~1H-qNMR quantification of total ginsenosides in Shenmai Injection / 中国中药杂志

A content determination method based on ~1H-qNMR was developed for the determination of total ginsenosides in Shenmai Injection. The parameters were optimized with CD_3OD as the solvent, dimethyl terephthalate as the internal standard, the peak at δ 8.11 as the internal standard peak, and the peaks at δ 1.68 and δ 0.79 as quantitative peaks of total ginsenosides. The developed ~1H-qNMR-based method was validated methodologically. The results showed that the method could achieve accurate measurement of total ginsenosides in Shenmai Injection in the range of 0.167 6-3.091 1 mmol·L~(-1). The developed ~1H-qNMR-based method for total ginsenosides is simple in operation, short in analysis time, strong in specificity, independent of accompanying standard curve, and small in sample volume, which can serve as a reliable mean for the quality control of Shenmai Injection. This study is expected to provide new ideas for the development of quantification methods of total ginsenosides.

Quality evaluation of ginsenoside reference substances based on qNMR spectroscopy / 中国中药杂志

The present study established a quality evaluation method for ginsenoside reference substances based on quantitative nuclear magnetic resonance(qNMR) spectroscopy. ~1H-NMR spectra were collected on Bruker Avance Ⅲ 500 MHz NMR spectrometer equipped with a 5 mm BBO probe. The acquire parameters were set up as follows: pulse sequence of 30°, D_1=20 s, probe temperature= 303 K, and the scan number = 32. Dimethyl terephthalate, a high-quality ~1H-qNMR standard, was used as the internal standard and measured by the absolute quantitative method. Methyl peaks of comparatively good sensitivity were selected for quantification, and linear fitting deconvolution was adopted to improve the accuracy of integration results. The qNMR spectroscopy-based method was established and validated, which was then used for the quality evaluation of ginsenoside Rg_1, ginsenoside Re, ginsenoside Rb_1, ginsenoside Rd, and notoginsenoside R_1. The results suggested that the content of these ginsenoside reference standards obtained from the qNMR spectroscopy-based method was lower than that detected by the normalization method in HPLC provided by the manufacturers. In conclusion, the qNMR spectroscopy-based method can ensure the quality of ginsenoside reference substances and provide powerful support for the accurate quality evaluation of Chinese medicine and its preparations. The qNMR spectroscopy-based method is simple, rapid, and accurate, which can be developed for the quantitative assay of Chinese medicine standard references.

Assessment of the Purity of Emodin by Quantitative Nuclear Magnetic Resonance Spectroscopy and Mass Balance

Quantitative nuclear magnetic resonance (qNMR) is a well-established method adopted by international pharmacopoeia for quantitative and purity analyses. Emodin is a type of anthraquinone, well known as the main active component of Fabaceae, Polygonaceae and Rhamnaceae. Purity analysis of emodin is usually performed by using the high-performance liquid chromatography (HPLC)-UV method. However, it cannot detect impurities such as salts, volatile matter, and trace elements. Using the qNMR method, it is possible to determine the compound content as well as the nature of the impurities. Several experimental parameters were optimized for the quantification, such as relaxation delay, spectral width, number of scans, temperature, pulse width, and acquisition time. The method was validated, and the results of the qNMR method were compared with those obtained by the HPLC and mass balance analysis methods. The qNMR method is specific, rapid, simple, and therefore, a valuable and reliable method for the purity analysis of emodin.

Determination of Phenanthrenes in the Anxiolytic Fraction of Juncus effusus L. by QNMR / 中国药学杂志

OBJECTIVE: To establish a method for quantification of phenanthrenes in the anxiolytic fraction of Juncus effusus L by QNMR. METHODS: The analysis was conducted using terephthalic acid as an internal standard, the 5 mm SEI probe temperature was 298.2 K with NS=16 and d1=1 s. C4-H of dehydroeffusol, C4-H of effusol and C4-H juncusol peaks were chosen as the characteristic peaks. RESULTS: The contents of effusol, dehydroeffusol, juncusol and dehydrojuncusol were 338.75, 41.14 and 109.13 mg·g-1, respectively, by QNMR, and 340.87, 42.99, 107.73 and 9.561 mg·g-1, respectively, by HPLC. CONCLUSION: The determined contents of phenanthrenes by QNMR are in accordance with the results by HPLC, indicating that QNMR can be applied to determine phenanthrenes in the anxiolytic fraction of Juncus effusus L. QNMR is rapid, accurate, and does not need reference substances and complex sample preparation.