Preparative separation of gypenoside XVII, ginsenoside Rd2, and notoginsenosides Fe and Fd from Panax notoginseng leaves by countercurrent chromatography and orthogonality evaluation for their separation

An online preparative high-performance liquid chromatography system with enrichment and purification modes for the efficient and systematic separation of Panax notoginseng saponins

In this study, an online preparative high-performance liquid chromatography (prep-HPLC) system based on the combination of the enrichment and purification modes for the efficient and systematic separation of Panax notoginseng saponins (PNS) was achieved. Five separation columns were used for the first and second separation of target components, eighteen trap columns were used to capture the effluents from the first separation or loading the trapped sample effluents, and a two-position eight-port valve was used to switch between the first and second separations. The conditions for the first and second separation of PNS were simulated and optimized with the online prep-HPLC system. Then, the PNS were separated using optimized chromatographic conditions. Notably, 14 monomer compounds with >90% purity (11 compounds with purity >97%) were simultaneously isolated from PNS using the above self-developed device, and their chemical structures were identified. Moreover, the separation time was less than 33.0 h. After 6 repeated enrichment and purification, the weight of each compound obtained was more than 5.0 mg, with compound 2 weighing over 900 mg. In brief, the self-developed prep-HPLC system, which integrated enrichment and purification, is suitable for the efficient and systematic separation of PNS and has broad application prospects, especially for the separation of complex chemical components in natural products.

An instant beverage rich in nutrients and secondary metabolites manufactured from stems and leaves of Panax notoginseng

Introduction

Radix Notoginseng, one of the most famous Chinese traditional medicines, is the dried root of Panax notoginseng (Araliaceae). Stems and leaves of P. notoginseng (SLPN) are rich in secondary metabolites and nutrients, and authorized as a food resource, however, its utilization needs further research.

Methods

A SLPN-instant beverage was manufactured from SLPN through optimization by response surface design with 21-fold of 48.50% ethanol for 39 h, and this extraction was repeated twice; the extraction solution was concentrated to 1/3 volume using a vacuum rotatory evaporator at 45°C, and then spray dried at 110°C. Nutritional components including 14 amino acids, ten mineral elements, 15 vitamins were detected in the SLPN-instant beverage; forty-three triterpenoid saponins, e.g., ginsenoside La, ginsenoside Rb3, notoginsenoside R1, and two flavonoid glycosides, as well as dencichine were identified by UPLC-MS.

Results

The extraction rate of SLPN-instant beverage was 37.89 ± 0.02%. The majority nutrients were Gly (2.10 ± 0.63 mg/g), His (1.23 ± 0.07 mg/g), α-VE (18.89 ± 1.87 μg/g), β-VE (17.53 ± 1.98 μg/g), potassium (49.26 ± 2.70 mg/g), calcium (6.73 ± 0.27 mg/g). The total saponin of the SLPN-instant beverage was 403.05 ± 34.98 mg/g, majority was notoginsenoside Fd and with contents of 227 ± 2.02 mg/g. In addition, catechin and γ-aminobutyric acid were detected with levels of 24.57 ± 0.21 mg/g and 7.50 ± 1.85 mg/g, respectively. The SLPN-instant beverage showed good antioxidant activities with half maximal inhibitory concentration (IC₅₀) for scavenging hydroxyl (OH^-) radicals, superoxide anion (O^2-) radicals, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS+) radicals were 0.1954, 0.2314, 0.4083, and 0.3874 mg/mL, respectively.

Conclusion

We optimized an analytical method for in depth analysis of the newly authorized food resource SLPN. Together, an instant beverage with antioxidant activity, rich in nutrients and secondary metabolites, was manufactured from SLPN, which may improve the utilization of SLPN.

In Silico Screening of Off-line Comprehensive Two-Dimensional Counter-current Chromatography with Liquid Chromatography for Four Saponins Isolation

Be restrained by the limited peak capacity, one dimension chromatography usually leads to an unsatisfactory separation with low purity of compounds in a complex mixture. To obtain more highly pure targets for standard reference and to discover new substances for structural elucidation, two-dimensional chromatography is more and more prevalent in many fields. As few metrics on assessment of preparative capability of two-dimensional chromatographic separations is reported, a methodology of in silico screening of various two-dimensional chromatographic separations with a minimal number of experiments was demonstrated in this work, which was based on three descriptors including the occupation rate of peaks and system homogeneity of a two-dimensional separation space, and the minimal distance of all nearest-neighbor distances of peaks. Combining the advantages of counter-current chromatography and liquid chromatography, we elaborated the methodology by employing off-line comprehensive two-dimensional counter-current chromatography with liquid chromatography to be in silico screened for separation of four saponins from Panax notoginseng at analytical scale to simulate the case of preparative scale transfer. The predictive results were presented by two-dimensional contour plots and verified by experiments. The result showed that the experimental results were in general accord with the predictive results. This article is protected by copyright. All rights reserved.

Recent Advances in Separation and Analysis of Saponins in Natural Products

To better control the quality of saponins, ensure their biological activity and clinical therapeutic effect, and expand the development and application of saponins, this paper systematically and comprehensively reviews the separation and analytical methods of saponins in the past decade. Since 2010, the electronic databases of PubMed, Google Scholar, ISI Web of Science, Science Direct, Wiley, Springer, CNKI (National Knowledge Infrastructure, CNKI), Wanfang Med online, and other databases have been searched systematically. As a result, it is found that ionic liquids and high-performance countercurrent chromatography are the most popular extraction and separation techniques for saponins, and the combined chromatography technique is the most widely used method for the analysis of saponins. Liquid chromatography can be used in combination with different detectors to achieve qualitative or quantitative analysis and quality control of saponin compounds in medicinal materials and their preparations. This paper provides the latest valuable insights and references for the analytical methods and continued development and application of saponins.