Kyungho Row

Extraction of catechin compounds from green tea with a new green solvent

An emerging green solvent called a deep eutectic solvent(DES) was applied to the extraction and determination of catechin(C), (+)epicatechin gallate(ECG) and (−)epigallocatechin gallate(EGCG) from Chinese green tea. After evaluating different combinations of them by extraction methods and DESs, a DES-based extraction method was established and optimized by a systematic investigation of the influencing factors. As a result, a total of 3.629, 35.25 or 114.2 mg/g catechin, (+)epicatechin gallate or (−)epigallocatechin gallate were extracted respectively under optimal conditions with extraction efficiencies of 82.7%, 92.3% and 97.0%, respectively. By comparing with other common used solvents for extracting catechin compounds, DESs were proved to be potential extraction solvents for bioactive ingredients.

Preparation and Application of Ionic Liquid-Modified Stationary Phases in High Performance Liquid Chromatography

Ionic liquid-modified stationary phases are an important class of stationary phase. They have been shown to have a capability of separating various classes of compounds in HPLC. In this review, we focus on the preparation and application of ionic liquid-modified stationary phases in HPLC. First, two common theories of retention mechanism in the ionic liquid-modified stationary phases in HPLC were discussed. Then, the preparations of two important types of stationary phase, ionic liquid-modified and poly(ionic liquids)-grafted silicas, were illustrated. Finally, applications of the ionic liquid-modified stationary phases in HPLC were reviewed, giving regard to the varieties of compounds separated or analyzed.

Sesquiterpenoids from Carpesium divaricatum and their cytotoxic activity.

In the course of searching for cytotoxic terpenoids from medicinal plants in China, two new eudesmane sesquiterpenoids, 5α-hydroxy-13-methoxy-7αH,11αH-eudesm-4(15)-en-12,8β-lactone (1) and 1β-hydroxy-7αH,11αH-eudesm-4(15)-en-12,8β-lactone (2), along with fourteen known sesquiterpenoids were isolated from the whole plant of Carpesium divaricatum. The structures of new compounds were determined using spectroscopic methods, including IR, HRESIMS, and 1D and 2D NMR spectroscopy. The cytotoxicity of selected sesquiterpene lactones against human oral epidermoid carcinoma (KB), human breast cancer (MCF-7) and human hepatoma (HepG-2) cells was also evaluated by MTT method.

Molecularly Imprinted Polymer for Solid-Phase Extraction of Phenolic Acids from Salicornia herbacea L.

This paper reports the application of a molecularly imprinted polymer (MIP) for the extraction and separation of phenolic acids from Salicornia herbacea L. (S. herbacea) using a solid phase extraction (SPE) system. The template of the MIP for phenolic acid extraction and separation was selected experimentally as one of seven templates. The obtained material with Benzoic acid (BA) as a template had the best extraction capacity of phenolic acids from S. herbacea. Water and methanol/HCl were selected as a washing solvent and elution solvent, respectively. The good linearity was obtained for the three targets, ranging from 10 to 500 μg mL−1 (R2 > 0.999), with relative standard deviations ≤ 5.0%. Overall, the proposed method using MIPs is expected to have a wide range of applications.

Optimum of Mobile Phase Condition for Resolving Isoflavones in RP-HPLC

Abstract In reversed-phase high performance liquid chromatography (RP-HPLC), the mobile phase condition for separating eight isoflavones (daidzin, glycitin, genistin, 6′-o-acetyl daidzin, 6-o-malonyl genistin, daidzein, glycitein and genistein) was optimized using the HCI (High-Purity Separation Laboratory, Department of Chemical Engineering, Inha University) program software. The optimum composition of mobile phase for the separation of the eight isoflavones was obtained. The elution profiles were calculated by the plate theory based on the equations of retention factor, In k = A+BF+CF2, where F was the volume percentage of acetonitrile with 0.1% acetic acid (AA). The first mobile phase composition was water with 0.1% AA/acetonitrile with 0.1% AA (88%/12%, by volume), followed at 9min later by the second composition of mobile phase which was step-changed to 85%/15%, at 19min by the third composition which was step-changed to 73%/27%, at 30min when it was changed to 65%/35% and finally it was maintained in isocratic mode to the end of the run time at 50min. Although, using step gradient mode to separate the isoflavones, the calculated and experimented data were not achieved very good agreement, we could estimate the closed retention time before experiment. And the agreement between the experimental data and the calculated values was relatively good using isocratic separation for eight isoflavones, but the retention time is very long.

