Article pubs.acs.org/jnp
In Vitro and in Vivo Evaluation of Phenylbutenoid Dimers as Inhibitors of P‑Glycoprotein Song Wha Chae,† Ah-Reum Han,† Jung Hyun Park,† Jeong Yeon Rhie,† Hee-Jong Lim,‡ Eun-Kyoung Seo,† and Hwa Jeong Lee*,† †
College of Pharmacy, Graduate School of Pharmaceutical Sciences (Ewha Global Top 5 Program), Ewha Womans University, Seoul 120-750, Korea ‡ Bio-Organic Science Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Yusung-gu, Daejeon 305-600, Korea S Supporting Information *
ABSTRACT: The expression of P-glycoprotein (P-gp), an ATP-dependent efflux transporter, is closely associated with the failure of chemotherapy and drug absorption. Two synthesized optically active phenylbutenoid dimers, 3S-(3,4-dimethoxyphenyl)-4R-{(E)-3,4-dimethoxystyryl}cyclohex-1-ene (1) and 3R-(3,4-dimethoxyphenyl)-4S-{(E)-3,4-dimethoxystyryl}cyclohex-1-ene (2), were tested for their P-gp inhibitory effects by measuring cellular accumulation and efflux of daunomycin in P-gp-overexpressed human breast cancer cells (MCF-7/ADR). Compound 2 significantly increased the accumulation of daunomycin (539%) and decreased the efflux of this compound (55.4%), and similar results were observed for 1. ATPase assays and Western blot analysis were performed to identify the mechanisms by which compounds 1 and 2 inhibit P-gp. In addition, changes in the pharmacokinetic profile of paclitaxel coadministered with 2 in rats were evaluated. Paclitaxel (25 mg/kg) when orally administered with 2 (5 mg/kg) improved its relative bioavailability by 185%. Compound 2 effectively improved cellular accumulation by reducing the efflux of daunomycin and significantly enhanced oral exposure to paclitaxel. Therefore, compound 2 may be useful for improving oral exposure and cellular availability of drugs that are also substrates of P-gp.
pharmacological effects of racemic mixtures are different from those of the individual enantiomers. An example of this effect is verapamil, a calcium channel blocker used for hypertension and prophylaxis of supraventricular and ventricular arrhythmias. Verapamil is available commercially as a racemic mixture; however, the pharmacokinetic properties of each enantiomer have been reported to be different, with the bioavailability of Sand R-verapamil being 20% and 50%, respectively. 13 Furthermore, the antiarrhythmic effect of S-verapamil is 10 to 15 times higher than that of R-verapamil in humans.15,16 Recently, the effects of the R and S enantiomers of verapamil on MRP1 activity were also reported.17 Accordingly, the optically active phenylbutenoid dimers 3S-(3,4-dimethoxyphenyl)-4R-{(E)-3,4-dimethoxystyryl}cyclohex-1-ene (1) and 3R(3,4-dimethoxyphenyl)-4S-{(E)-3,4-dimethoxystyryl}cyclohex1-ene (2) were synthesized, and their effects on P-gp inhibition were evaluated in a preliminary manner in a previous study.18 The aim of the present study is to confirm the in vitro P-gp inhibitory activity of two synthesized optically active phenylbutenoid dimers, 1 and 2, and to identify their mechanism of action. In addition, the ability of compound 2 to enhance absorption and inhibit intestinal P-gp in vivo was investigated in rats using orally coadministered paclitaxel, an anticancer drug and P-gp substrate.
