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ABSTRACT: Psoralea corylifolia L. (Fabaceae) is a traditional Chinese medicine with many beneficial effects in medical therapies. Bakuchiol was the main active ingredient of Psoralea corylifolia L. In this study, a novel method of pre-column derivatization with dansyl chloride followed by analysis of ultra high-performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) was established and validated for quantification of bakuchiol in rat plasma. The linearity of this approach was confirmed to be within the concentration range of 0.5-1000ng/mL and the lower limit of quantification was at 0.5ng/mL. The total analysis time was 1.5min for each pretreated sample. Also, the precision, accuracy, stability, recovery and matrix effect of this method were proved to meet the requirements for bioanalysis. The intravenous and oral pharmacokinetic profiles of bakuchiol were obtained by utilizing this approach. The oral bioavailability of bakuchiol in rats (3.2%) was identified.
Journal of pharmaceutical and biomedical analysis 03/2013; 75:18-24. · 2.45 Impact Factor
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ABSTRACT: The metabolite profiling of DAPA-7012 and DAAN-4442, the lead compounds from two new kinds of non-nucleoside reverse transcriptase inhibitors (NNRTIs), was performed using an ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS), with the assistance of a metabolite data processing software. By utilizing the mass defect filter (MDF) technique, the data acquired from the 0 h-incubation and the 2 h-incubation were compared and analyzed with the MetaboLynx software. After incubation, 14 metabolites of DAPA-7012 and 14 metabolites of DAAN-4442 were found in rat liver microsome. The MS2 spectra for some metabolites were obtained using the MS(E) technique to get fragment ions for structural elucidation. The results indicated that both compounds could undergo extensive metabolism in rat liver microsomes. The major phase I reaction was oxidation/hydroxylation. The major phase II reaction was S-glutathione conjugation. The metabolic pathways were similar between the two lead compounds, though they have different backbone structures. Besides, the 4-NO2 of ring B in DAAN-4442 was susceptible to reduction, the benzyl of ring C in DAPA-7012 was tend to be oxidized. The common metabolic soft spots were primary amine of ring B and two methyl groups of ring C. Early SAR results showed that the primary amine and methyl were necessary substituent groups. The stability of these active groups needs to be improved and optimized. The approach of combining metabolites information and structure-activity analysis can provide a reference for further structural optimization.
Yao xue xue bao = Acta pharmaceutica Sinica 12/2012; 47(12):1671-7.
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ABSTRACT: A simple and sensitive LC–MS–MS method was developed and validated to quantify CMDCK, a novel non-nucleoside reverse transcriptase
inhibitor in rat plasma. A simple protein precipitation with acetonitrile was used to pretreat plasma samples. Chromatographic
separation was carried out on a Hypersil GOLD-C18 (50mm×2.1mm, 5μm) column with the mobile phase consisting of acetonitrile and 0.1% formic acid solution (60:40 v/v) at a flow rate of 0.2mLmin−1. A triple-quadrupole tandem mass spectrometer with ESI source was operated in the positive ion mode. Quantitative analysis
was conducted in the selected reaction monitoring mode with precursor/product ion transitions of m/z 698/500 and 693/495, respectively for CMDCK and IS. The calibration curves were linear over the concentration range of 5–2,000ngmL−1 with the lower limit of quantification of 5ngmL−1. The intra- and inter-day precisions and accuracies were satisfactory, with the coefficient of variation and the relative
error being less than 13.2 and 3.38%, respectively. The recovery of CMDCK in plasma ranged from 84.6±6.5 to 100.8±9.3%.
This LC–MS–MS method was successfully used as a new approach for the preclinical pharmacokinetics study of CMDCK in rat.
KeywordsColumn liquid chromatography–tandem mass spectrometry–CMDCK–Pharmacokinetics
Chromatographia 04/2012; 73(7):649-657. · 1.20 Impact Factor
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ABSTRACT: 3-Hydroxymethyl-4-methyl-DCK (3, HMDCK) was discovered previously as a potent HIV non-nucleoside reverse transcriptase inhibitor (NNRTIs) (EC50: 0.004 μM, TI: 6225) with a novel mechanism of action. It exerts anti-HIV activity by inhibiting the production of HIV-1 double-stranded viral DNA from a single-stranded DNA intermediate, rather than blocking the generation of single-stranded DNA from a RNA template, which is the mechanism of action of current HIV-1 RT inhibitors. However, the insufficient metabolic stability of 3 limits its further clinical development. In the current study, a series of ester prodrugs of 3 was designed and synthesized to explore the new drug candidates as NNRTIs. The l-alanine ester prodrug 10 exhibited desirable pharmacokinetic properties in vitro and in vivo and showed improved oral bioavailability of 26% in rat, and would be a potential clinical candidate as a new anti-AIDS drug.
Acta pharmaceutica Sinica. B. 04/2012; 2(2):213-219.
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ABSTRACT: To investigate the metabolism of 3-cyanomethyl-4-methyl-DCK (CMDCK), a novel anti-HIV agent, by human liver microsomes (HLMs) and recombinant cytochrome P450 enzymes (CYPs).
CMDCK was incubated with HLMs or a panel of recombinant cytochrome P450 enzymes including CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4, and 3A5. LC-ion trap mass spectrometry was used to separate and identify CMDCK metabolites. In the experiments with recombinant cytochrome P450 enzymes, specific chemical inhibitors combined with CYP antibodies were used to identify the CYP isoforms involved in CMDCK metabolism.
