Separation and purification of nootkatone from fermentation broth of Yarrowia lipolytica with high-speed counter-current chromatography

Nootkatone is an important functional sesquiterpene, which can be obtained by the biotransformation of valencene. It is increasingly important because of its pleasant citrus aroma and physiological effects. Yarrowia lipolytica is beneficial for biotechnology applications and has ability to transform valencene to nootkatone. High-speed counter-current chromatography (HSCCC) was used to isolate and purify the product of nootkatone in this study. The suitable two-phase solvent system was selected and the optimum separation conditions were determined. The partition coefficients of nootkatone and the separation factor between nootkatone and valencene were considered as the indexes. The results showed that there were numerous products during the transformation of valencene by Yarrowia lipolytica, and the content of nootkatone was 13.75%. The obtained nootkatone was separated by HSCCC with a solvent system n-hexane/methanol/water (5/4/1, v/v). The final purity of nootkatone was 91.61 ± 0.20% and the elution time was 290-310 min. The structure of nootkatone was identified by gas chromatography-mass spectrometry (GC-MS), infrared spectrum and nuclear magnetic resonance hydrogen spectroscopy (1H NMR). This was the first report on the separation of nootkatone from the fermentation broth by HSCCC. This study proved that HSCCC could be used as an effective method to separate and purify the nootkatone from valencene transformed by Yarrowia lipolytica with n-hexane/methanol/water (5/4/1, v/v).

Separation of five flavone glycosides including two groups with similar polarities from Dracocephalum tanguticum by a combination of three high-speed counter-current chromatography modes

The separation of compounds with similar polarities is challenging. In the present study, five flavone glycosides, including two groups with similar polarities, were obtained from Dracocephalum tanguticum by three high-speed counter-current chromatography modes, including flow rate conversion mode, recycling mode, and heart-cut mode. With flow rate conversion mode, compounds 3 and 4 with similar polarities and compound 5 were separated by high-speed counter-current chromatography with ethyl acetate/methanol/water (5.0% acetic acid) (8:2:10, v/v) system. The flow rate was controlled as: 1.8 mL/min for 0-160 min, 2.2 mL/min for 160-200 min, and 2.5 mL/min for 200-400 min. However, compounds 1 and 2 with similar polarities were not separated due to the similar distributive properties. Then, a recycling and heart-cut mode were introduced to improve the separation efficiency. The heart-cut mode was introduced in the second and third cycles, and compounds 1 and 2 were well separated in the fourth cycle. Consequently, five flavone glycosides, including two groups with similar polarities were obtained and identified as cosmosiin (1), pedaliin (2), quercetin-3-O-rutinoside (3), pedaliin-6''-acetate (4), and sorbifolin-6-O-β-glucopyranoside (5). The current strategy provides a reference for separating compounds with similar polarities from a crude sample.

Extraction and purification of cis/trans asarone from Acorus tatarinowii Schott: Accelerated solvent extraction and silver ion coordination high-speed counter-current chromatography

Acorus tatarinowii Schott is a traditional Chinese medicine used to treat memory and cognitive dysfunction. Because of their efficacy and lower toxic effects, research on α- and β-asarone, the phytoconstituents, has attracted attention owing to their remarkable pharmacological activities. Silver ion coordination complexation high-speed counter-current chromatography was used to separate these isomers from A. tatarinowii extract, coupled with accelerated solvent extraction. Accelerated solvent extraction parameters were investigated with single-factor and orthogonal testing. A two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (2:1:2:1, v/v) with 0.50 mol/L silver ions was selected for separation. From 2.0 g crude extract, 1.4 g of β-asarone and 0.09 g of α-asarone were obtained with purities over 98% by sequential sample loading in 20 h. The isolated compounds were identified by electrospray ionization mass spectrometry, ¹H and ¹³C NMR. Silver ions significantly increased the separation factor and retention of the stationary phase. The chromatographic behavior indicated that cis-configuration was more strongly complexed with the silver ion. This was further demonstrated with the help of computational analysis. In conclusion, the established method could be employed to separate other cis-trans or E/Z isomers that form coordination complexes.

Gallate-Based Metal–Organic Frameworks, a New Family of Hybrid Materials and Their Applications: A Review

Within three decades of fundamental findings in research on metal–organic frameworks (MOFs), a new family of hybrid materials known as gallate-based MOFs, consisting of metal salt and gallic acid, have been of great interest. Due to the fact that gallic acid is acknowledged to display a range of bioactivities, gallate-based MOFs have been initially expended in biomedical applications. Recently, gallate-based MOFs have been gradually acting as new alternative materials in chemical industrial applications, in which they were first reported for the adsorptive separation of light hydrocarbon separations. However, to date, none of them have been related to CO2/CH4 separation. These porous materials have a bright future and can be kept in development for variety of applications in order to be applied in real industrial practices. Therefore, this circumstance creates a new opportunity to concentrate more on studies in CO2/CH4 applications by using porous material gallate-based MOFs. This review includes the description of recent gallate-based MOFs that presented remarkable properties in biomedical areas and gas adsorption and separation, as well as their future potential application.

