Preparative separation of minor saponins from Platycodi Radix by high-speed counter-current chromatography

Biotransformation of Platycosides, Saponins from Balloon Flower Root, into Bioactive Deglycosylated Platycosides

Platycosides, saponins from balloon flower root (Platycodi radix), have diverse health benefits, such as antioxidant, anti-inflammatory, anti-tussive, anti-cancer, anti-obesity, anti-diabetes, and whitening activities. Deglycosylated platycosides, which show greater biological effects than glycosylated platycosides, are produced by the hydrolysis of glycoside moieties in glycosylated platycosides. In this review, platycosides are classified according to the chemical structures of the aglycone sapogenins and also divided into natural platycosides, including major, minor, and rare platycosides, depending on the content in Platycodi radix extract and biotransformed platycosides. The biological activities of platycosides are summarized and methods for deglycosylation of saponins, including physical, chemical, and biological methods, are introduced. The biotransformation of glycosylated platycosides into deglycosylated platycosides was described based on the hydrolytic pathways of glycosides, substrate specificity of glycosidases, and specific productivities of deglycosylated platycosides. Methods for producing diverse and/or new deglycosylated platycosides are also proposed.

Rhamnose-Containing Compounds: Biosynthesis and Applications

Rhamnose-associated molecules are attracting attention because they are present in bacteria but not mammals, making them potentially useful as antibacterial agents. Additionally, they are also valuable for tumor immunotherapy. Thus, studies on the functions and biosynthetic pathways of rhamnose-containing compounds are in progress. In this paper, studies on the biosynthetic pathways of three rhamnose donors, i.e., deoxythymidinediphosphate-L-rhamnose (dTDP-Rha), uridine diphosphate-rhamnose (UDP-Rha), and guanosine diphosphate rhamnose (GDP-Rha), are firstly reviewed, together with the functions and crystal structures of those associated enzymes. Among them, dTDP-Rha is the most common rhamnose donor, and four enzymes, including glucose-1-phosphate thymidylyltransferase RmlA, dTDP-Glc-4,6-dehydratase RmlB, dTDP-4-keto-6-deoxy-Glc-3,5-epimerase RmlC, and dTDP-4-keto-Rha reductase RmlD, are involved in its biosynthesis. Secondly, several known rhamnosyltransferases from Geobacillus stearothermophilus, Saccharopolyspora spinosa, Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Streptococcus pneumoniae are discussed. In these studies, however, the functions of rhamnosyltransferases were verified by employing gene knockout and radiolabeled substrates, which were almost impossible to obtain and characterize the products of enzymatic reactions. Finally, the application of rhamnose-containing compounds in disease treatments is briefly described.

A multidimensional strategy to rapidly identify the chemical constituents in Shengxian Decoction by using ultra-performance liquid chromatography coupled with ion mobility spectrometry quadrupole time-of-flight mass spectrometry

As a well-known traditional Chinese medicine formula, the chemical constituents of Shengxian Decoction still remain unclear due to its complexity. In this study, a multidimensional strategy based on ultra-performance liquid chromatography coupled with ion mobility spectrometry quadrupole time-of-flight mass spectrometry and informatics UNIFI™ platform was applied to achieve rapid and comprehensive identification of the complex composition of Shengxian Decoction. Data-independent acquisition, fast data-directed analysis, and high-definition MS^E were used to obtain more and cleaner mass spectrum information. As a result, a total of 120 compounds including 74 saponins, 17 flavonoids,7 cinnamic acid derivatives, 8 triterpenoids and 14 others were identified or tentatively characterized by high-resolution molecular mass, fragment ions, and collision cross-section values. Furthermore, high-definition MS^E was used to identify six pairs of co-eluting isomers that could not be detected from conventional data-independent acquisition and data-independent acquisition. This research strategy has a certain potential for the analysis of other Compound formulae and lays the foundation for the study of traditional Chinese medicine efficacy. 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.

