved prior to storage and S(IV) species have been determined as hydroxy methanesulfonate (HMS) together with the low molecular weight carboxylic acid anions, formate and acetate. Samples have been divided and treated differently such that total S(IV) as well as the non-oxidizable fraction of S(IV) (as given by the reactivity with H₂O₂, added in surplus) could be determined. The difference between the two corresponds to the S(IV) fraction subjected to oxididation, which is of paramount interest in cloud and fogwater chemistry.     

Piperazinophenols as stabilizers for unsaturated compounds and their chloro derivatives

Polyfunctional piperazinophenols, which are effective stabilizers during the distillation or storage of unsaturated hydrocarbons and their chloro derivatives, were obtained by the aminomethylation of phenols, which proceeds with the participation of piperazine and N,N-bis(piperazinoethyl)ethylenediamine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1367–1369, October, 1990.     

Algorithms for calculating excluded volume and its derivatives as a function of molecular conformation and their use in energy minimization

A numerical method for calculating the volume of a macromolecule and its first and second derivatives as a function of atomic coordinates is presented. For N atoms, the method requires about 0.3 N ln(N) seconds of CPU time on a VAX-8800 to evaluate the volume and derivatives. As a test case, the method was used to evaluate a pressure-volume energy term in energy minimizations of the protein lysozyme at 1000 atm (1 atm = 1.013 × 10⁵ Pa). R.m.s. gradients of 10^?4 kcal/mol/Å were obtained at convergence. The calculated structures exhibited pressure-induced changes which were qualitatively similar to the changes observed in the 1000 atm structure determined by X-ray crystallography.     

Synthesis of 1-aminoanthrapyridones and their derivatives

1-Aminoanthrapyridones are obtained when 1-anthrapyridonylpyridinium chlorides are heated in high-boiling amines. The synthesis of a number of substituted N-chloroacetyl-1-aminoanthraquinones. 1-anthrapyridonylpyridinium chlorides. and 1-aminoanthrapyridones is described.Translated from Khimiya Geterotsiklicheskikh Soedinenii. No. 12. pp. 1651–1655. December. 1972.     

A sensitive liquid chromatographic method for the analysis of isovaleric and valeric acids in urine as fluorescent derivatives

A simple and sensitive isocratic liquid chromatographic method was developed for the analysis of isovaleric and valeric acids in human urine as biomarkers in metabolic acidosis. The method is based on the derivatization of isovaleric and valeric acids with a fluorescent reagent 2-(2-naphthoxy)ethyl-2-(piperidino)ethanesulfonate for labeling the analytes with the naphthoxy fluorophore. The resulting fluorescent derivatives of isovaleric and valeric acids were separated on a phenyl-hexyl column, using a mixed solvent of methanol-water-tetrahydrofuran (55:31:14, v/v) as the mobile phase. The separated derivatives were monitored with a fluorimetric detector (excitation at 225 nm and emission at 360 nm). The linear range of the method for the determination of isovaleric acid or valeric acid derivative was over 0.2 approximately 8.0 microM. The detection limit (signal to noise ratio=3 with 10 microl injected) of isovaleric acid or valeric acid was about 0.04 microM. Application of the method to the analysis of isovaleric acid in the urine of a patient with isovaleric acidemia proved feasible.     

Development of an analytical method for polycyclic aromatic hydrocarbons and their derivatives

Garlic and onion, are well known for their medical value, especially in against cancer and anticardiovacular diseases. "Alliins" (S-alk(en)yl-L-cysteine sulphoxides) are sources of major active compounds in Allium plants. Se incorporation into garlic significantly increases activities of garlic in cancer prevention and inhibition. Selenomethionine, selenocysteine and Se-methylselenocysteine have been identified in garlic and onion. Previously we identified gamma-glutamyl-Se-methyl-L-selenocysteine, in extracts of garlic cultivated in Se-rich soil [Med. Res. Rev. 16 (1) (1996) 111], suggesting the possible existence of Se-alk(en)yl-L-cysteine selenoxides (Se-"alliins") in garlic. Several comparative experiments were carried out to demonstrate the existence of Se-"alliins" in Se-enriched garlic and onion. We found that there was one similar time-dependent Se signal in HPLC-inductively coupled plasma MS chromatograms of cold-water extracts of freeze-dried garlic powder and fresh garlic. This signal was lost when the extracts of garlic powder and fresh garlic were stored for 1 day at >4 degrees C, but remained in fresh onion extract at the same storage conditions. These phenomena and possible mechanisms are discussed. An additional experiment showed that Allium species cultivated in Se-rich soil might contain two different Se-"alliins".     

