Large-scale separation of alkaloids from Corydalis decumbens by pH-zone-refining counter-current chromatography

pH-zone-refining counter-current chromatography was successfully applied to the separation of alkaloids from a crude extract of Corydalis decumbens (Thunb.) Pers. using a multilayer coil planet centrifuge (CPC). The experiment was performed with a two-phase solvent system composed of methyl tert-butyl ether (MtBE)-acetonitrile-water (2:2:3, v/v) where triethylamine (5-10 mM) was added to the upper organic stationary phase as a retainer and hydrochloric acid (5-10 mM) to the aqueous mobile phase as an eluter. From 3.1 g of the crude extract, 495 mg protopine, 626 mg tetrahydropalmatine and 423 mg bicuculline were obtained each with a purity of over 93% as determined by high performance liquid chromatography. The structures of the isolated compounds were identified by electron ionization mass spectrometry (EI-MS), high-performance liquid chromatography (HPLC)-electrospray ionisation-mass spectrometry (ESI-MS) and 1H NMR.     

Preparative isolation and purification of psoralen and isopsoralen from Psoralea corylifolia by high-speed counter-current chromatography

Psoralen and isopsoralen were separated from Psoralea corylifolia by high-speed counter-current chromatography (HSCCC). A two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (5:5:4.5:5.5, v/v) was used for HSCCC separation, and yielded, from 100 mg of crude extract, 39.6 mg of psoralen and 50.8 mg of isopsoralen each at over 99% purity as determined by high performance liquid chromatography (HPLC). The identification of psoralen and isopsoralen were performed with 1H NMR and 13C NMR.     

Isolation of quercetin-3-O-L-rhamnoside from Acer truncatum Bunge by high-speed counter-current chromatography

Preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of quercetin-3-O-L-rhamnoside from the ethyl acetate extract of the leaves of Acer truncatum Bunge using a two-phase-system composed of ethyl acetate-ethanol-water at a volume ratio of 5:1:5 (v/v/v). In a single operation, 41.9mg of quercetin-3-O-L-rhamnoside was obtained from 366mg of the crude extract. High-performance liquid chromatography (HPLC) analyses of the CCC fraction revealed that the purity of quercetin-3-O-L-rhamnoside was over 96%. Its structure was identified by MS, 1H NMR and 13C NMR. Quercetin-3-O-L-rhamnoside was obtained from this plant for the first time.     

Preparative isolation and purification of two isoflavones from Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao by high-speed counter-current chromatography

Two isoflavones, calycosin-7-O-beta-D-glycoside and formononetin-7-O-beta-D-glycoside, were separated from n-butanol extract of the root of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao by high-speed counter-current chromatography in two steps using two different solvent systems composed of ethyl acetate-ethanol-n-butanol-water (30:10:6:50, v/v) and ethyl acetate-ethanol-water (5:1:5, v/v). From 200 mg of crude extract, calycosin-7-O-beta-D-glycoside (12 mg) and formononetin-7-O-beta-D-glycoside (10 mg) were isolated at over 95% purity by HPLC analyses, and their structures were identified by MS, 1H NMR and 13C NMR.     

Separation of salidroside from Rhodiola crenulata by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) was used to purify salidroside from an extract of Rhodiola crenulata with two steps using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:4:5, v/v) in the first run and chloroform-methanol-isopropanol-water (5:6:1:4) in the second run. The method yielded 21.9 mg of salidroside from 1.216 g of the crude sample at 98% purity determined by HPLC analyses. Identification was performed by 1H NMR, 13C NMR, and MS.     

Isolation of three sesquiterpene lactones from the roots of Cichorium glandulosum Boiss. et Huet. by high-speed counter-current chromatography

Because of the skeletal complexity and similarity of the polarity, little research was reported on the isolation of sesquiterpene lactones by high-speed counter-current chromatography (HSCCC). Herein, three sesquiterpene lactones were successfully purified from the ethyl acetate extract of the roots of the traditional Uyghur medicinal plant Cichorium glandulosum Boiss. et Huet. by HSCCC. The separation was performed in two steps with two solvent systems: n-hexane-ethyl acetate-methanol-water (1.5:5:2.75:5, v/v/v/v) and ethyl acetate-methanol-water (20:1:20, v/v/v). From 166 mg of the ethyl acetate extract, 19 mg of lactucopicrin was isolated with the first solvent system and 10 mg of 11beta,13-dihydrolactucin and 16 mg of lactucin were obtained with the second solvent system. All purified compounds were over 94% purity as determined by HPLC analysis, and these chemical structures were confirmed by (1)H NMR and (13)C NMR.     

