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1.
J Sep Sci ; 2022 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-35322921

RESUMO

Analytical enantioseparations of five N-alkyl drugs, fluoxetine hydrochloride, labetalol, venlafaxine hydrochloride, trans-paroxol, and atropine sulfate, were investigated by reverse phase high-performance liquid chromatography with sulfobutylether-ß-cyclodextrin as chiral mobile phase additive. Effects of various factors such as composition of mobile phase, concentration of cyclodextrins, and column temperature on retention and enantioselectivity were studied. Apparent formation constant between methanol, acetonitrile, and sulfobutylether-ß-cyclodextrin were determined to be 2.90 × 10-3 and 1.00 × 10-4 L mmol-1 under 25°C using UV-spectrophotometry. Van't Hoff plots were used to investigate thermodynamic parameters for enantiomers-stationary phase interaction and formation of inclusion complex. Two retention models were employed individually for evaluation of inclusion complexation between five racemates and sulfobutylether-ß-cyclodextrin. The second model with complex adsorption was more accord with the retention behavior of fluoxetine hydrochloride, labetalol, and venlafaxine hydrochloride enantiomers, while the first model was more consistent with the retention behaviors of trans-paroxol and atropine sulfate. In the selected mobile phase, stoichiometric ratio for both of inclusion complex was found to be 1:1.

2.
J Chromatogr A ; 1664: 462794, 2022 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-34998026

RESUMO

A sensitive capillary electrophoresis strategy was developed by combining salting-out assisted liquid-liquid extraction and online three-step stacking to detect trace quantities of antitumour indole alkaloids in complex biological samples. The proposed strategy fully exploits these two technologies such that extraction, online stacking and separation are combined in a fast and efficient manner. First, salting-out assisted liquid-liquid extraction was used to extract three indole alkaloids (vinblastine sulfate, catharanthine sulfate and vindoline) from complex biomasses. An appropriate volume of acetonitrile (ACN) was mixed with a faecal aqueous solution to precipitate proteins. The mixed solution was vortexed, followed by the addition of ammonium sulfate ((NH4)2SO4) to induce two-phase separation. Alkaloids were effectively extracted into the organic phase, which was then subjected to capillary electrophoresis (CE) analysis. The sensitivity of capillary electrophoresis was effectively improved by online three-step stacking. Good linearity of the calibration curve for each indole alkaloid was obtained in the concentration range of 0.1-1 µg/mL. Under optimal conditions, the sensitivity of ordinary injection was increased by up to 2366-fold, confirming the applicability of the proposed strategy for the sensitive determination of trace indole alkaloids in complex biological samples.


Assuntos
Alcaloides , Vimblastina , Eletroforese Capilar , Extração Líquido-Líquido , Cloreto de Sódio
3.
J Chromatogr A ; 1663: 462767, 2022 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-34971862

RESUMO

In the present work, influence of solvent strength of aqueous phase for two frequently-used biphasic solvent system in partition coefficient (K) of selected solutes were mainly studied, and a new method for selection of biphasic solvent system was proposed for high-speed countercurrent chromatographic separations. Solvent strength was referred to the typical theory that was deeply investigated in conventional reversed-phase liquid chromatography. Experimental results showed that a linear relationship between log(K) of solutes and apparent content of methanol in biphasic solvent system was found for the biphasic solvent system hexane-ethyl acetate-methanol-water (HEMWat), which was consistent with the relationship between real content and apparent content of methanol in this system. Meanwhile, a quadratic relationship was found between log(K) of solutes and apparent content of methanol in biphasic solvent system chloroform-methanol-water (ChMWat), in which it was found that the relationship between real content and apparent content of methanol in this system was also quadratic. In addition, a visual and simple method was proposed to select a suitable biphasic solvent system for separation of target compounds by high-speed countercurrent chromatography with isocratic elution, which saves a lot of manpower and material resources in order to find a suitable two-solvent system. An optimal biphasic solvent system for isolation of several tested compounds by high-speed countercurrent chromatography was easily obtained using our proposed method.