Stepwise elution by high-speed counter-current chromatography combined with a modified macroporous resin to isolate and purify antioxidant phenolics from discarded jackfruit (Artocarpusheterophyllus Lam.) peels

Combined with modified macroporous resin (MR), high-speed counter-current chromatography (HSCCC) was developed to separate and purify the antioxidant phenolics from waste jackfruit peels. First, the 4,4'-bis(chloromethyl)-1,1'-biphenyl was used to modify the commercially available adsorbent resin XAD-4 in order to enrich the antioxidant phenolics. Second, the resultant phenolics-rich fractions were further purified by HSCCC. In the separation process, the petroleum ether-ethyl acetate-methanol-0.1% acetic acid (5 : 5 : 3 : 7, v/v) upper phase was employed as an immobile phase. Afterwards, stepwise elution using petroleum the ether-ethyl acetate-methanol-0.1% acetic acid (5 : 5 : 3 : 7, v/v) lower phase was carried out during the initial 3.5 h, whereas the petroleum ether-ethyl acetate-methanol-0.1% acetic acid (5 : 5 : 6 : 4, v/v) lower phase was adopted for stepwise elution during the later 2.0 h. Four phenolics were obtained from 179 mg of the phenolics-rich fraction in a single run, including 41 mg chlorogenic, 27 mg gallic acid, 33 mg quercetin, and 29 mg catechin. 13C NMR, 1H NMR, and ESI-MS were employed to identify their structures.

Preparative separation of liquiritigenin and glycyrrhetic acid from Glycyrrhiza uralensis Fisch using hydrolytic extraction combined with high-speed countercurrent chromatography

The objective of this paper was to develop a preparative method for the isolation and purification of liquiritigenin and glycyrrhetic acid from Glycyrrhiza uralensis Fisch using hydrolytic extraction combined with high-speed countercurrent chromatography (HSCCC). Liquiritigenin and glycyrrhetic acid were well hydrolyzed from liquiritin and glycyrrhizic acid by hydrochloric acid, respectively. The optimal extraction conditions were obtained by single-factor and orthogonal experiments, which were 100% ethanol, 1.5 mol/L hydrochloric acid, 1:25 ratio of solid to liquid, and extracted 2 h for one time. Using the two-phase solvent system of n-hexane-ethyl acetate-methanol-water (4:5:4:5, v/v), 2.1 mg liquiritigenin (the purity was 96.5% with a recovery of 87.6%) and 12.3 mg glycyrrhetic acid (the purity was 97.1% with a recovery of 74.4%) were obtained from 315-mg crude extraction by HSCCC. The retention ratio of stationary phase was 47.2%. Their structures were identified by HPLC, melting points, UV, Fourier-transform infrared, Electrospray ionization-MS, ¹ H nuclear magnetic resonance (NMR), and ¹³ C NMR spectra. According to the antioxidant activity assays, liquiritigenin and glycyrrhetic acid had some scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl free radicals; liquiritigenin had stronger scavenging ability on hydroxyl radicals.

Preparative Separation of Alkaloids from Stem of Euchresta tubulosa Dunn. by High-Speed Counter-Current Chromatography Using Stepwise Elution

Euchresta tubulosa Dunn. is a Chinese herbal medicine with biological activity, but there are few studies on its components at present. Alkaloids in the stem of Euchresta tubulosa Dunn. were isolated and purified by high-speed counter-current chromatography (HSCCC) using stepwise elution. First of all, liquid-liquid extraction (methylene chloride-methanol-water, 5:1:4, v/v) was used for the preliminary enrichment. According to the partition coefficient (K) of a target compound in a series of different two-phase solvents, the final result was that carbon tetrachloride-methylene chloride-methanol-water (2:3:3:2, v/v) (1) and methylene chloride-methanol-water (5:3:2, v/v) (2) were suitable for the HSCCC using stepwise elution. As a result, the purity was all higher than 93% and matrine (1), oxymatrine (2), N-formyl cytisine (3), and N-acetyl cytisine (4) can be eluted at one time by this mode. Cytisine-type alkaloids were isolated for the first time in this plant. Finally, the applicability of the mode was verified.

A simple gradient equilibrium method for better separation in countercurrent chromatography

The stationary phase retention is one of the most important parameters in countercurrent chromatography. In this work, a simple gradient equilibrium method was developed to further improve the stationary phase retention based on the optimized condition in the traditional equilibrium model. Meanwhile, this novel gradient equilibrium method was used to separate three flavone model compounds and compared with the conventional isocratic equilibrium method to evaluate the separation efficiency. The results show that better resolution or shorter separation time could be achieved with gradient equilibrium compared to isocratic equilibrium. So this novel equilibrium method has enormous potential for obtaining a better separation or saving the separating time in the preparative separation of target compounds.