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1.
Isorhizochalin (1) was isolated as its peracetate from the EtOH extract of the sponge Rhizochalina incrustata. Its structure and absolute stereochemistry were elucidated as (2S,3R,26R,27R)-2,27-diamino-3-O-β-d-galactopyranosyl-oxy-26-hydroxyoctacosan-18-one by extensive NMR, MS studies, chemical transformations, including micromolar-scale Baeyer–Villiger oxidation, and by analysis of CD spectra of isorhizochalinin perbenzoate (2b). Isorhizochalin is an unprecedented C-2 epimer of rhizochalin having an erythro configuration at the glycosylated 2-amino-3-alkanol α-terminus in contrast with a canonical threo configuration for other representatives of this structural group. Probable biogenesis of 1 is discussed in the context of known sphingolipid biosynthesis beginning with condensation of alanine with a fatty acyl CoA thioester. The aglycone, isorhizochalinin (2a), shows cytotoxicity against human leukemia HL-60 and THP-1 cells with IC50 values of 2.90 and 2.20 μM, respectively.  相似文献   

2.
To highlight the role of plants in traditional healing, the leaves and the stems of cultivated Triumfetta cordifolia were phytochemically studied yielding a new nor-ursane type (1), a new ceramide (2) and a new piperidinic ceramide derivative (3) named, respectively, 2α,19α-dihydroxy-3-oxo-23-nor-urs-12-en-28-oic acid, (2R)-2-hydroxy-N-[(2S,3S,4R,26E)-1,3,4-trihydroxy-26-triaconten-2-yl] tetradecanamide and (2R,8Z)-2-hydroxy-{(2S,3R,5R,6S)-3,5-dihydroxy-6-[(1E,5Z)-hexadeca-1,5-dienyl]-2-(β-d-glucopyranosyloxy)methyl piperidine-1-yl} tetracos-8-enamide (3). These were obtained together with lupeol (4), stigmasterol (5), 3-O-β-d-glucopyranoside of β-sitosterol (6), tormentic acid (7) from stems and heptadecanoic acid (8), β-carotene (9), oleanolic acid (10), and 24-hydroxytormentic acid (11) from leaves. The structures were determined on the basis of NMR data (1H-, 13C-, 2D-NMR analyses), mass spectrometry and confirmed by chemical transformations as well as comparison of spectral data with those reported in the literature. The FRAP method was used to evaluate the antioxidant activity of fractions collected from flash chromatography and isolated compounds. Among the fractions, four reduced FeIII-TPTZ to FeII-TPTZ while isolated pure compounds showed no activity.  相似文献   

3.
Spectroscopic and physical properties of Nd3+-doped alkali lead borate glasses of type 20R 2O · 30PbO · 49.5B2O3 · 0.5Nd2O3 (R = Li and K) and alkaline-earth lead borate glasses 20RO · 30PbO · 49.5B2O3 · 0.5Nd2O3 (R = Ca, Ba, and Pb) have been investigated. Optical absorption spectra have been used to determine the Slater-Condon (F2, F4, and F6), spin orbit ξ4f, and Racah parameters (E1, E2, and E3). The oscillator strengths and the intensity parameters Ω2, Ω4, and Ω6 have been determined by the Judd-Ofelt theory, which, in turn, provide the radiative transition probability (A), total transition probability (A T ), radiative lifetime (τ R ), and branching ratio (β R , %) for the fluorescent levels. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω46), the value of which is in the range 0.2–1.5, typical of Nd3+ in different laser hosts. A red shift of the peak wavelength is observed upon addition of alkali or alkaline-earth oxides to the lead borate glass. A higher value of the W2 parameter for potassium-doped glass indicates a higher covalency for this glass matrix. The relative intensity of the peaks 4I9/24F7/2, 4S3/2 has also been studied. The text was submitted by the authors in English.  相似文献   

4.
Zhan ZJ  Yue JM 《Lipids》2003,38(12):1299-1303
Iwo new compounds (1,2) were isolated from the ethanolic extract of the leaves of Premna microphylla, together with five known compounds. The structures of compounds 1 and 2 were elucidated as (2S,3S,4R,11E)-2-[(2R)-2-hydroxytetracosanoylamino]-11-octadecene-1,3,4-triol (1) and 1-O(9Z,12Z, 15Z-octadecatrienoyl)-3-O-[β-d-galactopyranosyl-(1→6)-O-β-d-galactopyranosyl-(1→6)-α-d-galactopyranosyl] glycerol (2) by means of spectroscopic and chemical methods.  相似文献   