Assuntos
Distribuição Contracorrente , Água , Cromatografia Líquida de Alta Pressão , Metanol , Extratos Vegetais , Solventes
4.
J Pharm Biomed Anal ; 207: 114420, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34662781

RESUMO

Retention behavior of two structural isomeric pentacyclic triterpenic acids, maslinic acid and corosolic acid, was investigated by reverse phase high performance liquid chromatography (HPLC) with hydroxypropyl-ß-cyclodextrin (HP-ß-CD) as mobile phase additive. Inclusion complexation of maslinic acid, corosolic acid with hydroxypropyl-ß-cyclodextrin was evaluated under different concentration of hydroxypropyl-ß-cyclodextrin. Apparent formation constant (Km) between methanol and hydroxypropyl-ß-cyclodextrin was determined to be 13.82 L mol-1 under 25 °C using UV-spectrophotometry. Two retention models were employed individually for evaluation of inclusion complexation between the two pentacyclic triterpenic acids and hydroxypropyl-ß-cyclodextrin. It was found that a higher apparent formation constant (Kf) for corosolic acid and hydroxypropyl-ß-cyclodextrin was obtained, 19115 L mol-1, indicating that a greater affinity of hydroxypropyl-ß-cyclodextrin with corosolic acid was produced compared with that of maslinic acid, 11775 L mol-1, in the selected mobile phase, and stoichiometric ratio for both of inclusion complex was found to be 1:1. Thermodynamic analysis showed that a negative standard enthalpy change (ΔH) and an entropy change (ΔS*) for analyte transfer were obtained, where ΔH of maslinic acid and corosolic acid was found to be -10.188 kJ mol-1 and -10.650 kJ mol-1, ΔS* of two compounds was -2.092 and -2.180, respectively, indicating that transfer of structural isomers from mobile phase to stationary phase was enthalpically driven. Meanwhile, positive values were obtained for standard enthalpy change and standard entropy change, 136 kJ mol-1 and 274 kJ mol-1 and 536 J mol-1 K-1and 1004 J mol-1 K-1, for inclusion complexation between maslinic acid, corosolic acid and hydroxypropyl-ß-cyclodextrin, while negative values were obtained for Gibbs free energy during formation of inclusion complex, -160 kJ mol-1 and -299 kJ mol-1, indicating a spontaneous inclusion reaction happened.


Assuntos
beta-Ciclodextrinas , 2-Hidroxipropil-beta-Ciclodextrina , Cromatografia Líquida , Cromatografia de Fase Reversa , Triterpenos Pentacíclicos , Termodinâmica
5.
J Ethnopharmacol ; 282: 114607, 2022 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-34506940

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: The root of Paeonia lactiflora is a traditionally-used whitening medicine in China for thousands of years. Although some tyrosinase inhibitors and/or antioxidants such as 1,2,3,4,6-pentagalloylglucose, gallic acid, have been isolated and identified, their tyrosinase inhibition pathway (monophenolase or diphenolase inhibition, or both two) have not been systematically studied and the underlying tyrosinase inhibition mechanism has not been revealed yet. Moreover, the exploring of new natural tyrosinase inhibitors and antioxidants is urgently needed. AIM OF THE STUDY: This review aimed to develop a new microplate-based high-resolution tyrosinase inhibition profiling assay and establish a furthermore triple high-resolution monophenolase/diphenolase/radical scavenging profiling for accelerating identification bioactive compounds from complicated plant extract. MATERIALS AND METHODS: The targeted isolation and structure elucidation were performed with high-performance liquid chromatography-high-resolution mass spectrometry and preparative high-performance liquid chromatography. It allows to be a proof of concept with the root of Paeonia lactiflora crude extract as a natural whitening herbal drug. RESULTS: The result showed that galloylpaeoniflorin specifically inhibited monophenolase activity. While 1,2,3,4,6-pentagalloylglucose, gallic acid and catechin demonstrated the inhibition towards both monophenolase and diphenolase. Among them, 1,2,3,4,6-pentagalloylglucose can inhibit monophenolase activity was reported for the first time. In addition, antioxidant properties were attributed to catechin, 1,2,3,4,6-pentagalloylglucose and gallic acid. Due to its low content and complicated configuration in the root of Paeonia lactiflora, a new potential tyrosinase inhibitor and radical scavenger which tentatively identified as hexagalloylglucose by high-resolution MS was still need further verification. What's more, the molecular docking unveiled that bioactive enzymatic inhibitors mainly interacted with amino acid catalytic residues of tyrosinase via H-bonds and van der wals, which may be helpful to understand their inhibition mechanisms with tyrosinase in the skin whitening. CONCLUSIONS: The platform provided a promising and efficient strategy for the rapid screening of whitening active components from natural sources.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Monofenol Mono-Oxigenase/antagonistas & inibidores , Oxirredutases/antagonistas & inibidores , Paeonia , Preparações Clareadoras de Pele/farmacologia , Antioxidantes/farmacologia , Inibidores Enzimáticos/farmacologia , Humanos , Taninos Hidrolisáveis/farmacologia , Simulação de Acoplamento Molecular/métodos , Compostos Fitoquímicos/farmacologia , Extratos Vegetais/análise , Extratos Vegetais/farmacologia
6.
J Sep Sci ; 44(15): 2996-3003, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34086419

