Jinping Qiao

Effect of Tea Polyphenol Compounds on Anticancer Drugs in Terms of Anti-Tumor Activity, Toxicology, and Pharmacokinetics.

Multidrug resistance and various adverse side effects have long been major problems in cancer chemotherapy. Recently, chemotherapy has gradually transitioned from mono-substance therapy to multidrug therapy. As a result, the drug cocktail strategy has gained more recognition and wider use. It is believed that properly-formulated drug combinations have greater therapeutic efficacy than single drugs. Tea is a popular beverage consumed by cancer patients and the general public for its perceived health benefits. The major bioactive molecules in green tea are catechins, a class of flavanols. The combination of green tea extract or green tea catechins and anticancer compounds has been paid more attention in cancer treatment. Previous studies demonstrated that the combination of chemotherapeutic drugs and green tea extract or tea polyphenols could synergistically enhance treatment efficacy and reduce the adverse side effects of anticancer drugs in cancer patients. In this review, we summarize the experimental evidence regarding the effects of green tea-derived polyphenols in conjunction with chemotherapeutic drugs on anti-tumor activity, toxicology, and pharmacokinetics. We believe that the combination of multidrug cancer treatment with green tea catechins may improve treatment efficacy and diminish negative side effects.

Study the effect of a pseudo-carrier on pharmacokinetics of 9-fluoropropyl-(+)-dihydrotetrabenazine in rat plasma by ultra-performance liquid chromatography–tandem mass spectrometry

To evaluate the effect of a pseudo-carrier (9-hydroxypropyl-(+)-dihydrotetrabenazine, AV-149) on pharmacokinetics of 9-fluoropropyl-(+)-dihydrotetrabenazine (AV-133), an ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method was developed and validated for the determination of AV-133 and AV-149 in rat plasma. AV-133 and AV-149 were extracted from plasma following protein precipitation. The chromatographic analysis was performed on an ACQUITY UPLC BEH™ C₁₈ column (50 mm x 2.1 mm x 1.7 μm) by a gradient elution. The mass spectrometer was operated in positive mode using electrospray ionization. The analytes were measured using the multiple reaction-monitoring mode (MRM). An external calibration was used, and the calibration curves were linear in the range of 1.00-800 ng/mL for AV-133 and AV-149. The accuracy ranged from 90.8% to 113.2% and the precision ranged from 2.7% to 9.9% for each analyte. The effect of a pseudo-carrier on pharmacokinetics of AV-133 was studied using the presented method.

Determination of the penetration of 9-fluoropropyl-(+)-dihydrotetrabenazine across the blood–brain barrier in rats by microdialysis combined with liquid chromatography–tandem mass spectrometry

To evaluate the penetration of the blood-brain barrier by 9-fluoropropyl-(+)-dihydrotetrabenazine (AV-133), microdialysis probes were implanted simultaneously into rat blood and brain, and a liquid chromatography-tandem mass spectrometric method was developed and validated to monitor the AV-133 concentration in the microdialysates. The chromatographic separation was performed on an XTerra C(18) column (150 mm × 2.1 mm i.d., 5 μm particles) with gradient elution. The mass spectrometer was operated in positive mode using electrospray ionization. The analytes were measured using the multiple-reaction-monitoring mode. The calibration curves were linear over the range of 5.00-1000 ng/mL AV-133, with a coefficient of determination >0.995. The accuracies ranged from 99.5% to 105.0% and the precisions were <10% for AV-133. This method was used to determine the concentrations of AV-133 and its pharmacokinetics in the brains and blood of rats. The blood and brain concentration-time profiles for AV-133 were obtained, and the blood-brain barrier penetration was evaluated.

Study the pharmacokinetics of AV‐45 in rat plasma and metabolism in liver microsomes by ultra‐performance liquid chromatography with mass spectrometry

An ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method was developed and validated to determine AV-45 in rat plasma. After the addition of the internal standard benzophenone, plasma samples were pretreated by protein precipitation. Chromatographic separation was achieved on an Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, 1.7 µm) by gradient elution at a flow rate of 0.4 mL/min. Detection of analytes and internal standard (IS) was done by tandem mass spectrometry, operating in positive-ion and multiple reaction monitoring mode. The method was fully validated for its sensitivity, selectivity, accuracy and precision, matrix effect and stability study. The calibration curve showed good linearity over the concentration range 2.00-1000 ng/mL for AV-45. Intra- and inter-day precisions were less than 7.6%, and accuracy ranged from 100.6 to 107.8%. There was no matrix effect. The validated method was successfully applied to a pharmacokinetic study of AV-45 in rats. Additionally, the metabolism of AV-45 in rat liver microsomes was also studied by ultra-performance liquid chromatography combined with time-of-flight mass spectrometry (UPLC/TOF-MS). With the help of chromatographic behavior and accurate mass measurements, the metabolites were characterized.