Sesquiterpenoids from Petasites tatewakianus

850 0009-3130/11/4705-0850 2011 Springer Science+Business Media, Inc.1) Marine College, Shandong University at Weihai, Weihai 264209, P. R. China, fax: +86 631 5688303, e-mail:wdxie@sdu.edu.cn; 2) Department of Chemical Engineering, Inha University, Incheon 402-751, Korea, fax: +82 32 8720959,e-mail: rowkho@inha.ac.kr. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 742–743, September–October, 2011.Original article submitted June 19, 2010.

Extraction and Purification of Depigmenting Agents from Chinese Plants

Depigmenting agents were solvent-extracted and purified by preparative and analytical HPLC from three Chinese plants; Chrysanthemum morifolium Ramat (Xizang Caijuhua), Rhodiola sachalinensis , and Terminalia chebula Retzius . Four fractions obtained from the ethyl ether layer of C. m. Rama and two fractions from the ethyl acetate layer of Rhodiola salientness show depigmenting effects. At δ 200, the ethyl acetate layers of Chrysanthemum morifolium Ramat, Rhodiola sachalinensis and the methanol extract of Terminalia chebula Retzius , can inhibit the melanin production of mouse B16 melanoma cells by 92%, 60% and 90%, respectively, whereas 46% inhibition was observed by commercially available depigmenting agents (arbutin). These results show the potential of these three Chinese plants as a novel resource for depigmenting agents in the cosmetic industry.

Optimized Analytical Conditions for Eicosapentaenoic and Docosahexaenoic Acids in Antarctic krill Using Gas Chromatography

A simple method for the esterification of EPA and DHA in Antarctic krill was developed. When EPA and DHA standard solution (1.0 mg/mL in acetonitrile) reacted with equal volumes of 0.5% sulfuric acid-methanol at 60°C for 30 min, approximately 100% esterification conversion of EPA and DHA was achieved. Based on the esterification of EPA and DHA in Antarctic krill extraction solutions under these optimization conditions, the concentrations of EPA and DHA in fresh Antarctic krill were, respectively, 4.87 and 4.26 mg/g in the head, and 2.79 and 2.62 mg/g in the pleon. In the freeze-dried Antarctic krill, the amount of EPA and DHA were, respectively, 27.80 and 24.68 mg/g in the head, and 19.89 and 18.46 mg/g in the pleon.

Synthesis of 13-amino telekin derivatives and their cytotoxic activity

Telekin is a eudesmane sesquiterpene-lactone naturally occurring in many medicinal plants with antitumour and anti-inflammatory activity. In this study, a series of 13-amino derivatives of telekin have been synthesised through Michael addition reaction, and their relative configurations were exemplified by the single crystal X-ray diffraction of the dimethylamine adduct. The in vitro cytotoxicity against three tumour cell lines of these amine derivatives was evaluated. The piperidine and 4-hydroxypiperidine adducts displayed stronger cytotoxic activity than telekin.

Optimization and application of liquid chromatography determination of dispersive liquid-liquid microextraction purified astaxanthin in shrimp waste

A new molecularly imprinted solid-phase extraction(MISPE) monolithic cartridge was synthesized, and MISPE-DLLME(DLLME=dispersive liquid-liquid microextraction) was developed for purification of astaxanthin in shrimp waste. The eluent(methanol) from MISPE was used as the dispersive solvent in subsequent DLLME for further purifying and enriching the analyte prior to high-performance liquid chromatography(HPLC) analysis. The mobile phase was methanol-acetonitrile-water-dichloromethane(85:5:5:5, volume ratio), flow rate was 0.7 mL/min and UV wavelength was 476 nm. Under optimal conditions, good linearity was obtained in a range of 0.2–200.0 μg/mL(r2=0.9998) with a limit of detection(LOD) of 0.08 μg/mL, and the extraction recoveries at three spiked levels ranged from 88.3%–92.5% with a relative standard deviation(RSD) less than 4.3%. Moreover, the mean contents of astaxanthin in the three batches of shrimp waste were 95.9, 85.4 and 77.2 μg/g, respectively. This method combining the advantages of MISPE and DLLME results in high selectivity and low cost, which was applied to determining the astaxanthin level in shrimp waste samples.