RESUMO

The minor ginsenosides with less polarity may have more potent biological activities. Four minor saponins, i.e., gypenoside XVII, ginsenoside Rd2, notoginsenoside Fe, and notoginsenoside Fd, were successfully separated from Panax notoginseng leaves (PNL) after biotransformation by one-step countercurrent chromatography using the biphasic solvent system consisting of n-butanol-ethyl acetate-water (1:4:5, v/v/v). 30 mg of the refined extract of PNL produced 1 mg of gypenoside XVII, 4 mg of notoginsenoside Fe, 2.5 mg of ginsenoside Rd2, and 8.4 mg of notoginsenoside Fd, with purity of 74.9, 95.2, 87.3, and 97.6%, respectively. Besides, orthogonality evaluation for the separation of the four saponins using countercurrent chromatography and liquid chromatography was discussed. Four minor saponins were successfully separated from each other on a preparative scale by countercurrent chromatography from PNL, which will facilitate to provide ample of these minor saponins for further pharmacological studies.


Assuntos
Distribuição Contracorrente/métodos , Ginsenosídeos/isolamento & purificação , Panax notoginseng/química , Folhas de Planta/química , Saponinas/isolamento & purificação , Solventes/química
7.
Zhongguo Zhong Yao Za Zhi ; 46(8): 2061-2066, 2021 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-33982520

RESUMO

In the pharmacopoeia, many process parameters for the purification process of Scutellariae Radix are unclear. In this study, deterministic screening design combined with design space method was used to optimize the purification process of Scutellariae Radix extract. Nine method parameters such as mass fraction of solution(X_1), first acid precipitation pH(X_2) and first holding time(X_3) in the purification process were firstly studied by definitive screening design. The yield of baicalin was defined as the evaluation index. A stepwise regression method was used then to build quantitative models between evaluation index and method parameters and the three most critical impact parameters were determined. Probability-based design space was calculated and successfully verified with the experimental error simulation method. Finally, the second standing temperature, the first standing temperature and the pH value of the second acid precipitation were determined as the three most critical method parameters. The recommended operating space was as follows: the second standing temperature 5-7 ℃, the first standing temperature 13-15 ℃, and the pH of the second acid precipitation 1.5-1.7. Within this operating space, the baicalin yield in the purification process was over 80%, and the probability of reaching the standard was over 0.96. In this study, we optimized the effect of various parameters for the purification process of the Scutellariae Radix extract in the pharmacopoeia on the yield of baicalin and provided a reference for industrial production of the exact of Scutellariae Radix.