Zingiber cassumunar Roxb. (Zingiberaceae), widely distributed in Southeast Asia,1 is used in traditional medicine for bronchitis and gastrointestinal distress.2 Several phenylbutenoid dimers have been isolated from the rhizomes of Z. cassumunar, and diverse biological effects have been reported.3−9 Interest in phenylbutenoid dimers is growing due to their potential clinically applicable activities including modulation of cyclooxygenase-2 activity,7 neurotropic effects,8 and inhibition of Pglycoprotein (P-gp).9 Among these activities, P-gp inhibition is considered to be highly relevant for clinical applications. P-Glycoprotein is a 170 kDa membrane-binding glycoprotein and a member of the ATP-binding cassette (ABC) superfamily of drug efflux transporters. P-gp is expressed in the liver, small intestine, colon mucosa, blood−brain barrier, and kidneys of rodents and human.10,11 P-gp substrates exhibit a wide range of structural diversity, and 50% of all marketed drugs are either substrates or inhibitors of P-gp.12 The efflux function of P-gp in the intestines is a major reason for the low bioavailability of orally administered drugs. Previously, a phenylbutenoid dimer, (±)-trans-3-(3,4-dimethoxyphenyl)-4-[(E)-3,4-dimethoxystyryl]cyclohex-1-ene, isolated from a CHCl3 extract of the rhizomes of Z. cassumunar, has been tested for its ability to reverse multidrug resistance (MDR) activity in vitro.9 Since this phenylbutenoid dimer was isolated as a racemic mixture, it was subjected to biological evaluation in this form in the previous study.9 However, several studies have reported that the pharmacokinetic properties and © 2013 American Chemical Society and American Society of Pharmacognosy
Received: August 8, 2013 Published: November 22, 2013 2277
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RESULTS AND DISCUSSION Effects of Synthesized Optically Active Phenylbutenoid Dimers on Accumulation and Efflux of Daunomycin. Two synthesized optically active phenylbutenoid dimers (1 and 2) were evaluated in vitro for their cytotoxicity against Pgp-overexpressed human breast cancer cells (MCF-7/ADR). Verapamil, a well-known P-gp inhibitor, which was used as a positive control, was also tested for its cytotoxicity. At a concentration of 50 μM, none of the compounds were cytotoxic to MCF-7/ADR cells. Next, the accumulation and efflux of [3H]-daunomycin, a Pgp substrate, in MCF-7/ADR cells in the presence or absence (control) of 1 and 2 (50 μM) were probed to confirm its ability to inhibit the function of P-gp by 1 and 2 (Figure 1). As shown in Figure 1A, the accumulation of [3H]-daunomycin in the presence of 1 and 2 was increased significantly. In particular, the [3H]-daunomycin accumulation ratio was enhanced dramatically in the presence of compound 2 (539 ± 83.2%, p < 0.01), and the [3H]-daunomycin accumulation ratios of two synthesized optically active phenylbutenoid dimers were higher than that of verapamil (297 ± 16.5%, p < 0.01). The effects of 1 and 2 on [3H]-daunomycin efflux are shown in Figure 1B. According to this figure, compound 2 reduced the [3H]daunomycin efflux ratio significantly more than that of verapamil (55.4 ± 2.5%, p < 0.05 and 74.0 ± 6.6%, p < 0.05, respectively). In addition, compound 1 was also found to decrease the efflux ratio of [3H]-daunomycin. The accumulation and efflux results were also expressed as a percentage of the control treatment (Figure 1). According to the results obtained for the racemic mixture of 1 and 2 isolated from Z. cassumunar,9 the accumulation ratio of [3H]-daunomycin was 395 ± 14.4% and the [3H]-daunomycin efflux ratio was 42.5 ± 4.23% in the presence of 100 μM of the racemic mixture. In present study, compounds 1 and 2 were used at a 50 μM concentration, while the racemic mixtures isolated from Z. cassumunar were used at 100 μM.9 Despite using a lower concentration, the accumulation ratio of [3H]-daunomycin was increased to 1.4-fold by compound 2. Therefore, synthesized optically active phenylbutenoid dimers are more effective P-gp inhibitors than racemic mixtures. Mechanisms of P-gp Inhibitory Activity of the Synthesized Optically Active Phenylbutenoid Dimers. To evaluate the mechanism of the P-gp inhibitory activity of 1 and 2, ATPase assays and Western blot analysis were performed. As shown in Table 1, the ATPase activities of compounds 1, 2 and verapamil all exhibited a meaningful increase (>2-fold) on human P-gp membrane ATPase activity when compared with the control (2.4-, 2.2-, and 2.5-fold, respectively). The effects of 1 and 2 were also examined on cellular P-gp expression in MCF-7/ADR cells by Western blot analysis. As shown in Figure 2, MCF-7 cells exhibited no detectable expression of P-gp. In contrast, MCF-7/ADR cells significantly overexpressed P-gp in a significant manner. On the basis of
Figure 1. Effect of the synthesized optically active phenylbutenoid dimers (1 and 2) on [3H]-daunomycin accumulation (A) and efflux (B) in MCF-7/ADR cells. [3H]-daunomycin was examined in the presence of the phenylbutenoid dimers (50 μM) for 2 h (accumulation) or for 1 h (efflux). The control represents the [3H]daunomycin accumulation or efflux in the absence of the synthesized optically active phenylbutenoid dimers. Verapamil was used as a positive control. Each data point represents the mean ± SD of triplicate measurements from three independent experiments (*p < 0.05, **p < 0.01).
