Artykuły w czasopismach: „HSQC experiments”

1

Krishnamurthy, V. V. "Sensitivity-Enhanced 3D HSQC-TOCSY Experiments". Journal of Magnetic Resonance, Series B 106, nr 2 (luty 1995): 170–77. http://dx.doi.org/10.1006/jmrb.1995.1028.

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Xia, Youlin, Kong Hung Sze, Ning Li, Pang Chui Shaw i Guang Zhu. "Protein Dynamics Measurements by 3D HNCO Based NMR Experiments". Spectroscopy 16, nr 1 (2002): 1–13. http://dx.doi.org/10.1155/2002/828353.

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Protein dynamics can be characterized by relaxation parameters obtained from traditional 2D HSQC based NMR experiments. This approach is hampered when applied to proteins with severe spectral overlap. In the present work, several novel 3D TROSY-HNCO and 3D HSQC-HNCO based NMR experiments were applied for measuring15NT1,T2and1H-15N NOE with improved spectral dispersion by introducing a third13C dimension. The number of phase cycling steps in these 3D pulse sequences was restricted to two in order to minimize the time required to perform the dynamics measurements. For a uniformly 100%15N, 100%13C, and 70%2H-labelled trichosanthin sample (~27 kDa, 1.0 mM) at 30°C, the sensitivity of 3D TROSY-HNCO based experiment was, on the average, enhanced by 72% compared to that of 3D HSQC-HNCO based experiments. However, the 3D HSQC-HNCO based experiments should be more effective for non-deuterated proteins with smaller molecular weights and seriously overlapped 2D HSQC spectra. Results from the 3D TROSY-HNCO and 3D HSQC-HNCO based experiments were in good agreement with those obtained from traditional 2D HSQC based experiments.

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Weitzel, Alexander, Claudia Samol, Peter J. Oefner i Wolfram Gronwald. "Robust Metabolite Quantification from J-Compensated 2D 1H-13C-HSQC Experiments". Metabolites 10, nr 11 (7.11.2020): 449. http://dx.doi.org/10.3390/metabo10110449.

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The spectral resolution of 2D 1H-13C heteronuclear single quantum coherence (1H-13C-HSQC) nuclear magnetic resonance (NMR) spectra facilitates both metabolite identification and quantification in nuclear magnetic resonance-based metabolomics. However, quantification is complicated by variations in magnetization transfer, which among others originate mainly from scalar coupling differences. Methods that compensate for variation in scalar coupling include the generation of calibration factors for individual signals or the use of additional pulse sequence schemes such as quantitative HSQC (Q-HSQC) that suppress the JCH-dependence by modulating the polarization transfer delays of HSQC or, additionally, employ a pure-shift homodecoupling approach in the 1H dimension, such as Quantitative, Perfected and Pure Shifted HSQC (QUIPU-HSQC). To test the quantitative accuracy of these three methods, employing a 600 MHz NMR spectrometer equipped with a helium cooled cryoprobe, a Latin-square design that covered the physiological concentration ranges of 10 metabolites was used. The results show the suitability of all three methods for the quantification of highly abundant metabolites. However, the substantially increased residual water signal observed in QUIPU-HSQC spectra impeded the quantification of low abundant metabolites located near the residual water signal, thus limiting its utility in high-throughput metabolite fingerprinting studies.

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Rouger, Laetitia, Serge Akoka i Patrick Giraudeau. "Optimized decoupling schemes in ultrafast HSQC experiments". Journal of Magnetic Resonance 283 (październik 2017): 89–95. http://dx.doi.org/10.1016/j.jmr.2017.08.015.

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Yang, Linyao, Jiangchao Du, Rongtao Li, Fei Yu i Jindong Zhong. "Bodiniosides S–Y, Seven New Triterpenoid Saponins from Elsholtzia bodinieri and Their Anti-Influenza Activities". Molecules 26, nr 21 (29.10.2021): 6535. http://dx.doi.org/10.3390/molecules26216535.

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Investigation of the n-BuOH extract of the aerial parts of Elsholtzia bodinieri led to the isolation of seven new triterpenoid saponins, Bodiniosides S–Y (1–7, resp.). Their strictures were elucidated on the basis of spectroscopic techniques, including HSQC, HSBC, and HSQC–TOCSY experiments, together with acid hydrolysis and GC analysis. The anti-influenza activities of compounds 1–7 were evaluated against A/WSN/33/2009 (H1N1) virus in MDCK cells. The results showed that compounds 2 and 5 exhibited moderate anti-influenza activities against A/WSN/33/2009 (H1N1), with inhibition rates of 35.33% and 24.08%, respectively.