Assuntos
Medicamentos de Ervas Chinesas , Scutellaria baicalensis , Flavonoides , Extratos Vegetais
8.
J Chromatogr A ; 1646: 462066, 2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-33845265

RESUMO

Maslinic acid and corosolic acid with high purity were successfully separated from Eriobotrya japonica (Thunb.) leaves by two-step countercurrent chromatographic separation. Two biphasic solvent systems composed of petroleum ether-ethyl acetate-ethanol-water (6:4:5:5, v/v) and petroleum ether-ethyl acetate-ethanol-0.10 mol/L of hydroxypropyl-ß-cyclodextrin with pH 7.0 (8:2:3.5:6.5, v/v) were selected according to the partition performance of the main structural isomeric pentacyclic triterpenes. The influences of pH value and concentration of hydroxypropyl-ß-cyclodextrin in separation of two isomers were investigated. In first step countercurrent chromatographic separation, a mixture of two target structural isomers (14.12 mg of sample I) was separated from 40.00 mg of a partially purified sample. In second step countercurrent chromatographic separation, maslinic acid and corosolic acid were completely isolated from 12.00 mg of sample I with hydroxypropyl-ß-cyclodextrin as aqueous phase additive. The recoveries of the two isomers were over 90%, yielding 5.18 mg of maslinic acid and 5.47 mg of corosolic acid, respectively.


Assuntos
2-Hidroxipropil-beta-Ciclodextrina/química , Distribuição Contracorrente/métodos , Eriobotrya/química , Triterpenos Pentacíclicos/isolamento & purificação , Folhas de Planta/química , Cromatografia Líquida de Alta Pressão/métodos , Triterpenos Pentacíclicos/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Estereoisomerismo
9.
J Sep Sci ; 44(13): 2655-2662, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33884745

RESUMO

To avoid irreversible stationary phase adsorption and tedious and time-consuming separation steps, high-speed countercurrent chromatography was employed for the preparative separation of anti-tumor compound antroquinonol from solid fermentation culture of Antrodia camphorata for the first time. A Box-Behnken experimental design, based on three parameters including liquid-to-solid ratio, extraction time, and extraction temperature, was applied to optimize the ultrasonic extraction procedure. The optimal extraction condition was set as follows: liquid-to-solid ratio: 49.57:1; extraction time: 55.76 min; extraction temperature was arranged as 44.21°C. Meanwhile, an optimized solvent system containing petroleum ether, ethyl acetate, methanol, and water (4:1:4:1, v/v/v/v) was selected for the preparative separation of antroquinonol at a flow rate of 2.0 mL/min. The yield of isolated antroquinonol was determined to be 6.0 mg from 0.67 g of ethyl acetate extracts. The isolated antroquinonol was elucidated by ultra-high-performance liquid chromatography-tandem mass spectrometry, and NMR spectroscopy, and by comparison with literature data. The purity of isolated antroquinonol was determined to be 97.12%. This study confirmed that high-speed countercurrent chromatography was powerful and cost-effective for the preparative separation of the high-potently anti-tumor compound antroquinonol from solid fermentation culture of A. camphorata.


Assuntos
Antineoplásicos/isolamento & purificação , Distribuição Contracorrente/métodos , Polyporales/química , Ubiquinona/análogos & derivados , Extratos Vegetais/química , Ubiquinona/biossíntese , Ubiquinona/isolamento & purificação
10.
J Sep Sci ; 44(1): 6-16, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32926765

RESUMO

As a liquid-liquid partition chromatography, counter-current chromatography has advantages in large sample loading capacity without irreversible adsorption, which has been widely applied in separation and purification fields. The main factors, including partition coefficient, two-phase solvent systems, apparatus, and operating parameters greatly affect the separation process of counter-current chromatography. To promote the applications of counter-current chromatography, it is essential to develop theoretical research to master the principles of counter-current chromatographic separations so as to achieve predictions before laborious trials. In this article, recent progress about separation prediction methods are reviewed from a point of the steady and unsteady state of the mass transfer process of counter-current chromatography and its mass transfer characteristics, and then it is divided into three aspects: prediction of partition coefficient, modeling the thermodynamic process of counter-current chromatography, and modeling the dynamic process of counter-current chromatography.