Table 1. Effect of Compounds 1 and 2 (each 50 μM) on P-gp ATPase Activity (nmol/min·mg protein)a compound 1 2 control verapamil a b
human P-gp membrane 126.2 113.1 52.21 130.3
± ± ± ±
4.90b 7.89b 6.39 2.86c
Values are presented as the means ± SD from duplicate experiments. p < 0.05 compared with control. cp < 0.01 compared with control.
these observations, neither of the phenylbutenoid dimers appeared to alter the expression of cellular P-gp level in MCF-7/ADR cells. Taken together, the results obtained suggested that compounds 1 and 2 may be P-gp inhibitors as well as P-gp substrates due to the observation of increased stimulation of ATPase activity.19 It has been reported that P-gp has multiple binding sites and that P-gp substrates can bind to more than one site at a time.20 Thus, compounds 1 and 2 may bind to one 2278
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Table 2. Pharmacokinetic Parameters of Paclitaxel after Injection (2 mg/kg, iv) or Oral Administration (25 mg/kg) with or without Compound 2 (5 mg/kg) in Ratsa
PK parameter C0 (ng/mL) Cmax (ng/mL) Tmax (h) AUClast (ng·h/mL) t1/2 (h) AB (%) RB (%)
Figure 2. Western blot analysis of P-gp expression in MCF-7/ADR cells after incubation for 2 h with 50 μM of the synthesized optically active phenylbutenoid dimers: (a) MCF-7; (b) MCF-7/ADR; (c) MCF-7/ADR treated with verapamil; (d) with compound 1; or (e) with compound 2.
paclitaxel iv (2 mg/kg)
paclitaxel po (25 mg/kg)
paclitaxel (25 mg/ kg, po) + compound 2 (5 mg/kg, po)
2910 ± 107
1067 ± 177 5.3 ± 1.3
173 2.0 892 5.9 6.7
± ± ± ±
49 0.0 69 0.63
228 4.0 1650 6.9 12.4 185
± ± ± ±
62 1.9b 350c 0.9
Data are presented as the means ± SD, n = 4−6. bp < 0.05 compared with paclitaxel po alone. cp < 0.01 compared with paclitaxel po alone. a
of the binding sites of P-gp. In addition, the results indicated that the binding affinity between P-gp and compounds 1 and 2 was higher than that of the P-gp substrate daunomycin. Therefore, while the latter substance may enter cells to reverse multidrug resistance, resulting in increased cytotoxicity, compounds 1 and 2 may inhibit the efflux function of P-gp by binding to at least one of the substrate binding sites. Thus, these in vitro results show that compound 2 significantly altered the ratio of [3H]-daunomycin accumulation and efflux, indicating that compound 2 is a good candidate for its ability to inhibit P-gp. Effect of 3R-(3,4-Dimethoxyphenyl)-4S-{(E)-3,4dimethoxystyryl}cyclohex-1-ene (2) on the Pharmacokinetics of Paclitaxel in Rats. To investigate the in vivo application of compound 2, which exhibited more potent P-gp inhibitory activity, the effect of this compound was tested on the oral absorption profile of paclitaxel, a P-gp specific substrate,21,22 in rats. The mean plasma concentration−time profiles of paclitaxel and pharmacokinetic parameters of this compound are shown in Figure 3 and Table 2, respectively. There were no statistically significant changes in the Cmax or eliminaton half-life (t1/2) of paclitaxel when the rats were administered 5 mg/kg of compound 2. However, the Tmax of paclitaxel was extended significantly from 2 to 4 h, increasing the amount of time paclitaxel has to absorb in the intestine. As the result, the AUClast of paclitaxel was increased by coadministration with compound 2, thus increasing the absolute bioavailability of paclitaxel by 1.9-fold.