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Kiraly, Peter, Mathias Nilsson i Gareth A. Morris. "Practical aspects of real-time pure shift HSQC experiments". Magnetic Resonance in Chemistry 56, nr 10 (12.01.2018): 993–1005. http://dx.doi.org/10.1002/mrc.4704.

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Gschwind, Ruth M., Xiulan Xie i Pattuparambil R. Rajamohanan. "Gs-HSQC-NOESY versus gs-NOESY-HSQC experiments: signal attenuation due to diffusion; application to symmetrical molecules". Magnetic Resonance in Chemistry 42, nr 3 (12.02.2004): 308–12. http://dx.doi.org/10.1002/mrc.1344.

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Hu, Haitao, i Krish Krishnamurthy. "Doubly compensated multiplicity-edited HSQC experiments utilizing broadband inversion pulses". Magnetic Resonance in Chemistry 46, nr 7 (2008): 683–89. http://dx.doi.org/10.1002/mrc.2221.

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Charlier, Cyril, Neil Cox, Sophie Martine Prud'homme, Alain Geffard, Jean-Marc Nuzillard, Burkhard Luy i Guy Lippens. "Virtual decoupling to break the simplification versus resolution trade-off in nuclear magnetic resonance of complex metabolic mixtures". Magnetic Resonance 2, nr 2 (10.08.2021): 619–27. http://dx.doi.org/10.5194/mr-2-619-2021.

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Abstract. The heteronuclear single quantum correlation (HSQC) experiment developed by Bodenhausen and Ruben (1980) in the early days of modern nuclear magnetic resonance (NMR) is without a doubt one of the most widely used experiments, with applications in almost every aspect of NMR including metabolomics. Acquiring this experiment, however, always implies a trade-off: simplification versus resolution. Here, we present a method that artificially lifts this barrier and demonstrate its application towards metabolite identification in a complex mixture. Based on the measurement of clean in-phase and clean anti-phase (CLIP/CLAP) HSQC spectra (Enthart et al., 2008), we construct a virtually decoupled HSQC (vd-HSQC) spectrum that maintains the highest possible resolution in the proton dimension. Combining this vd-HSQC spectrum with a J-resolved spectrum (Pell and Keeler, 2007) provides useful information for the one-dimensional proton spectrum assignment and for the identification of metabolites in Dreissena polymorpha (Prud'homme et al., 2020).

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Nolis, Pau, Kumar Motiram-Corral, Míriam Pérez-Trujillo i Teodor Parella. "Broadband homodecoupled time-shared 1H-13C and 1H-15N HSQC experiments". Journal of Magnetic Resonance 298 (styczeń 2019): 23–30. http://dx.doi.org/10.1016/j.jmr.2018.11.005.

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Castañar, Laura, Eduard Sistaré, Albert Virgili, R. Thomas Williamson i Teodor Parella. "Suppression of phase and amplitude J(HH) modulations in HSQC experiments". Magnetic Resonance in Chemistry 53, nr 2 (3.10.2014): 115–19. http://dx.doi.org/10.1002/mrc.4149.

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Parella, Teodor, i Jordi Belloc. "Gradient-enhanced 1D HMQC- and HSQC-relayed experiments with maximum sensitivity". Magnetic Resonance in Chemistry 39, nr 6 (2001): 311–15. http://dx.doi.org/10.1002/mrc.848.

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Gaillet, Christine, Christelle Lequart, Philippe Debeire i Jean-Marc Nuzillard. "Band-Selective HSQC and HMBC Experiments Using Excitation Sculpting and PFGSE". Journal of Magnetic Resonance 139, nr 2 (sierpień 1999): 454–59. http://dx.doi.org/10.1006/jmre.1999.1808.

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Gavin, Jose A., Jean L. Pons i Marc A. Delsuc. "Relative Sensitivity of Different Acquisition Schemes for13C Natural-Abundance HSQC Experiments". Journal of Magnetic Resonance, Series A 122, nr 1 (wrzesień 1996): 64–66. http://dx.doi.org/10.1006/jmra.1996.0175.

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Kiraly, Peter, Gareth Morris, Liu Quanxiu i Mathias Nilsson. "Sharpening Up Your Spectra: Broadband Homonuclear Decoupling in HSQC by Real-Time Pure Shift Acquisition". Synlett 30, nr 09 (6.02.2019): 1015–25. http://dx.doi.org/10.1055/s-0037-1612057.

