Xiao-Mei Zhuang

Academy of Military Medical Sciences, T’ien-ching-shih, Tianjin Shi, China

Are you Xiao-Mei Zhuang?

Claim your profile

Publications (9)18.91 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Triptolide (TP), a main bioactive component of Tripterygium wilfordii Hook F., is a promising agent for treatment of autoimmune diseases. However, a high incidence of dose-limiting hepatotoxicity was observed in the clinic. Sandwich-cultured rat heptocyte model was used in this study to identify the involvement of P-glycoprotein (P-gp) in TP disposition and to evaluate TP-induced hepatotocivity after modulation of P-gp by the known inhibitors, ritonavir and tariquidar, and known inducers, phenobarbital, quercetin, and H2O2. Our data showed that biliary clearance of TP reduced 73.7% and 84.2% upon treatment of ritonavir (25 μM) and tariquidar (5 μM), respectively. In contrast, increases of 346%, 280%, and 273% in biliary clearance of TP were observed with treatment of Phenobarbital (1.0 mM), quercetin (20 μM), and H2O2 (0.5 mM), respectively. The TP-induced heaptotoxicity increased by 2-fold when CYP activity was blocked by 1-Aminobenzotriazole, suggesting that CYP and P-gp may both contribute to the detoxification of TP in the SCRH model. In addition, hepatotoxicity and the expression of apoptosis proteins, Bax and Bcl-2, were correlated qualitatively with the TP exposure duration and its intracellular concentration which, in turn, can be modulated by P-gp inhibitors or inducers. Our results, for the first time, demonstrated that in addition to CYP-mediated metabolism, P-gp also plays an important role in the disposition of TP and TP induced hepatoxicity. Thus, the modulation of canalicular P-gp has a potential to cause drug-drug interaction between TP and the co-administered P-gp inhibitors or inducers in the clinic.
    Drug metabolism and disposition: the biological fate of chemicals 09/2013; · 3.74 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Psoralen (PRN) and isopsoralen (IPRN), naturally occurred furanocoumarin compounds, are the bioactive constituents found in herbaceous plants. They are widely used as active ingredients in several Chinese herb medicines. In this study, the CYP1A2 inhibitory potential of PRN and IPRN was investigated in rat in vitro and in vivo, and as well as in human liver microsomes. Both compounds exhibited reversible and time-dependent inhibition toward rat microsomal cyp1a2. The IC50, kinact, and KI were 10.4 ± 1.4 μM, 0.060 ± 0.002 min(-1), and 1.13 ± 0.12 μM for PRN, and 7.1 ± 0.6 μM, 0.10 ± 0.01 min(-1) and 1.95 ±0.31 μM for IPRN, respectively. In human liver microsomal incubations, much potent reversible CYP1A2 inhibition was observed for both compounds as the IC50 values were 0.26 ± 0.01 and 0.22 ± 0.03 μM for PRN and IPRN, respectively. However, time-dependent inhibition was only observed for IPRN with kinact and KI of 0.050 ± 0.002 min(-1) and 0.40 ± 0.06 μM, respectively. Co-administered with PRN or IPRN significantly inhibited cyp1a2 activity in rats, with AUC of phenacetin increasing more than 5-fold. Simcyp(®) simulation predicted that PRN would cause 1.71 and 2.12-fold increase in phenacetin AUC in healthy and smoker populations, respectively. IPRN, on the other hand, would result in 3.24 and 5.01-fold increase in phenacetin AUC in healthy and smoker populations, respectively. These findings represent the first detailed report on DDI potential comparison of PRN and IPRN, and provide useful information for balancing the safe and efficacious doses of PRN and IPRN.