In conclusion, compound 2 effectively improved cellular accumulation of daunomycin by decreasing the efflux of this compound as well as the oral exposure of paclitaxel via the inhibition of intestinal P-gp. The results of this study suggest that this synthesized optically active phenylbutenoid dimer may provide a therapeutic benefit when administered with orally delivered P-gp substrates.
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EXPERIMENTAL SECTION
Chemicals and Reagents. 3S-(3,4-Dimethxoyphenyl)-4R-{(E)3,4-dimethoxystyryl}cyclohex-1-ene (1, purity 98%) and 3R-(3,4dimethoxyphenyl)-4S-{(E)-3,4-dimethoxystyryl}cyclohex-1-ene (2, purity 99%) were prepared as described earlier.18 EIA grade affinitypurified goat anti-mouse IgG horseradish peroxidase conjugate was purchased from Bio-Rad Laboratories (Hercules, CA, USA). An antibiotic−antimycotic agent and RPMI 1640 medium were obtained from Invitrogen (Carlsbad, CA, USA). Fetal bovine serum was supplied by Wisent Inc. (Québec, Canada). Human P-glycoprotein membranes, BD Gentest ATPase assay kit, and Tris-base were purchased from BD Bioscience (Woburn, MA, USA). Mouse monoclonal anti-human P-glycoprotein clone (C219) and mouse monoclonal anti-β-actin, which was used as loading protein control, were obtained from Abcam (Cambridge, UK). Gel blotting paper and Protran nitrocellulose transfer membrane were purchased from Schleicher & Schuell (Dassel, Germany). TritonX-100 was purchased from USB (Cleveland, OH, USA). [3H]-Daunomycin (16 Ci/mmol) and Microscint 40 were supplied by PerkinElmer Life and Analytical
Figure 3. Mean plasma concentration−time profile after iv injection of paclitaxel (2 mg/kg) and oral administration of paclitaxel (25 mg/kg) alone or in combination with compound 2 in rats. Bars represent the standard deviation (n = 4−6): (●) paclitaxel (2 mg/kg) iv control, (○) paclitaxel (25 mg/kg, po) alone, (■) paclitaxel (25 mg/kg, po) coadministrated with compound 2 (5 mg/kg, po). 2279
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Cells were harvested and centrifuged at 13 000 rpm for 10 min at 4 °C. Next, 15 μL of RIPA buffer containing 1% protease inhibitor cocktail was added to lysates. The cell lysates were then incubated on ice for 20 min, sonicated for 2 min, and centrifuged at 13 000 rpm for 15 min at 4 °C. Supernatants were stored at −20 °C until used. Protein (30 μg) was electrophoresed using 7.5% SDS-polyacrylamide gels and transferred to nitrocellulose membranes. The membranes were blocked and incubated overnight with the primary antibody at 4 °C. After incubation with primary antibodies, membranes were incubated with anti-mouse IgG horseradish peroxidase for 2 h at room temperature. Western blot images were visualized with ECL Prime Western blotting reagent and analyzed using Multi-Gauge software (Fuji Photo Film Co., Ltd., Tokyo, Japan). Animal Preparations. Healthy male Sprague−Dawley rats (6−7 weeks old and 275−300 g) were housed individually in a lightcontrolled room maintained at 23 ± 3 °C and a relative humidity of 50 ± 5% with free access to a normal standard chow diet and tap water. Rats were kept under these conditions for at least five days prior to experiments. All rats underwent surgery for blood sampling one day before experiments. For the blood sampling procedure, each rat was anesthetized lightly with diethyl ether during the operation. After the carotid arteries of the rats were exposed surgically and cannulated using polyethylene tubing (PE-60) for blood sampling, the cannula were exteriorized by subcutaneous tunneling from the vascular incision site to the dorsal side of the neck. The external cannulas were extended using PE-60 tubing covered with a wire spring, and the PE60 tubing was connected to a heparin-filled 1 mL syringe to prevent