Isolation of two new prenylated flavonoids from Sinopodophyllum emodi fruit by silica gel column and high-speed counter-current chromatography

Sinoflavonoids NJ and NK, anti-inflammatory prenylated flavonoids from the fruits of Podophyllum hexandrum Royle

Two new prenylated flavonoids named sinoflavonoids NJ and NK (1-2), along with ten known compounds were isolated from the fruits of Podophyllum hexandrum Royle. The chemical structures were determined through NMR spectroscopic data and MS analysis. Sinoflavonoid NJ (1) with an unusual 5,11-dioxabenzo[b]fluoren-10-one skeleton was firstly reported from Berberidaceae. The isolated flavonoids were tested with LPS-induced RAW 264.7 mouse macrophages model for their anti-inflammatory activity. Sinoflavonoid NJ (1) showed the most potent inhibition on nitric oxide production with IC50 value as 0.06 μM.

Selective adsorption of flavonoids on cerium-doped ferroferric oxide magnetic particles

Ce-doped Fe₃O₄ magnetic particles (Ce-Fe₃O₄ MPs) were synthesized by co-precipitation method. The coordination and adsorption properties of Ce-Fe₃O₄ MPs to different natural products were investigated. The results verified that the "catechol-like","maltol-like" and "acetylacetone-like" donor sets of flavonoids were the binding sites with Ce-Fe₃O₄ MPs. The adsorption was conformed to be pseudo-second-order model and single-layer adsorption after being characterized by adsorption kinetics and adsorption thermodynamics. The adsorption and desorption conditions were optimized. It was found that different components adsorbed on the Ce-Fe₃O₄ MPs surface can be selective desorbed in different solvents, which was helpful for the selective separation to adsorbed components. The Ce-Fe₃O₄ MPs were successfully applied to selective adsorption of compounds containing "catechol-like", "maltol-like" and "acetylacetone-like" donor sets in the crude extract of Scutellaria baicalensis Georgi and Rheum palmatum L. The results demonstrated that the magnetic solid phase extraction (MSPE) method based on Ce-Fe₃O₄ MPs has the advantages of high structural selectivity, high efficiency and low consumption, and can be used for efficient separation of flavonoids with specific structures from natural products.

Nonlinear behavior in preparative liquid chromatography: A method-development case study for hydroxytyrosol purification

Preparative liquid chromatography has become an important purification method owing to its advantages of high separation efficiency, good reproducibility, and low solvent consumption. Because overloading in preparative liquid chromatography must be performed to increase the throughput in a cycle, nonlinear chromatographic behavior is observed. Therefore, it is crucial to carefully study nonlinear chromatography for the purification of a given product, which facilitates the efficient optimization of the purification parameters. In this work, a method for the development of a purification method using preparative liquid chromatography based on nonlinear chromatography is proposed. Hydroxytyrosol was selected as the subject for method demonstration. Using methanol and ethanol as organic modifiers, the optimum flow rate was determined on three commercial columns entitled C₈ TDE, C₁₈ ME, and C₁₈ TDE, respectively. The curves were fitted with the van Deemter equation, with thorough analysis of the A, B, and C terms. Adsorption isotherms were subsequently studied to explore the distribution of solutes between the stationary and mobile phases at equilibrium. C₁₈ TDE, 5 vol% ethanol-water, and 0.2 mL/min were selected as the optimal separation material, elution solvent, and flow rate, respectively. Purification of hydroxytyrosol was tentatively confirmed on a C₁₈ TDE column with 1.6% sample loading, 90.98% recovery, and 98.01% purity.

Two new flavonoid glucosides from the fruits of Sinopodophyllum hexandrum

Two new flavonoid glucosides, sinoflavonoidgs A (1) and B (2), along with three known analogues 3-5, were isolated from the fruits of Sinopodophyllum hexandrum. Their structures were established on the basis of extensive spectroscopic (UV, IR, HR-ESI-MS, ¹H-NMR, ¹³C-NMR, HSQC, HMBC) and chromatographic (HPLC) analysis. The isolation of compounds 1-2 represents the first report of ring B-glucosided flavonoids from the genus Sinopodophyllum. The cytotoxic activities of all isolated compounds were evaluated in comparison with etoposide against four cell lines (MCF-7, HepG2, HeLa, KB). The antioxidant activities of all isolated compounds were examined by DPPH free radical-scavenging assay. The preliminary structure-activity relationships showed that the glycosilation of 3-methoxyquercetin at C-3' resulted in a greater decrease of cytotoxic and antioxidant activity.