Simultaneous separation and determination of three diterpenoids in Euphorbia lathyris L. and its formulations by hydrophobic interaction electrokinetic chromatography

In this study, a hydrophobic interaction electrokinetic chromatography method has been developed for simultaneous separation and determination of three diterpenoids in Euphorbia lathyris L.: Euphorbia factors L₁ , L₂ , and L₃ . After optimization of separation conditions, the electrolyte solution was 5.0 mM ammonium acetate buffer containing 30 mM sodium dodecyl sulfate in a 60% v/v methanol (pH 6.86), 25 kV of electric field across the capillary was applied at 25°C, and the detection wavelength was at 280 nm. Under optimum conditions, good linearity was achieved with correlation coefficients from 0.9945 to 0.9995. The limits of detection were 2.5, 7.5, and 5.6 μg/mL, and the limits of quantitation were 8.8, 23.9, and 15.3 μg/mL, respectively. Excellent accuracy and precision were obtained. Recoveries of the analytes varied from 98.5 to 103.8%. The established method was novel, simple, and rapid, and it was validated and confirmed to be applicable for the determination of the active ingredients in a quality control analysis.

Preparative separation of five polyphenols from the fruits of Sorbus pohuashanensis Hedl. by high-speed counter-current chromatography

The fruits of Sorbus pohuashanensis Hedl. (S. pohuashanensis) are rich in polyphenols with many beneficial effects such as anti-inflammatory, anti-tussive, anti-asthmatic and anti-cancer. In this study, five polyphenols, including three phenolic acids and two flavonoids, were successfully prepared from the fruits of S. pohuashanensis by high-speed counter-current chromatography (HSCCC) using different solvent systems for the first time. Ethyl acetate-n-butanol-water (3.5:1.5:5, v/v) was screened as the two-phase system to separate neochlorogenic acid (1), chlorogenic acid (2), quercetin 3-O-(6″-α-L-rhamnopyranosyl-4'″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (3) and rutin (5). N-hexane-ethyl acetate-methanol-water (1:3:1:3.5, v/v) was first utilized to isolate 3,5-O-dicaffeoylquinic acid (4). The purities of all these compounds were above 95%. In addition, their chemical structures were identified by mass spectrometer (MS), nuclear magnetic resonance (NMR) or the standards. These results indicated that HSCCC was an effective method to separate polyphenols compounds from the fruits of S. pohuashanensis.

A strategy based on isocratic and linear-gradient high-speed counter-current chromatography for the comprehensive separation of platycosides from Platycodi radix

Platycosides, the generally recognized main active constituents of Platycodi radix, have been studied extensively for their wide pharmacological activities. Herein, we have successfully developed an efficient method for the enrichment and comprehensive isolation of platycosides from Platycodi radix by MCI resin column chromatography (CC) and two different modes of high-speed counter-current chromatography (HSCCC). MCI resin CC was the preferable enrichment operation for platycosides from the 70%-ethanol extract of Platycodi radix and rendered target platycosides when eluted by 60% aqueous methanol solution. As for the separation, two different modes, including isocratic HSCCC and linear-gradient HSCCC, were applied together to separate the platycosides using a mixture of ethyl acetate, n-butanol and water coupled with evaporative light scattering detection, for the first time. Isocratic HSCCC was applied to separate crude platycosides from Platycodi radix using ethyl acetate-n-butanol-water (1 : 1 : 2, v/v), yielding seven pure platycosides (compounds 1-6, 8) and two fractions of enriched mixtures of compounds 7, 9, 10, and 11. Linear-gradient HSCCC was employed to rapidly separate compounds 7, 9, 10, and 11 by constantly changing the proportions of ethyl acetate and n-butanol in the ethyl acetate-n-butanol-water solvent system. Finally, platycoside E (1), deapio-platycodin D₃ (2), platycodin D₃ (3), deapio-platycodin D₂ (4), platycodin D₂ (5), platycodin D (6), polygalacin D₂ (7), polygalacin D (8), and three tautomers, namely 2''-O-acetylplatycodin D (9) and 3''-O-acetylplatycodin D (9'), 2''-O-acetylpolygalacin D₂ (10) and 3''-O-acetylpolygalacin D₂ (10'), and 2''-O-acetylpolygalacin D (11) and 3''-O-acetylpolygalacin D (11'), were obtained from 300 mg of crude platycosides from Platycodi radix.

A strategy to comprehensively and quickly identify the chemical constituents in Platycodi Radix by ultra-performance liquid chromatography coupled with traveling wave ion mobility quadrupole time-of-flight mass spectrometry

Quick identification of the complex composition of traditional Chinese medicine only through liquid-mass spectrometry technology is difficult. Especially the identification of isomers and co-eluting compounds is even more difficult. In this study, an approach of multidimensional data modes based on ultra-performance liquid chromatography coupled with traveling wave ion mobility quadrupole time-of-flight mass spectrometry was proposed to quickly and comprehensively identify the compounds in Platycodi Radix. First, data-independent acquisition, high-definition acquisition, and tandem mass spectrometry acquisition modes were used to acquire integrated multidimensional mass spectral data. Second, summarize the diagnostic ions of compounds according to the fragmentation pathway of references. Third, unknown compounds and isomers were identified via the UNIFI™ software with an in-house library. Finally, a total of 87 compounds were identified, seven compounds were explicitly identified by comparing the retention time and fragment ions with the references. Fourteen compounds were first detected in the Platycodi Radix, four of them tentatively were identified by comparing with previous literature, eight compounds were observed and reported for the first time by comparing typical fragmentation pathway with the known standard substances in this paper. This research strategy has a certain potential for the analysis of complex components of other traditional Chinese medicine.