DETERMINATION OF FLORFENICOL AMINE IN SWINE MUSCLE BY HYDROPHILIC INTERACTION LIQUID CHROMATOGRAPHY–TANDEM MASS SPECTROSCOPY

Nuflor (florfenicol) Premix for Swine is approved by the U.S. Food and Drug Administration (FDA) and the same regulatory agencies from many other countries for control of swine respiratory disease. A simple and fast LC-MS/MS method for the assay of florfenicol amine, the marker residue of florfenicol in swine muscle is described. A 24-hr strong acid hydrolysis of tissue residues converts florfenicol and its known metabolites into florfenicol amine and also fully releases florfenicol amine from florfenicol residues covalently bound to the swine muscle. The majority of fatty acids and lipids are removed via hexane extraction. Then, the pH of the extracted hydrolysate is adjusted to 11 and florfenicol amine is extracted by ethyl acetate. A portion of ethyl acetate extract is dried under nitrogen and reconstituted with 1 mL acetonitrile. Dispersive solid-phase extraction is used for cleanup in which 100 mg primary secondary amine sorbent is mixed with the extract. After the centrifugation, the supernatant is diluted 20-fold for a hydrophilic interaction LC-MS/MS analysis. No matrix effect is observed in the LC-MS/MS assay and the recovery is nearly 100%. In the comparison with the current US FDA Center for Veterinary Medicine regulatory surveillance method, the new method is simple, fast, and accurate. The validated method is used to investigate the depletion of florfenicol from the swine administrated with Nuflor (florfenicol) Premix.

Mapping the Target Localization and Biodistribution of Non-Radiolabeled VMAT2 Ligands in rat Brain

Imaging targeting vesicular monoamine transporter (VMAT2) alterations is a sensitive tool for early diagnosis of Parkinson’s disease. Our group has reported several novel 2-amino-DTBZ derivatives as potential VMAT2 imaging agents. The objective of this paper is to develop a non-radiolabeled methodology to screen the candidate compounds for accelerating the drug discovery process. 9-[18F]fluoropropyl-(+)-dihydrotetrabenazine ([18F]AV-133) is a PET imaging agent targeting VMAT2 binding sites in the brain. Nonradioactive AV-133 was injected (iv) into rats, at the end of the allotted time, the animals were killed and six regions of brain and plasma from each animal were processed for quantitative measurement of AV-133 by LC-MS/MS. These data were converted to the percentage injected dose per gram tissue weight (%ID/g tissue) and the brain target tissue to background ratios to allow direct comparison with data obtained by gamma counting of the injected radioactive [18F]AV-133. The %ID/g and the brain target tissue to background ratios calculated using the LC-MS/MS method were highly correlated to the values obtained by standard radioactivity measurements of [18F]AV-133. The pattern of AV-133 in rat brain was consistent with the known distribution of VMAT2. The concordance indicated that high-sensitivity LC-MS/MS is an indispensable tool in evaluating the quantity of administered chemical in tissue as part of the development of new molecular imaging probes. Furthermore, several novel 2-amino-DTBZ derivatives were detected using this methodology, and their biodistribution data in rat brain were obtained. The information about target engagements of candidates was provided.

Dose–response relationships of FMISO between trace dose and various macro-doses in rat by ultra-performance liquid chromatography with mass spectrometry and radioactivity analysis

Screening the pharmacokinetics of candidates using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) may be efficacious and safe for the research and development of new PET imaging agents. However, the PET imaging agent is administered as trace dose and the sensitivity of LC-MS/MS is often insufficient. If the dose was increased to be quantifiable, it should be necessary to prove whether the pharmacokinetics between trace and macro-doses is consistent or not. In this paper, fluoromisonidazole (FMISO), a tumor PET imaging agent, was chosen to evaluate the dose-response pharmacokinetics by administering various single intravenous doses (0.1, 0.4, 1.6 and 6.4 mg/kg) in male Sprague-Dawley rats. The plasma concentration of FMISO was determined by an ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method, and the blood radioactivity of [(18)F]FMISO was detected by a gamma counter. By calculating and comparing the pharmacokinetic parameters, the total area under the plasma concentration-time curve from time zero to infinity (AUC(0-∞)) and peak plasma concentration (C(max)) values increased with the selected FMISO doses, and showing linear dose-dependent. On the other hand, some parameters related to time, such as the elimination half-lives (t(1/2)) and elimination rate constant (K(e)) were dose-independent, and there is no significant deference between trace dose and various macro-doses. The data should be useful to evaluate the novel 2-nitroimidazole derivatives as potential PET tumor imaging agents.

