Preparative separation of alkaloids from the root of Sophora flavescens Ait by pH-zone-refining counter-current chromatography

Application of pH-zone refining hydrostatic countercurrent chromatography (hCCC) for the recovery of antioxidant phenolics and the isolation of alkaloids from Siberian barberry herb

The development of a fast hCCC method tailored to recover phenolics of Siberian barberry (Berberis sibirica, Berberidaceae) responsible for the observed strong antioxidant activity was performed. Initially, the optimization of extraction procedure was evaluated based on the antiradical potential assessment (DPPH and Folin-Ciocalteu assays). 100 °C methanol ASE extract exhibited the highest antiradical activity (IC50=60 ± 4 μg/mL), and a significant TPC (159 ± 2 mgGAE/g). Thorough determination of phenolic content by UHPLC-DAD-ESI(-)HRMS revealed the presence of 10 phenolics as major constituents, and several groups of alkaloids. pH-zone refining hCCC was chosen as the most promising method for the extract's fractionation due to the ionizable character of its constituents. For this purpose a MtBE-H2O (1:1) system with 10mM TEA and HCl was applied leading to a phenolic fraction, free of alkaloids, with higher antioxidant capacity (IC50=25 μg/mL, TPC=178 mg GAE/g). Additionally, fractionation of alkaloids was achieved resulting isolation of pharmacologically important alkaloids: magnoflorine and berberine.

Intestinal transport of sophocarpine across the Caco-2 cell monolayer model and quantification by LC/MS

Sophocarpine is a biologically active component obtained from the foxtail-like sophora herb and seed that is often orally administered for the treatment of cancer and chronic bronchial asthma. The aim of this study was to develop a rapid and specific LC/MS method for the determination of sophocarpine and to explore its transcellular transport mechanism across the Caco-2 (the human colon adenocarcia cell lines) monolayer cell transwell model. Caco-2 cells were seeded on permeable polycarbonate membranes and incubated for 21 days. Before the experiment, the trans-epithelial electric resistance, integrity and alkaline phosphatase activity of the Caco-2 monolayers were verified and used in subsequent experiments. In the Caco-2 model constructed, many influencing factors were investigated, including time, concentration, pH and different protein inhibitors. The results suggested that sophocarpine was transported mainly by passive diffusion. The flux of sophocarpine was time- and concentration-dependent, and the pH also had an effect on its transportation. The PappBA was higher than PappAB , indicating that a polarized transport might exist for sophocarpine. MK-571 and reserpine, inhibitors of the multidrug resistance associated protein 2 and the breast cancer resistance protein, decreased the efflux of sophocarpine, while verapamil had no effect on its transport. These results revealed that sophocarpine is absorbed mainly by passive diffusion, and that a carrier-mediated mechanism is also involved in the transport of sophocarpine.

Subcritical water extraction of alkaloids in Sophora flavescens Ait. and determination by capillary electrophoresis with field-amplified sample stacking

The extraction and determination of cytisine, sophocarpine, matrine, sophoridine and oxymatrine in Sophora flavescens Ait. were performed using subcritical water extraction and capillary electrophoresis with field-amplified sample stacking. The effects of extraction temperature, pressure, time and cycle number on the extraction yields were investigated systematically for accelerated solvent extraction with ethanol (ASE) and accelerated solvent extraction with water (subcritical water extraction, SWE). The extraction yields obtained using SWE, ASE, water ultrasonic extraction and chloroform soaking extraction methods were compared. The electrophoresis separation buffer was monosodium phosphate (pH 3.0; 110 mM)-isopropanol (85:15, v/v). The effect of phosphoric acid added to the sample matrix on the reproducibility of the peak heights of the analytes was also examined. Cytisine, sophoridine and oxymatrine showed good linearity (R(2)>0.999) within 0.125-4.0 μg/mL, and sophocarpine and matrine exhibited good linearity (R(2)>0.998) within 0.0625-2.0 μg/mL, with the detection limits in the range of 0.004-0.0013 μg/mL. The five alkaloid contents in medicinal plants from different sources and Sophora instant granule were determined and compared.

Separation of alkaloids from herbs using high-speed counter-current chromatography

Alkaloids represent a most widespread group of bioactive natural products. Because of their alkalinity and structural diversity, the fractionation and purification of the alkaloids from herbs can often present a number of practical difficulties using the conventional chromatographic techniques. High-speed counter-current chromatography (HSCCC) is a liquid-liquid partition chromatography with a support-free liquid stationary phase, and is gaining more and more popularity as a viable separation technique for bioactive compounds from natural resources. In the present review, focus is placed on the separation of alkaloids by both conventional HSCCC and pH-zone-refining counter-current chromatography (CCC) techniques from herbs. The review presents the separation of over 120 different alkaloid compounds from more than 30 plant species by the conventional HSCCC and pH-zone-refining CCC. Based on the data from the literature, the proper solvent systems for the separation of alkaloids by the conventional HSCCC and pH-zone-refining CCC are also summarized.