Sixteen New Prenylated Flavonoids from the Fruit of Sinopodophyllum hexandrum

Sixteen new prenylated flavonoids, sinoflavonoids P–Z (1–11) and sinoflavonoids NA–NE (12–16), were isolated from the fruit of Sinopodophyllum hexandrum, along with eight known analogues (17–24). Their structures were elucidated on the basis of extensive spectroscopic data (HR-ESI-MS, ¹H-NMR, ¹³C-NMR, HSQC, HMBC). The cytotoxic activities of compounds 1–18, 20, and 22 were evaluated by MTT assay. Compound 6 showed the most potent cytotoxicity in MCF-7, and HepG2 cell lines, with IC₅₀ values of 6.25 and 3.83 μM, respectively.

Preparative Purification of Total Flavonoids from Sophora tonkinensis Gagnep. by Macroporous Resin Column Chromatography and Comparative Analysis of Flavonoid Profiles by HPLC-PAD

For the full development and utilization of Sophora tonkinensis Gagnep., this study was primarily intended to established a simple and efficient approach for the preparative purification of total flavonoids from S. tonkinensis by macroporous resin column chromatography (MRCC). The adsorption and desorption characteristics of the total flavonoids on ten macroporous resins were first studied, and AB-8 resin was chosen as the most suitable, and the adsorption data were best fitted to the pseudo-second-order kinetics model and Langmuir isotherm model. Furthermore, the technological parameters for the purification of the total flavonoids were optimized using column chromatography. After a sample one-step purification procedure, the content of the total flavonoids increased by about 4.76-fold from 12.14% to 57.82%, with a recovery yield of 84.93%. In addition, the comparative analysis of the flavonoid extracts before and after purification was performed by high-performance liquid chromatography coupled with photodiode-array detection (HPLC-PAD). The results showed that the contents of six major flavonoids in the purified product were all higher than before the purification. Therefore, the AB-8 MRCC established in this work was a promising method for the industrial-scale purification of the total flavonoids from S. tonkinensis.

Simultaneous Separation and Purification of Five Polymethoxylated Flavones from "Dahongpao" Tangerine (Citrus tangerina Tanaka) Using Macroporous Adsorptive Resins Combined with Prep-HPLC

In this study, a preparative separation method was established to simultaneously isolate the polymethoxylated flavones (PMFs) from the peel of “Dahongpao” tangerine using macroporous adsorptive resins (MARs) combined with prep-HPLC. The total PMFs were enriched using MARs to remove most sugars, water-soluble pigments, and flavanones, and the eluents obtained were analyzed by ultra-performance liquid chromatography (UPLC) to determine the PMF composition. The separation and purification of PMFs were carried out by using a mass spectrometry-guided prep-HPLC with a gradient elution of acetonitrile-water (v/v), simultaneously. The purity of these PMFs was determined by UPLC, and their chemical structures were confirmed by electrospray ionization mass spectrometry (ESI-MS-MS), ultraviolet (UV), and nuclear magnetic resonance (NMR). Using the present method, five PMFs, including 5,6,7,4’-tetramethoxyflavone (1), nobiletin (2), tangeretin (3), sinensetin (4), and 5-hydroxy-6,7,8,3’,4’-pentamethoxyflavone (5), can be purified simultaneously, and the purity of the compounds obtained were 95.3%, 99.7%, 99.5%, 98.9%, and 98.1%, respectively. The method reported here is simple, rapid, and efficient, and it can be used to separate PMFs from citrus fruit peels and, potentially, other plant materials.