Biotransformation of Glycosylated Saponins in Balloon Flower Root Extract into 3-O-β-D-Glucopyranosyl Platycosides by Deglycosylation of Pectinase from Aspergillus aculeatus

Platycodon grandiflorum root (Platycodi radix) saponins, platycosides, have been used as health supplements and food items for the treatment of respiratory disorders and pulmonary diseases. Deglycosylated saponins have been known to exert stronger biological effects than their glycosylated forms. In the present study, glycosylated platycosides in Platycodi radix extract were biotransformed into deglycosylated 3-O-β-D-glucopyranosyl platycosides, including 3-O-β-Dglucopyranosyl platycodigenin, 3-O-β-D-glucopyranosyl polygalacic acid, and 3-O-β-Dglucopyranosyl platyconic acid, by pectinase from Aspergillus aculeatus. This is the first report on the quantitative enzymatic production of 3-O-β-D-glucopyranosyl platycosides. The chemical structures of 3-O-β-D-glucopyranosyl platycosides were identified with LC/MS. Moreover, the biotransformation pathways of the three types of platycosides in Platycodi radix into 3-O-β-Dglucopyranosyl platycosides were established.

Platycodon saponins from Platycodi Radix (Platycodon grandiflorum) for the Green Synthesis of Gold and Silver Nanoparticles

A green synthesis of gold and silver nanoparticles is described in the present report using platycodon saponins from Platycodi Radix (Platycodon grandiflorum) as reducing agents. Platycodin D (PD), a major triterpenoidal platycodon saponin, was enriched by an enzymatic transformation of an aqueous extract of Platycodi Radix. This PD-enriched fraction was utilized for processing reduction reactions of gold and silver salts to synthesize gold nanoparticles (PD-AuNPs) and silver nanoparticles (PD-AgNPs), respectively. No other chemicals were introduced during the reduction reactions, providing an entirely green, eco-friendly, and sustainable method. UV-visible spectra showed the surface plasmon resonance bands of PD-AuNPs at 536 nm and PD-AgNPs at 427 nm. Spherically shaped nanoparticles were observed from high-resolution transmission electron microscopy with average diameters of 14.94 ± 2.14 nm for PD-AuNPs and 18.40 ± 3.20 nm for PD-AgNPs. Minor triangular and other polygonal shapes were also observed for PD-AuNPs along with spherical ones. Atomic force microscopy (AFM) images also demonstrated that both nanoparticles were mostly spherical in shape. Curvature-dependent evolution was employed to enhance the AFM images and precisely measure the sizes of the nanoparticles. The sizes were measured as 19.14 nm for PD-AuNPs and 29.93 nm for PD-AgNPs from the enhanced AFM images. Face-centered cubic structures for both nanoparticles were confirmed by strong diffraction patterns from high-resolution X-ray diffraction analyses. Fourier transform infrared spectra revealed the contribution of -OH, aromatic C=C, C-O, and C-H functional groups to the synthesis. Furthermore, the catalytic activity of PD-AuNPs was assessed with a reduction reaction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. The catalytic activity results suggest the potential application of these gold nanoparticles as catalysts in the future. The green strategy reported in this study using saponins as reducing agents will pave new roads to develop novel nanomaterials with versatile applications.

Advanced development in phytochemicals analysis of medicine and food dual purposes plants used in China (2011-2014)

In 2011, we wrote a review for summarizing the phytochemical analysis (2006-2010) of medicine and food dual purposes plants used in China (Zhao et al., J. Chromatogr. A 1218 (2011) 7453-7475). Since then, more than 750 articles related to their phytochemical analysis have been published. Therefore, an updated review for the advanced development (2011-2014) in this topic is necessary for well understanding the quality control and health beneficial phytochemicals in these materials, as well as their research trends.