blood coagulation and allow free movement of each rat. To prevent blood coagulation, the cannulas were first flushed and filled with heparinized isotonic saline (100 IU/mL). Rats were housed individually in cages for one day after surgery and prior to experiments to allow them to recover. During this time, rats were fasted overnight with free access to tap water. All animal procedures were approved by the Institutional Animal Ethics Committee of Ewha Womans University, Korea (IACUC No. 2012-01-019). Drug Formulation. Paclitaxel was dissolved in Cremophor EL (Sigma-Aldrich, St. Louis, MO, USA) and anhydrous ethanol (1/1, v/ v) to a concentration of 6 mg/mL, followed by dilution with isotonic saline to a final concentration of 2 mg/mL immediately prior to use. An oral formulation of 3R-(3,4-dimethoxyphenyl)-4S-{(E)-3,4dimethoxystyryl}cyclohex-1-ene (2) was prepared in a similar method to the paclitaxel formulation. Intravenous Injection or Oral Administration. Rats were divided into three groups consisting of two control groups and one experimental treatment group. Rats in the first control group were injected with paclitaxel (2 mg/kg) intravenously (iv), while the other was administered this compound (25 mg/kg) orally (po). The treatment group was coadministered paclitaxel (25 mg/kg) with 2 (5 mg/kg) orally. For the iv injection group, blood samples (0.2 mL) were obtained from the common carotid artery at 0, 0.033, 0.083, 0.25, 0.5, 1, 2, 3, 4, 6, 10, and 24 h. For the oral administration groups, blood samples (0.2 mL) were obtained at 0, 0.25, 0.5, 1, 2, 3, 4, 6, 8, 10, and 24 h. Collected blood samples were immediately centrifuged at 11 000 rpm for 15 min, and approximately 120 μL of plasma was obtained and stored at −20 °C until being analyzed by HPLC. HPLC Conditions. HPLC was performed with an Agilent HP1100 series system consisting of a model 1100 quaternary pump with a degasser pump, a model 1100 variable wavelength detector, a model 1100 thermostatic autosampler, and model HPLC 2D Agilent ChemStation software. Capcell-pak C18 MG120 columns (3 mm × 250 mm, 5 μm, Shiseido, Tokyo, Japan) were used as the analytical column. The mobile phase consisted of acetonitrile and 0.1% phosphoric acid (1:1, v/v) with a flow rate of 0.5 mL/min. Samples were detected at a wavelength of 227 nm using a UV detector. Sample Preparation Procedure. A total of 50 μL of internal standard dissolved in acetonitrile was added to 50 μL of each plasma sample and mixed by vortexing for 2 min. The mixture was then centrifuged at 13 000 rpm for 15 min at room temperature. Finally, 40 μL of each sample was injected into the HPLC system for analysis.
Sciences (Boston, MA, USA). Paclitaxel was purchased from Samyang Genex (Daejeon, Korea). The internal standard 4-hydroxybenzoic acid n-hexyl ester was purchased from Tokyo Kassei Kogyo (Tokyo, Japan). Phosphoric acid was obtained from Showa Chemical (Tokyo, Japan). High-performance liquid chromatography (HPLC)-grade acetonitrile and daunomycin were supplied by Merck (Darmstadt, Germany). Diethyl ether was purchased from Samchun Pure Chemical (Pyeongtaek, Korea). Heparin sodium injection was purchased from Hanlim Pharm (Yongin, Korea). (±)-Verapamil hydrochloride and all other reagents were purchased from Sigma-Aldrich (St. Louis, MO, USA). Male Sprague−Dawley rats were purchased from Orient Bio (Seongnam, Korea). Human breast cancer cells (MCF-7) and P-gpoverexpressed human breast cancer cells (MCF-7/ADR) were kindly donated by Dr. Marilyn E. Morris (State University of New York at Buffalo, NY, USA). Cell Cultures. Human breast cancer cells (MCF-7) and P-gpoverexpressing human breast cancer cells (MCF-7/ADR) were grown in RPMI 1640 supplemented with 10% fetal bovine serum, 2 mM Lglutamine, 10 mM HEPES, 24 mM NaHCO3, and 