Macrophyllosaponin E: a novel compound from the roots of Astragalus. oleifolius

Macrophyllosaponin E, a novel cycloartane-type triterpene, has been isolated from the roots of Astragalus oleifolius. The structure elucidation of the compound was achieved by a combination of one- and two-dimensional NMR techniques [1H-1H-correlation spectroscopy (COSY), 1H-13C-heteronuclear multiple guantum correlation spectroscopy (HMQC), and 1H-13C-heteronuclear multiple-bond correlation spectroscopy (HMBC)l and high resolution electrospray ionization Fourier transformation mass spectrometry (HR-ESI-FT-MS).     

Trojanosides I-K: new cycloartane-type glycosides from the aerial parts of Astragalus trojanus.

Three new cycloartane-type triterpene glycosides have been isolated from the aerial parts of Astragalus trojanus. The structures were established mainly by a combination of one- and two-dimensional NMR techniques [1H-1H-correlation spectroscopy (COSY), 1H-13C-heteronuclear multiple quantum correlation spectroscopy (HMQC), and 1H-13C-heteronuclear multiple-bond correlation spectroscopy (HMBC)] and high resolution electrospray ionization mass spectrometry (HR-ESI-MS) as 3-O-beta-(2',3'-di-O-acetyl)-D-xylopyranosyl-6-O-beta-D-glucopyranosyl-16-O- acetoxy-20(R),24(S)-epoxycycloartane-3beta,6alpha,16beta,25-tetrol, 3-0-[alpha-L-rhamnopyranosyl-(1-->2)-beta-(3',4'-di-O-acetyl)-D-xylopyranosyll-6-O-beta-D-xylopyranosyl-20(R),24(S)-epoxycycloartane-3p,6alpha,16beta,25-tetrol, 3-O-beta-D-xylopyranosyl-6,16-di-O-beta-D-glucopyranosyl-20(R)24(S)-epoxycycloartane-3beta,6alpha,16beta,25-tetrol.     

Nuclear magnetic resonance studies of cytochalasin E and its decomposition product

The proton and carbon-13 nuclear magnetic resonance signals of cytochalasin E (1) were assigned with the aid of 1H-1H, 1H-13C and 1H-13C long-range chemical shift correlation spectroscopy spectra, and the structure of the decomposition product (2) generated under neutral conditions was determined.     

New eudesmane derivatives and other sesquiterpenes from the epigeal parts of Dittrichia graveolens

In bioassay-guided searches for novel bioactive natural products from higher plants of the Egyptian flora, two new eudesmane sesquiterpene derivatives, 3alpha-hydroxyilicic acid methyl ester (1) and 2alpha-hydroxy-4-epi-ilicic acid (2), together with 11 known sesquiterpenes were isolated from bioactive fractions of the active epigeal parts extracts of Dittrichia graveolens (L.) GREUTER (Asteraceae) growing in the coastal regions of northwestern Egypt. Four other known sesquiterpene lactones with different carbon skeletons, named 2alpha-hydroxy-2R-xanthalongin (8), 4-epi-isoinuviscolide (9), 8-epi-helenalin (10), and bigelovin (11), were also isolated for the first time from the same source. The stereochemical structures of the isolated compounds were elucidated on the basis of physical and spectroscopic methods including UV, IR, 1H-, 13C-NMR, distortionless enhancement by polarization transfer, 2D NMR, 1H-1H correlation spectroscopy, 1H-13C heteronuclear single-quantum coherence, 1H-13C heteronuclear multiple-bond connectivity, 1H-1H nuclear Overhauser effect spectroscopy experiments, and high-resolution mass spectrometry, as well as some chemical transformations. The antimicrobial, antiinflammatory, and antipyretic activities of D. graveolens extracts and chromatographic fractions were carried out and the various bioactivities of our findings are discussed.     