Preparative separation of isovitexin and isoorientin from Patrinia villosa Juss by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) with a solvent system composed of ethyl acetate-n-butanol-water (2:1:3, v/v/v) was used to isolate and separate two C-glycosylflavones from Patrinia villosa Juss, a traditional Chinese medicine. The separation produced 42.9 mg isovitexin and 20.1 mg isoorientin with purities of 99.3% and 98.5%, respectively as determined by high-performance liquid chromatography (HPLC) in one step elution from 250 mg crude extract, and identification was performed by MS, 1H NMR and 13C NMR. It is the first report of discovering isovitexin and isoorientin from the plant of Patrinia genus.     

Isolation of high purity 1-[2',4'-dihydroxy-3',5'-di-(3"-methylbut-2"-enyl)-6'-methoxy] phenylethanone from Acronychia pedunculata (L.) Miq. by high-speed counter-current chromatography

Following an initial clean-up step on silica, high-speed counter-current chromatography (HSCCC) was used to purify an aryl ketone, 1-[2',4'-dihydroxy-3',5'-di-(3"-methylbut-2"-enyl)-6'-methoxy] phenylethanone from an extract of the stem bark of the shrub Acronychia pedunculata. The two-phase solvent system used was composed of n-heptane-ethyl acetate-methanol-water at an optimized volume ratio of 4:1:4:1 (v/v/v/v). Target compound (58.1 mg) with a purity of 98.9% was obtained after HSCCC of 183.5 mg sample with a purity of 35.7% recovered after the silica clean-up step. Identification of the target compound was performed by 1H NMR, 13C NMR, two-dimensional NMR and LC-electrospray ionization MS.     

Preparative isolation and purification of syringin and edgeworoside C from Edgeworthia chrysantha Lindl by high-speed counter-current chromatography

The bioactive compound syringin along with edgeworoside C were separated from the n-butanol extract of the stems and barks of Edgeworthia chrysantha Lindl (E. papyrifera) by high-speed counter-current chromatography (HSCCC) while it was difficult to purify each compound by silica gel column chromatography. Syringin was isolated from this plant for the first time. The two-phase solvent system used was composed of ethyl acetate-ethanol-water at an optimized volume ratio of 15:1:15 (v/v/v). Preparative HSCCC yielded, from 110mg of the partially purified extract, 28mg of syringin and 45 mg edgeworoside C each at over 96% purity by high-performance liquid chromatography analysis. Their structures were identified by electron impact ionization MS, 1H NMR and 13C NMR.     

Preparative isolation of osthol and xanthotoxol from Common Cnidium Fruit (Chinese traditional herb) using stepwise elution by high-speed counter-current chromatography

Preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of osthol and xanthotoxol from Cnidium monnieri (L.) Cusson (Common Cnidium Fruit) using stepwise elution with a pair of two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water at (1:1:1:1, v/v), and (5:5:6:4, v/v), which had been selected by analytical high-speed counter-current chromatography. Using a preparative unit of the HSCCC centrifuge, about a 308 mg amount of the crude extract was separated, yielding 88.3 mg of osthol and 19.4 mg of xanthotoxol at a high purity of over 98%.     

Preparative isolation and purification of antioxidative diarylheptanoid derivatives from Alnus japonica by high-speed counter-current chromatography

This study employed the online HPLC-2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS)(+) bioassay to rapidly determine the antioxidant compounds occurring in the crude extract of Alnus japonica. The negative peaks of the ABTS(+) radical scavenging detection system, which indicated the presence of antioxidant activity, were monitored by measuring the decrease in absorbance at 734 nm. The ABTS(+)-based antioxidant activity profile showed that three negative peaks exhibited antioxidant activity. High-speed counter-current chromatography (HSCCC) was used for preparative scale separation of the three active peaks from the extract. The purity of the isolated compounds was analyzed by HPLC and their structures were identified by (1)H- and (13)C-nuclear magnetic resonance spectrometry (NMR), heteronuclear multiple bond correlation (HMBC), and heteronuclear single quantum correlation (HSQC). Two solvent systems composed of n-hexane/ethylacetate/methanol/water (4:6:4:6, v/v) and of ethyl acetate/methanol/water (1:0.1:1, v/v) were performed in high-speed counter-current chromatography. Consequently, a total of 527 mg of hirsutanonol 5-O-β-D-glucopyranoside, 80.04 mg of 3-deoxohirsutenonol 5-O-β-D-glucopyranoside, and 91.0 mg of hirsutenone were obtained with purity of 94.7, 90.5, and 98.6%, respectively.     