1% antibiotic− antimycotic agent. The cells were maintained at 37 °C in a humidified 5% CO2 atmosphere. Cells were cultured in 75 cm2 flasks for in vitro studies. [3H]-Daunomycin Accumulation and Efflux Assay. Accumulation and efflux studies using [3H]-daunomycin were performed as described previously23 with some modification. Cells were seeded in six-well plates at a density of 150 000 cells per well. After reaching 80− 90% confluence, cells were washed with uptake buffer (137 mM NaCl, 5.4 mM KCl, 2.8 mM CaCl2, 1.2 mM MgCl2, and 10 mM HEPES, pH 7.4). To test the effects of the synthesized optically active phenylbutenoid dimers on daunomycin accumulation, they were added along with 0.05 μM [3H]-daunomycin to MCF-7/ADR cells and incubated for 2 h. For efflux studies, cells were incubated with 0.05 μM [3H]-daunomycin dissolved in uptake buffer for 1 h. After being washed with uptake buffer, 1 mL of 50 μM of the synthesized compounds dissolved in uptake buffer was added to the cells for 1 h. The reaction was then quenched by removing the incubated compounds and washing cells with ice-cold stop buffer (137 mM NaCl, 14 mM Tris base, pH 7.4). Cells were then solubilized using 1 mL of lysis buffer (containing 1% TritonX-100) with shaking for 1 h. A 100 μL amount of each aliquot was then mixed with 200 μL of liquid scintillation counter cocktail in 96-well plates by overnight shaking. The radioactivity of each aliquot was determined with a liquid scintillation counter. Accumulation and efflux values were normalized per 107 cells, and each value was expressed as the percentage ratio of the control. Verapamil was used as a positive control. Experiments were performed three times with triplicate measurements. Human P-Glycoprotein ATPase Activity Assay. P-gp ATPase activity was determined using human P-gp membrane, according to the manufacturer’s instructions. The ATPase activity of human P-gp membrane was estimated by measuring the amount of inorganic phosphate (Pi) liberated by hydrolysis of ATP. First, synthesized compounds and verapamil at 50 μM (the final concentrations) were added to each well of a 96-well plate with or without 300 μM sodium orthovanadate. Next, 20 μg of human P-gp membrane was loaded into wells, followed by incubation of the plate in a 37 °C water bath for 5 min. After incubation, preincubated 4 mM Mg-ATP was added to all of the wells to initiate the ATPase reaction, and the plate was incubated in a 37 °C water bath for 0 or 20 min. At the indicated times, the reaction was terminated, and the ATPase activities were estimated by measuring the difference in released Pi after incubation periods of 0 and 20 min. The released Pi was measured by a colorimetric reaction and quantified using a phosphate standard curve. ATPase activities were expressed as the rate of phosphate release per milligram of membrane protein. Western Blot Analysis. MCF-7/ADR cells were seeded in six-well plates at a density of 150 000 cells per well. When cells reached 80− 90% confluence, they were washed with uptake buffer and treated with or without 50 μM of the synthesized compounds dissolved in uptake buffer for 2 h. At that time, MCF-7 cells that were not treated with compounds were prepared to provide a control for P-gp expression. 2280
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Pharmacokinetic Analysis. The pharmacokinetic parameters of paclitaxel following iv and oral administration to rats were estimated by noncompartmental analysis using WinNonlin Professional version 5.2 software (Pharsight Corporation, Mountain View, CA, USA). The pharmacokinetic parameters estimated from plasma concentration− time profiles were as follows: area under the plasma concentration− time curve from time 0 to the last sampling time (AUClast), initial plasma concentration (C0), and elimination half-life (t1/2). The maximum plasma concentration (Cmax) and the time required to reach Cmax (Tmax) were determined directly from plasma concentration−time curves. The absolute bioavailability (AB, %) and relative bioavailability (RB, %) of paclitaxel were calculated using the following formulas:
