Nonglyceride lipids of the seed coats ofArtemisia absinthium andOnopordum acanthium

The seed coats ofArtemisia absinthium andOnoporum acanthium have been shown to contain paraffinic hydrocarbons (C₃₁-C₂₅ and C₃₁-C₂₇, respectively), wax esters (C₃₂-C₂₃ and C₅₁-C₃₃), acetyltriterpenols (six types, five types), and acyltriterpenols with a predominance of palmitoyltriterpenols (esters of higher saturated unbranched C_32:0-C_12:0 fatty acids and triterpenols with a molecular weight of 426 belonging to the ursene group).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 154–157, March–April, 1981.     

Lipids of the seeds ofSecurinega suffruticosa

The lipid composition of the seeds ofSecurinega suffruticosa (Euphorbiaceae) has been studied, and eight classes of lipids have been identified with a predominance of triacylglycerols; the fatty acid compositions and structures of the triacylglycerols have been determined. Among the hydroxy acids of the hydroxyacylglycerols 13 components belonging to saturated, monoenic, and dienic acids of the C₁₇, C₁₈, and C₂₀ series have been identified; 12-hydroxyheptadecanoic and 12-hydroxyeicosanoic acids are new.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 277–281, May–June, 1986.     

Lipids of the vegetative and generative organs ofHibiscus sp.

The lipids of the leaves, stems, and roots ofHibiscus sp. have been studied. Their fatty acid compositions have been determined. The greatest amount of unsaturated fatty acids was present in the glycolipids of the leaves and the stems. More than 25% of low-molecular-mass C₁₀-C₁₂ fatty acids have been found in the neutral lipids of the roots.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 705–708, September–October, 1996. Original article submitted March 11, 1996.     

Lipids of microalgae. III. Lipids of the biomass ofMonocrysis lutheri grown under the conditons of an accumulation culture

The class composition of the lipids of the biomass of the microalgaMonochrysis lutheri grown under the accumulation regime of cultivation has been investigated for the first time. A predominance of triacylglycerols in the neutral lipids, of phosphatidylcholine in the phospholipids, and of digalactosyldiacylglycerols in the glycolipids has been established. New natural alkan-8-ones of the C₃₆-C₅₀ series have been detected. Institute of the Chemistry of Plant Substances. Academy of Sciences, of the Republic of Uzbekistan, Tashkent. FAX (3712) 62 73 48. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 325–330, May–June, 1994.     

A thorough study of the surface wax of apple fruits

The composition of the surface waxes of three apple ( Malus domestica L.) cultivars ("Florina", "Golden B" and "Ozark Gold") has been studied by means of spectroscopic and GC–MS analysis of the class-fractionated mixture of components. Odd n -alkanes, mainly C₂₇ and C₂₉ molecules, are prevalent in the saturated fraction. Small concentrations of alkenes were also found; the C_28:1 component is strongly (72%) in excess over the other 1-alkenes. Straight-chain esters (mainly of palmitic acid) of saturated primary alcohols (C₁₈–C₃₀) were also detected; whereas the acyl moiety is made up essentially of an even number of carbons, the alcohol counterpart does not exhibit this characteristic. Aldehydes are present (C₂₀–C₃₀) with the homologue patterns C₂₆–C₃₀ most strongly represented. Straight-chain free secondary alcohols characterize the waxes of "Florina" and "Ozark Gold"; the hydroxy function is located far from the extremity of the carbon framework. Outstanding is the presence of three alcohols with 29 carbon centres. These alcohols are accompanied by free straight-chain primary alcohols, mainly with even-numbered carbon chains in the range C₂₆–C₃₀. Free fatty acids are present; all of have a framework of even-numbered carbon chains mainly in the range C₁₆–C₂₀. C_18:1 (oleic acid) is well represented.     

Gas-chromatographic method of evaluation ofn-alkanol ability for self-association in pure liquid

The values of the gas-chromatographic indicator reflecting the capacity of analytes for self-association in pure liquids, δT _b.p., were estimated for C₁–C₉ and C₁₁ n-alkanols by capillary gas chromatography on a nonpolar stationary phase under isothermal conditions. The δT _b.p. values ofn-alkanols, found as the difference between the boiling points measured directly and those calculated from GC data, are correlated with thermodynamic characteristics of the formation ofn-alkanol associates in pure liquids. Usingn-alkanols as analytes with insignificant temperature increments of the retention indices, it was shown that the δT _b.p. values can be determined under conditions used in gas chromatography with temperature programming. In this way a single chromatographic run can be used to compare the capacities for self-association of analytes boiling over a wide temperature range. The C₂–C₉ n-alkanethiols, which are not associated in neat liquids, have negative δT _b.p. values. An interpretation of this finding is proposed. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 315–318 February, 2000.     

