A triterpenoid saponin from Phytolacca esculenta.

A new triterpenoid saponin, 3-O-[beta-D-glucopyranosyl(1----4)-beta-D- xylopyranosyl]-28-O-beta-D-glucopyranosyl-30-methyloleanate-9(11), 12-dien- 2,3,23-trihydroxyl-28-oic acid, was isolated from the roots of Phytolacca esculenta. The structure was assigned by chemical methods and spectral analysis (1H, 13C, DEPT NMR, EIMS and FABMS) including 1H-1H COSY, 1H-13C COSY and 1H-1H NOESY.     

A New Diterpene Glycoside in Aster ageratoides Turcz.

A new natural diterpene glycoside was isolated from Aster ageratoides Turcz. Its structure was elucidated by means of IR, MS (FAB, EI), NMR (1H-, 13C-, DEPT), 2D-NMR (1H-1H COSY, 13C-1 H COSY, J-resolved, CoLoC) spectra and chemical method as 16β, 17-dihydroxy- (—) -kauran- 19-oic acid-β-D-glucopyanosyl ester.     

Re-characterization of three conjugated linolenic acid isomers by GC-MS and NMR

Conjugated linolenic acids (CLN) refer to a group of octadecatrienoic acids with three conjugated double bonds. Minor positional and geometrical differences among CLN isomers make their separation and identification difficult. We have used GC-MS and NMR to study three common CLN isomers namely alpha-eleostearic acid, beta-eleostearic acid and punicic acid, finding that some signals of olefinic carbon atoms in NMR spectra were mistakenly assigned in the literature. The present study was therefore undertaken to re-characterize the location of CC double bonds and assign the chemical signals of proton and carbon atoms using (1)H NMR, (13)C NMR, (1)H-(1)H two-dimensional correlation spectra ((1)H-(1)H COSY) and (13)C-(1)H two-dimensional correlation spectra ((13)C-(1)H COSY). The geometrical structure of double bonds in these three CLN isomers was identified using homonuclear decoupling technique.     

Abruquinone A,B,D,E,F and G from the Root of Abrus precatorius

Eight flavonoids have been isolated from the root of Abrus precatorius L. Among them, six isoflavanquinones, designated (3R)-abruquinone A, B, D and E, (3S)-abruquinone F and G, are characterized by chemical and spectral means including 1H-1H COSY, 1H-13C COSY and CD methods.     

Buzonamine, a new alkaloid from the defensive secretion of the millipede, Buzonium crassipes

GC-MS analysis of the defensive secretion from the millipede Buzonium crassipes showed three volatile components, beta-pinene (35%), limonene (6%) and a new alkaloid, buzonamine (59%). Buzonamine had an HRMS molecular ion at m/z=221.1785 (calculated for C(14)H(23)NO, 221.1781), 14 carbons in the 13C-NMR and 23 hydrogens by SFORD, DEPT and APT experiments. All distinct 1H nuclei were assigned to 13C resonances with 2D 1H-13C COSY data, and the final structure was determined by 1H-1H COSY, 1H-13C HMBC and nOe experiments. Buzonamine contains four rings including an epoxy group and a tertiary nitrogen. beta-Pinene, limonene or buzonamine, kept the mound nesting ant, Formica obscuripes, from eating mealworms (Tenebrio molitor) treated with 1mg of the chemical. A 150mg millipede expels 4mg of secretion.     

Two Cyclic Dipeptides from Pseudomonas fluorescens GcM5-1A Carried by the Pine Wood Nematode and Their Toxicities to Japanese Black Pine Suspension Cells and Seedlings in vitro

Pseudomonas fluorescens GcM5-1A, isolated from the pine wood nematode (PWN), Bursaphelenchus xylophilus, was cultured in Luria Broth medium (LB). The clarified culture was extracted with ethyl acetate, and two dipeptides were purified from the extract. The chemical structures of 1 and 2 were identified as cyclo(-Pro-Val-)and cyclo(-Pro-Tyr-), respectively, by MS, ¹H NMR, ¹³C NMR,¹H-¹H COSY, 1H -¹³C COSY spectra. Bioassay results showed that the two compounds were toxic to both suspension cells and seedlings of Pinus thunbergii, which may offer some clues to research the mechanism of pine wilt disease caused by PWN.     