Two new pentacyclic triterpenoids from Lantana camara LINN

Two new pentacyclic triterpenoids, namely lantanoic acid (1) and camaranoic acid (2), and six known compounds such as lantic acid, camarinic acid, camangeloyl acid, camarinin, oleanonic acid, and ursonic acid were isolated from the aerial parts of Lantana camara LINN. Structures of the new constituents were elucidated by chemical transformation and spectral studies including 1D ((1)H- and (13)C-NMR) and 2D ((1)H-(1)H correlation spectroscopy (COSY), nuclear Overhauser effect spectroscopy (NOESY), (1)H-(1)H total correlation spectroscopy (TOCSY), J-resolved, (1)H-detected heteronuclear multiple quantum coherence (HMQC), and heteronuclear multiple bond connectivity (HMBC)) NMR spectroscopy.     

1-(2,6-二氟苯甲基)-N-甲基-1H-1,2,3-三唑-4-甲酰胺核磁共振峰的归属

采用一维(1D)和二维(2D)核磁共振(NMR)技术对一种抗癫痫活性的化合物1-(2,6-二氟苯甲基)-N-甲基-1H-1,2,3-三唑-4甲酰胺的1H和13C NMR信号进行了归属。     

多司马酯的波谱特征与结构确证

对多司马酯的紫外(UV)光谱、红外(IR)光谱、氢谱(^1HNMR)、碳谱(^13CNMR)、氢氢相关谱(^1H-^1HCOSY)、碳氢相关谱(HETCOR)及碳氢远程相关谱(COLOC)进行了解析报道,并对所有的^1HNMR,^13CNMR谱的信号进行了归属,讨论了红外吸收光谱峰所对应的官能团的振动形式。     

Assignments of 1H and 13C NMR spectral data for ondansetron and its two novel metabolites, 1-hydroxy-ondansetron diastereoisomers

Assignments of 1H and 13C NMR chemical shifts were made by means of heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments for ondansetron, and by means of 1H-1H correlation spectroscopy (1H-1H COSY) and two-dimensional nuclear Overhauser effect spectroscopy (NOESY) experiments for two novel metabolites (M1 and M2) of ondansetron. These two metabolites were isolated for the first time from Mucor circinelloides.     

Characterization of n-butyl acrylate centered triads in poly(n-butyl acrylate-co-carbon monoxide-co-ethylene) by isotopic labeling and two dimensional NMR

Poly(n-butylacrylate-co-carbon monoxide-co-ethylene) (polyEBC) samples prepared from 13C-labeled monomer, n-butyl acrylate, were characterized using two dimensional (2D) pulsed field gradient (PFG) 750 MHz NMR spectroscopy. To elucidate the complex structure of the terpolymer, 2D-1H/13C-heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments were conducted by selectively exciting the enhanced resonances in the spectra of two polymer samples, one polymer resulting from synthesis with 1-13C-n-butylacrylate monomer and a second polymer obtained from a synthesis with 2-13C-n-butylacrylate monomer. High-resolution 2D-NMR combined with 13C-labeling of the polymer greatly simplifies the 2D-NMR spectra, selectively enhances the weak peaks from low occurrence B-centered triad structures, and aids in their resonance assignments. In all experiments, the sample temperature was 120 degrees C, to ensure a homogeneous solution and sufficient molecular mobility. Electronic Supplementary Material: Supplementary material (1D 13C NMR spectra of the 13C-labeled and unlabeled polymers) is available in the online version of this article at http://dx.doi.org/100.1007/s00216-003-2402-3.     

Complete 1H and 13C NMR spectral assignment of symmetric and asymmetric bis-spiropyran derivatives

(1)H and (13)C NMR spectra of symmetric and asymmetric bis-spiropyrans, Series 1-3, were completely assigned. Especially, the (1)H assignment of asymmetric spiropyrans was achieved by utilizing (1)H-(1)H COSY and nOe experiments. All of the carbons in the dye molecules were investigated through a combination of heteronuclear 2D-shift correlation spectroscopy (HETCOR), together with an attached proton test (APT).     