AB (%) =
RB (%) =
AUCpo AUCiv
×
(9) Chung, S. Y.; Han, A. R.; Sung, M. K.; Jung, H. J.; Nam, J. W.; Seo, E. K.; Lee, H. J. Phytother. Res. 2009, 23, 472−476. (10) Lin, J. H. Adv. Drug Delivery Rev. 2003, 55, 53−81. (11) Chan, L.; Lowes, S.; Hirst, B. H. Eur. J. Pharm. Sci. 2004, 21, 25−51. (12) Keogh, J. P.; Kunta, J. R. Eur. J. Pharm. Sci. 2006, 27, 543−554. (13) Echizen, H.; Manz, M.; Eichelbaum, M. J. Cardiovasc. Pharmacol. 1988, 12, 543−546. (14) Vogelgesang, B.; Echizen, H.; Schmidt, E.; Eichelbaum, M. Br. J. Clin. Pharmacol. 2004, 58, S796−S803. (15) Echizen, H.; Brecht, T.; Niedergesäss, S.; Vogelgesang, B.; Eichelbaum, M. Am. Heart J. 1985, 109, 210−217. (16) Echizen, H.; Vogelgesang, B.; Eichelbaum, M. Clin. Pharmacol. Ther. 1985, 38, 71−76. (17) Perrotton, T.; Trompier, D.; Chang, X. B.; Di Pietro, A.; Baubichon-Cortay, H. J. Biol. Chem. 2007, 282, 31542−31548. (18) Chu, J.; Suh, D. H.; Lee, G.; Han, A. R.; Chae, S. W.; Lee, H. J.; Seo, E. K.; Lim, H. J. J. Nat. Prod. 2011, 74, 1817−1821. (19) Loo, T. W.; Clarke, D. M. J. Biol. Chem. 2001, 276, 14972− 14919. (20) Becker, J.; Depret, G.; Van Bambeke, F.; Tulkens, P.; Prévost, M. BMC Struct. Biol. 2009, 9, 3. (21) Huizing, M.; Misser, V. H. S.; Pieters, R.; ten Bokkel Huinink, W.; Veenhof, C.; Vermorken, J.; Pinedo, H.; Beijnen, J. Cancer Invest. 1995, 13, 381−404. (22) Wood, A. J. J.; Rowinsky, E. K.; Donehower, R. C. N. Engl. J. Med. 1995, 332, 1004−1014. (23) Harker, W. G.; Sikic, B. I. Cancer Res. 1985, 45, 4091−4096.
iv dose × 100 po dose
AUCcoadministration × 100 AUCpocontrol
where AUCpo is the AUC obtained from the oral administration of paclitaxel, AUCiv is the AUC obtained from intravenous injection of paclitaxel, AUCcoadministration is the AUC obtained from the oral coadministration of paclitaxel with compound 2, and AUCpo control is obtained from the oral administration of paclitaxel alone. Statistical Analysis. All data are presented as the mean with standard deviation (means ± SD). Statistical analyses were conducted using Student’s t test. Values of p < 0.05 are considered statistically significant.
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ASSOCIATED CONTENT
S Supporting Information *
This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author
*Tel: +82 2 3277 3409. Fax: +82 2 3277 3051. E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (Basic Science Research Program: 2012-0004439).
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REFERENCES
(1) Mori, I.; Nakachi, Y.; Ueda, K.; Uemura, D.; Hirata, Y. Tetrahedron Lett. 1978, 19, 2297−2298. (2) Amatayakul, T.; Cannon, J.; Dampawan, P.; Dechatiwongse, T.; Giles, R.; Huntrakul, C.; Kusamran, K.; Mokkhasamit, M.; Raston, C.; Reutrakul, V. Aust. J. Chem. 1979, 32, 71−88. (3) Jitoe, A.; Masuda, T.; Nakatani, N. Phytochemistry 1993, 32, 357− 363. (4) Lee, J. W.; Min, H. Y.; Han, A. R.; Chung, H. J.; Park, E. J.; Park, H. J.; Hong, J. Y.; Seo, E. K.; Lee, S. K. Biol. Pharm. Bull. 2007, 30, 1561−1564. (5) Lu, Y.; Liu, R.; Berthod, A.; Pan, Y. J. Chromatogr. A 2008, 1181, 33−44. (6) Han, A. R.; Min, H. Y.; Windono, T.; Jeohn, G. H.; Jang, D. S.; Lee, S. K.; Seo, E. K. Planta Med. 2004, 70, 1095−1097. (7) Han, A. R.; Kim, M. S.; Jeong, Y. H.; Lee, S. K.; Seo, E. K. Chem. Pharm. Bull. 2005, 53, 1466−1468. (8) Matsui, N.; Kido, Y.; Okada, H.; Kubo, M.; Nakai, M.; Fukuishi, N.; Fukuyama, Y.; Akagi, M. Neurosci. Lett. 2012, 513, 72−77. 2281
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