5.
Impedance spectroscopy studies of the interface between lithium and ionic liquid (IL) showed the formation of a film (solid electrolyte interface, SEI), protecting metal from its further dissolution. Consequently, the potential of metallic lithium immersed in an electrolyte containing Li+ cations may be described as a Li|SEI|Li+ system, rather than simply Li/Li+. The potential of lithium-metal in a series of ionic liquids (and in a number of molecular liquids) containing Li+ cation (0.1 M) was measured versus the Ag|(Ag+ 0.01 M, cryptand 222 0.1 M, in acetonitrile) reference. The lithium-metal potential (E(Li|SEI|Li+)) was ca. −2.633 ± 0.017 V in ILs based on the [N(CF3SO2)2 ] anion, while −2.848 ± 0.043 V in ILs containing [BF4 ] anion (the difference is ca. 200 mV). In the case of ILs based on the triflate anion ([CF3SO3 ]), the cation of ionic liquid also influences the E(Li|SEI|Li+) value: it was ca. −1.987 ± 0.075 V for imidazolium based cations and much lower (−2.855 V) for the pyrrolidinium based cation. In ionic liquid based on the imidazolium cation and hexafluorophosphate anion ([PF6 ]), the Li/SEI/Li+ potential was −2.245 V. The Li|SEI|Li+ potential measured in cyclic carbonates was −2.780 ± 0.069 V while in dimethylsulfoxide showed the lowest value of ca. −3.285 V. The measured potentials were also expressed versus the formal potential of the ferrocene/ferrocinium redox couple, obtained from cyclic voltammetry.  相似文献   

6.
Fourier transform infrared (FTIR) spectroscopy provides a simple and rapid means of detecting lard blended with chicken, lamb, and cow body fats. The spectral bands associated with chicken, lamb, and cow body fats and their lard blends were recorded, interpreted, and identified. Qualitative differences between the spectra are proposed as a basis for differentiating between the pure animal fats and their blends. A semiquantitative approach is proposed to measure the percent of lard in blends with lamb body fat (LBF) on the basis of the frequency shift of the band in the region 3009–3000 cm−1, using the equation y=0.1616x+3002.10. The coefficient of determination (R 2) was 0.9457 with a standard error (SE) of 1.23. The percentage of lard in lard/LBF blends was also correlated to the absorbance at 1417.89 and 966.39 cm−1 by the equations y=0.0061x+0.1404 (R 2=0.9388, SE=0.018) and y=0.004x+0.1117 (R 2=0.9715, SE=0.009), respectively. For the qualitative determination of lard blended with chicken body fat (CF), the FTIR spectral bands in the frequency ranges of 3008–3000, 1418–1417, 1385–1370, and 1126–1085 cm−1 were employed. Semiquantitative determination by measurement of the absorbance at 3005.6 cm−1 is proposed, using the equation y=0.0071x+0.1301 (R 2=0.983, SE=0.012). The percentage of lard in lard/GF blends was also correlated to the absorbance at 1417.85 cm−1 (y=0.0053x+0.0821, with R 2=0.9233, SE=0.019) and at 1377.58 cm−1 (y=0.0069x+0.1327, with R 2=0.9426, SE=0.022). For blends of lard with cow body fat (CBF) bands in the range 3008–3006 cm−1 and at 1417.8 and 966 cm−1 were used for qualitative detection. The equation y=−0.005x+0.3188 with R 2=0.9831 and SE=0.0086 was obtained for semiquantitative determination at 966.22 cm−1.  相似文献   

7.
Wu ZP  Chen Y  Xia B  Wang M  Dong YF  Feng X 《Lipids》2009,44(1):63-70
Two novel ceramides, Candidamide A (1) with a phytosphingolipid structure, and Candidamide B (2) with a tertiary amide structure, together with 12 known compounds (3–14) have been isolated from the bulbs of Zephyranthes candida, The structures of 1 and 2 have been elucidated to be 1,3,5,6-tetrahydroxy-2-(2′-hydroxytetracosanoyl amino)-8-(E)-octadecadiene (1) and (2S,3S,4R,8E,2′R)-2-[N-(2′-hydroxyoctadecanoyl)-N-(1′′,2′′-dihydroxyethyl)-amino]-8-hexacosene-1,3,4-triol (2) on the basis of spectroscopic evidence including IR, MS, NMR (1H-NMR, 13C-NMR, DEPT, 1H–1H COSY, HSQC, HMBC). The known compounds were identified as (2S)-3′,7-dihydroxy-4′-methoxyflavan (3), (2S)-4′-hydroxy-7-methoxyflavan (4), (2S)-4′,7-dihydroxyflavan (5), 7-hydroxy-3′, 4′-methylenedioxyflavan (6), ambrettolide (7), β-sitostero1 (8), β-daucosterin (9), rutin (10), pancratistatin (11), lycorine (12), haemanthidine (13), and haemanthamine (14). In the antimicrobial assay, candidamide A (1) and candidamide B (2) displayed moderate activities against bacteria Staphylococcus aureus and Escherichia coli, and fungi Aspergillus niger, Candida albicans and Trichophyton rubrum.  相似文献   