Preparative separation of gambogic acid and its C-2 epimer using recycling high-speed counter-current chromatography

A recycling counter-current chromatographic system was first set up with a high-speed counter-current chromatography instrument coupled with a column switching valve. This system was first successfully applied to the preparative separation of epimers, gambogic acid and epigambogic acid from Garcinia hanburyi using n-hexane-methanol-water (5:4:1, v/v/v) as the two-phase solvent system. As a result, 28.2 mg gambogic acid and 18.4 mg epigambogic acid were separated from 50 mg of mixture. Their purities were both above 97% as determined by HPLC. The chemical structures were then identified by their (1)H NMR and (13)C NMR spectra.     

Preparative isolation and purification of isoflavan and pterocarpan glycosides from Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao by high-speed counter-current chromatography

(3R)-(-)-7,2'-Dihydroxy-3',4'-dimethyl isoflavan-7-O-beta-D-glucopyranoside and (6aR, 11aR) 9,10-di-methoxypterocarpan-3-O-beta-D-glucopyranoside were separated from the ethyl acetate extract of the root of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao by high-speed counter-current chromatography (HSCCC). A two-phase system composed of ethyl acetate-ethanol-acetic acid-water (4:1:0.25:5, v/v) was selected by analytical HSCCC. Preparative HSCCC yielded, from 100 mg of the partially purified extract, 50 mg of isoflavan glycoside and 10 mg of pterocarpan glycoside each at over 95% purity by high-performance liquid chromatography (HPLC) analysis. Their structures were identified by MS, 1H NMR and 13C NMR.     

Bioassay-guided isolation of antioxidants from Astragalus altaicus by combination of chromatographic techniques

An efficient method for bioassay-guided preparative isolation of antioxidants from the n-butanol extract of Astragalus altaicus Bunge was ingeniously developed by combination of silica gel column chromatography and high-speed counter-current chromatography. Under the bioassay-guidance of antioxidant activities, the antioxidants were gradually separated from the crude sample of Astragalus altaicus Bunge by silica gel column chromatography and high-speed counter-current chromatography. Silica gel column chromatography separation was performed with chloroform, chloroform-methanol (100:1~5:1, v/v) and chloroform-methanol-water (5:1:0.1~2:1:0.1, v/v/v). High-speed counter-current chromatography separation was performed with a two-phase solvent system composed of ethyl acetate-n-butanol-water (2:1:6, v/v/v), which was successfully selected by thin layer chromatography analysis, at a flow rate of 1.5 mL/min. As a result, isorhamnetin-3-gentiobioside (20.8 mg), rutin (82.0 mg), and narcissin (12.8 mg) were obtained for the first time from 200 mg of the crude sample, ABS-5 of Astragalus altaicus Bunge. The purities were all at over 95% by high-performance liquid chromatography analysis, and their structures were unambiguously identified by mass spectroscopy, (1) H, and (13) C nuclear magnetic resonance spectroscopy. Antioxidant activities of the three compounds were also assayed by in vitro ABTS [2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diamonium salt] radical cation scavenging activity. Among them, rutin possessed the highest antioxidant capacity with SC(50) value of 22.15 μg/mL.     

Isolation of a novel flavanone 6-glucoside from the flowers of Carthamus tinctorium (Honghua) by high-speed counter-current chromatography

A novel flavanone glycoside, (2S)-4',5,6,7-tetrahydroxyflavavone 6-O-beta-D-glucopyranoside was isolated from the ethyl acetate extract of the flowers of Carthamus tinctorium by high-speed counter-current chromatography (HSCCC). Using an optimized two-phase solvent system composed of ethyl acetate-methanol-water (5:1:5, v/v), target compound (52 mg) with purity of 98.0% was obtained from 2.0 g of sample by HSCCC in seven times run. The structure of the target compound was elucidated by means of spectroscopic methods including IR, MS, 1D and 2D NMR techniques.     