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Structure elucidation using NMR spectroscopy has become a vital part of the toolkit of modern synthetic chemistry. Characterisation of final products, quality control of production, analysis of complex mixtures in synthetic method development, and structure elucidation of isolated natural products are examples where NMR spectroscopy is a part of daily routine. The two factors that usually limit the applicability of NMR are resolution and sensitivity. The experimental method described in this Account, real-time pure shift acquisition, yields heteronuclear correlation spectra such as HSQC that offer significant improvements in both resolution and sensitivity, at negligible cost to the analyst. The advantages that real-time pure shift acquisition enjoys over conventional experiments are discussed and illustrated with selected examples including carbohydrate and alkaloid mixtures. Advanced data acquisition and processing techniques that reduce experiment time and are easily combined with pure shift NMR methods are also described.1 Introduction2 Simultaneous Sensitivity and Resolution Enhancement Using Real-Time Acquisition in HSQC3 Processing Pure Shift Data4 Pulse Sequences for Real-Time Pure Shift HSQC5 Conclusions and Future Perspectives

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16

Marek, Radek, Lukáš Králík i Vladimír Sklenář. "Gradient-enhanced HSQC experiments for phase-sensitive detection of multiple bond interactions". Tetrahedron Letters 38, nr 4 (styczeń 1997): 665–68. http://dx.doi.org/10.1016/s0040-4039(96)02387-8.

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17

Bernassau, J. M., i J. M. Nuzillard. "Enhancement of F1-Selective HMQC and HSQC Experiments by Field-Gradient Pulses". Journal of Magnetic Resonance, Series A 108, nr 2 (czerwiec 1994): 248–54. http://dx.doi.org/10.1006/jmra.1994.1119.

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Parella, Teodor, Francisco Sánchez-Ferrando i Albert Virgili. "Improved Sensitivity in Gradient-Based 1D and 2D Multiplicity-Edited HSQC Experiments". Journal of Magnetic Resonance 126, nr 2 (czerwiec 1997): 274–77. http://dx.doi.org/10.1006/jmre.1997.1164.

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Watermann, Stephanie, Caroline Schmitt, Tobias Schneider i Thomas Hackl. "Comparison of Regular, Pure Shift, and Fast 2D NMR Experiments for Determination of the Geographical Origin of Walnuts". Metabolites 11, nr 1 (8.01.2021): 39. http://dx.doi.org/10.3390/metabo11010039.

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1H NMR spectroscopy, in combination with chemometric methods, was used to analyze the methanol/acetonitrile (1:1) extract of walnut (Juglans Regia L.) regarding the geographical origin of 128 authentic samples from different countries (France, Germany, China) and harvest years (2016–2019). Due to the large number of different metabolites within the acetonitrile/methanol extract, the one-dimensional (1D) 1H NOESY (nuclear Overhauser effect spectroscopy) spectra suffer from strongly overlapping signals. The identification of specific metabolites and statistical analysis are complicated. The use of pure shift 1H NMR spectra such as PSYCHE (pure shift yielded by chirp excitation) or two-dimensional ASAP-HSQC (acceleration by sharing adjacent polarization-heteronuclear single quantum correlation) spectra for multivariate analysis to determine the geographical origin of foods may be a promising method. Different types of NMR spectra (1D 1H NOESY, PSYCHE, and ASAP-HSQC) were acquired for each of the 128 walnut samples and the results of the statistical analysis were compared. A support vector machine classifier was applied for differentiation of samples from Germany/China, France/Germany, and France/China. The models obtained by conduction of a repeated nested cross-validation showed accuracies from 58.9% (±1.3%) to 95.9% (±0.8%). The potential of the 1H-13C HSQC as a 2D NMR experiment for metabolomics studies was shown.

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Watermann, Stephanie, Caroline Schmitt, Tobias Schneider i Thomas Hackl. "Comparison of Regular, Pure Shift, and Fast 2D NMR Experiments for Determination of the Geographical Origin of Walnuts". Metabolites 11, nr 1 (8.01.2021): 39. http://dx.doi.org/10.3390/metabo11010039.