Unusual Fragmentation of β-Linked Peptides by ExD Tandem Mass Spectrometry

Ion-electron reaction based fragmentation methods (ExD) in tandem mass spectrometry (MS), such as electron capture dissociation (ECD) and electron transfer dissociation (ETD) represent a powerful tool for biological analysis. ExD methods have been used to differentiate the presence of the isoaspartate (isoAsp) from the aspartate (Asp) in peptides and proteins. IsoAsp is a β₃-type amino acid that has an additional methylene group in the backbone, forming a C_α–C_β bond within the polypeptide chain. Cleavage of this bond provides specific fragments that allow differentiation of the isomers. The presence of a C_α–C_β bond within the backbone is unique to β-amino acids, suggesting a similar application of ExD toward the analysis of peptides containing other β-type amino acids. In the current study, ECD and ETD analysis of several β-amino acid containing peptides was performed. It was found that N–C_β and C_α–C_β bond cleavages were rare, providing few c and z type fragments, which was attributed to the instability of the C_β radical. Instead, the electron capture resulted primarily in the formation of a and y fragments, representing an alternative fragmentation pathway, likely initiated by the electron capture at a backbone amide nitrogen protonation site within the β amino acid residues.     

Lipids of the fruit of Feijoa sellowiana

The composition and amounts of liposoluble substances in the flesh and peel of feijoa fruit has been investigated. About 30 groups of lipid substances have been identified. The main groups of lipids in the flesh were triacylglycerols, sterols, cerebrosides, ceramide phosphate inositol oligosides, sulfoquinovosyldiacylglycerols, phosphatidic acids, phosphotidylglycerols and phosphatidylcholines. In the peel, hydrocarbons, sterols, esters of fatty acids and lower alcohols, cerebrosides, digalactosyldiacylglycerols, ceramide oligosides, phosphatidylglycerols, and include predominated. The fatty acids of the flesh were found to include 15 representatives (C_12:0–C_28:0), and those of the flesh 11 representatives tives (C_12:0–C_18:3). M. V. Lomonosov Technological Institute of the Food Industry, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 464–467, July–August, 1991.     

Charge transfer in complexes of C60 and C70 in solutions and solid state

Electronic absorption spectra of complexes of C₆₀ and C₇₀ fullerenes with donors, tetrathiafulvalene and pyranylidene derivatives, were studied in solutions and in the solid state. Charge transfer bands were found in the 680–1300 nm range. The charge transfer energies (hv _ct) for the C₆₀ and C₇₀ complexes in solutions are close and almost independent of the solvent polarity. For the C₆₀ complexes in the solid state, the dependence ofhv _ct on the ionization potential (IP) of donors was found to behv _ct=0.82IP–3.93 eV. In the C₆₀ complexes in the solid state, thehv _ct values are 0.15–0.20 eV lower than those in the solution. The linear dependences ofhv _ct onIP of donors for the C₆₀ complexes lie 0.6–0.7 eV higher than those in the complexes with tetracyanoethylene (TCNE). This is associated with lower values of the electron affinity of C₆₀ and the energy of the electrostatic interaction in the fullerene complexes as compared to those of the TCNE complexes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 478–483, March, 1999.     

Temperature dependence of the free energy of sorption ofn-alkanes and energy contribution of their methylene groups on columns with fullerene C60

The partial molar free energy, enthalpy, and entropy of sorption of C₁₁−C₂₃ n-alkanes were calculated on the basis of the GC data obtained on the glass capillary column coated with fullerene C₆₀ (Ful-60) as stationary phase. The thermodynamic parameters ofn-alkane sorption on a column with Ful-60 and a fused silica capillary column with polydimethylsiloxane OV-1 were determined and compared. The enthalpy-entropy compensation effect for the sorption ofn-alkanes on Ful-60 and OV-1 was found. A linear dependence of the partial molar free energy ofn-alkane sorption on the temperature of analysis and carbon chain length was found. The free energy contributions of the methylene groups were calculated, and their temperature dependences were studied. The differences in the temperature dependences of the energy contributions of methylene groups ofn-alkanes on Ful-60 and OV-1 were revealed. The entropy contribution is 68–82% of the enthalpy contribution which indicates a substantial role of the number of contacts with Ful-60 in retention ofn-alkanes. The ability of Ful-60 for dispersive interactions is similar to those of nonpolar liquid phases and substantially differs from that for carbon adsorbents. Fullerene columns were shown to be convenient for analysis of highly boiling organic substances in aqueous and organic solutions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1490–1495, August, 1999.     