NMR study of thymulin, a lymphocyte differentiating thymic nonapeptide. Conformational states of free peptide in solution

The nonapeptide less than Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn (formerly called serum thymic factor) is a factor produced by the thymic epithelium, which needs a zinc ion to express its immunoregulatory properties. We report here on 1H and 13C NMR investigation of the conformational properties of the free peptide in aqueous medium and in dimethyl sulfoxide-d6 solution by a combination of homo- and heteronuclear one- and two-dimensional experiments. The various resonances have been assigned in a straightforward manner on the basis of 1H,1H COSY spectroscopy for the recognition of the proton spin systems; two-dimensional NOESY spectra with the correlation peaks across amide bonds and for the amino acid sequence assignment; amide bonds and for the amino acid sequence assignment; 13C,1H COSY experiments using selective polarization transfer from 1H- to 13C-nucleus via the 13C,1H long-range couplings for the attribution of the carboxyl and carbonyl groups; and 13C,1H COSY experiments with selective polarization transfer via the 13C,1H direct couplings for the assignment of all the aliphatic carbons. Other experiments such as pH-dependent chemical shifts, combined use of multiple and selective proton-decoupled 1H and 13C NMR spectra, the temperature and the concentration dependence of the proton shifts of the amide resonances, the solvent dependences of peptide carbonyl carbon resonances, and comparison of the spectra with three different analogues were performed. In aqueous solution, the data are compatible with the assumption of a highly mobile dynamic equilibrium among different conformations, whereas in dimethyl sulfoxide-d6, a more rigid structure is found involving three internal hydrogen bonds. These observations provide an insight into the conformational tendencies of this peptidic hormone in two different media.     

Diastereomeric stilbene glucoside dimers from the bark of Norway spruce (Picea abies)

As part of a long-term study of the chemical defenses of Norway spruce (Picea abies) against herbivores and pathogens, a phytochemical survey of the phenolics in the bark was carried out. Eight stilbene glucoside dimers, designated as piceasides A-H (1a-4b), were isolated as four 1:1 mixtures of inseparable diastereomers. Their structures were determined by extensive spectroscopic means including 1D (1H and 13C) and 2D NMR (1H-1H COSY, HSQC, HMBC, ROESY) spectra, and were supported by enzymatic hydrolysis and computational analysis.     

Triterpenoid saponins from Argania spinosa.

Five new oleanane saponins named arganine A, B, D, E and F and two known saponins: arganine C and mi-saponin A were isolated from the kernel of Argania spinosa. The structures of these saponins were elucidated by using 1H NMR, 1H-1H COSY NMR, 13C NMR, FAB mass spectrometry and chemical evidence.     

Complete 1H and 13C NMR assignment of mono-sulfated galactosylceramides with four types of ceramides from human kidney

The full assignment of 1H and 13C NMR signals of galactosylceramide 3-sulfate (galactosyl sulfatide) and 1H signals of galactosylceramide 6-sulfate was achieved by using 1H-1H DQF-COSY and 1H-13C heteronuclear COSY. Analyses were performed on a mixture of galactosyl sulfatides with four representative ceramide types consisting of a combination of non-hydroxy or 2-hydroxy fatty acids and sphingenine or 4D-hydroxysphinganine (trihydroxysphinganine) as the long-chain bases. The 1H and 13C NMR parameters of galactosyl sulfatide with 4-hydroxysphinganine as well as 13C signals of complex lipids with 4-hydroxysphinganine were elucidated for the first time. Not only sulfation of the galactosyl residue, but also modification of the aglycon, including hydroxylation of fatty acids and hydration of the double bond in sphingoid bases, altered the chemical shifts substantially. In addition, the unique long-range coupling constants, 4J(H,H) and 5J(H,H), in the galactosyl residue of galactosyl sulfatide could be determined.     