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1H NMR spectroscopy, in combination with chemometric methods, was used to analyze the methanol/acetonitrile (1:1) extract of walnut (Juglans Regia L.) regarding the geographical origin of 128 authentic samples from different countries (France, Germany, China) and harvest years (2016–2019). Due to the large number of different metabolites within the acetonitrile/methanol extract, the one-dimensional (1D) 1H NOESY (nuclear Overhauser effect spectroscopy) spectra suffer from strongly overlapping signals. The identification of specific metabolites and statistical analysis are complicated. The use of pure shift 1H NMR spectra such as PSYCHE (pure shift yielded by chirp excitation) or two-dimensional ASAP-HSQC (acceleration by sharing adjacent polarization-heteronuclear single quantum correlation) spectra for multivariate analysis to determine the geographical origin of foods may be a promising method. Different types of NMR spectra (1D 1H NOESY, PSYCHE, and ASAP-HSQC) were acquired for each of the 128 walnut samples and the results of the statistical analysis were compared. A support vector machine classifier was applied for differentiation of samples from Germany/China, France/Germany, and France/China. The models obtained by conduction of a repeated nested cross-validation showed accuracies from 58.9% (±1.3%) to 95.9% (±0.8%). The potential of the 1H-13C HSQC as a 2D NMR experiment for metabolomics studies was shown.

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21

Penchev, Plamen N., Stefka R. Nachkova, Tonka A. Vasileva i Petko I. Bozov. "1H and 13C NMR Analysis of the neo-Clerodane Diterpenoid Scutecyprin". Natural Product Communications 9, nr 8 (sierpień 2014): 1934578X1400900. http://dx.doi.org/10.1177/1934578x1400900803.

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The 1H and 13C NMR spectra of the neo-clerodane diterpenoid scutecyprin were completely assigned by using a combination of 2D NMR experiments, which included 1H-1H COSY, HSQC, HMBC and NOESY sequences.

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Uhrı́n, Dušan. "3D HSQC-HSQMBC—increasing the resolution of long-range proton–carbon correlation experiments". Journal of Magnetic Resonance 159, nr 2 (grudzień 2002): 145–50. http://dx.doi.org/10.1016/s1090-7807(02)00018-6.

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Skrynnikov, Nikolai R., Frederick W. Dahlquist i Lewis E. Kay. "Reconstructing NMR Spectra of “Invisible” Excited Protein States Using HSQC and HMQC Experiments". Journal of the American Chemical Society 124, nr 41 (październik 2002): 12352–60. http://dx.doi.org/10.1021/ja0207089.

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Nolis, Pau, Miriam Pérez i Teodor Parella. "Time-sharing evolution and sensitivity enhancements in 2D HSQC-TOCSY and HSQMBC experiments". Magnetic Resonance in Chemistry 44, nr 11 (2006): 1031–36. http://dx.doi.org/10.1002/mrc.1898.

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Nolis, Pau, Kumar Motiram‐Corral, Míriam Pérez‐Trujillo i Teodor Parella. "Interleaved Dual NMR Acquisition of Equivalent Transfer Pathways in TOCSY and HSQC Experiments". ChemPhysChem 20, nr 3 (7.12.2018): 356–60. http://dx.doi.org/10.1002/cphc.201801034.

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Díaz T., Eduardo, Christopher K. Jankowski, Celine Hocquelet, Federico del Rio P. i Héctor Barrios. "The unambiguous assignment of NMR spectra of per-O-methylated 6-mono and 6,6-diamino-β-cyclodextrins". Canadian Journal of Chemistry 86, nr 7 (1.07.2008): 726–36. http://dx.doi.org/10.1139/v08-063.

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The step-by-step analysis of high-resolution proton and 13C NMR spectra of per-O-methylated-6-monoamino and 6,6-diamino-A,D-β-cyclodextrins is described. Selected 2-D experiments (COSY, NOESY, HSQC, DEPT, and HMBC) allowed us to challenge the current interpretation. The full assignment of the proton and carbon-13 NMR spectra of these two compounds was performed enabling us to complete the assignment of NMR spectra acquired at 500 and 800 MHz for these important synthetic intermediates.Key words: COSY, NOESY, HSQC, DEPT, HMBC, NMR, 6-amino-β-cyclodextrins, 6,6-diamino-β-cyclodextrins.

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Sklenar, V., M. Piotto, R. Leppik i V. Saudek. "Gradient-Tailored Water Suppression for 1H-15N HSQC Experiments Optimized to Retain Full Sensitivity". Journal of Magnetic Resonance, Series A 102, nr 2 (kwiecień 1993): 241–45. http://dx.doi.org/10.1006/jmra.1993.1098.

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Waudby, Christopher A., Margaux Ouvry, Ben Davis i John Christodoulou. "Two-dimensional NMR lineshape analysis of single, multiple, zero and double quantum correlation experiments". Journal of Biomolecular NMR 74, nr 1 (styczeń 2020): 95–109. http://dx.doi.org/10.1007/s10858-019-00297-7.