Preparative separation of quaternary ammonium alkaloids from Corydalis yanhusuo W. T. Wang by pH-zone-refining counter-current chromatography

The optimal extraction condition for extracting quaternary ammonium alkaloid dehydrocorydaline from Corydalis yanhusuo W. T. Wang was investigated using orthogonal experimental design. pH-zone-refining counter-current chromatography (CCC) with normal phase elution was successfully applied to preparative separation of alkaloids from the crude extract of Corydalis yanhusuo. The separation was performed with a biphasic solvent system composed of chloroform (CHCl(3))-methanol (MeOH)-water (2:1:1, v/v), in which the lower organic phase containing 10 mM of triethylamine was used as the mobile phase, while the upper aqueous phase containing 10 mM of hydrochloric acid was used as the stationary phase. The separation mechanism of quaternary ammonium alkaloids using pH-zone-refining CCC was discussed in comparison with standard high-speed CCC. In the present study, the separation of 1.200 g of crude sample yielded 129 mg of dehydrocorydaline and 12 mg of palmatine at a high purity of 94 and 92%, respectively. Recovery for dehydrocorydaline and palmatine was 85 and 86%, respectively.

Solid-phase extraction of matrine and oxymatrine from Sophora Flavescens Ait using amino-imidazolium polymer

A new, polymer-confined, ionic liquid sorbent was developed by a process involving polymerization and modification. The obtained particles were successfully used as a special sorbent in SPE process to isolate matrine and oxymatrine from Sophora Flavescens Ait. Different washing and elution solvents, such as ethanol, methanol, acetonitrile and methanol/triethylamine (90:10, v/v), were evaluated. Compared with the C(18) and NH(2) sorbents, the amino-imidazolium polymer sorbent exhibited higher selectivity. Quantitative analysis was carried out by using a C(18) column. The two compounds exhibited good linearity from 5x10(-3) to 0.50 mg/mL (r(2)>0.99). The bound amounts between target compounds and proteins were obtained by this sorbent. After three recycles of amino-imidazolium polymer, the extract amounts of the target compounds were not significantly decreased.

Countercurrent separation of natural products

An assessment of the technology and method development in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CS), is provided. More than six decades of CS theory and applications are critically reviewed and developed into a practical guide to CS for natural products research. The necessary theoretical foundation is given for better use of CS in the separation of biological molecules of any size, small to large, and from any matrix, simple to complex. The three operational fundamentals of CS--instrumentation, biphasic solvent systems, and theory--are covered in a prismatic fashion. The goal of this review is to provide the necessary background and references for an up-to-date perspective of CS and to point out its potential for the natural products scientist for applications in natural products chemistry, metabolome, and proteome research involving organisms from terrestrial and marine sources.

Preparative isolation and purification of flavone compounds fromSophora japonica L. by high-speed counter-current chromatography combined with macroporous resin column separation

High-speed counter-current chromatography combined with macroporous resin column separation was applied to the isolation and purification of genistein-7,4'-di-O-beta-D-glucoside (I), genistein-7-O-beta-D-glucopyranoside-4'-O-[(alpha-L-rhamnopyransoyl)-(1-2)-beta-D-glucopyranoside] (II), kaempferol-3-O-beta-D-sophoroside(III), quercetin-3-O-beta-L-ramnopyranosyl-(1 - 6)-beta-D-glucopyranoside (IV), genistein-4'-beta-L-rhamnopyransoyl-(1 - 2)-alpha-D-glucopyranoside (V), and kaempferol-3-O-beta-L-ramnopyranosyl-(1 - 6)-beta-D-glucopyranoside (VI) from the Chinese medicinal herb Sophora japonica L. The crude extracts from the pericarps of Sophora japonica L. were pre-separated on a D-101 macroporous resin column and divided into two parts as sample 1 and sample 2. An 80-mg portion of sample 1 was separated by using n-butanol-acetic acid (1%) (5:5, v/v) as the two-phase solvent system and yielded 30.1 mg of compound I, 23.3 mg of compound II. A 120 mg portion of sample 2 was separated by using ethyl acetate-n-butanol-acetic acid (1%) (5:0.8:5, v/v) as the two-phase solvent system and yielded 5.5 mg of compound III, 31.7 mg of compound IV, 37.4 mg of compound V, and 6.2 mg of compound VI. The purities of compounds I, II, III, IV, V, and VI were 98.7, 98.2, 97.8, 98.5, 99.3, and 98.9%, respectively, as determined by HPLC. The chemical structures of these components were identified by 1H-NMR and 13C-NMR.