11.
J Ethnopharmacol ; 264: 113282, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32890716

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Shenqi Jiangtang granule (SJG) is an ancient Chinese herbal formula used for treatment of Diabetes mellitus and its complications. AIM OF THE STUDY: To establish an integrated approach for discovery of effective Aldose reductase inhibitors (ARIs) from SJG. MATERIALS AND METHODS: An integrated approach combining ultrafiltration-liquid chromatography-mass spectrometry (UF-LC-MS) with in silico molecular docking was established for development of ARIs. AR enzyme was separated from the rabbit's crystalline lens. The inhibitory activities of these compounds were detected by UV spectrophotometry with DL-glyceraldehyde as a substrate. Furthermore, molecular docking was used to understand the binding mechanism of these screened compounds interacting with AR. RESULTS: After optimization of AR reaction system and ultrafiltration incubation system, 17 active ingredients were screened from SJG by UF-LC-MS technique. Among these potential AR inhibitors, ginsenoside Rd exhibited the strongest activity with IC50 value of 45.77 µM. Three of them, calycosin, gomisin J and schisandrin A were demonstrated to be potential inhibitors for the first time, with IC50 at 447.34 µM, 181.73 µM, and 429.00 µM, respectively. Most of the active compounds exhibited competitive inhibition against AR. The docking scores of saponins were higher than that of lignans, which was consistent with the verification results. CONCLUSION: The results indicated that TCM formula with clinical efficacy was indeed hopeful source for screening active ingredients, and the combination of UF-LC-MS and in silico molecular docking was a universal and promising approach for development of effective enzyme inhibitors.


Assuntos
Aldeído Redutase/antagonistas & inibidores , Simulação por Computador , Medicamentos de Ervas Chinesas/análise , Medicina Tradicional Chinesa , Simulação de Acoplamento Molecular/métodos , Espectrometria de Massas em Tandem/métodos , Aldeído Redutase/química , Aldeído Redutase/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Avaliação Pré-Clínica de Medicamentos/métodos , Medicamentos de Ervas Chinesas/farmacologia , Inibidores Enzimáticos/análise , Inibidores Enzimáticos/farmacologia , Medicina Tradicional Chinesa/métodos , Estrutura Secundária de Proteína , Coelhos , Ultrafiltração/métodos
12.
J Chromatogr A ; 1637: 461804, 2021 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-33352504

RESUMO

2-(3-Methylphenyl)propanic acid and 2-(4-methylphenyl)propanoic acid were successfully enantioseparated by countercurrent chromatography using hydroxypropyl-ß-cyclodextrin (HP-ß-CD) as a chiral selector. 2-(2-Methylphenyl)propanoic acid was also studied to compare the enantioseparation ability of three isomeric 2-(methylphenyl)propanoic acids. Totally 20 mg of 2-(3-methylphenyl)propanic acid and 20mg of 2-(4-methylphenyl)propanic acid were enantioseparated individually by countercurrent chromatography. Recovery for the (±)-2-(3-methylphenyl)propanic acid enantiomer was in the range of 85%-90% with 98.0%-98.8% purity and recovery for the (±)-2-(4-methylphenyl)propanic acid enantiomer was in the range of 80%-83% with 97.0%-98.0% purity. The enantioseparation factor in countercurrent chromatography for 2-(4-methylphenyl)propanic acid and 2-(3-methylphenyl)propanic acid were 1.31 and 1.26, and the peak resolution in HPLC reached 2.2 and 1.4. However, no enantioseparation could be found for 2-(2-methylphenyl)propanic acid. In addition, the inclusion complexes were investigated by UV spectrophotometer. The inclusion formation constant of inclusion complex between 2-(4-methylphenyl)propanic acid, 2-(3-methylphenyl)propanic acid, 2-(2-methylphenyl)propanic acid and HP-ß-CD were determined as 121.73 mol/L, 78.12 mol/L and 53.18 mol/L, respectively. The present results showed that enantiorecognition was greatly affected by substituted positions of methyl group on the benzene ring. Combined with our previous results, the steric hindrance had a significant effect on inclusion interaction between HP-ß-CD and racemic 2-(substitutedphenyl)propanoic acids. No enantiorecognition could be achieved for 2-(substitutedphenyl)propanoic acids with ortho-substituent group on benzene, while the influence of meta- and para- group on enantiorecognition varies with different substituent groups on benzene ring.