8.
Luo Y  Liu Y  Qi H  Zhang G 《Lipids》2004,39(10):1037-1042
A new glucoceramide named pellioniareside (1) was isolated from the aqueous ethanolic extract of whole plants of Pellionia repens, together with lupeol (2), uracil (3), (22E,20S,24R)-5α,8α-epidioxyergosta-6,22-dien-3-β-ol (4), and daucosterol (5). The structure and relative configurations of pellioniareside were identified as (2S,3S,4R,6E,8E)-1-O-β-d-glucopyranosyl-2-[(2R)-2-hydroxytetracosanoylamino]-1,3,4-octadecanetriol-6,8-diene by analysis of spectral data and by chemical evidence.  相似文献   

9.
Compositions are developed, technological parameters are determined, and the main properties are investigated for devitrified glass composite heat-resistant coatings of the R x O - Al2O3 - SiO2 - TiO2 system (R is Na+, K+, Mg2+, Ca2+, Ba2+) for Nichrome alloys. Translated from Steklo i Keramika, No. 1, pp. 29–31, January, 2000.  相似文献   

10.
Bile acids constitute a group of structurally closely related molecules and represent the most abundant constituents of human bile. Investigations of bile acids have garnered increased interest owing to their recently discovered additional biological functions including their role as signaling molecules that govern glucose, fat and energy metabolism. Recent NMR methodological developments have enabled single-step analysis of several highly abundant and common glycine- and taurine- conjugated bile acids, such as glycocholic acid, glycodeoxycholic acid, glycochenodeoxycholic acid, taurocholic acid, taurodeoxycholic acid, and taurochenodeoxycholic acid. Investigation of these conjugated bile acids in human bile employing high field (800 MHz) 1H-NMR spectroscopy reveals that the ratios between two glycine-conjugated bile acids and their taurine counterparts correlate positively (R 2 = 0.83–0.97; p = 0.001 × 10−2–0.006 × 10−7) as do the ratios between a glycine-conjugated bile acid and its taurine counterpart (R 2 = 0.92–0.95; p = 0.004 × 10−3–0.002 × 10−10). Using such correlations, concentration of individual bile acids in each sample could be predicted in good agreement with the experimentally determined values. These insights into the pattern of bile acid conjugation in human bile between glycine and taurine promise useful clues to the mechanism of bile acids’ biosynthesis, conjugation and enterohepatic circulation, and may improve our understanding of the role of individual conjugated bile acids in health and disease. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

11.
A Th4+ ion-selective membrane sensor was fabricated from poly (vinyl chloride) (PVC) matrix membrane containing 2-(diphenylphosphorothioyl)-N′,N′-diphenyl acetamide (DPTD) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of the membrane composition, pH and additive anionic influence on the response properties were investigated. The sensor, comprising 30% PVC, 63% solvent mediator, 4% ionophore and 3% anionic additive demonstrates the best potentiometric response characteristics. It displays Nernstian behavior (15.2 ± 0.5 mV per decade) over the concentration range 1.0 × 10−2–1.0 × 10−6 M. The detection limit of the electrode is 6.3 × 10−7 M (∼140 ng/ml). The response time of the electrode is 30 s .The sensor can be used in the pH range 3.0–9.0 for about 6 weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of Th4+ ions with EDTA. It was successfully applied to the determination of thorium ions in binary mixture.  相似文献   