Application of preparative high-speed counter-current chromatography for isolation and separation of schizandrin and gomisin A from Schisandra chinensis

Following an initial cleaning-up step on the D101 macroporous resin, a preparative high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.9:0.9:1, v/v) was used to isolate and separate schizandrin and gomisin A from Schisandra chinensis. A total of 107 mg schizandrin and 36 mg gomisin A with purities of 99.5% and 99.1% were obtained from 400 mg crude extract in one-step elution and less than 3 h, and the structure identification was performed by UV, IR, MS, 1H NMR and 13C NMR.     

Preparative separation of alkaloids from Gelsemium elegans Benth. using pH-zone-refining counter-current chromatography

Alkaloids in Gelsemium elegans possess a variety of therapeutic properties, including tumor suppression, analgesic and anti-inflammatory effects. In China, G. elegans has been used for centuries to treat a variety of medical conditions, including chronic pain and skin ulcer. Methods currently used to separate the active components of G. elegans are time-consuming and have low recovery. In the present study, we used pH-zone-refining counter-current chromatography to separate major alkaloids from a crude extract of G. elegans. The two-phase solvent system was methyl tert-butyl ether (MtBE)/acetonitrile/water (3:1.5:4, v/v). Triethylamine (20 mM) was added to the upper organic stationary phase as a retainer. Hydrochloric acid (10 mM) was added to the lower aqueous phase as an eluter. From 1.5 g of crude extract, we obtained 312 mg gelsemine, 420 mg koumine and 195 mg gelsevirine, with purities at 94.8%, 95.9% and 96.7%, respectively, which were determined by HPLC at 256 nm. The chemical identity of the isolated compounds was verified by electrospray ionization-mass spectrometry (ESI-MS), 1H NMR and 13C NMR. These results demonstrated that pH-zone-refining counter-current chromatography is an effective method to separate and purify major alkaloids from G. elegans.     

Separation and purification of harmine and harmaline from Peganum harmala using pH-zone-refining counter-current chromatography

pH-zone-refining counter-current chromatography was successfully applied to the separation of alkaloids from a crude extract of Peganum harmala L. using a multilayer coil planet centrifuge. The experiment was performed with a two-phase solvent system composed of methyl tert-butyl ether/THF/water (2:2:3 by volume) where triethylamine (10 mM) was added to the upper organic stationary phase as a retainer and hydrochloric acid (5 mM) to the aqueous mobile phase as an eluter. From 1.2 g of the crude extract, 554 mg harmine and 325 mg harmaline were obtained each with a purity of over 96% as determined by HPLC. The structures of the isolated compounds were identified by electron ionization MS (EI-MS), (1)H NMR, and (13)C NMR.     

Preparative isolation and purification of astaxanthin from the microalga Chlorococcum sp. by high-speed counter-current chromatography

High-speed counter-current chromatography was applied to the isolation and purification of astaxanthin from microalgae. The crude astaxanthin was obtained by extraction with organic solvents after the astaxanthin esters were saponified. Preparative high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (5:5:6.5:3, v/v) was successfully performed yielding astaxanthin at 97% purity from 250 mg of the crude extract in a one-step separation.     

Preparative isolation and purification of alkaloids from the Chinese medicinal herb Evodia rutaecarpa (Juss.) Benth by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water system (5:5:7:5, v/v) was applied to the isolation and purification of alkaloids from the Chinese medicinal plant Evodia rutaecarpa (Juss.) Benth. Five kinds of alkaloids were obtained and yielded 28 mg of evodiamine (I), 19 mg of rutaecarpine (II), 21 mg of evocarpine (III), 16mg of 1-methy-2-[(6Z,9Z)]-6,9-pentadecadienyl-4-(1H)-quinolone (IV), 12 mg of 1-methyl-2-dodecyl-4-(1H)-quinolone (V) from 180 mg of crude extract in a one-step separation, with the purity of 98.7%, 98.4%, 96.9%, 98.0%, 97.2%, respectively, as determined by high performance liquid chromatography (HPLC). The structures of these compounds were identified by 1H NMR and 13CNMR.