一种新的六氢嘧啶并嘧啶二酮衍生物的核磁共振分析

采用氢谱(1H NMR)、碳谱(13C NMR)、梯度场氢氢化学位移相关谱(1H-1H COSY)、梯度场质子检测异核单量子化学位移相关谱(HSQC)、梯度场质子检测异核多重键化学位移相关谱(HMBC)等多种NMR分析方法,确证了8a-对甲氧苯基-4,5-双(对氯苯基)六氢嘧啶[4,5-d]并嘧啶-2,7(1H,3H)-二酮的结构,对它的1H和13C NMR谱信号进行了归属,为其结构鉴定提供了重要依据。     

去羧氯雷他定的波谱学数据与结构确证

对去羧氯雷他定的红外（IR）、质谱（MS）、氢-氢相关谱(^1H-HCOSY)、碳谱（BB、DEPT-90、DEPT-135）、碳氢相关谱（HMQC）、碳氢远程相关谱（HMBC）解析并进行了报道。对所有的^1HNMR、^13CNMR谱的信号进行了归属，同时讨论了质谱的主要碎片离子的可能的裂解方式和红外特征吸收峰所对应的官能团的振动形式。     

A new bis(1-naphthylimino)acenaphthene compound and its Pd(II) and Zn(II) complexes: synthesis, characterization, solid-state structures and density functional theory studies on the syn and anti isomers

A new rigid bidentate ligand, bis(1-naphthylimino)acenaphthene, L1, and its Zn(II) and Pd(II) complexes [ZnCl 2( L1)], 1, and [PdCl 2( L1)], 2, were synthesized. L1 was prepared by the "template method", reacting 1-naphthyl amine and acenaphthenequinone in the presence of ZnCl 2, giving 1, which was further demetallated. Reaction of 1-naphthyl amine with acenaphthenequinone and PdCl 2 afforded dichloride bis(1-naphthyl)acenaphthenequinonediimine palladium, 2. L1, 1, and 2 were obtained as a mixture of syn and anti isomers. Compound 2 was also obtained by the reaction of PdCl 2 activated by refluxing it in acetonitrile followed by the addition of L1; by this route also a mixture of syn and anti isomers was obtained, but at a different rate. The solid-state structures of L1 and the anti isomer of compound 2 have been determined by single-crystal X-ray diffraction. All compounds have been characterized by elemental analyses; matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry; IR; UV-vis; (1)H, (13)C, and (1)H- (1)H correlation spectroscopy; (1)H- (13)C heteronuclear single quantum coherence; (1)H- (13)C heteronuclear single quantum coherence-total correlation spectroscopy; and (1)H- (1)H nuclear Overhauser effect spectrometry NMR spectroscopies when applied. Density functional theory studies showed that both conformers for [PdCl 2(BIAN)] are isoenergetic, and they can both be obtained experimentally. However, we can predict that the isomerization process is not available in a square-planar complex, but it is possible for the free ligand. The molecular geometry is very similar in both isomers, and only different orientations for naphthyl groups can be expected.     

咪喹莫特的波谱学数据与结构表征

对咪喹莫特的红外(IR)、紫外(UV)、质谱(MS)、氢-氢相关谱(^1H--^1H COSY)、碳氢相关谱(HMQC)、碳氢远程相关谱(HMBC)予以解析并进行了报道。对所有的^1H NMR、^13C NMR谱的信号进行了归属；讨论了质谱的主要碎片离子的可能的裂解方式和红外特征吸收峰所对应的官能团的振动形式。     

One metabolite, two pathways: convergence of polypropionate biosynthesis in fungi and marine molluscs

Structural similarity or even the identity of polyketide compounds does not necessarily imply unique biosynthesis. Feeding experiments with a (13)C labeled precursor establish that the C(3) units in 7-methyl-cyercene-1 (1) are derived from intact propionate in the marine mollusc Ercolania funerea. The same compound in the terrestrial fungus Leptosphaeria maculans/Phoma lingam is synthesized by an acetate/SAM pathway thus proving for the first time metabolic convergence of polyketide biosynthesis in eukaryotes. Traditional (1)H-(13)C NMR correlation spectroscopy has been successfully applied to estimate (13)C incorporation in biosynthetic experiments.     