Lipids ofSilene brahuica

The qualitative and quantitative compositions of the lipid complex of the epigeal part ofSilene brahuica Boiss. (family Caryophyllaaceae) have been studied. The fatty acid composition of the acyl-containing lipids has been determined. Some differences have been found in the compositions of the fatty acids of the neutral lipids and the phospholipids. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 512–514, July–August, 1993.     

Lipids of the petals ofCarthamus tinctorius

The following compounds have been identified in the lipids of the petals ofCarthamus tinctorius: C₃₂ and C₂₉ isoparaffins; free fatty acids, the main component of which is palmitic acid; 33 esters of phytol, esterified with three groups of fatty acids — paraffinic, isoparaffinic, and monoenoic of the C₉–C₂₆ series; and β-sitosterol and its β-D-glucopyranoside.     

Some components of the seed oil ofMalva sylvestris

The lipid composition of the free fatty acids of the seed oil ofMalva sylvestris from the Ukrainian flora has been studied by chromato-mass spectrometry. The fatty acid composition was represented by 20 compounds, among which malvic and sterculic acids were detected. The presence of terpineols and retinol has been shown. Zaporozh'e Medical Institute. Translated from Khimiya Prirodnykh Soedenii, No. 3, pp. 322–325, May–June, 1994.     

Phospholipids of the fruit kernels ofCrataegus turkestanica

The lipids of the kernels of the fruit ofC. turkestanica contain five classes of phospholipids, the main ones being phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. Their fatty acid compositions and, in the main phospholipids, the position distributions of the acyls have been studied.     

Direct Mass Spectrometric Study of the Ionic Species Content of a C<Subscript>2</Subscript>HCl<Subscript>3</Subscript>/He/O<Subscript>2</Subscript> Microwave Discharge Plasma

Direct on-line studies of a C₂HCl₃/He/O₂ microwave discharge plasma made possible the evolution and detection of many unfamiliar ionic species. Numerous ionic chlorocarbons, chlorohydrocarbons, oxygenated chlorohydrocarbons, oxygenated hydrocarbon radicals, and simple hydrocarbon species were identified mass spectrometrically as by-products: C _m Cl _n (m = 1–4, 6, 8; n = 1–8), C _m H _n Cl _x (m = 1–4, 6, 7, 10; n, x = 1–6), C _m H _n Cl _x O _y (m = 1–5, 12; n = 1–7; x = 1, 2, 4, 6; y = 1–3), C _n H_2n−1O (n = 2, 3), C _m H _n (m = 2, 4, 6, 8; n = 2, 4), and so on. The studies clearly showed the presence of various unfamiliar positive ionic O-containing species such as C₂ClO₂, CCl₃CO, C₂H₂Cl₄O₂, and C₄H₂Cl₆O₃. It is apparent that positive-ion reactions play a significant role in producing many ionic species in the chemistry of C₂HCl₃ plasmas.     

Simulation of the structure of some silicon carbide clusters by the MNDO method

Simulations of the geometric and electronic structure of C₄₄, C₄₅, Si₄₅, C₄₀Si₅, and C₄₄Si clusters were performed by the MNDO method. The geometries of the filled clusters, calculated by the MM2 method, were used as initial approximations. It was found that the filled clusters C₄₅ and C₄₄Si are transformed into endohedral clusters X@C₄₄ (X-C or Si, respectively) after energy optimization. The highest occupied energy level of the HOMO of the filled tetrahedral cluster Si₄₅ ofT symmetry is triply degenerate and is only occupied by four electrons. The structure of Si₄₅ ²⁻ dianion ofT symmetry was calculated. Two filled structures for the C₄₀Si₅ cluster were found. The coordination numbers of the central Si atom in these structures are 4 and 3, respectively. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 54–56, January, 1997.     