12.
The structures of endohedral complexes of the polyhedral oligomeric silsesquioxane (POSS) cage molecule (HSiO3/2)12, with both D 2d and D 6h starting cage symmetries, containing the atomic or ionic species: Li0, Li+, Li, Na0, Na+, Na, K0, K+, K, F, Cl, Br, He, Ne, Ar were optimized by density functional theory using B3LYP and the 6-311G(d,p) and 6-311 ++G(2d,2p) basis sets. The exohedral Li+, Na+, K+, K, F, Cl, Br, He, Ne, Ar complexes, were also optimized. The properties of these complexes depend on the nature of the species encapsulated in, or bound to, the (HSiO3/2)12 cage. Noble gas (He, Ne and Ar) encapsulation in (HSiO3/2)12 has almost no effect on the cage geometry. Alkali metal cation encapsulation, in contrast, exhibits attractive interactions with cage oxygen atoms, leading to cage shrinkage. Halide ion encapsulation expands the cage. The endohedral X@(HSiO3/2)12 (X = Li+, Na+, K+, F, Cl, Br, He and Ne) complexes form exothermically from the isolated species. The very low ionization potentials of endohedral Li0, Na0, K0 complexes suggest that they behave like “superalkalis”. Several endohedral complexes with small guests appear to be viable synthetic targets. The D 2d symmetry of the empty cage was the minimum energy structure in accord with experiment. An exohedral fluoride penetrates the D 6h cage to form the endohedral complex without a barrier.  相似文献   

13.
The effect of Mo6+ on the current efficiency, deposit quality, surface morphology, crystallographic orientations and polarisation behaviour of the cathode during electrodeposition of nickel from sulfate solutions was investigated. Mo6+ did not have a significant effect on current efficiency over the concentration range 2–100 mg dm−3. However; a decrease in current efficiency by a magnitude of more than 20% was seen at 500 mg dm−3. The quality of the nickel deposit with reference to the visual appearance and contamination level varied with varying concentration of Mo6+; this was also reflected in the morphology and crystallographic orientations of the deposits. Addition of Mo6+ to the electrolyte introduced two new crystal planes i.e., (220) and (311). Depolarisation of the cathode was noted at lower concentrations of Mo6+ (2–40 mg dm−3) whereas polarisation of the cathode was observed at Mo6+ concentration >40 mg dm−3 .The effect of Mo6+ on parameters such as Tafel slope (b), transfer coefficient (α) and exchange current density (i 0) were also determined.  相似文献   

14.
From the water-insoluble lipid fraction of the methylene chloride/methanol extract of the starfish Cosmasterias lurida, two new glucosylceramides together with a known glucosylceramide, ophidiacerebroside E, were isolated by chromatographic procedures and characterized by spectroscopic (1H and 13C nuclear magnetic resonance, mass spectrometry) methods. The new compounds were identified as (2S, 3R, 4E, 8E, 10E)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxyheptadecanoyl)amino]-9-methyl-4,8,10-octadecatriene (3) and (2S,3R,4E,8E,10E)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxyoctadecanoyl)amino]-9-methyl-4,8,10-octadecatriene (4).  相似文献   

15.
This paper reports on the preparation and spectral properties of europium (Eu3+) and terbium (Tb3+) ions doped cadmium lead boro tellurite (CLBT) glasses. For reference glasses, physical properties have been evaluated. From the [measurements of X-ray diffraction (XRD), glass amorphous nature of these [glasses has been studied. From the emission spectra of Eu3+: CLBT glasses, five [transitions (5 D 07 F 0, 7 F 1, 7 F 2, 7 F 3 and 7 F 4) at 579, 591, 613, 652 and 701 nm are observed with λexci = 392 nm (7 F 05 L 6) and in the case of Tb3+: CLBT glasses, four emission transitions 5 D 4 → (7 F 6, 7 F 5, 7 F 4 and 7 F 3) are observed at 489, 543, 584 and 621nm respectively monitered with λexci = 376 nm (7 F 65 G 6).  相似文献   

16.
The effect of pulegone chiral center configuration on its antifeedant activity to Myzus persicae was examined. Biological consequences of structural modifications of (R)-(+)- and (S)-(−)-pulegone, the lactonization, iodolactonization, and incorporation of hydroxyl and carbonyl groups were studied, as well. The most active compounds were (R)-(+)-pulegone (1a) and δ-hydroxy-γ-spirolactones (5S,6R,8S)-(−)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2-one (5b) and (5R,6S,8S)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2-one (6b) derived from (S)-(−)-pulegone (1b). The compounds deterred aphid probing and feeding at preingestional, ingestional, and postingestional phases of feeding. The preingestional effect of (R)-(+)-pulegone (1a) was manifested as difficulty in finding and reaching the phloem (i.e., prolonged time preceding the first contact with phloem vessels), a high proportion of probes not reaching beyond the mesophyll layer before first phloem phase, and/or failure to find sieve elements by 20% of aphids during the 8-hr experiment. The ingestional activity of (R)-(+)-pulegone (1a) and hydroxylactones 5b and 6b resulted in a decrease in duration of phloem sap ingestion, a decrease in the proportion of aphids with sustained sap ingestion, and an increase in the proportion of aphid salivation in phloem. δ-Keto-γ-spirolactone (5R,8S)-(−)-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2,6-dione (8b) produced a weak ingestional effect (shortened phloem phase). The postingestional deterrence of (R)-(+)-pulegone (1a) and δ-hydroxy-γ-spirolactones (5R,6S,8R)-(+)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]-decan-2-one (5a), 5b, (5S,6R,8R)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2-one (6a), 6b, and δ-keto-γ-spirolactone 8b prevented aphids from settling on treated leaves. The trans position of methyl group CH3–8 and the bond C5–O1 in lactone 6b appeared to weaken the deterrent activity in relation to the cis diastereoisomer (5b).  相似文献   

