Cynanchum paniculatum(Bunge) Kitagawa is usually used as an herbal medicine for treating many diseases. Paeonol is the main active component, and its content is the key indicator for quality control of C. paniculatum....Cynanchum paniculatum(Bunge) Kitagawa is usually used as an herbal medicine for treating many diseases. Paeonol is the main active component, and its content is the key indicator for quality control of C. paniculatum. In the present study, we developed a rapid, accurate and precise method for quantitation of paeonol in C. paniculatum using 1 H NMR spectra. The deuterated solvent of methanol-d4 enabled satisfactory separation of the signals to be integrated in 1 H NMR spectrum. H-6(δ 7.78) of 1 H NMR spectrum of C. paniculatum was selected as the feature signal for quantitation, and trimesic acid(TMA) was selected as an internal standard. Validation of the quantitative method was performed in terms of linearity, specificity, repeatability and stability. This is the first time to report quantitative 1 H NMR(qHNMR) applied to determine the content of paeonol in C. paniculatum and showed a wider linearity range than the reported quantitation of paeonol in others. The simple extraction of paeonol from C. paniculatum was rapid and will prompt the application of the developed method. This work implied that qHNMR represented a feasible alternative to HPLC-based methods for quantitation of paeonol in C. paniculatum, and it was suitable for the quality control of C. paniculatum.展开更多
We present here the application of one-dimensional and two-dimensional NMR techniques to characterize the structure of methoxyl end-functionalized polystyrenes （PS）. The peaks in 1H-NMR spectra corresponding to main...We present here the application of one-dimensional and two-dimensional NMR techniques to characterize the structure of methoxyl end-functionalized polystyrenes （PS）. The peaks in 1H-NMR spectra corresponding to main-chain, side-chain and chain-end groups are assigned by 1H-1H gCOSY, 1H-13C gHSQC and gHMBC spectra. For the first time, the spin-lattice relaxation time （T1） of protons of the chain-ends is revealed to be affected more by polymer molecular weight （MW） than by the protons of the main-chains and the side-chains （almost independent from MW）. As a result, a much higher delay time （dl） for chain-ends （d1〉 20T1） is needed for quantitative NMR measurement when using end-group estimation method to obtain the MW of PS, which is in accordance with the value estimated by GPC. An improved method for the polymer MW determination is established, by combination of different NMR techniques to distinguish the peaks, and a large dl setting to achieve quantitative NMR analysis.展开更多
Herein, a strategy is proposed for the simultaneous determination of primary coumarins in Peucedani Radix(Chinese name: Qianhu). The methodology consists of three consecutive steps: 1) Semi-preparative LC in combinati...Herein, a strategy is proposed for the simultaneous determination of primary coumarins in Peucedani Radix(Chinese name: Qianhu). The methodology consists of three consecutive steps: 1) Semi-preparative LC in combination with a home-made automated fraction collection module to fragment the universal metabolome standard into ten fractions(Frs. I–X); 2) LC–accurate MS/MS and quantitative1 H NMR spectroscopy conducted in parallel to acquire the qualitative and quantitative data of each fraction; 3) Robust identification and quantification of components by use of LC coupled to multiple reaction monitoring. In this final step, the most significant fractions(Frs. III–X) were pooled to serve as the pseudo-mixed standard solution. Meticulous online parameter optimization was performed to obtain the optimal parameters, including ion transitions and collision energies. Concerns were particularly paid onto pursuing the parameters being capable of monitoring regiospecific isomers, notably praeruptorin E vs. 3′-isovaleryl-4′-angeloylkhellactone. The quantitative performance of the method was validated according to diverse assays. Eleven primary coumarins(1–11) were unambiguously identified and absolutely quantified, even though no external reference compound was used. Above all, the integrated strategy not only provides a feasible pipeline for the quality assessment of Peucedani Radix, but more importantly, shows the potential for authentic compound-free quantitative evaluation of traditional Chinese medicines.展开更多