Qualitative gas chromatographic analysis of bacterial amines as their Schiff bases and other derivatives

Summary Columns of SE-30 and OV-17 on Chromosorb W, Apiezon N on Chromosorb G and Tenax-GC porous polymer were compared for their ability to separate bacterial amines converted to carbethoxy, dinitrophenyl, trimethylsilyl, Schiff base and fluorinated Schiff base derivatives.Tenax-GC performed less well than the other packings with respect to the number of plates and peak resolution. Dinitrophenyl and trimethylsilyl derivatives were both unsatisfactory for analysis of bacterial amines. Schiff bases and their fluorinated derivatives were found to be the most suitable. However, the former were preferred as the use of fluorinated Schiff bases confered little advantage when a flame ionization detector was employed. A maximum of 16 amines was separated, using columns of OV17 on Chromosorb W programmed from 110 °C to 280 °C at 5.5 °C min^–1 after an initial holding time of 6 min. The application of the method to analysis of cultures ofProteus mirabilis yielded two amines tentatively identified asiso-butylamine andiso-amylamine.     

Distribution of phospholipid molecular species in autogenous access grafts for hemodialysis analyzed using imaging mass spectrometry

Arteriovenous fistulae (AVF) using vein grafts are frequently used for vascular access in hemodialysis. When superficial veins are used as autogenous access grafts for hemodialysis, atherosclerotic-like tissue degeneration often causes stenosis and obstruction. Although the differences between the pathology of degeneration in AVF and atherosclerosis (i.e., peripheral artery occlusive disease (PAD)) are known, their underlying molecular mechanisms are not. We determined the characteristic abnormal lipid metabolism of AVF. Oil red O staining clearly showed the accumulation of lipid molecules in AVF and PAD tissues. We found that the staining pattern was different between AVF and PAD tissues. The media and adventitia of AVF and the intima and media of PAD were intensely stained. Quantitative lipid analysis revealed that the amount of PL was significantly increased in AVF and PAD. Next, we performed matrix-assisted laser desorption/ionization imaging mass spectroscopy and determined the characteristic distribution of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) in AVF. The distribution patterns of LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) were consistent with the Oil red O staining images, suggesting that metabolisms related to LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) are altered in AVF.     

Separation of the molecular species of diacyl and alkenylacyl subclasses of the methyl ester of dinitrophenylethanolamine glycerophospholipid by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) procedure for the separation of the molecular species of alkenylacyl and diacyl subclasses after the derivatization of ethanolamine glycero-phospholipids (EGP) to the methyl ester of the dinitrophenylated lipids is described. Methyl esters of dinitrophenylethanolamine glycerophospholipids were first separated into alkenylacyl, alkylacyl and diacyl subclasses by thin-layer chromatography, then each subclass was separated into individual molecular species by reversed-phase HPLC. By converting the EGP into UV-absorbing derivatives, it proved possible to utilize the specificity of spectrophotometric detection for the determination of the individual molecular species. Alkenylacyl and diacyl derivatives were resolved into fifteen to twenty different species in a single HPLC run. The method should facilitate studies on the metabolism of the polar head group of both molecular species of alkenylacyl and diacyl glycerophosphoethanolamine in a variety of tissues using radioactive precursors.     

Pyridine-containing chiral macrocycles for the enantioselective recognition of amino acid derivatives and their molecular dynamics simulations

Two novel C₂-symmetric optically active pyridine-15-crown-5 type ligands containing lipophilic chains at the stereogenic centres, macrocycles 5 and 6, were prepared from (S)-1,2-propanediol and (S)-3-aryloxy-1,2-propanediol for the enantiomeric recognition of amino acid ester derivatives. These novel macrocycles have been shown to be strong complexing agents for primary organic ammonium salts (with K values of up to 1363.5 M^?1, ΔG^o of up to 17.86 kJ mol^?1 and a selectivity ratio of 80:20) by ¹H NMR titration method. These macrocyclic host exhibited enantioselective binding towards the l-enantiomer of phenylalanine methyl ester hydrochloride with K_L/K_D up to 8.57 in CDCl₃ containing 0.25% CD₃OD. Experimental results have been detailed with molecular dynamic calculations at atomic level concerning the molecular recognition and discrimination properties of a chiral pyridino-15-crown-5. The binding free energies were calculated as ～?25 kJ mol^?1. The results indicated that the host binds and discriminates valine salts better than phenylalanine salts. The molecular dynamics, MM/PBSA calculations are consistent with the ¹H NMR results.