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AbstractNMR spectroscopy provides a powerful approach for the characterisation of chemical exchange and molecular interactions by analysis of series of experiments acquired over the course of a titration measurement. The appearance of NMR resonances undergoing chemical exchange depends on the frequency difference relative to the rate of exchange, and in the case of one-dimensional experiments chemical exchange regimes are well established and well known. However, two-dimensional experiments present additional complexity, as at least one additional frequency difference must be considered. Here we provide a systematic classification of chemical exchange regimes in two-dimensional NMR spectra. We highlight important differences between exchange in HSQC and HMQC experiments, that on a practical level result in more severe exchange broadening in HMQC spectra, but show that complementary alternatives to the HMQC are available in the form of HZQC and HDQC experiments. We present the longitudinal relaxation optimised SOFAST-H(Z/D)QC experiment for the simultaneous acquisition of sensitivity-enhanced HZQC and HDQC spectra, and the longitudinal and transverse relaxation optimised BEST-ZQ-TROSY for analysis of large molecular weight systems. We describe the application of these experiments to the characterisation of the interaction between the Hsp90 N-terminal domain and a small molecule ligand, and show that the independent analysis of HSQC, HMQC, HZQC and HDQC experiments provides improved confidence in the fitted dissociation constant and dissociation rate. Joint analysis of such data may provide improved sensitivity to detect and analyse more complex multi-state interaction mechanisms such as induced fit or conformational selection.

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Vassallo, Antonio, Ammar Bader, Alessandra Braca, Angela Bisio, Luca Rastrelli, Francesco De Simone i Nunziatina De Tommasi. "Secondary Metabolites from the Roots of Salvia Palaestina Bentham". Natural Product Communications 3, nr 12 (grudzień 2008): 1934578X0800301. http://dx.doi.org/10.1177/1934578x0800301205.

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Two new sesquiterpenes (1–2), and one diterpene (3) were isolated from the roots of Salvia palaestina Bentham (Lamiaceae), together with eight known diterpenes and two triterpenes. Their structures were elucidated by 1D and 2D NMR spectroscopy, including 1D-TOCSY, DQF-COSY, ROESY, HSQC, and HMBC experiments, as well as ESIMS and chemical analysis.

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Diercks, Tammo, Mark Daniels i Robert Kaptein. "Extended Flip-back Schemes for Sensitivity Enhancement in Multidimensional HSQC-type Out-and-back Experiments". Journal of Biomolecular NMR 33, nr 4 (grudzień 2005): 243–59. http://dx.doi.org/10.1007/s10858-005-3868-4.

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Parella, Teodor, Jordi Belloc, Francisco Sánchez-Ferrando i Albert Virgili. "A general building block to introduce carbon multiplicity information into multi-dimensional HSQC-type experiments". Magnetic Resonance in Chemistry 36, nr 10 (październik 1998): 715–19. http://dx.doi.org/10.1002/(sici)1097-458x(199810)36:10<715::aid-omr355>3.0.co;2-t.

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Vassallo, Antonio, Mariasabina Pesca, Letizia Ambrosio, Nicola Malafronte, Nadia Dekdouk Melle, Fabrizio Dal Piaz i Lorella Severino. "Antiproliferative Oleanane Saponins from Dizygotheca Elegantissima". Natural Product Communications 7, nr 11 (listopad 2012): 1934578X1200701. http://dx.doi.org/10.1177/1934578x1200701106.

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Four new oleanane saponins (1-4), together with three known saponins, were isolated from the aerial parts of Dizygotheca elegantissima R. Vig. & Guillaumin. Their structures were elucidated by 1D and 2D NMR experiments including 1D TOCSY, DQF-COSY, HSQC, and HMBC spectroscopy, as well as ESIMS analysis. The antiproliferative activity of all isolated compounds was evaluated.

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Boudermine, Sihem, Nicola Malafronte, Teresa Mencherini, Tiziana Esposito, Rita Patrizia Aquino, Noureddine Beghidja, Samir Benayache, Massimiliano D'Ambola i Antonio Vassallo. "Phenolic Compounds from Limonium pruinosum". Natural Product Communications 10, nr 2 (luty 2015): 1934578X1501000. http://dx.doi.org/10.1177/1934578x1501000228.

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A new phenolic compound, 6′- O-sulfonyl-salidroside (1), together with fifteen known compounds, were isolated from the all parts of Limonium pruinosum. Their structures were elucidated by 1D and 2D NMR experiments including 1D TOCSY, DQF-COSY, HSQC and HMBC spectroscopy, as well as ESIMS analysis. The antioxidant activity of the extracts and all isolated compounds was evaluated by DPPH test.