基金Science and Technology Project of Yunnan Provincial Department of Science and Technology(Grant No.2018FD081)Yunnan Local Colleges Applied Basic Research Projects[Grant Nos.2019FH001-(109),2017FH001-092,2017FH001-094 and 2018FH001-019]Youth Research Foundation of Qujing Normal University in 2019(Grant No.2019QN004)。
文摘Cynanchum paniculatum(Bunge) Kitagawa is usually used as an herbal medicine for treating many diseases. Paeonol is the main active component, and its content is the key indicator for quality control of C. paniculatum. In the present study, we developed a rapid, accurate and precise method for quantitation of paeonol in C. paniculatum using 1 H NMR spectra. The deuterated solvent of methanol-d4 enabled satisfactory separation of the signals to be integrated in 1 H NMR spectrum. H-6(δ 7.78) of 1 H NMR spectrum of C. paniculatum was selected as the feature signal for quantitation, and trimesic acid(TMA) was selected as an internal standard. Validation of the quantitative method was performed in terms of linearity, specificity, repeatability and stability. This is the first time to report quantitative 1 H NMR(qHNMR) applied to determine the content of paeonol in C. paniculatum and showed a wider linearity range than the reported quantitation of paeonol in others. The simple extraction of paeonol from C. paniculatum was rapid and will prompt the application of the developed method. This work implied that qHNMR represented a feasible alternative to HPLC-based methods for quantitation of paeonol in C. paniculatum, and it was suitable for the quality control of C. paniculatum.
基金supported by the National Natural Science Foundation of China(Nos.21274099,21305098 and 21474067)the Priority Academic Program Development of Jiangsu High Education Institutions
文摘We present here the application of one-dimensional and two-dimensional NMR techniques to characterize the structure of methoxyl end-functionalized polystyrenes （PS）. The peaks in 1H-NMR spectra corresponding to main-chain, side-chain and chain-end groups are assigned by 1H-1H gCOSY, 1H-13C gHSQC and gHMBC spectra. For the first time, the spin-lattice relaxation time （T1） of protons of the chain-ends is revealed to be affected more by polymer molecular weight （MW） than by the protons of the main-chains and the side-chains （almost independent from MW）. As a result, a much higher delay time （dl） for chain-ends （d1〉 20T1） is needed for quantitative NMR measurement when using end-group estimation method to obtain the MW of PS, which is in accordance with the value estimated by GPC. An improved method for the polymer MW determination is established, by combination of different NMR techniques to distinguish the peaks, and a large dl setting to achieve quantitative NMR analysis.
基金financially supported by National Science Fund of China (Nos. 81773875,81403073 and 81530097)Quality Guarantee System of Chinese Herbal Medicines (No. 201507002)+1 种基金foundation from Beijing University of Chinese Medicine (No. 2016-JYB-XJQ004)the Macao Science and Technology Development Fund (007/2014/AMJ)
文摘Herein, a strategy is proposed for the simultaneous determination of primary coumarins in Peucedani Radix(Chinese name: Qianhu). The methodology consists of three consecutive steps: 1) Semi-preparative LC in combination with a home-made automated fraction collection module to fragment the universal metabolome standard into ten fractions(Frs. I–X); 2) LC–accurate MS/MS and quantitative1 H NMR spectroscopy conducted in parallel to acquire the qualitative and quantitative data of each fraction; 3) Robust identification and quantification of components by use of LC coupled to multiple reaction monitoring. In this final step, the most significant fractions(Frs. III–X) were pooled to serve as the pseudo-mixed standard solution. Meticulous online parameter optimization was performed to obtain the optimal parameters, including ion transitions and collision energies. Concerns were particularly paid onto pursuing the parameters being capable of monitoring regiospecific isomers, notably praeruptorin E vs. 3′-isovaleryl-4′-angeloylkhellactone. The quantitative performance of the method was validated according to diverse assays. Eleven primary coumarins(1–11) were unambiguously identified and absolutely quantified, even though no external reference compound was used. Above all, the integrated strategy not only provides a feasible pipeline for the quality assessment of Peucedani Radix, but more importantly, shows the potential for authentic compound-free quantitative evaluation of traditional Chinese medicines.
