Quantitative and Differential Analysis between Bupleurum chinense DC. and Bupleurum scorzonerifolium Willd. Using HPLC-MS and GC-MS Coupled with Multivariate Statistical Analysis.

Bupleurum chinense DC. and Bupleurum scorzonerifolium Willd. have different clinical efficacies, with the former typically used to treat typhoid fever and the latter mainly used to clear liver heat. The differences in their clinical efficacy are closely related to their complex chemical composition, especially the active components. In this study, the saponins and volatile oils in two varieties of Radix Bupleuri grown in different regions were extracted and analyzed using high-performance liquid chromatography (HPLC) and gas chromatography coupled with mass spectrometry (MS), and the absolute contents of five saikosaponins were accurately quantified using an established HPLC-MS method in the multiple reaction monitoring mode. Multivariate statistical analysis was performed to reveal the difference in the active components between the two varieties. The saikosaponin content was significantly affected by variety and growing region, with all five saikosaponins being significantly higher in Bupleurum chinense DC. than in Bupleurum scorzonerifolium Willd. The results of principal component analysis and hierarchical cluster analysis show a clear distinction between the two varieties in terms of both saponins and volatile oils. Twenty-one saponins, including saikosaponin b2 and b1, and fifty-two volatile oils, including 2-tetradecyloxirane and chloromethyl cyanide, were screened and identified as differential compounds contributing to the significant difference between the two varieties. These compounds may also be responsible for the difference in clinical efficacy between Bupleurum chinense DC. and Bupleurum scorzonerifolium Willd. All the results suggest that the accumulation and diversity of active components in Radix Bupleuri are significantly affected by the variety. In contrast to previous reports, this study provides the absolute contents of five saikosaponins in Radix Bupleuri of different varieties and reduces the influence of the growing region on the analytical results by collecting samples from different regions. The results of this study may provide a reference for the identification and quality evaluation of different varieties of Radix Bupleuri.

Methanol-involved heterogeneous transformation of ginsenoside Rb1 to rare ginsenosides using heteropolyacids embedded in mesoporous silica with HPLC-MS investigation.

Background: The biological activity and pharmacological effects of rare ginsenosides have been proven to be superior to those of the major ginsenosides, but they are rarely found in ginseng. Methods: Ginsenoside Rb1 was chemically transformed with the involvement of methanol molecules by a synthesized heterogeneous catalyst 12-HPW@MeSi, which was obtained by the immobilization of 12-phosphotungstic acid on a mesoporous silica framework. High-performance liquid chromatography coupled with mass spectrometry was used to identify the transformation products. Results: A total of 18 transformation products were obtained and identified. Methanol was found to be involved in the formation of 8 products formed by the addition of methanol molecules to the C-24 (25), C-20 (21) or C-20 (22) double bonds of the aglycone. The transformation pathways of ginsenoside Rb1 involved deglycosylation, addition, elimination, cycloaddition, and epimerization reactions. These pathways could be elucidated in terms of the stability of the generated carbenium ion. In addition, 12-HPW@MeSi was able to maintain a 60.5% conversion rate of Rb1 after 5 cycles. Conclusion: Tandem and high-resolution mass spectrometry analysis allowed rapid and accurate identification of the transformation products through the characteristic fragment ions and neutral loss. Rare ginsenosides with methoxyl groups grafted at the C-25 and C-20 positions were obtained for the first time by chemical transformation using the composite catalyst 12-HPW@MeSi, which also enabled cyclic heterogeneous transformation and facile centrifugal separation of ginsenosides. This work provides an efficient and recyclable strategy for the preparation of rare ginsenosides with the involvement of organic molecules.

Heterogeneous Transformation of Ginsenoside Rb1 with Ethanol Using Heteropolyacid-Loaded Mesoporous Silica and Identification by HPLC-MS.

Rare ginsenosides with major pharmacological effects are barely present in natural ginseng and are required to be obtained by transformation. In the current study, ginsenoside Rb1 was chemically transformed with the involvement of ethanol molecules to prepare rare ginsenosides using the synthesized heterogeneous catalyst 12-HPW@MeSi. A total of 16 transformation products were obtained and identified using high-performance liquid chromatography coupled with multistage tandem mass spectrometry and high-resolution mass spectrometry. Ethanol molecules were involved in the production of 6 transformation products by adding to the C-20(21), C-20(22), or C-24(25) double bonds on the aglycone to produce ethoxyl groups at the C-25 and C-20 positions. Transformation pathways of ginsenoside Rb1 are summarized, which involve deglycosylation, elimination, cycloaddition, epimerization, and addition reactions. In addition, 12-HPW@MeSi was recyclable through a simple centrifugation, maintaining an 85.1% conversion rate of Rb1 after 3 cycles. This work opens up an efficient and recycled process for the preparation of rare ginsenosides with the involvement of organic molecules.