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Gonçalves, Itamar Luís, Mariana Maier Gaelzer, Gabriel Oliveira de Azambuja, Christianne Gazzana Salbego i Vera Lucia Eifler-Lima. "A COMPLETE NMR STUDY OF DOXAZOSIN CHARACTERIZATION". Drug Analytical Research 1, nr 1 (28.08.2017): 56–60. http://dx.doi.org/10.22456/2527-2616.73960.

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Doxazosin is an important drug used for treating hypertension and prostatic hyperplasia. An enantiomeric mixture (R)/(S) doxazosin mesylate was complete characterized by NMR and additionally FT-IR spectroscopy techniques. Were performed different NMR experiments, such as APT, HSQC, and HMBC in order to confirm the NMR signals assignments. All the hydrogens and the most of carbons atoms were assigned.

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Malafronte, Anna, Fabrizio Dal Piaz, Giuseppina Cioffi, Alessandra Braca, Antonella Leone i Nunziatina De Tommasi. "Secondary Metabolites from the Aerial Parts of Salvia Aethiopis L". Natural Product Communications 3, nr 6 (czerwiec 2008): 1934578X0800300. http://dx.doi.org/10.1177/1934578x0800300610.

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Three new sesterterpenes (1–3), and one new diterpene (4) were isolated from the aerial parts of Salvia aethiopis L. (Lamiaceae), together with two known sesterterpenes, and four diterpenes. Their structural elucidation was accomplished by extensive spectroscopic methods including 1D (1H, 13C, 13C DEPT, TOCSY, NOESY) and 2D NMR experiments (DQF-COSY, HSQC, HMBC, ROESY), as well as ESIMS and chemical analysis.

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Kasprzyk, Wiktor, Tomasz Świergosz i Filip Koper. "Fluorescence Assay for the Determination of d-Panthenol Based on Novel Ring-Fused 2-Pyridone Derivative". International Journal of Molecular Sciences 21, nr 21 (9.11.2020): 8386. http://dx.doi.org/10.3390/ijms21218386.

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Herein, a novel fluorescent method for the determination of d-panthenol (DP) level in solutions with no separate hydrolysis step has been revealed based on the utilization of citric acid (CA) as a derivatizing agent. Consequently, the essential parameters of the derivatization process were established, resulting in the development of sensitive, repeatable, and accurate determination of panthenol. The method was approved, and its usefulness in characterizing the concentration of DP in pharmaceutical formulations and selectivity in the determination of DP were validated. The chemical structure of the new fluorophore formulating in the reaction in DP with CA, i.e., 6-oxo-3,4-dihydro-2H,6H-pyrido[2,1-b][1,3]oxazine-8-carboxylic acid (ODPC), was elucidated using detailed NMR experiments: one-dimensional (1H, 13C) as well as two-dimensional NMR spectra (1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC, 1H-15N HSQC, 1H-15N HMBC).

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Souza, Alexandre A., Roberto R. Gil i Teodor Parella. "Highly resolved HSQC experiments for the fast and accurate measurement of homonuclear and heteronuclear coupling constants". Journal of Magnetic Resonance 282 (wrzesień 2017): 54–61. http://dx.doi.org/10.1016/j.jmr.2017.07.004.

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Sun, Zhen-Yu J., Dominique P. Frueh, Philipp Selenko, Jeffrey C. Hoch i Gerhard Wagner. "Fast Assignment of 15N-HSQC Peaks using High-Resolution 3D HNcocaNH Experiments with Non-Uniform Sampling". Journal of Biomolecular NMR 33, nr 1 (wrzesień 2005): 43–50. http://dx.doi.org/10.1007/s10858-005-1284-4.

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Brucka, Marta, Kirill F. Sheberstov i Damien Jeannerat. "Homonuclear decoupling in the 13 C indirect dimension of HSQC experiments for 13 C-enriched compounds". Magnetic Resonance in Chemistry 56, nr 10 (12.01.2018): 1021–28. http://dx.doi.org/10.1002/mrc.4697.

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Anwar, E. M. Noreljaleel. "Long-range proton–carbon coupling constants for the determination of the stereochemical structure of organic compounds." Journal of The Faculty of Science and Technology, nr 7 (17.08.2021): 125–31. http://dx.doi.org/10.52981/jfst.vi7.965.

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A new methods for elucidating stereochemistry of organic compounds was developed on the basis of long-range proton–carbon coupling constants (2,3JC,H) and interpreting spin-coupling constants (3JH,H). Reaction of compound containing pyrin ring with nucleophile reagent was done to open the ring. HSQC-TOCSY experiments one of the new NMR spectroscopy method used to measure this values of spin-coupling constants and elucidating the stereochemistry of the product.