Assuntos
Distribuição Contracorrente/métodos , Propionatos/química , 2-Hidroxipropil-beta-Ciclodextrina/química , Cromatografia Líquida de Alta Pressão/métodos , Espectrofotometria Ultravioleta , Estereoisomerismo
13.
J Sep Sci ; 44(3): 752-758, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33247875

RESUMO

2-(4-Chlorophenyl)succinic acid was successfully enantioseparated by countercurrent chromatography using hydroxypropyl-ß-cyclodextrin as chiral selector. A two-phase solvent system composed of n-hexane-ethyl acetate-0.1 mol/L phosphate buffer with pH 2.65 (5:5:10, v/v) was selected. Enantioselective liquid-liquid extraction was used to optimize the enantioseparation conditions. Meanwhile, the influence of injection volume on resolution in countercurrent chromatography was investigated and a linear relationship between the inflection point of injection volume and sample loading was tentatively obtained. The peak resolution will decrease significantly when the injection volume over the inflection point was used. In addition, it could be found that the smaller amount of sample loading, the larger impact of injection volume on resolution could be observed, which might serve as a good reference for the selection of sample volume in enantioseparations by countercurrent chromatography. Under optimized conditions, 20 mg of 2-(4-chlorophenyl)succinic acid racemate dissolved in 10 mL of aqueous phase was successfully enantioseparated by countercurrent chromatography. The recovery for both of the enantiomer of (±)-2-(4-chlorophenyl)succinic acid reached within 70-75% with a purity of 99.0%.

14.
J Chromatogr Sci ; 59(3): 212-216, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33257934

RESUMO

Five non-polar phloroglucinol derivatives, viz. pseudo-aspidin, α-kosin and agripinol A-C were isolated and purified from Agrimonia pilosa Ledeb by semi-preparative counter-current chromatography. The separation was performed by a two-step elution with non-aqueous solvent systems. In the first step, an elution mode of a two-phase solvent system consisting of n-hexane-acetonitrile-dichloromethane-methanol (6:6:0.5:0.5, v/v/v/v) was used. We obtained sample Ι containing three components (47.0 mg) and sample ΙΙ containing two components (24.8 mg) from crude extract (371.0 mg). In the second step, sample Ι was successfully separated by closed-loop recycling mode with a solvent system consisting of n-hexane-acetonitrile-dichloromethane (10:7:3, v/v/v), yielding 17.8 mg of pseudo-aspidin, 18.5 mg of α-kosin and 6.4 mg of agripinol A. The other two compounds-8.7 mg of agripinol B and 13.6 mg of agripinol C-were obtained from sample ΙΙ in the same manner. All the isolated compounds had a high purity exceeding 95%.


Assuntos
Agrimonia/química , Distribuição Contracorrente/métodos , Floroglucinol , Isomerismo , Floroglucinol/análogos & derivados , Floroglucinol/análise , Floroglucinol/isolamento & purificação , Extratos Vegetais/química , Solventes/química
15.
J Sep Sci ; 44(4): 922-930, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33284511

RESUMO

Ondansetron, a highly selective 5-hydroxytryptamine 3 receptor antagonist, was successfully enantioseparated by recycling countercurrent chromatography using sulfobutyl ether-ß-cyclodextrin as chiral selector. Important factors for the enantioseparation were optimized, including different organic solvent, type of substituted ß-cyclodextrin, pH of aqueous phase, concentration of chiral selector, and separation temperature. A biphasic solvent system composed of n-hexane: n-butyl acetate: 0.1 mol/L phosphate buffer solution pH 9.2 with 50 mmol/L of sulfobutyl ether-ß-cyclodextrin (2.5:7.5:10, v/v/v) was selected. Under optimized separation conditions, 5 mg of ondansetron was enantioseparated using recycling countercurrent chromatography, yielding 1.2 and 1.5 mg of ondansetron enantiomers with 97.5 and 95.8% purity and the recovery reached 48-60%.


