Application of high-speed counter-current chromatography for the isolation of 9′-cis-neoxanthin from fresh spinach

Neoxanthin in young vegetable leaves prevents fat accumulation in differentiated adipocytes

The present study aimed to investigate the effect of young leaves on fat accumulation in differentiated 3T3-L1 adipocytes. A potent preventive effect on fat accumulation was observed in fractions of young leaves of spinach, beet, and arugula extracted with a low-polarity solvent (hexane:acetone:ethanol:toluene = 10:6:7:6). This effect was seemingly associated with the leaf carotenoid content, including lutein, β-carotene, and neoxanthin. Among these, only neoxanthin, with the characteristic structure of 5,6-monoepoxide and an allenic bond, significantly prevented fat accumulation in a dose-dependent manner. The preventive effect and carotenoid content, including neoxanthin, of these young leaves did not differ from those of the corresponding adult leaves. Therefore, our study demonstrated that young vegetable leaves, such as spinach, beet, and arugula leaves, contained neoxanthin, which prevented fat accumulation in adipocytes in vitro. In the future, the effectiveness of such young leaves and neoxanthin should be investigated in vivo.

Development of an effective method based upon second-order overlapping repeated sample injections for isolation of carotenoids from Lycium barbarum L. fruits with elution-extrusion counter-current chromatography

Carotenoids are one of the main active components in Lycium barbarum L. fruit, which has a wide range of excellent biological activities. In this study, a novel second-order overlapping repeated injection method with elution-extrusion counter-current chromatography was developed for isolation and preparation of carotenoids from L. barbarum fruits. And three carotenoids were successfully separated using the solvent system composed of n-hexane/dichloromethane/acetonitrile (10:3.5:6.5, v/v) with the injection before equilibrium method. The entire separation process consisted of three complete elution-extrusion cycles with a total of 9 injections (80 mg crude extract per injection). Finally, three target compounds including zeaxanthin (28.5 mg), zeaxanthin monopalmitate (45.8 mg), and zeaxanthin dipalmitate (161.5 mg) with average purities of 87.9%, 88.9%, and 91.2% were successfully obtained in one complete second-order overlapping repeated elution-extrusion CCC process within 651 min. The result indicated that this second-order overlapping repeated method is efficient for large-scale preparation of carotenoids based on its advantages of large amount of sample injection and low solvent consumption. So this novel second-order overlapping repeated elution-extrusion counter-current chromatography separation method has enormous potential for largely preparative separation of natural bioactive compounds, such as carotenoids, which have good biological activity but possess unstable or other special chemical structure. It is worth noting that this overlapping repeated injections method requires target compounds to meet the requirements of elution-extrusion counter-current chromatography, and the normal implementation of this method is closely related to the sufficient interval of elution time between the target compounds.

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.

Developments of instruments and methods related with high-speed countercurrent chromatography and their applications in research of natural medicines

High-speed countercurrent chromatography (HSCCC) is a liquid-liquid separation chromatographic technique which uses no solid supporting medium. During its rapid development in the last 30 years, great progress has been made in the instrumentation, the basic study and application of HSCCC. It has significant advantages over other instrumental separation techniques, in its high efficiency and continuous processing capability. In recent years, HSCCC has been widely used in research and development of natural medicines and functional foods, including preparative separation, fingerprint analysis and screening of bioactive constituents. A review of the technique is presented in this paper.

A preparative method for isolation of fucoxanthin from Eisenia bicyclis by centrifugal partition chromatography

INTRODUCTION

Eisenia bicyclis (Kjellman) Setchell (Laminariaceae) is a common brown alga that inhabits around the coast of Korea, Japan and China. It contains fucoxanthin, a major carotenoid of brown algae which shows a variety of pharmaceutical functions.

OBJECTIVE

The aim of this investigation was the quantification and preparative isolation of fucoxanthin from fresh E. bicyclis using a new separation scheme, centrifugal partition chromatography (CPC).

METHODOLOGY

The fucoxanthin fraction (Fuco fraction) was prepared by solvent partition method from the acetone extract of fresh E. bicyclis. Fuco fraction was used for CPC using a two-phase solvent system of n-hexane-ethyl acetate-ethanol-water (5:5:7:3, v/v/v/v). The flow rate of mobile phase was 2 mL/min with descending mode while rotating at 1000 rpm. The eluate was monitored at 410 nm. The content and structure of fucoxanthin in the CPC fraction were confirmed with HPLC, UV, APCI/MS and NMR spectra.