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41

Hung, Nguyen Huy. "CHEMICAL CONSTITUENTS FROM THE SEEDS OF ANNONA RETICULATA L. IN VIETNAM". Vietnam Journal of Science and Technology 54, nr 4A (21.03.2018): 221. http://dx.doi.org/10.15625/2525-2518/54/4a/11997.

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In the present study, the chemical investigation of the seeds of A. reticulata L. (Annonaceae) in Vietnam has resulted in the identification of four known compounds, including two triterpenoids (rotundic acid (1), pedunculoside (2)), and two phenolic compounds (eleutheroside B (3), sinapaldehyde glucoside (4). Their chemical structures were elucidated on the basis of spectroscopic analysis, including homonuclear and heteronuclear correlation NMR (1H-NMR, 13C-NMR, COSY, HSQC, and HMBC) experiments.

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42

Perrone, Angela, Milena Masullo, Alberto Plaza, Arafa Hamed i Sonia Piacente. "Flavone and Flavonol Glycosides from Astragalus eremophilus and Astragalus Vogelii". Natural Product Communications 4, nr 1 (styczeń 2009): 1934578X0900400. http://dx.doi.org/10.1177/1934578x0900400117.

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Two new rhamnocitrin glycosides (1 and 2) were isolated from the aerial parts of Astragalus vogelii, along with one known rhamnocitrin glycoside (3). Two known flavonol glycosides (4 and 5) and four known flavone derivatives (6-9) were isolated from the aerial parts of Astragalus eremophilus. Their structures were elucidated by extensive spectroscopic methods including 1D- (1H, 13C and TOCSY) and 2D-NMR (DQF-COSY, HSQC, HMBC) experiments, as well as ESIMS analysis.

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43

Hynninen, Paavo H., i Markku Mesilaakso. "Protonation-deprotonation equilibria in tetrapyrroles Part 2: Mono- and diprotonation of methyl pyropheophorbide a in methanolic hydrochloric acid as verified by the 1H, 13C HSQC and 1H, 15N HMBC NMR experiments". Journal of Porphyrins and Phthalocyanines 16, nr 01 (styczeń 2012): 39–46. http://dx.doi.org/10.1142/s1088424611004348.

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The two-dimensional 1H, 13C and 1H, 15N heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) NMR techniques were applied to investigate the formation of N-protonated cationic species of methyl pyropheophorbide a in methanolic hydrochloric acid (CD3OH-HCl). The 1H, 13C HSQC and 1H, 15N HMBC NMR spectra, recorded at the temperature of 278 K, verified that the CD3OH-HCl solution with [H]+ = 0.021 M, contained the N22-protonated monocations of methyl pyropheophorbide a, whereas the CD3OH-HCl solution with [H]+ = 5.0 M contained the N22, N24-protonated dications of the phorbin. No further protonations to form the trication or tetracation were observed. Consequently, the two middle electronic spectra, which were previously tentatively interpreted as representing the dication and trication, were now attributed to conformational alterations originating from steric hindrance between the central hydrogens and changes in counter-ion and solvation interactions and/or conformational alterations intimately connected to NH-tautomerism. These possibilities to explain the previously observed middle electronic spectra are briefly discussed.

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44

Invernici, Michele, Inês B. Trindade, Francesca Cantini, Ricardo O. Louro i Mario Piccioli. "Measuring transverse relaxation in highly paramagnetic systems". Journal of Biomolecular NMR 74, nr 8-9 (24.07.2020): 431–42. http://dx.doi.org/10.1007/s10858-020-00334-w.

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Abstract The enhancement of nuclear relaxation rates due to the interaction with a paramagnetic center (known as Paramagnetic Relaxation Enhancement) is a powerful source of structural and dynamics information, widely used in structural biology. However, many signals affected by the hyperfine interaction relax faster than the evolution periods of common NMR experiments and therefore they are broadened beyond detection. This gives rise to a so-called blind sphere around the paramagnetic center, which is a major limitation in the use of PREs. Reducing the blind sphere is extremely important in paramagnetic metalloproteins. The identification, characterization, and proper structural restraining of the first coordination sphere of the metal ion(s) and its immediate neighboring regions is key to understand their biological function. The novel HSQC scheme we propose here, that we termed R2-weighted, HSQC-AP, achieves this aim by detecting signals that escaped detection in a conventional HSQC experiment and provides fully reliable R2 values in the range of 1H R2 rates ca. 50–400 s−1. Independently on the type of paramagnetic center and on the size of the molecule, this experiment decreases the radius of the blind sphere and increases the number of detectable PREs. Here, we report the validation of this approach for the case of PioC, a small protein containing a high potential 4Fe-4S cluster in the reduced [Fe4S4]2+ form. The blind sphere was contracted to a minimal extent, enabling the measurement of R2 rates for the cluster coordinating residues.