Assuntos
Distribuição Contracorrente , Ondansetron/isolamento & purificação , beta-Ciclodextrinas/química , Concentração de Íons de Hidrogênio , Estrutura Molecular , Ondansetron/química , Estereoisomerismo
16.
J Chromatogr A ; 1634: 461666, 2020 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-33197846

RESUMO

Off-line two-dimensional countercurrent chromatography has been widely applied to the isolation of complex samples, but little research on the investigation of orthogonality in the selection of biphasic solvent systems is available. In the present work, the orthogonality in the selection of a biphasic solvent system for liquid-liquid chromatographic separation of aqueous extract and ether extract from the traditional Chinese medicinal plant Polygonum cuspidatum Sieb. et Zucc was evaluated by the correlation coefficient and space occupancy rate. In total, 25 different biphasic solvent systems were tested, and 313 system combinations were analysed. A convex hull methodology was used to determine the separation space and to optimize separation conditions. The correlation coefficient matrix was transformed into dendrograms and a colour map to visualize the dissimilarity between, and orthogonality for, all solvent systems. The aqueous extracts from Polygonum cuspidatum were separated using selected biphasic solvent systems with high orthogonality: ethyl acetate-ethanol-water (70:1:70, v/v) and petroleum ether-ethyl acetate-water (1:5:5, v/v). The ether extracts from Polygonum cuspidatum were also separated using selected biphasic solvent systems with high orthogonality: petroleum-ethyl acetate-methanol-aqueous 0.25 M NH3•H2O (5:5:5:5, v/v) and petroleum-ethyl acetate-methanol-water (5:5:5:5, v/v). Thirteen compounds were successfully obtained. The experimental results demonstrated that the evaluation of orthogonality provided an alternative strategy to select an applicable solvent system for the separation of complex samples using off-line two-dimensional countercurrent chromatography.


Assuntos
Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Cromatografia Líquida de Alta Pressão , Distribuição Contracorrente , Fallopia japonica/química , Extratos Vegetais/isolamento & purificação , Éter/química , Extratos Vegetais/química , Plantas Medicinais/química , Solventes/química , Água/química
17.
J Chromatogr A ; 1626: 461345, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797825

RESUMO

Modern liquid-liquid chromatography mainly refers to the following two kinds of chromatographic apparatuses: countercurrent chromatography based on hydrodynamic equilibrium systems and centrifugal partition chromatography based on hydrostatic equilibrium systems. In this paper, the recent advancements in enantioseparations by liquid-liquid chromatography, including the separation mechanism, chiral selector, two-phase solvent system, methods to improve the peak resolution and recent applications, are reviewed. The future outlook for liquid-liquid chromatography in enantioseparations is also proposed.


Assuntos
Cromatografia Líquida/métodos , Algoritmos , Distribuição Contracorrente , Concentração de Íons de Hidrogênio , Ligantes , Solventes/química , Estereoisomerismo
18.
Chirality ; 32(10): 1257-1263, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32743855

RESUMO

The inclusion interaction between hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and 21 2-aryl carboxylic acids was investigated by UV (ultraviolet) spectrophotometer. The inclusion constant of each 2-aryl carboxylic acids with HP-ß-CD was determined by Benesi-Hildebrand's equation. According to our previous work, it was found that a high inclusion constant for inclusion complex formed by a racemate and cyclodextrin was always observed with the fact that a high enantioseparation factor was achieved for the racemate in enantioseparation by liquid-liquid chromatography, which suggested that high binding combination between racemate and cyclodextrin is very important for a successful enantioseparation in enantioselective liquid-liquid extraction. Among all the studied subjects, mandelic acid enantiomer, 2,3-diphenylpropionic acid enantiomer, and naproxen enantiomer were selected for the further study. The inclusion constants of enantiomers of these three subjects were determined by UV spectra, which indicated that a necessary difference in inclusion constants between enantiomer and cyclodextrin was also essential. It was found in UV spectra that the absorbance of the analytes with the addition of cyclodextrin would increase or decrease, which was determined by the type of electron excitation. The conformation changes of small molecules can lead to the changes of chromophore valence electron clouds distribution, causing the HOMO-LUMO energy difference decreased. Thus, a red shift of the wavelength of the maximum absorption was produced indicating that the possibility of the molecular interaction of enantiomers with HP-ß-CD exists.