Two-dimensional concurrent HMQC-COSY as an approach for small molecule chemical shift assignment and compound identification

Chemical shift assignment is the first step toward the structure elucidation of natural products and other chemical compounds. We propose here the use of 2D concurrent HMQC-COSY as an experiment for rapid chemical shift assignment of small molecules. This experiment provides well-dispersed (1)H-(13)C peak patterns that are distinctive for different functional groups plus (1)H-(1)H COSY connectivities that serve to identify adjacent groups. The COSY diagonal peaks, which are phased to be absorptive, resemble (1)H-(13)C HMQC cross peaks. We demonstrate the applicability of this experiment for rapidly and unambiguously establishing correlations between different functional groups through the analysis of the spectrum of a metabolite (jasmonic acid) dissolved in CDCl(3). In addition, we show that the experiment can be used to assign spectra of compounds in a mixture of metabolites in D(2)O.     

Structure of the O-specific polysaccharide of Proteus mirabilis O16 containing ethanolamine phosphate and ribitol phosphate

The O-specific polysaccharide of Proteus mirabilis O16 was studied by 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, NOESY, H-detected 1H,13C HMQC, HMQC-TOCSY, and 1H,31P HMQC experiments, along with chemical methods. The polysaccharide was found to be a ribitol teichoic acid-like polymer having the following structure [structure: see text].     

Diterpene glucosides from Pieris formosa

Five diterpene glucosides, pierisformosides B-F were isolated from Pieris formosa D. Don (Ericaceae). Their structures were elucidated on the basis of spectral analysis. including 1H-1H COSY, 13C-1H COSY, HMBC and NOESY experiments.     

Monoepoxy octadecadienoates and monoepoxy octadecatrienoates 1: NMR spectral characterization

Methyl esters of gamma-linolenic acid, alpha-linolenic acid and stearidonic acid were epoxidised using m-chloroperbenzoic acid to achieve nine cis-monoepoxy-C18 fatty acid methyl esters (FAMEs), including novel methyl cis-monoepoxy derivatives of stearidonic acid and a cis-6,7-epoxy derivative of gamma-linolenic acid. These nine monoepoxy FAMEs were purified by normal-phase HPLC, identified by LC-MS, 1H and 13C NMR, and characterized by mass spectrometry and NMR spectroscopy. This study is focused on structural characterization of these C18 monoepoxy FAMEs using techniques in NMR spectroscopy including 1H, 13C, 1H-1H correlated spectroscopy (COSY) and 1H-13C heteronuclear correlation (HETCOR). The proton and carbon NMR chemical shifts of the epoxide, the double bonds, and the interrupted methylenes are assigned. Also discussed is an interpretation of the 1H and 13C NMR spectra of these monoepoxides including the changes in the 13C resonance of the olefinic carbons on the neighboring double bonds resulting from epoxide formation.     

Molluscicidal saponins from Phytolacca icosandra

Five monodesmosidic serjanic acid saponins and a monodesmosidic spergulagenic acid saponin were isolated from an aqueous extract of the berries of Phytolacca icosandra. A methanol extract of the berries furnished three bidesmosidic serjanic acid glycosides. Their structures were established by spectroscopic (ES-MS, 1H NMR, COSY, HSQC, HMBC, 13C NMR) and chemical methods. The molluscicidal, spermicidal and haemolytic properties of the saponins were investigated.     

Innovations in generation and analysis of 2D [(13)C,(1)H] COSY NMR spectra for metabolic flux analysis purposes.

2D [(13)C,(1)H] COSY NMR is used by the metabolic engineering community for determining (13)C-(13)C connectivities in intracellular compounds that contain information regarding the steady-state fluxes in cellular metabolism. This paper proposes innovations in the generation and analysis of these specific NMR spectra. These include a computer tool that allows accurate determination of the relative peak areas and their complete covariance matrices even in very complex spectra. Additionally, a method is introduced for correcting the results for isotopic non-steady-state conditions. The proposed methods were applied to measured 2D [(13)C,(1)H] COSY NMR spectra. Peak intensities in a one-dimensional section of the spectrum are frequently not representative for relative peak volumes in the two-dimensional spectrum. It is shown that for some spectra a significant amount of additional information can be gained from long-range (13)C-(13)C scalar couplings in 2D [(13)C,(1)H] COSY NMR spectra. Finally, the NMR resolution enhancement by dissolving amino acid derivatives in a nonpolar solvent is demonstrated.     