Characterization of flavonoids in the extract of Sophora flavescens Ait. by high-performance liquid chromatography coupled with diode-array detector and electrospray ionization mass spectrometry

A method coupling high-performance liquid chromatography (HPLC) with diode-array detector (DAD) and electrospray ionization mass spectrometry (ESI) was established for the separation and characterization of flavonoids in Sophora flavescens Ait. Based on the chromatographic separation of most flavonoids present in S. flavescens Ait., a total of 24 flavonoids were identified. Fourteen compounds were unambiguously identified comparing experimental data for retention time (t(R)), UV and MS spectra with those of the authentic compounds: 3',7-dihydroxy-4'-methoxy-isoflavone (13), trifolirhizin (14), kurarinol (18), formononetin (19), 7,4'-dihydroxy-5-methoxy-8-(gamma,gamma-dimethylallyl)-flavanone (22), maackiain (21), isoxanthohumol (23), kuraridine (26), kuraridinol (27), sophoraflavanone G (30), xanthohumol (31), isokurarinone (33), kurarinone (35) and kushenol D (38), and additional 10 compounds were tentatively identified as kushenol O (10), trifolirhizin-6''-malonate (15), sophoraisoflavanone A (20), norkurarinol/kosamol Q (24), kushenol I/N (25), kushenol C (28), 2'-methoxykurarinone (29), kosamol R (32), kushecarpin A (34) and kushenol A (37) by comparing experimental data for UV and MS spectra with those of literature. Furthermore, fragmentation pathways in positive ions mode of 24 flavonoid compounds of types of flavanone, flavanonol, flavonol, chalcone, isoflavone, isoflavanone and ptercocarpane were summarized. Some common features, such as CH(3)., H(2)O, CO, CO(2), C(3)O(2) and C(2)H(2)O losses, together with Retro-Diels-Alder fragmentations were observed in the prenylated flavonoids in S. flavescens Ait. The loss of the lanandulyl chain was their characteristic fragmentation, which might help deducing the structure of unknown flavonoid compounds. The present study provided an approach to rapidly characterize bioactive constituents in S. flavescens Ait.

Developments in the application of counter-current chromatography to plant analysis

Counter-current chromatography is a very versatile separation technique which does not require a solid stationary phase. It relies simply on the partition of a sample between the two phases of an immiscible solvent system. Some of the more recent applications of the method to the separation of plant-derived natural products are described here. Crude plant extracts and semi-pure fractions can be chromatographed, with sample loads ranging from milligrams to grams. Aqueous and non-aqueous solvent systems are used and the separation of compounds with a wide range of polarities is possible. The technique is complementary to other chromatographic methods and is compatible with gradient systems. The possibilities for solvent selection are almost limitless but some guidelines for the choice of successful systems are presented.

Isolation and purification of coumarin compounds from Cortex fraxinus by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) was successfully used for the isolation and purification of coumarin compounds from Cortex fraxinus, the Chinese herbal drug. n-Butanol-methanol-0.5% acetic acid (5:1.5:5, v/v) was used as the two-phase solvent system. 14.3 mg of fraxin, 26.5 mg of aesculin, 5.8 mg of fraxetin and 32.4 mg of aesculetin with the purity of 97.6, 99.5, 97.2 and 98.7%, respectively were obtained from 150 mg of crude extracts of C. fraxinus in a single run. The structures of the isolated compounds were identified by 1H NMR and 13C NMR.

Preparative separation and determination of matrine from the Chinese medicinal plant Sophora flavescens Ait by molecularly imprinted solid-phase extraction

Molecularly imprinted microspheres (MIMs) were synthesized by micro-suspension polymerization using matrine (MT) as template. The MIMs were employed for solid-phase extraction (SPE) and as chromatographic stationary phase for the determination of MT from the Chinese medicinal plant Sophora flavescens. The effects of the various eluents, their concentrations and volumes on the retention behavior were investigated. The selectivity and capacity of the imprinted microspheres against MT was also discussed. The results showed that the MIMs exhibited stronger specific affinity to MT than to oxymatrine (OMT). Methanol-water (3:7, v/v) was used for washing impurities from the MIMs-SPE cartridge loaded with the herb extracts, while methanol-glacial acetic acid (9:1, v/v) was used for eluting MT. The maximum load of MT and the recovery of MIMs cartridge towards MT were 38.7 microg g(-1) and 71.4%, respectively. The method developed might be used to separate and extract effective constituents from Chinese medicinal plants on a large scale.

PH-Zone-refining counter-current chromatography of lappaconitine from Aconitum sinomontanum nakai I. Separation of prepurified extract

pH-Zone-refining counter-current chromatography was applied to the separation of diterpenoid alkaloids from a crude sample from a crude prepurified sample containing lappaconitine at about 90% purity using a multilayer coil planet centrifuge. The experiment was performed with a two-phase solvent system composed of methyl tert.-butyl ether-tetrahydrofuran-distilled water (2:2:3, v/v) where triethylamine (10 mM) was added to the upper organic stationary phase as a retainer and hydrochloric acid (10 mM) to the aqueous mobile phase as an eluter. The separation of 10.5 g of the sample yielded 9.0 g of lappaconitine at a high purity of over 99% as determined by HPLC.