Composition of the lipids and carbohydrates of the seeds ofAmaranthus caudatus

The chemical composition of the seed lipids ofAmaranthus caudatus L. has been investigated. The fatty acid compositions of the neutral lipids and of the phospho- and glycolipids have been determined. The hydrocarbon components ofA. caudatus have been identified and its alcohol-soluble carbohydrates, water-soluble polysaccharides, and pectin substances have been characterized.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 40 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 797–799, November–December, 1997.     

The stabilization of titanium dioxide in dry benzene by n-aliphatic carboxylic acids

Summary The colloidal stability of rutile, of primary particle radius 25 ?, in solutions ofn-aliphatic carboxylic acids in benzene has been examined under rigorously dry conditions. Very stable suspensions were obtained for acid chain lengths of 12 to 18 carbons and surface fractional coverages of 0.4. A rather less stable suspension was given by acetic acid. The C_{4, 6, 8, and 10} acids gave poor stability. The suspensions generally, and that for lauric acid in particular, appeared to consist mainly of particles whose radius was of the order of 0.08Μ. It has been argued that these particles were probably loosely packed aggregates of primary particles and that their stability was conferred by the C_12–18 molecules by an “entropic” repulsion produced when the hydrocarbon chains on opposing particle surfaces tended to interpenetrate. The stability in the acetic, and to a lesser extent, butyric acid systems has been attributed tentatively to the existence of some electrostatic repulsion.

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Zusammenfassung Die Stabilit?t von Rutil von einem Radius von 25 ? der Prim?rteilchen in kolloiden L?sungen von Benzol mitn-aliphatischen Carboxyls?uren wurde unter extremem Feuchtigkeitsausschlu\ geprüft. Sehr stabile Suspensionen lagen für Kettenl?ngen von 12–18 Kohlenstoff-Atomen und einer Oberfl?chenbedeckung von 0,4 vor. Ziemliche Stabilit?t ergab sich für Essigs?ure als Zusatz. Sehr gro\e Instabilit?t zeigte sich für Kettenl?ngen von 4–10. Die Suspensionen im allgemeinen und die für Lauryls?ure im besonderen scheinen haupts?chlich aus Partikeln von einem Radius der Gr?\enordnung von 0.08Μ zu bestehen. Es wird vermutet, da\ diese Teilchen wahrscheinlich locker gepackte Aggregate von Prim?rpartikeln sind und da ihre Stabilit?t wahrscheinlich für die C_12–18-Moleküle durch eine entropische Absto\ung hervorgerufen wird, wenn sich die Kohlenwasserstoffketten senkrecht der Oberfl?chen der verschiedenen Partikel zu durchdringen beginnen. Die Stabilit?t in dem Essigs?ure- und in einem geringeren Ausma\ in dem Butters?uresystem — wird der Existenz einer gewissen elektrostatischen Abschirmung zugeschrieben.

     

Synthesis of natural triisopentenylated flavanone, euchrenone a2

Euchrenone a₂ (7) isolated from the roots ofEuchresta japonica has been synthesised from 3-prenylphloroacetophenone (1) by other workers. We carried out its cyclodehydrogenation with dichloro dicyano quinone (DDQ) to obtain 6-acetyl-5,7-dihydroxy-2,2-dimethylchromene (2) which was ethoxymethylated in the 7-position to give 6-acetyl-7-ethoxymethoxy-5-hydroxychromene (3). Chalcone condensation of3 and 4-ethoxymethoxy-3-C-prenylbenzaldehyde (4) gave 4,6′-bisethoxymethoxy-2′-hydroxy-6″, 6″-dimethyl-3-C-prenylpyrano (2″, 3″–4,3) chalcone (5) which cyclised with methanolic sodium acetate to give protected 5,4′-bisethoxymethoxy-6″, 6″-dimethyl-3′-C-prenylpyrano (2″, 3″–7,8) flavanone (6). Deprotection of6 with 4% methanolic HCl yielded (7) with melting point and spectral data identical to that of the natural compound.     

ESR spectra of C60 in concentrated sulfuric acid

On dissolution of C₆₀ in concentrated sulfuric acid, ESR spectra of paramagnetic species, which were identified as dimers (C₁₂₀ ⁺) or oligomers (nC₆₀)⁺, were recorded. The ESR spectra recorded upon the reaction of a toluene solution of C₆₀ with sulfuric acid were assigned to the radical cation C₆₀ ⁺. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2373–2376, November, 1998.