RESULTS

A preparative CPC yielded 20 mg of fucoxanthin (87% recovery from Fuco fraction) in a two-step separation from 516 mg of Fuco fraction containing 4.59% fucoxanthin. The purity of the isolated fucoxanthin was about 81% in the first CPC step and over 98% in the second CPC step based on the calibration curve. The isolated fucoxanthin was identified as all-trans-fucoxanthin with APCI/MS (parent ion at m/z 641 [M + H - H(2) O](+) ) and (1) H, (13) C and 2-D NMR spectra.

CONCLUSION

High-purity fucoxanthin was successfully isolated from fresh E. bicyclis, suggesting further potential applications in the industrial use of this valuable carotenoid.

Isolation and tandem mass fragmentations of an anti-inflammatory compound from Aralia elata

One-step isolation of a saponin from Aralia elata was undertaken using high-speed countercurrent chromatography coupled with evaporative light scattering detection. A triterpenoid saponin, elatoside F, was purified with 96.8% purity using a two-phase-system comprising chloroform-methanol-water-isopropanol. The yield was 35.0 mg from 348.2 mg of the enriched saponin fraction. In vitro anti-inflammatory study demonstrated that elatoside F inhibited lipopolysaccharide-induced nitric oxide production, as well as nuclear factor kappaB activation, in a dose-dependent manner. Two types of mass ionization technique were compared on elatoside F to investigate characteristic fragmentation patterns. MALDI-TOF tandem mass spectrometric fragmentation patterns of sodiated ions provided structural information on glycosidic cleavages and on extensive cross-ring cleavages. Electrospray ionization multiple-stage tandem mass fragmentation of both sodiated and lithiated ions could provide information on glycosidic cleavages. All observed tandem mass fragmentation spectra provided valuable elatoside F structural information when unknown samples from crude extracts are under screening by mass spectrometry.

PREPARATIVE SEPARATION OF AXIFOLIN-3-GLUCOSIDE, HYPEROSIDE AND AMYGDALIN FROM PLANT EXTRACTS BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY

High-speed countercurrent chromatography (HSCCC) was successfully used to isolate three bioactive compounds, i.e., amygdalin from bitter almond and taxifolin-3-glucoside and quercetin-3-galactoside (hyperoside) from water extract of Agrimonia pilosa Ledeb, respectively. From 1 g of the crude extract 65 mg of amygdalin was isolated at 97% purity using a two-phase solvent system composed of ethyl acetate-n-butanol-water (5:2:5, v/v) by preparative HSCCC. From a 400 mg amount of crude extract of Agrimonia pilosa Ledeb, 11 mg of taxifolin-3-glucoside and 8 mg of hyperoside were isolated at 96% purity using a two-phase solvent system composed of ethyl acetate-methanol-water (25:1:25, v/v) similarly by preparative HSCCC. The final structural identification was performed by MS, (1)H-NMR and (13)C-NMR Spectra.

Countercurrent chromatography: people and applications

The scientific literature was scanned for the published research articles dealing with countercurrent chromatography (CCC) over the time period 1980-May 2008. The search returned 1638 articles that were analyzed focussing on people and applications. Concerning the people, it was found that the geographical location of the CCC authors was relatively well balanced between USA, Asia with mainly China and Japan and Europe. Yoichiro Ito, the inventor of the technique, is by far the most productive author in the field with 331 articles or more than one over five CCC articles published in the time period. Without surprise, English is the dominant language with more than 82% of the articles. A significant 8% amount of CCC articles were published in Chinese in Chinese journals. Chromatography journals are the logical tribune for half of the published CCC articles. Concerning the applications, the separation and purification of natural compounds is the dominant theme in CCC making the subject of more than one article over two. Starting from the plant extract, CCC in few steps can produce significant amounts of more than 95% pure compounds used for identification and/or property studies. Other applications are found in the pharmaceutical and chemical field. The separation of enantiomers on the preparative scale is a field of growing importance.