Search Results
You are looking at 121 - 130 of 190 items for
- Author or Editor: X. Wang x
- Refine by Access: All Content x
Summary
The chemical compositions of essential oils extracted by n-hexane extract (HE), petroleum ether extract (PE), dichloromethane extract (DE), and hydrodistillation (HD) from Carthamus tinctorius L. (safflower) were analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 86 compounds from four different extracts were identified, and the contents were 97.65%, 98.05%, 98.93%, and 99.68%, respectively. 6,10,14-Trimethyl-2-pentadecanone, hexadecanoic acid, methyl ester, hexadecanoic acid, 8,11-octadecadienoic acid, methyl ester, and 9,12,15-octadecatrien-1-ol were the major constituents of the extracts. The antidiabete activity was assayed in vitro by against protein tyrosine phosphatase 1B (PTP1B). The results showed that the HE exhibited the best in vitro inhibitory enzyme activity against PTP1B, which holds a good potential for treating diabetes and obesity.
Summary
Silica-gel column chromatography and preparative reversed-phase high-performance liquid chromatography (RP-HPLC) were sequentially employed for the isolation of two antioxidants including gallic acid and methyl gallate from Folium Toonea Sinensis. An RP-HPLC-UV method was then developed and validated to rapidly determine their content in this herb with ethyl gallate as internal standard. The quantitation was performed on an XBridge Shield RP18 column (150 mm × 4.6 mm, 5 μm) under 40°C. The mobile phase consisting of acetonitrile and 0.1% formic acid aqueous solution was driven at 1.0 mL min−1 under gradient elution, and 270 nm was selected to monitor the separation. To evaluate the fitness for purpose of the method and to investigate the difference in the content of analytes among different samples, the leaves collected from five production sites were analyzed. The newly established method is suitable for routine analysis of gallic acid and methyl gallate in the herb and, hence, can assist in its quality assessment. It was also found that not only the content of two antioxidants but also the ratio varied significantly among different geographical origins. In addition, three samples from Yantai, Zumadian, and Zhenjiang were distinguished as they have a much higher content ratio than the other two.
Summary
A preparative high-speed countercurrent chromatograph (HSCCC) method for the isolation and purification of C6-C2 natural alcohol and benzyl ethanol from Forsythia suspensa was successfully established. Cornoside, forsythenside F, forsythiaside, and acteoside were rapidly obtained for the first time by HSCCC with a two-phase solvent system ethyl acetate-n-butanol-methanol-water (5:1:0.5:5, υ/υ) in one-step separation. The purities of them were all above 97% as determined by high-performance liquid chromatography, and the combination of ESI-MS and NMR analysis confirmed the chemical structures of the four compounds.
A sensitive and simple liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for determination of dasatinib in rat plasma using one-step protein precipitation was developed. After addition of carbamazepine as internal standard (IS), protein precipitation by acetonitrile was used as sample preparation. Chromatographic separation was achieved on an SB-C18 (2.1 mm × 150 mm, 5 μm) column with methanol-0.1% formic acid as mobile phase with gradient elution. Electrospray ionization (ESI) source was applied and operated in positive ion mode; selective ion monitoring (SIM) mode was used to quantification using target fragment ions m/z 488.2 for dasatinib and m/z 338.7 for the IS. Calibration plots were linear over the range of 10–1000 ng mL−1 for dasatinib in rat plasma. Lower limit of quantification (LLOQ) for dasatinib was 10 ng mL−1. Mean recovery of dasatinib from plasma was in the range 82.2%–93.6%. Relative standard deviation (RSD) of intra-day and inter-day precision were both less than 8%. This developed method is successfully used in pharmacokinetic study of dasatinib in rats.
Epimedium pubescens Maxim. and Epimedium koreanum Nakai. are two common and confused species of Herba Epimedii in Chinese Pharmacopoeia 2010 edition. Different species and growing conditions lead to chemical differences between the two species which may result in the improper clinical usage. In this work, a new method based on rapid-resolution liquid chromatography combined with time-of-flight mass spectrometry (RRLC/TOFMS) has been developed for identification and differentiation of major flavonoids in two kinds of Epimedium extract and rat plasma. The compounds were identified effectively based on the accurate extract masses and formulae acquired by RRLC/TOFMS. The fragmentation rules deduced by collision-induced dissociation (CID) were successfully implemented in distinguishing some of the isomers, further validating the results. By using the combined analytical techniques, a total of 40 major flavonoids in extracts of two kinds of Epimedium were identified within 30 min, including 31 common components and 9 characteristic components. After oral administration, three prototype compounds in rat plasma were detected by comparing the constituents measured in vitro with those in vivo, and five metabolites were identified by contrasting the fragmentation rules. The identification and structural elucidation of the chemical constituents provided essential data for further pharmacological and clinical studies on different species of Epimedium.
