Purification of lignans from Fructus Arctii using off-line two-dimensional supercritical fluid chromatography/reversed-phase liquid chromatography

Separation Methods of Phenolic Compounds from Plant Extract as Antioxidant Agents Candidate

In recent years, discovering new drug candidates has become a top priority in research. Natural products have proven to be a promising source for such discoveries as many researchers have successfully isolated bioactive compounds with various activities that show potential as drug candidates. Among these compounds, phenolic compounds have been frequently isolated due to their many biological activities, including their role as antioxidants, making them candidates for treating diseases related to oxidative stress. The isolation method is essential, and researchers have sought to find effective procedures that maximize the purity and yield of bioactive compounds. This review aims to provide information on the isolation or separation methods for phenolic compounds with antioxidant activities using column chromatography, medium-pressure liquid chromatography, high-performance liquid chromatography, counter-current chromatography, hydrophilic interaction chromatography, supercritical fluid chromatography, molecularly imprinted technologies, and high-performance thin layer chromatography. For isolation or purification, the molecularly imprinted technologies represent a more accessible and more efficient procedure because they can be applied directly to the extract to reduce the complicated isolation process. However, it still requires further development and refinement.

Separation and purification of glycosides from medicinal plants based on strong polar separation medium with online closed-loop mode

Natural glycosides widely distributed in medicinal plants are valuable sources of therapeutic agents, showing various pharmacological effects. The separation and purification of natural glycosides are meaningful for their pharmacological research, which face with great challenges due to the complex of medicinal plants samples. In this work, two kinds of functional monolithic separation mediums A and S were fabricated and fully applied in the online extraction, separation and purification of active glycoside components from medicinal plants with a simple-procedure closed-loop mode. Chrysophanol glucoside and physcion glucoside were detected and separated from Rhei Radix et Rhizoma using separation medium A as a solid-phase extraction adsorbent. Rhapontin was isolated and purified from Rheum hotaoense C. Y. Cheng et Kao using separation medium S as the stationary phase of high-performance liquid chromatography. Compared to the reported literatures, high yield of 5.68, 1.20 and 4.76 mg g-1 of these three products were obtained with high purity. These two online closed-loop mode methods were carried out using high-performance liquid chromatography system, in which the sample injection, isolation and purification procedures are all online mode, and reduced loss compared to offline extraction and purification procedures, thus achieving high recovery and high purity.

Advanced Development of Supercritical Fluid Chromatography in Herbal Medicine Analysis

The greatest challenge in the analysis of herbal components lies in their variety and complexity. Therefore, efficient analytical tools for the separation and qualitative and quantitative analysis of multi-components are essential. In recent years, various emerging analytical techniques have offered significant support for complicated component analysis, with breakthroughs in selectivity, sensitivity, and rapid analysis. Among these techniques, supercritical fluid chromatography (SFC) has attracted much attention because of its high column efficiency and environmental protection. SFC can be used to analyze a wide range of compounds, including non-polar and polar compounds, making it a prominent analytical platform. The applicability of SFC for the separation and determination of natural products in herbal medicines is overviewed in this article. The range of applications was expanded through the selection and optimization of stationary phases and mobile phases. We also focus on the two-dimensional SFC analysis. This paper provides new insight into SFC method development for herbal medicine analysis.

Chemical profiling of Qingfei Paidu Decoction by triplex off-line two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Qingfei Paidu Decoction is a Chinese medicine formula which has been proved effective in the treatment of Coronavirus Disease 2019. However, the comprehensive separation and characterization of Qingfei Paidu Decoction is of great challenge due to the diversity of chemical components in a wide range of polarity. In this study, a triplex off-line two-dimensional liquid chromatography (LC) coupled with quadrupole time-of-flight mass spectrometry (MS) is developed for the analysis of Qingfei Paidu Decoction. One reversed phase LC×hydrophilic interaction LC system and two reversed phase LC×reversed phase LC systems were constructed to separate polar components and weak-polar components in Qingfei Paidu Decoction, respectively. Benefiting from the good orthogonality of two-dimensional LC and high sensitivity of quadrupole time-of-flight MS, chemical components with different polarities and content were discovered. A total of 749 peaks were detected in positive and negative ionization mode, and presented as a four-dimensional data plot. Meanwhile, 498 compounds belonging to 14 categories were tentatively identified. These results provide good supplementary to elucidate the material basis of Qingfei Paidu Decoction. The triplex off-line two-dimensional LC-quadrupole time-of-flight MS strategy can be a powerful and efficient tool for the separation and characterization of chemical substances in traditional Chinese medicine formulas. This article is protected by copyright. All rights reserved.