CMDCK was rapidly and extensively metabolized by HLMs. Its intrinsic hepatic clearance estimated from the in vitro data was 19.4 mL·min(-1)·kg(-1), which was comparable to the mean human hepatic blood flow rate (20.7 mL·min(-1)·kg(-1)). The major metabolic pathway of CMDCK was oxidation, and a total of 14 metabolites were detected. CYP3A4 and 3A5 were found to be the principal CYP enzymes responsible for CMDCK metabolism.
CMDCK was metabolized rapidly and extensively in human hepatic microsomes to form a number of oxidative metabolites. CYP3A4 and 3A5 were the predominant enzymes responsible for the oxidation of CMDCK.
Acta Pharmacologica Sinica 10/2011; 32(10):1276-84. · 1.95 Impact Factor
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ABSTRACT: The biotransformation, CYP reaction phenotyping, the impact of CYP inhibitors and enzyme kinetics of 3-cyanomethyl-4-methyl-DCK (CMDCK), a new anti-HIV preclinical candidate belonging to DCK analogs, were investigated in human intestinal microsomes and recombinant cytochrome P450 (CYP) enzymes. CMDCK (4 micromol L(-1)) was incubated with a panel of rCYP enzymes (CYP1A2, 2C9, 2C19, 2D6 and 3A4) in vitro. The remaining parent drug in incubates was quantitatively analyzed by a LC-MS method. CYP3A4 was identified as the principal CYP isoenzyme responsible for its metabolism in intestinal microsomes. The major metabolic pathway of CMDCK was oxidation and a number of oxidative metabolites were screened with LC-MS. The Km, Vmax, CLint and T1/2 of CMDCK obtained from human intestinal microsome were 45.6 micromol L(-1), 0.33 micromol L(-1) min(-1), 12.1 mL min(-1) kg(-1) and 25.7 min, respectively. Intestinal clearance of CMDCK was estimated from in vitro data to be 3.3 mL min(-1) kg(-1), and was almost equal to the intestinal blood flow rate (4.6 mL min(-1) kg(-1)). The selective CYP3A4 inhibitors, ketoconazole, troleandomycin and ritonavir demonstrated significant inhibitory effects on CMDCK intestinal metabolism, which suggested that co-administration of CMDCK with potent CYP3A inhibitors, such as ritonavir, might decrease its intestinal metabolic clearance and subsequently improve its bioavailability in body.
Yao xue xue bao = Acta pharmaceutica Sinica 09/2010; 45(9):1116-22.
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ABSTRACT: Rotundine (1 micromol L(-1)) was incubated with a panel of rCYP enzymes (1A2, 2C9, 2C19, 2D6 and 3A4) in vitro. The remained parent drug in incubates was quantitatively analyzed by an Agilent LC-MS. CYP2C19, 3A4 and 2D6 were identified to be the isoenzymes involved in the metabolism of rotundine. The individual contributions of CYP2C19, 3A4 and 2D6 to the rotundine metabolism were assessed using the method of total normalized rate to be 31.46%, 60.37% and 8.17%, respectively. The metabolites of rotundine in incubates were screened with ESI-MS at selected ion mode, and were further identified using MS2 spectra and precise molecular mass obtained from an Agilent LC/Q-TOF-MSMS, as well as MS(n) spectra of LC-iTrap-MS(n). The predominant metabolic pathway of rotundine in rCYP incubates was O-demethylation. A total 5 metabolites were identified including 4 isomerides of mono demethylated rotundine and one di-demethylated metabolite. The results also showed that CYP2C19, 2D6 and 3A4 mediated O-demethylation of methoxyl groups at different positions of rotundine. Furthermore, the ESI-MS cleavage patterns of rotundine and its metabolites were explored by using LC/Q-TOF-MSMS and LC/iTrap-MS(n) techniques.
Yao xue xue bao = Acta pharmaceutica Sinica 03/2010; 45(3):307-13.
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ABSTRACT: The inter-species differences of thienorphine metabolism were investigated in human, Beagle dog and rat liver microsomes, by comparing enzyme kinetics of the parent drug and the formation of its major metabolites. The incubation systems of thienorphine with liver microsomes of the three species were optimized in terms of thienorphine concentration, microsomal protein content and incubation time. The concentrations of thienorphine and its metabolites in incubates were measured by a LC-MS/MS method. The biotransformation of thienorphine by human liver microsomes was the lowest among the three species. The K(m), V(max), CL(int) and T1/2 of thienorphine obtained from human liver microsomes were (4.00 +/- 0.59) micromol x L(-1), (0.21 +/- 0.06) micromol x L(-1) x min(-1), (117 +/- 3.19) mL x min(-1) x kg(-1) and (223 +/- 6.10) min, respectively. The corresponding kinetic parameters for dog and rat liver microsomes were (3.57 +/- 0.69) and (3.28 +/- 0.50) micromol x L(-1), (0.18 +/- 0.04) and (0.14 +/- 0.04) micromol x L(-1) x min(-1), (213 +/- 1.06) and (527 +/- 7.79) mL x min(-1) x kg(-1), (244 +/- 1.21) and (70.7 +/- 1.05) min, respectively. A total of six phase I metabolites were observed in liver microsomes, including one N-dealkylated metabolite, three oxidative metabolites and two N-dealkylated oxidation metabolites. All these six metabolites were detected in the liver microsomes of the three species. However, the relative amounts of the metabolites generated were different in three species. The results indicated that the major phase I metabolic pathway of thienorphine was similar in the liver microsomes from all three species. However, the inter-species differences observed were relative amounts of the metabolites as well as the metabolic characteristics of thienorphine in liver microsomal incubates.
Yao xue xue bao = Acta pharmaceutica Sinica 01/2010; 45(1):98-103.