Shenqi Fuzheng Injection (SFI) is a traditional Chinese medicine injection, widely used to enhance immune function of clinical cancer patients undergoing chemotherapy. In this study, a high-performance liquid chromatography-diode array detection-evaporative light scattering detection (HPLC-DAD-ELSD) method was established for quality control of SFI, which could simultaneously semiquantitatively reflect the constituents displayed in the chromatographic profile of SFI. The relative retention time and relative peak areas of the 21 common peaks related to the reference peak were calculated. The validity and advantage of this method were validated by systematically comparing chromatograms of 10 batches of SFI samples with the analytical methods of principal component analysis and angle cosine method recommended by the State Food and Drug Administration of China. Moreover, a total of 21 constituents of SFI were identified or tentatively characterized in the fingerprint via ultrafast liquid chromatography-diode array detection-quadrupole time-of-flight (UFLC-DAD-Q-TOF) tandem mass spectrometry technique on the basis of the retention time, ultraviolet spectra, fragmentation patterns, and reported literatures. All the results proved that the technique was useful in comprehensive quality evaluation of SFI and further study.
The rhizome of Sparganium stoloniferum Buch.-Ham has been used as a traditional Chinese folk medicine for thousands of years. Phenolic compounds are the main bioactive ingredients of the plant. In order to determine the content of phenolic compounds from different major cultivations, a reliable method has been developed using ultra-high performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry. Seven compounds, including rutin, kaempferol, p-hydroxybenzaldehyde, formononetin, ferulic acid, vanillic acid, and p-coumaric acid, were simultaneously measured in 10 min. The established approach was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery, and successfully applied to determine seven phenolic compounds of Rhizoma Sparganii. This study may be helpful in the quality control of Rhizoma Sparganii and can offer technical support for the pharmacological and clinical study of related drugs.
This paper develops an instrumental analytical approach for detection of fourteen polycyclic aromatic hydrocarbons (PAHs) in edible oil samples using gel permeation chromatography (GPC) and ultra-high performance liquid chromatography (UHPLC) coupled with diode array detector (DAD), and fluorescence detector (FLD). The GPC was used to remove triglycerides from edible oil samples. The extracted samples were then detected using UHPLC—DAD—FLD. In order to obtain good separation and high reproducibility, the UHPLC—DAD—FLD experimental condition was optimized. The PAHs including three groups of isomeric PAHs can be separated completely in 12 min using BEH Shield RP 18 column with a suitable gradient elution program. The mean recoveries were in the range of 73–110% with an acceptable reproducibility (RSD < 10%, n = 3). During real sample analysis, the method can decrease the chance of false positives with both DAD and FLD being used simultaneously. The results indicate that the approach is simple, easy, and acceptably reproducible, thereby showing great potential as a method for detection of fourteen PAHs contained in edible oil samples.
Phyllostachys edulis (PES), the most important bamboo species in China, is widely distributed in East Asia. Flavonoids, which are important bioactive natural compounds, often have similar structures, making their structural elucidation difficult. The aim of this study was to represent valuable, reliable mass spectral data for the identification of flavonoids in plant leaves. Ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC–Q-TOF-MS/MS) method was established for characterization and identification of the major flavonoids in PES leaf extract. A total of 13 flavonoids were simultaneously characterized, and their proposed characteristic product ions and fragmentation pathways were investigated. Thirteen compounds were separated on an Agilent Zorbax RRHD SB-C18 column (150 mm × 2.1 mm, 1.8 μm). On the basis of comparing with the 4 reference standards and the literature data, the other 9 flavonoids were identified by tandem mass spectrometry (MS/MS). Eight compounds (compounds 1, 4, 5, 8, 9, 10, 11, and 12) were found in PES leaves for the first time. An efficient UPLC–QTOF-MS/MS method was successfully applied for the structural identification of flavonoids in PES leaves. These results have practical applications for the rapid identification and structural characterization of these compounds in crude bioactive extracts or mixtures.
Molecularly imprinted polymers (MIPs) were synthesized by imprinting a new template—S(-)-1,1′-binaphthalene-2,2′-diamine (S-DABN) and applied as chiral stationary phases for chiral separation of DABN racemates by high-performance liquid chromatography (HPLC). The influence of some key factors on the chiral recognition ability of MIPs, such as the type of functional monomers and porogen and the molar ratio of template to monomer, was systematically investigated. The chromatographic conditions, such as mobile phase composition, sample loading, and flow rate, were also measured. The chiral separation for DABN racemates under the optimum chromatographic conditions by using MIP chiral stationary phase (CSP) of P3, prepared with the S-DABN/MAA ratio = 1/4 and used acetonitrile (2 mL) and chloroform (4 mL) as porogen, showed the highest separation factor (2.14). Frontal analysis was used to evaluate affinity to the target molecule of MIPs. The binding sites (B t) of MIPs and dissociation constant (K d) were estimated as 4.56 μmol g−1 and 1.40 mmol L−1, respectively. In comparison with the previous studies, this approach had the advantages, such as the higher separation factor, easy preparation, and cost-effectiveness, it not only has the value for research but also has a potential in industrial application.