Structural analysis of two glycosphingolipids from the lipopolysaccharide-lacking bacterium Sphingomonas capsulata.

Two glycosphingolipids, GSL-1 and GSL-3, were isolated from Sphingomonas capsulata and studied by methylation analysis, laser desorption mass spectrometry, and 1H and 13C NMR spectroscopy, including two-dimensional 1H,1H COSY and heteronuclear 13C,1H COSY experiments. GSL-1 and GSL-3 differ in their carbohydrate part, their structures being alpha-D-GlcpA-(1-->1)-Cer and alpha-D-Galp-(1-->6)-alpha-D-GlcpN-(1-->4)-alpha-D-GlcpA(1-- >1)Cer, respectively. Variations occur in the ceramide of GSL-1 and GSL-3, both having the same long-chain bases, erythro-2-amino-1, 3-octadecanediol (sphinganine), (13Z)-erythro-2-amino-13-eicosene-1, 3-diol and (13Z)-erythro-2-amino-13,14-methylene-1,3-eicosanediol, in the ratios 2.6 : 1 : 3.5 in GSL-1 and 1 : 1.2 : 1.5 in GSL-3. All bases are quantitatively substituted by amide-linked (S)-2-hydroxymyristic acid.     

应用FTIR和NMR研究短梗霉多糖分子结构

短梗霉多糖是出芽短梗霉产生的一种胞外多糖,具有极好的成膜、成纤维、阻气、粘接、易加工、无毒性等特性,是微生物多糖中最令人瞩目的多糖之一．本研究应用ＦＴＩＲ和ＮＭＲ技术对由出芽短梗霉胞外产生的短梗霉多糖进行了分析．短梗霉多糖的红外光谱（４０００～４００ｃｍ－１）,具有明显的多糖特征吸收峰,证明多糖是由α－Ｄ－吡喃葡萄糖残基组成．应用先进的一维和二维核磁共振技术,在绝对温度３４３Ｋ下获得短梗霉多糖１Ｈ－ＮＭＲ谱和１３Ｃ－ＮＭＲ谱,确证短梗霉多糖的结构单元是α－１,４麦芽三糖,归属了短梗霉多糖的１Ｈ和１３Ｃ的全部化学位移     

Structure of the O-specific polysaccharide of Providencia alcalifaciens O16 containing N-acetylmuramic acid

The O-specific polysaccharide of Providencia alcalifaciens O16 was obtained by mild-acid degradation of the lipopolysaccharide and studied by chemical methods and NMR spectroscopy, including 2D 1H,(1)H COSY, TOCSY, NOESY, and 1H,(13)C HSQC experiments. It was found that the polysaccharide contains N-acetylmuramic acid, which was isolated by solvolysis with trifluoromethanesulfonic acid and identified by the specific optical rotation and NMR spectroscopy. The following structure of the trisaccharide repeating-unit of the polysaccharide was established:     

Structural and serological studies of the O-antigen of Proteus mirabilis O-9

The following structure of the O-polysaccharide (O-antigen) of the lipopolysaccharide of Proteus mirabilis O-9 was determined by NMR spectroscopy, including 2D 1H,(1)H COSY, TOCSY, ROESY, and 1H,(13)C HMQC experiments, along with chemical methods: [chemical structure: see text] where the degree of O-acetylation is approximately 70%. Immunochemical studies using rabbit polyclonal anti-Proteus mirabilis O-9 serum showed the importance of the O-acetyl groups in manifesting the serological specificity of the O-9 antigen. Anti-P. mirabilis O-9 cross-reacted with the lipopolysaccharides (LPS) of P. vulgaris O-25 and Proteus penneri 14, which could be accounted for by a structural similarity of their O-polysaccharides.