Preparative Separation of High-Purity Dihydroartemisinic Acid from Artemisinin Production Waste by Combined Chromatography

In order to make full use of artemisinin production waste and thus to reduce the production cost of artemisinin, we developed an efficient and scalable method to isolate high-purity dihydroartemisinic acid from artemisinin production waste by combining anion-exchange resin with silica-gel column chromatography. The adsorption and desorption characteristics of dihydroartemisinic acid on 10 types of anion-exchange resin were investigated, and the results showed that the 717 anion-exchange resin exhibited the highest capacity of adsorption and desorption to dihydroartemisinic acid. Adsorption isotherms were established for the 717 anion-exchange resin and they fitted well with both Langmuir and Freundlich model. Dynamic adsorption and desorption properties of 717 anion-exchange resin were characterized to optimize the chromatographic conditions. Subsequently, the silica-gel column chromatography was performed and dihydroartemisinic acid with a purity of up to 98% (w/w) was obtained. Finally, the scale-up experiments validated the preparative separation of high-purity dihydroartemisinic acid from industrial waste developed in the present work. This work presented for the first time an isolation of dihydroartemisinic acid with a purity of 98% from Artemisia annua (A. annua) by-product, which adds more value to this crop and has the potential to lower the prices of anti-malarial drugs.

High-speed countercurrent chromatography isolation of flavans from Ixeris chinensis and their identification by NMR spectroscopy

High-speed countercurrent chromatography, combined with macroporous resin chromatography were applied to the separation and purification of flavans from Ixeris chinensis. Four flavans, namely, 5-methoxy-7,4'-dihydroxyflavan-3-ol (1), 5,7-dimethoxy-4'-hydroxyflavan-3-ol (2), 5,7-dimethoxy-4'-hydroxyflavan (3), and 5,7-dimethoxy-8-methyl-4'-hydroxyflavan (4), were obtained from I. chinensis for the first time. Their chemical structural identification was carried out by spectroscopic methods, including 1D and 2D NMR spectroscopy. Amounts of 13.2 mg of compound 1, 6.4 mg of compound 2, 5.8 mg of compound 3, and 14.5 mg of compound 4 were separated from 120 mg 75% ethanol fraction. The purities of 1-4 were 99.1, 99.2, 97.3, and 98.6 %, respectively.

Labdane Diterpenes from the Fruits of Sinopodophyllum emodi

Two new labdane diterpenes, sinoditerpene A (1) and B (2), were isolated from the fruits of Sinopodophyllum emodi, along with two known analogues 3 and 4. Their structures were established on the basis of extensive spectroscopic analysis. The isolation of compounds 1–4 represents the first report of diterpenes from the genus Sinopodophyllum. The cytotoxic activities of all isolated compounds were evaluated in comparison with 5-fluorouracil against the MCF-7 and HepG2 cell lines, towards which 3 showed more potent cytotoxicity.

Preparative Isolation of Two Prenylated Biflavonoids from the Roots and Rhizomes of Sinopodophyllum emodi by Sephadex LH-20 Column and High-Speed Counter-Current Chromatography

Two prenylated biflavonoids, podoverines B–C, were isolated from the dried roots and rhizomes of Sinopodophyllum emodi using a Sephadex LH-20 column (SLHC) and high-speed counter-current chromatography (HSCCC). The 95% ethanol extract was partitioned with ethyl acetate in water. Target compounds from the ethyl acetate fraction were further enriched and purified by the combined application of SLHC and HSCCC. n-Hexane–ethyl acetate–methanol–water (3.5:5:3.5:5, v/v) was chosen as the two phase solvent system. The flow rate of mobile phase was optimized at 2.0 mL·min⁻¹. Finally, under optimized conditions, 13.8 mg of podoverine B and 16.2 mg of podoverine C were obtained from 200 mg of the enriched sample. The purities of podoverines B and C were 98.62% and 99.05%, respectively, as determined by HPLC. For the first time, podoverins B and C were found in the genus Sinopodophyllum. Their structures were determined by spectroscopic methods (HR-ESI-MS, ¹H-NMR, ¹³C-NMR, HSQC, HMBC). Their absolute configurations were elucidated by comparison of their experimental and calculated ECD spectra. The cytotoxic activities were evaluated against MCF-7 and HepG2 cell lines. The separation procedures proved to be practical and economical, especially for trace prenylated biflavonoids from traditional Chinese medicine.

Prenylated flavonoids from the fruits of Sinopodophyllum emodi and their cytotoxic activities

Thirteen new prenylated flavonoids were isolated from Sinopodophyllum emodi together with eleven known analogues. Compound 22 exhibited the most potent cytotoxicity against MCF-7 and HepG2 cell lines.