Rapid Detection of the Residual Kryptofix 2.2.2 Levels in [18F]-Labeled Radiopharmaceuticals by Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry

A fast and sensitive ultra-performance liquid chromatography-tandem mass spectrometric (UPLC/MS/MS) method was developed and validated for determination of the residual levels of Kryptofix 2.2.2 (K222) in [18F]-labeled radiopharmaceuticals. The analytical time was only 3 min, and the injection volume was 5 μL. An electrospray ionization source was used in the positive mode (ESI+) for UPLC/MS/MS. The analytical measurements were performed in the multiple reaction monitoring (MRM) mode. The calibration curve at the spiked concentrations of 2–500 ng/mL for K222 showed good linearity. The intra- and inter-day precisions were not more than 5%. The accuracy satisfied the requirement of quality control analysis, the recoveries were found to be 80–120%. This method was successfully applied to detect the residue of K222 in [18F]-fluorodeoxyglucose [(18F)FDG], [18F]-fluoromisonizole[(18F)FMISO], 3′-deoxy-3′-[18F]-fluorothymidine [(18F)FLT], and two new [18F]-labeled radiopharmaceuticals 4-[-(2-[18F]fluoroethoxy) methyl]-1-[2-(2-methyl-5-nitro-1H- imidazol-1-yl) ethyl]-1H-1,2,3-triazole (named as 18F-BNU-1) and 4-[-(2-[18F] fluoroethoxy) methyl]-1-[2-(2-nitro-1H-imidazol-1-yl) ethyl]-1H-1,2,3-triazole (named as 18F-BNU-2) produced in our lab.

Brain uptake of a non-radioactive pseudo-carrier and its effect on the biodistribution of [18 F]AV-133 in mouse brain

INTRODUCTION 9-[(18)F]Fluoropropyl-(+)-dihydrotetrabenazine ([(18)F]AV-133) is a new PET imaging agent targeting vesicular monoamine transporter type II (VMAT2). To shorten the preparation of [(18)F]AV-133 and to make it more widely available, a simple and rapid purification method using solid-phase extraction (SPE) instead of high-pressure liquid chromatography (HPLC) was developed. The SPE method produced doses containing the non-radioactive pseudo-carrier 9-hydroxypropyl-(+)-dihydrotetrabenazine (AV-149). The objectives of this study were to evaluate the brain uptake of AV-149 by UPLC-MS/MS and its effect on the biodistribution of [(18)F]AV-133 in the brains of mice. METHODS The mice were injected with a bolus including [(18)F]AV-133 and different doses of AV-149. Brain tissue and blood samples were harvested. The effect of different amounts of AV-149 on [(18)F]AV-133 was evaluated by quantifying the brain distribution of radiolabelled tracer [(18)F]AV-133. The concentrations of AV-149 in the brain and plasma were analyzed using a UPLC-MS/MS method. RESULTS The concentrations of AV-149 in the brain and plasma exhibited a good linear relationship with the doses. The receptor occupancy curve was fit, and the calculated ED50 value was 8.165mg/kg. The brain biodistribution and regional selectivity of [(18)F]AV-133 had no obvious differences at AV-149 doses lower than 0.1mg/kg. With increasing doses of AV-149, the brain biodistribution of [(18)F]AV-133 changed significantly. CONCLUSION The results are important to further support that the improved radiolabelling procedure of [(18)F]AV-133 using an SPE method may be suitable for routine clinical application.

Developing a cassette microdosing approach to enhance the throughput of PET imaging agent screening

HIGHLIGHTSA novel cassette microdosing with LC‐MS/MS strategy was designed to evaluate the biodistribution of PET imaging agents.The results approached by LC‐MS/MS matched very well with the values obtained by standard radioactivity measurements.No significant differences between discrete microdosing and cassette microdosing were observed.The strategy would be a reasonably high throughput screening tool in the early research of PET imaging agents. ABSTRACT Cassette dosing is also known as N‐in‐One dosing: several compounds are simultaneously administrated to a single animal and then the samples are rapidly detected by LC–MS/MS. This approach is a successful strategy to enhance the efficiency of drug discovery and reduce animal usage. However, no report on the utility of the cassette approach in radiotracer discovery has appeared in the literature. This study designed a cassette microdose with LC–MS/MS method to enhance the throughput for screening radiopharmaceutical biodistribution in the rat brain directly. Three unradiolabeled compounds (FPBM FPBM2 and AV‐133) were chosen as model drugs administrated intravenously to the rats as a cassette as opposed to discrete study. The rat brain biodistribution data, target localization, the differential uptake ratio (%ID/g) and the brain tissue‐specific binding ratio were obtained by the LC–MS/MS analysis. These data matched very well with the values obtained by the standard radioactivity measurements. Moreover, no significant differences between discrete dosing and cassette dosing were observed. By circumventing the need for radiolabeled molecules, this method may be high‐throughput and safe for the research and development of new PET imaging agents. The combination of cassette microdosing and LC–MS/MS would be a medium throughput screening tool at an early stage in the discovery/development process of PET imaging agents.