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ABSTRACT: A sensitive and selective liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for the determination of paclitaxel (Taxol) and its two major metabolites in human plasma has been developed. Samples were prepared after liquid-liquid extraction and analyzed on a C(18) column interfaced with a Q-Trap tandem mass spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase consisted of acetonitrile-water (0.05% formic acid) (65:35) at the flow rate of 0.25 mL/min. The analytes and internal standard docetaxel were both detected by use of multiple reaction monitoring mode. The method was linear in the concentration range of 0.5-500.0 ng/mL for paclitaxel, 6α-hydroxypaclitaxel and p-3'-hydroxypaclitaxel, respectively. The lower limit of quantification (LLOQ) was 0.5 ng/mL for paclitaxel, 6α-hydroxypaclitaxel and p-3'-hydroxypaclitaxel, respectively. The intra- and inter-day relative standard deviation across three validation runs over the entire concentration range was less than 8.18%. The accuracy determined at three concentrations was within ±10.8% in terms of relative error. The total run time was 7.0 min. This assay offers advantages in terms of expediency, and suitability for the analysis of paclitaxel and its metabolites in various biological fluids.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 05/2011; 879(22):2018-22. · 2.78 Impact Factor
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ABSTRACT: Endogenous ribonucleotides and deoxyribonucleotides play a critical role in cell function, and determination of their levels is of fundamental importance in understanding key cellular processes involved in energy metabolism and molecular and biochemical signaling pathways. In this study, we determined the respective ribonucleotide and deoxyribonucleotide pool sizes in different human cell lines using a simple sample preparation method and LC/MS/MS. This assay was used to determine alterations in deoxyribonucleotide pools in human pancreatic PANC1 cells in response to hypoxia and to treatment with either hydroxyurea or aphidicolin. The levels of all deoxyribonucleotide metabolites decreased with hypoxia treatment, except for dUMP, which increased by two-fold. This LC/MS/MS assay is simple, fast, and sensitive, and it represents a significant advance over previously published methodologies.
Biochemical pharmacology 05/2011; 82(4):411-7. · 4.25 Impact Factor
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ABSTRACT: Traditional Chinese Medicine (TCM) is increasingly being used in combination with Western medicine. In general, TCM is comprised of multiple components in sharp contrast to Western medicine, where a single active chemical is used. Presently, there are no well-established standards for most of the chemical compounds of TCM and their respective metabolites. Moreover, there are no formal analytical methods for the identification of these chemicals, especially in trace amounts. The ability to measure the pharmacokinetic behaviors of chemicals and their metabolites from these herbal formulations are critical in understanding of the action of TCM. This paper describes the use of LC/MS/MS along with enzyme treatments and n-octanol/water partition coefficient, to investigate the chemical components of PHY906 and their metabolites in the plasma of a patient with metastatic colorectal cancer (mCRC) treated with irinotecan and PHY906. The chemicals from an aqueous extract of PHY906 and the plasma from a patient was prepared and separated on an Agilent ZORBAX-SB C(18) column, and eluted with acetonitrile/0.05% (v/v) formic acid. From the PHY906 aqueous extract, a total of 57 compounds and 27 metabolites were identified and tentatively assigned structures based on their identified mass spectrometry, enzyme digestion and n-octanol/water partition coefficient. In contrast, analysis of patient plasma identified only 33 chemicals and new metabolites. These findings demonstrated that LC/MS/MS was and effective and reliable method for studying the parent chemicals of the Chinese herbal medicine PHY906 and their metabolites in a patient with metastatic colorectal cancer.
Journal of chromatography. A 09/2010; 1217(37):5785-93. · 4.19 Impact Factor
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ABSTRACT: PHY906, a four-herb Chinese medicine formula first described 1800 years ago, decreases gastrointestinal toxicity induced by the chemotherapeutic drug CPT-11 (irinotecan), as shown in a phase I/II clinical study. Similarly, in a murine colon 38 allograft model, PHY906 increased the antitumor activity of CPT-11 while decreasing animal weight loss caused by CPT-11. Here, we have further examined the effect of PHY906 on the intestinal toxicity caused by CPT-11 in mice. PHY906 did not protect against the initial DNA damage and apoptosis triggered by CPT-11 in the intestine, but by 4 days after CPT-11 treatment, PHY906 had restored the intestinal epithelium by promoting the regeneration of intestinal progenitor or stem cells and several Wnt signaling components. PHY906 also potentiated Wnt3a activity in human embryonic kidney-293 cells. Furthermore, PHY906 exhibited anti-inflammatory effects in mice by decreasing the infiltration of neutrophils or macrophages, tumor necrosis factor-alpha expression in the intestine, and proinflammatory cytokine concentrations in plasma. Chemical constituents of PHY906 potently inhibited nuclear factor kappaB, cyclooxygenase-2, and inducible nitric oxide synthase. Our results show that the herbal medicine PHY906 can counteract the toxicity of CPT-11 via several mechanisms that act simultaneously.
Science translational medicine 08/2010; 2(45):45ra59. · 7.80 Impact Factor
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ABSTRACT: A sensitive and selective liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for the determination of Irinotecan (CPT-11) and its metabolites in human plasma has been developed. Samples were prepared after protein precipitation and analyzed on a C(18) column interfaced with a Q-Trap tandem mass spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase consisted of acetonitrile-water (0.05% formic acid), using gradient procedure. The analytes and internal standard camptothecin were both detected by use of multiple reaction monitoring mode. The method was linear in the concentration range of 10.0-2000.0ng/ml for CPT-11 and 0.5-200.0ng/ml for 7-ethyl-10-hydroxycamptothecin (SN-38), respectively. The lower limit of quantification (LLOQ) was 10ng/ml for CPT-11 and 0.5ng/ml for SN-38. The intra- and inter-day relative standard deviation across three validation runs over the entire concentration range was less than 10.6%. The accuracy determined at three concentrations was within +/-11.4% in terms of relative error. Due to the unavailability of standard for 7-ethyl-10-O-glucuronyl-camptothecin (SN-38G) and the importance of knowing the concentration of this metabolite, we developed a method for analysis SN-38G by taking advantage of the quantitive conversion of SN-38G to SN-38 using glucuronidase. This enzymatic method of identification and quantitation of gluconated compound can be widely used when the standard for phase II glucuronide metabolites are not available.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 08/2009; 877(27):3038-44. · 2.78 Impact Factor