Combining multinuclear high-resolution solid-state MAS NMR and computational methods for resonance assignment of glutathione tripeptide

We present a complete set of experimental approaches for the NMR assignment of powdered tripeptide glutathione at natural isotopic abundance, based on J-coupling and dipolar NMR techniques combined with (1)H CRAMPS decoupling. To fully assign the spectra, two-dimensional (2D) high-resolution methods, such as (1)H-(13)C INEPT-HSQC/PRESTO heteronuclear correlations (HETCOR), (1)H-(1)H double-quantum (DQ), and (1)H-(14)N D-HMQC correlation experiments, have been used. To support the interpretation of the experimental data, periodic density functional theory calculations together with the GIPAW approach have been used to calculate the (1)H and (13)C chemical shifts. It is found that the shifts calculated with two popular plane wave codes (CASTEP and Quantum ESPRESSO) are in excellent agreement with the experimental results.     

Combined use of Overhauser spectroscopy and NMR diffusion experiments for mapping the hydration structure of nucleosides: structure and dynamics of uridine in water

Complementary results from 13C intermolecular nuclear Overhauser effects (NOE), 1H-13C heteronuclear Overhauser spectroscopy (HOSEY) and 1H-NMR diffusion measurements were used for probing the structure of the first solvation shell of uridine in water. It is demonstrated that a cyclic dihydrate is formed. The two water molecules produce two hydrogen bonds with the two oxygen atoms from the pyrimidine ring and accept only one hydrogen bond from the amide proton. The dihydrate has only a short lifetime as compared with the rotational correlation time of the free nucleoside. The chemical exchange constant of the amide proton with water is then estimated by diffusion experiments. The results are consistent with previous data obtained for uracil in water and provide interesting information about water accessibility in nucleic acid bases.     

(6aR,11aR)-3-羟基-4,9-二甲氧基紫檀烷分子的晶体结构

(6aR,11aR)-4,9-dimethoxy-3-hydroxypterocarpan was isolated from the natural plant of Caragana spinifera Kom (Leguminosae). The structure was elucidated by infrared spectra(IR), mass spectrometry(MS), 1H-Nuclear magnetic resonance(1H-NMR),13C-Nuclear Magnetic Resonance(13C-NMR), 1H-1H correlation spectroscopy(1H-1H COSY), heteronuclear multiple quantum coherence(HMQC) and heteronuclear multiple bond coherence(HMBC). In addition, its crystal structure was determined by the single-crystal X-ray diffraction analysis. It crystalized in monoclinic, space group P21 with a=6.4778(13), b=12.631(3), c=8.8368(18)(A), β= 95.8(3)o, C17H16O5, Mr=300.30, V=719.3(3)(A)3, Z=2, Dc=1.386 Mg/m3, F(000)=316, μ=0.102 mm-1, the final R=0.0332 and wR=0.0862 for 1533 observed reflections (I>2σ(I)). The molecular backone of the compound includes a benzofuro and a benzopyran. The X-ray analysis shows that the absolute configuration of the compound is cis-pterocarpan.     

Triterpenoidal saponins acylated with two monoterpenic acids from Gleditsia sinensis

The isolation and characterization of three new oleanane-type triterpenoidal saponins, called gleditsiosides E-G, along with two known ones, from the anomalous fruits of Gleditsia sinensis LAM. are described. Their structural details were unambiguously determined by using a combination of modern NMR techniques, including distortionless enhancement by polarization transfer (DEPT), double-quantum filtered 1H-1H correlated spectroscopy (DQF-COSY), homonuclear hartmann-hahn (HOHAHA), 1H-13C heteronuclear correlation (HET-COR), heteronuclear multiple-bond connectivity (HMBC) and rotating-frame overhauser enhancement spectroscopy (ROESY) experiments as well as some chemical methods. The five bisdesmosidic triterpenoidal saponins consisting of the same sugar sequence were all acylated with two different or identical monoterpenic acids to the C-2 and C-3 positions of rhamnose moiety.     

西尼地平核磁共振碳谱氢谱的谱峰归属

利用普通1H-NMR，13C-NMR，极化转移谱(DEPT)以及同核相关谱(COSY)、异核相关谱(HSQC)，特别是远程偶合谱(HMBC)等多种核磁研究方法对新型的血管扩张药西尼地平的1H、13C信号进行完全归属。对由于分子结构对称而引起的化学位移相差最小为0．94Hz的两个碳加以区分，解决了由于样品的近似对称性而导致几组谱峰难以归属的问题。