Yutian Wu

Determination of synthetic drugs used to adulterate botanical dietary supplements using QTRAP LC-MS/MS

Adulteration of botanical dietary supplements with prohibited synthetic drugs has become a serious problem. In this paper, a method for testing synthetic drugs used to adulterate botanical dietary supplements was developed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) coupled with a linearity ion-trap system in the multiple reaction monitoring (MRM) plus enhanced product ion (EPI) mode. Twenty-three drugs exhibiting various pharmacological effects, comprising blood pressure and lipid-lowering agents, sedative drugs, anti-diabetic drugs, weight-reducing agents and aphrodisiac compounds, were studied. For all drugs, a single transition was monitored using protonated molecules as precursor ions. EPI spectra were stored in a library and recognized by library searching. Several undeclared drugs were identified in herbal remedies, e.g., glibenclamide, sibutramine hydrochloride and sildenafil. Overall, 35 positive samples were found out of a total of 105 botanical dietary supplements tested. The method was selective, sensitive, rapid, high-throughput and reliable.

A proteomic method for analysis of CYP450s protein expression changes in carbon tetrachloride induced male rat liver microsomes

Carbon tetrachloride (CCl(4)) is a well-known model compound for producing chemical hepatic injury. Cytochrome P450 is an important monooxygenase in biology. We investigated the CYP450 protein expression in the in vivo hepatotoxicity of rats induced by CCl(4). In this experiment, CCl(4) were administered to male rats, and their livers at 24h post-dosing were applied to the proteomic analysis. Blood biochemistry and histopathology were examined to identify specific changes. At the same time, a novel acetylation stable isotopic labeling method coupled with LTQ-FTICR mass spectrometry was applied to disclose the changes of cytochrome P450 expression amounts. The quantitative proteomics method demonstrated its correlation coefficient was 0.9998 in a 100-fold dynamic range and the average ratio of the labeled peptides was 1.04, which was very close to the theoretical ratio of 1.00 and the standard deviation (S.D.) of 0.21. With this approach, 17 cytochrome P450 proteins were identified and quantified with high confidence. Among them, the expression amount of 2C11, 3A2, and 2 E1 were down-regulated, while that of 2C6, 2B2, and 2B1 were up-regulated.

Determination of berberine in Rhizoma coptidis and its preparations by non-aqueous capillary electrophoresis.

A non-aqueous capillary electrophoretic method was established for the determination of berberine in Rhizoma coptidis and its preparations. The effects of organic solvent and the concentrations of sodium acetate were studied, which showed that berberine in extracts of traditional Chinese medicine can be separated successfully in a buffer solution of 75 mmol/L of sodium acetate in methanol containing 1 mol/L of acetic acid. The simple and rapid method was linear in the range 25-200 microgram/mL of berberine and had a good reproducibility, with the relative standard deviation below 2%. Non-aqueous capillary electrophoresis is a satisfactory system for the analysis of alkaloids in traditional Chinese medicine.

Preparative Separation and Isolation of Three Flavonoids and Three Phloroglucinol Derivatives from Hypericum japonicum Thumb. using High‐Speed Countercurrent Chromatography by Stepwise Increasing the Flow Rate of the Mobile Phase

Abstract A preparative high‐speed counter‐current chromatography (HSCCC) was used to isolate and separate chemical compounds from the medicinal plant H. japonicum. First, the ethanol extract of H. japonicum was directly isolated by HSCCC without any preparation and three flavonoid glycosides including isoquercitrin, quercitrin, and quercetin‐7‐O‐rhamnoside were successfully purified using a two‐phase solvent system composed of ethyl acetate–ethanol–water at the volume ratio of 5:1:5 (v/v) by increasing the flow rate of the mobile phase from 1.0 mL/min to 2.0 mL/min after 120 min. After 400 min, the remaining compounds, mainly containing three phloroglucinol derivatives including sarothialen A, sarothralen B, and sarothalin G in the HSCCC column were forced out by pressurized nitrogen gas, which were further successfully separated by HSCCC with a two‐phase solvent system composed of n‐hexane–ethyl acetate–ethanol–water at the volume ratio of 1:1.2:1.2:1 (v/v) by increasing the flow rate of the mobile phase from 1.2 mL/min to 2.2 mL/min after 120 min. The fractions obtained from HSCCC were analyzed by high performance liquid chromatography, and the separation produced a total of 124 mg isoquercitrin, 85 mg quercitrin, 68 mg quercetin‐7‐O‐rhamnoside, 24 mg sarothialen A, 18 mg sarothralen B, and 58 mg sarothalin G from 750 mg ethanol extract, with the purities of 98.6%, 95.8%, 95.6%, 96.5%, 95.4%, and 98.6%, respectively. The chemical structural identification was carried out by MS, 1H NMR, and 13C NMR.

Determination of tetrahydropalmatine in Chinese traditional medicine by nonaqueous capillary electrophoresis.

Tetrahydropalmatine in Rhizoma corydalis and its preparations were separated and determined with no pretreatment in the buffer solution of 50 mmol/L of sodium acetate in methanol containing 2 mol/L acetic acid.

Determination of icariin in Chinese traditional medicine by capillary zone electrophoresis

Icariin in Chinese traditional medicine was determined by an accurate and simple capillary zone electrophoresis method which used 30 mmol/L of borate solution containing 10% of acetonitrile as running buffer and needed no pretreatment.

Determination of glycyrrhizin in Radix glycyrrhizae and its preparations by capillary zone electrophoresis

A capillary zone electrophoresis method was set up for the separation and determination of glycyrrhizin in Chinese medicinal preparations. Concentrations of Na(2)B(4)O(7) were optimized, which showed that glycyrrhizin in the sample could be separated from interference in the running buffer of 30 mmol/L Na(2)B(4)O(7). Using declofenac as internal standard, the simple method was linear in the range 25-300 microg/mL of glycyrrhizin, and good reproducibility was obtained. The extracts of Radix glycyrrhizae and its preparations could be injected directly for analysis without any pretreatment.