17.
3D-supramolecular coordination polymers (SCP) of the type [(R3Sn)3FeIII(CN)6]; R = CH3 (I), n-Butyl (II) and phenyl (III) contain wide expandable channels capable of encapsulating and in situ oxidizing 2,4-dichlorophenol (DClP) and 2,6-di-t-butylphenol (DBP) to 2-chloro-1,4-benzoquinone (2-ClBQ) and 3,5,3,5-tertra-t-butyl-4,4-diphenoquinone (BDPQ), respectively, to form new host–guest supramolecular coordination polymers (HGSCP) (16). The oxidation products are investigated by spectrophotometry and HPLC methods. A kinetic study indicated a first-order reaction with respect to the hosts SCP I–III. The mechanism and rate of oxidation are discussed in relation to the structure of the SCP.  相似文献   

18.
New ceramides from <Emphasis Type="Italic">Rantherium suaveolens</Emphasis>   总被引:1,自引:0,他引:1  
Oueslati MH  Mighri Z  Ben Jannet H  Abreu PM 《Lipids》2005,40(10):1075-1079
A mixture of five new ceramides was isolated from the aerial parts of Rantherium suaveolens and characterized by spectroscopic and chemical methods. Their structures were elucidated by spectroscopic and chemical methods as (2S, 3S, 4R, 2′R, 14E)-2-(2′-hydroxydocosanoylamino)-14-octadecene-1,3,4-triol (1), (2S,3S,4R,2′R, 14F)-2-(2′-hydroxytricosanoylamino)-14-octadecene-1,3,4-triol (2), (2S,3S,4R,2′R,14F)-2-(2′-hydroxytetracosanoylamino)-14-octadecene-1,3,4-triol (3), (2S,3S,4R,2′R,14E)-2-(2′-hydroxypentacosanoylamino)-14-octadecene-1,3,4-triol (4), and (2S,3S,4R,2′R,14E)-2-(2′-hydroxyhexacosanoylamino)-14-octadecene-1,3,4-triol (5).  相似文献   

19.
It was demonstrated that R 2R 4 saturated monohydric alcohols can be synthesized from CO and H2 in the presence of Fe catalysts containing a carbon support of the Sibunit type with granule sizes of 3–5, 1–2, and 0.05–0.1 mm in a fixed-bed reactor at 3 MPa and 240–300°C. It was found that the activity of Fe/Sibunit catalysts and their selectivity for the formation of liquid synthetic products increased with the size of granules and the amount of iron. The catalysts make it possible to obtain fatty alcohols, in which the fraction of R 2R 4 alcohols is as high as 75%, in yields to 56 g/m3.  相似文献   

20.
In this work the molecular fatty components of Pecorino Sardo Protected Designation of Origin (PS PDO) cheese were characterized through an exhaustive investigation of the 1H- and 13C-NMR spectra of the extracted lipids. Several fatty acids (FA), such as long chain saturated, oleic, linoleic, linolenic, butyric, capric, caprylic, caproic, trans vaccenic, conjugated linoleic acid (cis9, trans11–18:2), and caproleic (9–10:1) were unambiguously detected. The positional isomery of some acyl groups in the glycerol backbone of triacylglycerols (TAG) was assessed. Furthermore, the NMR signals belonging to sn-1,2/2,3, sn-1,3 diacylglycerols (DAG), and free fatty acids (FFA) were analysed as a measure of lipolytic processes on cheese. Lastly, 1H-NMR resonances of saturated aldehydes and hydroperoxides were detected, their very low intensity indicating that the lipid oxidation process can be considered to be of minor relevance in Pecorino Sardo cheese.  相似文献   

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