    Drug metabolism and disposition: the biological fate of chemicals 08/2013; · 3.74 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: An in vitro P-glycoprotein mediated drug biliary excretion model (B-Clear model) was developed and validated using sandwich-cultured rat hepatocytes (SCRH) and a model substrate rhodamine 123 (Rh123). SCRH formed functional bile canalicular networks after 5 days of culture. Rh123 (10 micromol x L(-1)) was then incubated with the SCRH in standard Ca+ Hanks buffer or Ca(2+)-free buffer. The cumulative cell uptake and canalicular efflux of Rh123 under Ca2+ and Ca(2+)-free conditions were measured with a LC-MS/MS method. The biliary excretion index (BEI) and instinct biliary clearance (CL(bile, int)) were calculated. To assess the effect of known P-gp inhibitors on the efflux of Rh123, cyclosporine A (CyA), tariquidar (TQD) or quinidine (QND) (10, 50 and 100 micromol x L(-1)) was pre-incubated separately with SCRH for 30 min, then co-incubated with Rh123. The BEI and CL(bile, int) of Rh123 obtained from the SCRH model were (17.8 +/- 1.3) % and (10.7 +/- 0.9) mL x min(-1) x kg(-1), respectively. All the three P-gp inhibitors showed a dose-dependent inhibition on the bile clearance of Rh123, indicating that the B-Clear model with SCRH was functional properly. The biliary excretion of loperamide (LPAD) and the role of P-gp were further investigated with this validated model. The BEI and CL(bile, int) for LPAD (20 micromol x L(-1)) were obtained after it was incubated with SCRH for 30 min, and found to be (12.9 +/- 1.2)% and (6.1 +/- 0.3) mL x min(-1) x kg(-1) respectively. The dose-dependent inhibition on LPAD biliary excretion by CyA, TQD or QND confirmed the major role of P-gp in LPAD canalicular efflux. The results suggested that the B-Clear model with SCRH would be a useful tool for evaluation of P-gp mediated efflux and drug-drug interaction.
    Yao xue xue bao = Acta pharmaceutica Sinica 04/2012; 47(4):459-65.
  • Source
    [show abstract] [hide abstract]
    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. · 2.35 Impact Factor
  • [show abstract] [hide abstract]
    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.
  • [show abstract] [hide abstract]
    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.
  • Source
    Jing-Ting Deng, Xiao-Mei Zhuang, Hua Li
    [show abstract] [hide abstract]
    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.
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: In prior investigation, we discovered that (3'R,4'R)-3-cyanomethyl-4-methyl-3',4'-di-O-(S)-camphanoyl-(+)-cis-khellactone (4, 3-cyanomethyl-4-methyl-DCK) showed promising anti-HIV activity. In these current studies, we developed and optimized successfully a practical 10-step synthesis for scale-up preparation to increase the overall yield of 4 from 7.8% to 32%. Furthermore, compound 4 exhibited broad-spectrum anti-HIV activity against wild-type and drug-resistant viral infection of CD4+ T cell lines as well as peripheral blood mononuclear cells by both laboratory-adapted and primary HIV-1 isolates with distinct subtypes and tropisms. Compound 4 was further subjected to in vitro and in vivo pharmacokinetic studies. These studies indicated that 4 has moderate cell permeability, moderate oral bioavailability, and low systemic clearance. These results suggest that 4 should be developed as a promising anti-HIV agent for development as a clinical trial candidate.
    Journal of Medicinal Chemistry 12/2008; 51(24):7689-96. · 5.61 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: A new two components partial least squares discriminant analysis (PLS) model for the prediction of P-glycoprotein-associated ATPase activity of drugs by using VolSurf compute theoretical molecular descriptors derived from 3D molecular interaction field was reported in the present study. By using 27 diverse drugs from literature, two models were constructed (R(2)=0.9003, 0.8150; Q(2)=0.7165, 0.7630) in this paper, which were similar to models that utilized MolSurf parametrization (R(2)=0.7760, 0.7180; Q(2)=0.7420, 0.6950) by using 22 drugs reported in the same literature. The results investigated VolSurf software was superior to MolSurf in its simplicity. Properties associated with the volume, polarizability, and hydrogen bond could have important impact on the P-glycoprotein-associated ATPase activity.
    International Journal of Pharmaceutics 03/2006; 309(1-2):109-14. · 3.46 Impact Factor