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45

Gyöngyösi, Tamás, István Timári, Davy Sinnaeve, Burkhard Luy i Katalin E. Kövér. "Expedited Nuclear Magnetic Resonance Assignment of Small- to Medium-Sized Molecules with Improved HSQC−CLIP−COSY Experiments". Analytical Chemistry 93, nr 6 (3.02.2021): 3096–102. http://dx.doi.org/10.1021/acs.analchem.0c04124.

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46

Mazzola, Eugene P., Ainsley Parkinson, Edward J. Kennelly, Bruce Coxon, Linda S. Einbond i Darón I. Freedberg. "Utility of coupled-HSQC experiments in the intact structural elucidation of three complex saponins from Blighia sapida". Carbohydrate Research 346, nr 6 (maj 2011): 759–68. http://dx.doi.org/10.1016/j.carres.2011.02.019.

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47

Kövér, Katalin E., Victor J. Hruby i Dušan Uhrı́n. "Sensitivity- and Gradient-Enhanced Heteronuclear Coupled/Decoupled HSQC–TOCSY Experiments for Measuring Long-Range Heteronuclear Coupling Constants". Journal of Magnetic Resonance 129, nr 2 (grudzień 1997): 125–29. http://dx.doi.org/10.1006/jmre.1997.1265.

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48

Al-Hamoud, Gadah Abdulaziz, Raha Saud Orfali, Yoshio Takeda, Sachiko Sugimoto, Yoshi Yamano, Nawal M. Al Musayeib, Omer Ibrahim Fantoukh, Musarat Amina, Hideaki Otsuka i Katsuyoshi Matsunami. "Lasianosides F–I: A New Iridoid and Three New Bis-Iridoid Glycosides from the Leaves of Lasianthus verticillatus (Lour.) Merr." Molecules 25, nr 12 (17.06.2020): 2798. http://dx.doi.org/10.3390/molecules25122798.

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A series of iridoid glycosides were isolated from the leaves of Lasianthus verticillatus (Lour.) Merr., belonging to family Rubiaceae. A new iridoid glycoside, lasianoside F (1), and three new bis-iridoid glycosides, lasianosides G–I (2–4), together with four known compounds (5–8) were isolated. The structures were established by spectroscopic methods, including 1D and 2D NMR experiments (1H, 13C, DEPT, COSY, HSQC, HMBC, and NOESY) in combination with HR-ESI-MS and CD spectra.

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49

Avunduk, Sibel, Özgen Alankuş-Çalişkan, Tomofumi Miyamoto, Chiaki Tanaka i Marie-Aleth Lacaille-Dubois. "Secondary Metabolites from the Roots of Paronychia chionaea". Natural Product Communications 6, nr 2 (luty 2011): 1934578X1100600. http://dx.doi.org/10.1177/1934578x1100600212.

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Two novel secondary metabolites, compounds (1–2) were isolated from the roots of Paronychia chionaea. On the basis of spectroscopic data including 1D and 2D NMR experiments (COSY, TOCSY, HSQC, and HMBC), and mass spectroscopy, their structures were established as 6- C-[α-L-arabinopyranosyl-(1→2)-β-D-glucopyranosyl]-7- O-[β-D-glucopyranosyl]-luteolin 3′-methyl ether (1), and 2-(methoxy)-2-(3,5-dimethoxy 4-hydroxyphenyl)-ethane-1,2-diol 1- O-β-D-glucopyranoside (2).

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50

Tchinda, Alembert T., Victorine Fuendjiep, Yalemtsehay Mekonnen, Bernadette B. Ngo i Ermias Dagne. "A Bioactive Diterpene from Entada Abyssinica". Natural Product Communications 2, nr 1 (styczeń 2007): 1934578X0700200. http://dx.doi.org/10.1177/1934578x0700200103.

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Three clerodane diterpenoids, 8S-kolavic acid 18-methyl ester (1), 8S-kolavic acid 15-methyl ester (2) and 8S-kolavenol (3) were isolated from the acetone extract of the stem bark of Entada abyssinica along with trans-communic acid (4) and 1-octacosanol. Their structures were established mainly based on 1D (1H, 13C and DEPT) and 2D (1H-1H COSY, HSQC and HMBC) NMR experiments. Compound 1, described here for the first time, showed strong antimicrobial and moderate antileishmanial activities.

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