19.
Antioxidants (Basel) ; 9(8)2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32756519

RESUMO

Essential oils are an important source of natural antioxidants and multiple methods have been established for evaluation of their overall antioxidant activity, however, the antioxidant activities of their compounds are less investigated. In the present study, the hyphenation of 2,2'-diphenyl-1-picrylhydrazyl (DPPH)-gas chromatography (GC)-mass spectrometry (MS) offline and high-speed countercurrent chromatography (HSCCC) is established for efficient screening, identification, and isolation of antioxidants from essential oils and applied to the essential oil of Curcuma wenyujin Y.H. Chen et C. Ling. Five compounds are preliminarily screened as antioxidants using DPPH-GC according to the reduction of GC peak areas of each compound after reaction with DPPH and then identified as eucalyptol (7.66%), camphor (2.34%), δ-elemene (1.15%), ß-elemene (7.10%), and curzerene (15.77%) using GC-MS. Moreover, these five compounds are isolated by HSCCC using two solvent systems, n-hexane-acetonitrile-ethanol (5:3:2, v/v) and n-hexane-acetonitrile-acetone (4:3:1, v/v), and subjected to DPPH scavenging assay. Camphor, δ-elemene, and ß-elemene show weak DPPH scavenging activity, while curzerene and eucalyptol show moderate DPPH scavenging activity. Notably, a significant synergistic effect on DPPH scavenging is found between curzerene and eucalyptol. The result demonstrated that off-line DPPH-GC-MS coupling CCC is an efficient method for screening, identification, and separation of antioxidant compounds in essential oil.

20.
J Chromatogr A ; 1625: 461332, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709358

RESUMO

Two structural isomeric pentacyclic triterpenes, oleanolic acid and ursolic acid, were considered as the models for the quality control of many traditional Chinese herbal medicines and they have been proved to own important pharmacological activities. In the present work, liquid chromatographic and liquid-liquid chromatographic separation with high peak resolution of structural isomeric oleanolic acid and ursolic acid using hydroxypropyl-ß-cyclodextrin as mobile phase additive was successfully achieved, respectively. A high peak resolution, RS=8.143, was achieved for the two structural isomeric compounds by conventional reverse phase high performance liquid chromatography, which was greatly improved compared with the published values. Meanwhile, a biphasic solvent system composed of n-hexane-ethyl acetate-0.1 mol/L hydroxypropyl-ß-cyclodextrin (9:1:10, v/v) was selected for liquid-liquid chromatography, which provided a high peak resolution, RS = 6.573, for analytical apparatus and Rs = 8.500 for semi-preparative apparatus after optimization by liquid-liquid extractions. Two elution modes including reverse phase mode and normal phase mode were investigated for preparative separation of two acids from crude exact of Eriobotrya japonica Thunb. Furthermore, the inclusion complex between each of the two structural isomers and hydroxypropyl-ß-cyclodextrin were also investigated for high performance liquid chromatography and liquid-liquid chromatography, respectively, in which formation constants were determined for oleanolic acid and ursolic acid.


Assuntos
2-Hidroxipropil-beta-Ciclodextrina/química , Cromatografia Líquida/métodos , Ácido Oleanólico/química , Ácido Oleanólico/isolamento & purificação , Triterpenos/química , Triterpenos/isolamento & purificação , Cromatografia de Fase Reversa , Eriobotrya/química , Isomerismo , Solventes , Temperatura , Termodinâmica , beta-Ciclodextrinas/química
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