Characterization of chemical components and the potential anti-influenza mechanism of Fructus Arctii by a strategy integrating pharmacological evaluations, chemical profiling, serum pharmacochemistry, and network pharmacology

Chemical components in traditional Chinese medicine (TCM) were the functional basis for its therapy achievement, and the absorbed components under disease conditions were mainly contributing to the therapeutic effects. As...

Isolation of achiral aliphatic acid derivatives from Piper kadsura using preparative two-dimensional chiral supercritical fluid chromatography

The separation of structural analogues in natural products has always been one of the challenges in separation science, where supercritical fluid chromatography (SFC) with chiral stationary phases (CSPs) is an unconventional but potential solution. In this study, a preparative two-dimensional chiral SFC (2D cSFC) method that was established with two kinds of CSPs was applied in the isolation of the aliphatic acid derivatives in Piper kadsura (P. kadsura). The RPLC unseparated peaks of two samples A and B of P. kadsura were evenly scattered on the CSP-1 column while they clustered into two groups on the CSP-2 column by SFC. There was impressively complementary selectivity between CSP-1 and CSP-2, which were used for construction of 2D cSFC. The first dimension (¹D) separation with CSP-1 fractionated the sample A into six parts by a heart-cutting method and the sample B into nine parts for a comprehensive 2D analysis; then 29 and 71 peaks were respectively found in these parts in the second dimension (²D) separation with CSP-2. Further through ²D preparative separation, 19 high purity components were obtained, and the chemical structures of two of them were confirmed, including a novel unsaturated aliphatic acid compound (8Z,10Z)-12-methoxyheptadeca-8,10-dienoic acid and a known octadecadienoic acid lactone Lactariolide. The 2D cSFC method presented the superiority of separating the achiral compounds of complex samples.

Separation and characterization of phenylamides from Piper kadsura using preparative supercritical fluid chromatography and ultra-high-performance supercritical fluid chromatography-tandem mass spectrometry

A preparative supercritical fluid chromatography method for the separation of Piper kadsura obtained five phenylamide compounds, which had the same structural skeleton, but changed in the number and position of methoxyl substituents. To improve the separation selectivity of these structural analogues, silica, phenyl, and chiral stationary phases were screened. Only through the combination of Chiral C and phenyl columns could the separation of the five phenylamides be solved. The two-step strategy using preparative supercritical fluid chromatography presented good orthogonality that ensured the purity of the phenylamides. Then, an ultra-high-performance supercritical fluid chromatography hyphened tandem mass spectrometry method was developed, and the fragmentation pattern of phenylamides was summarized. It mainly cleaved in the amide bond to produce the fragment ion, which could help to judge the substituent positions. Twenty-eight possible molecular weights of hydroxyl and methoxyl substituted phenylamides were calculated and screened. Nine compounds were extracted in three [M + H]⁺ ions at m/z 284.13, 314.13, and 344.13, including five purified compounds and the other four positional or trans-cis phenylamide isomers in low content. The methods developed in this research were useful in the separation and characterization of phenylamide analogues.

Orthogonal strategy development using reversed macroporous resin coupled with hydrophilic interaction liquid chromatography for the separation of ginsenosides from ginseng root extract

Ginsenosides have been widely conceded as having various biological activities and are considered to be the active ingredient of ginseng. Nowadays, preparative high-performance liquid chromatography is considered to be a highly efficient method for ginseng saponins purification and preparation. However, in the process of practical application, due to the complex and varied composition of natural products and relatively simple pretreatment process, it is likely to block the chromatographic column and affect the separation efficiency and its service life. In this work, an orthogonal strategy was developed; in the first-dimension separation, reverse-phase macroporous resin was applied to remove impurities in ginseng crude extracts and classified ginseng extracts into protopanaxatriol and protopanaxadiol fractions. In the second-dimension separation, the obtained fractions were further separated by a preparative hydrophilic column, and finally yielded 11 pure compounds. Eight of them identified as ginsenoside Rh₁ , Rg₂ , Rd, Rc, Rb₂ , Rb₁ , Rg₁ , and Re by standards comparison and electrospray ionization mass spectrometry. The purity of these ginsenosides was assessed by high-performance liquid chromatography with UV detection.