Rapid preparative separation of six bioactive compounds from Gentiana crassicaulis Duthie ex Burk. using microwave-assisted extraction coupled with high-speed counter-current chromatography

A rapid method combining microwave-assisted extraction (MAE) and high-speed counter-current chromatography (HSCCC) was applied for preparative separation of six bioactive compounds including loganic acid (I), isoorientin-4'-O-glucoside (II), 6'-O-β-d-glucopyranosyl gentiopicroside (III), swertiamarin (IV), gentiopicroside (V), sweroside (VI) from traditional Tibetan medicine Gentiana crassicaulis Duthie ex Burk. MAE parameters were predicted by central composite design response surface methodology. That is, 5.0 g dried roots of G. crassicaulis were extracted with 50 mL 57.5% aqueous ethanol under 630 W for 3.39 min. The extract (gentian total glycosides) was separated by HSCCC with n-butanol/ethyl acetate/methanol/1% acetic acid water (7.5:0.5:0.5:3.5, v/v/v/v) using upper phase mobile in tail-to-head elution mode. 16.3, 8.8, 12., 25.1, 40.7, and 21.8 mg of compounds I-VI were obtained with high purities in one run from 500 mg of original sample. The purities and identities of separated components were confirmed using HPLC with photo diode array detection and quadrupole TOF-MS and NMR spectroscopy. The study reveals that response surface methodology is convenient and highly predictive for optimizing extraction process, MAE coupled with HSCCC could be an expeditious method for extraction and separation of phytochemicals from ethnomedicine.

Counter-current chromatography for the separation of terpenoids: a comprehensive review with respect to the solvent systems employed

Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications.

Glycosylated platycosides: identification by enzymatic hydrolysis and structural determination by LC-MS/MS

In this study, enzymatic hydrolysis and chemometric methods were utilized to discriminate glycosylated platycosides in the extract of Platycodi Radix by LC-MS. Laminarinase, whose enzymatic activity was evaluated using gentiobiose and laminaritriose, was a suitable enzyme to identify the glycosylated platycosides. The laminarinase produced deapi-platycodin D and platycodin D from the isolated deapi-platycoside E and platycoside E through the loss of two glucose units by enzymatic reaction, respectively. After hydrolyzing a crude extract by laminarinase, the reconstructed total ion chromatogram generated by a chemometric technique sorted peaks of deglycosylated platycosides easily. Structural information of the glycosylated isomers was revealed through fragment ions generated by the sodiated C0β ion corresponding to reduced disaccharides in the positive MS(4) spectra. Characteristic fragment ions of Glc-(1→6)-Glc moieties were observed through ring cleavages of (0,2)A0β, (0,3)A0β, and (0,4)A0β, whereas Glc-(1→3)-Glc moieties produced only (0,3)A0β ions. Lithium-adducted platycosides allowed more detailed structural analysis of glycosidic bond cleavage corresponding to Y1β and B1β in addition to ring cleavage.

A rapid and convenient method for preparative separation of three indissolvable polyphenols from Euphorbia pekinensis by the flexible application of solvent extraction combined with counter-current chromatography

A rapid and convenient method was established to preparatively isolate the three ellagic acid types of compounds, which were the main polyphenols in Euphorbia pekinensis, by flexibly applying solvent extraction combined with counter-current chromatography (CCC). The total extract (extracted using 95% ethanol) of E. pekinensis was pretreated by two simple steps before CCC isolation, following the procedure: the total extract was extracted by classical solvent extraction using petroleum ether and ethyl acetate, respectively, and then the ethyl acetate extract was suspended using 95% ethanol, after being allowed to stand overnight, the sediment was obtained. Partial sediment (100 mg) was then directly separated by CCC with a two-phase solvent system composed of chloroform-95% ethanol-water-85% formic acid (50:50:50:5, v/v/v/v). About 22 mg of 3,3'-dimethoxy ellagic acid (1), 12 mg of 3,3'-di-O-methyl-4-O-(β-D-xylopyranosyl)ellagic acid (2), and 35 mg of ellagic acid (3) with purities of 96.0, 95.2, and 95.4% were obtained respectively in one step within 4 h. After being purified by washing with methanol, the purities of the three compounds obtained were all above 98%. The purities were determined by HPLC and their chemical structures were further identified by (1)H and (13)C NMR spectroscopy. The recoveries were calculated as 84.6, 85.7, and 89.5%, respectively. The result demonstrated that the present isolation method was rapid, economical and efficient for the preparative separation of polyphenols from E. pekinensis.