Yuan Gao

Nanjing University of Traditional Chinese Medicine, Nan-ching, Jiangsu Sheng, China

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Publications (28)72.32 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the effect of preparation methods on cocrystallization between baicalein (BE) and nicotinamide (NCT), their intermolecular interaction, and to demonstrate that BE-NCT cocrystal can achieve the simultaneous enhancement in solubility, dissolution, and oral bioavailability of BE. The cocrystals from three preparation methods have the similar differential scanning calorimetry thermograms and X-ray powder diffraction patterns. Compared with crystalline BE, BE-NCT cocrystal has significantly improved the solubility and dissolution of BE. In addition, the cocrystal exhibits a 2.49-fold higher peak plasma concentration (Cmax ) and 2.80-fold higher area under the curve (AUC) in rats. This prominent improvement in oral bioavailability is even greater than the previously reported BE nanocrystal. This investigation enriched the present understanding of cocrystals on their behavior in vitro and in vivo, and built the groundwork for future development of BE as a promising compound into efficacious drug products. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci.
    Journal of Pharmaceutical Sciences 06/2014; · 3.13 Impact Factor
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    ABSTRACT: In this paper, a lipid material glycerol monooleate was used as the starting material to synthesize the oxidized glycerol monooleate (OGMO). OGMO was subsequently linked to chitosan (CS) via imine bonds (CN) to obtain a new chitosan-based polymer (OGMO-CS), which can form hydrogels rapidly in aqueous media. Scanning electron microscopy, swelling behavior studies and degradation kinetics studies were performed to demonstrate the effect of this synthetic modification on the hydrogels formation of chitosan network and in vitro drug release. The effects of OGMO-CS type, dry hydrogels percentage, release media and drug loading on the sustained release of the model drug trimetazidine hydrochloride were evaluated. The release profiles of the hydrogels could be described by the Peppas-Sahlin mechanism, a combination of Fickian diffusion and Case-II relaxation. Based on the fact that numerous pharmaceutical lipids are available, the present study may pave the way for other lipids to be employed as modifiers of chitosan for more innovative chitosan derivatives with versatile properties and pharmaceutical applications.
    International Journal of Pharmaceutics 02/2014; · 3.99 Impact Factor
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    ABSTRACT: Nrf2-mediated activation of ARE regulates expression of cytoprotective enzymes against oxidative stress, inflammation and carcinogenesis. We have discovered a novel structure (1) as an ARE inducer via luciferase reporter assay to screen the in-house database of our laboratory. The potency of 1 was evaluated by the expression of NQO-1, HO-1 and nuclear translocation of Nrf2 in HCT116 cells. In vivo potency of 1 was studied using AOM-DSS models, showing that the development of colorectal adenomas was significantly inhibited. Administration with 1 lowered the expression of IL-6, IL-1β and promoted Nrf2 nuclear translocation. These results indicated that 1 is a potent Nrf2/ARE activator, both in vitro and in vivo. 41 derivatives were synthesized for SAR study, and a more potent compound 17 was identified. To our knowledge, this is a potent ARE activator. Besides, its novel structure makes it promising for further optimization.
    Journal of Medicinal Chemistry 09/2013; · 5.61 Impact Factor
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    ABSTRACT: When exposed to electrophiles, human colorectal cancer cells (HCT116) counteract oxidative stress through activating NF-E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway. To identify new activators, luciferase reporter gene assay was used to screen in-house database of our laboratory, leading to a novel α-pyrone compound 1 as a hit. 2 with 2-fluoro phenyl group exhibited the strongest ARE inductive activity in the first round structure-activity relationship (SAR) study. Biological studies showed the compound induced nuclear translocation of Nrf2 preceded by phosphorylation of ERK1/2. The data encouraged us to use 2 as lead and 20 derivatives were synthesized to discuss a more detailed SAR, leading to a more potent compound 9, which can be the starting compound for further modification.
    European journal of medicinal chemistry 06/2013; 66C:364-371. · 3.27 Impact Factor
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    ABSTRACT: Recently, coamorphous systems composed of two drugs or a drug and a small molecule excipient, gained interests due to their ability in overcoming limitations associated with solid dispersions. In this study, coamorphous form of repaglinide (REP), a BCS class II anti-diabetic drug with low aqueous solubility and high permeability was achieved with saccharin (SAC) by solution crystallization and characterized. An accurate and precise HPLC method was established for the simultaneous determination of REP and SAC. Coamorphous REP-SAC with 1:1 stoichiometry had unique thermal behavior, obvious FTIR shifts and the absence of sharp diffraction peak, suggesting the formation of a coamorphous material and interaction of REP with SAC through hydrogen bonds formed between REP's secondary amine and SAC's carbonyl group. Coamorphous REP-SAC showed great improvement in solubility and dissolution under sink conditions in various media. In addition, It was conformed in supersaturated dissolution of coamorphous REP-SAC in distilled water that the coamorphous material had remarkably longer time length for REP to be remained at a supersaturated concentration and had better metastable solubility. This coamorphous system provides a feasible way to process drugs with low solubility into substances with enhanced dissolution and stabilized amorphous state that could be conducive to greater bioavailability than the crystalline drug.
    International Journal of Pharmaceutics 04/2013; · 3.99 Impact Factor
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    ABSTRACT: The aim of the study was to investigate the potential of nanocrystals to enhance the oral bioavailability of apigenin (AP), a bioactive flavonoid with various pharmacological activities but poor aqueous solubility. In the present investigation, the AP nanocrystals were prepared by the supercritical antisolvent process. In vitro characterization was performed by scanning electron microscopy, FT-IR, differential scanning calorimetry, X-ray powder diffractometry. In vitro dissolution of prepared nanocrystals was studied and compared with untreated coarse powder. In addition, the pharmacokinetic study of AP nanocrystals, in comparison to coarse powder, was also performed in rats after a single oral dose. The prepared AP nanocrystals, without change in crystalline structure, appeared in spherical shape with particle size of about 400-800 nm. The reduction of particle size resulted in a more rapid dissolution of AP from nanocrystals than from coarse powder. In comparison to coarse powder, AP nanocrystals exhibited a significantly decreased t(max), a 3.6-fold higher peak plasma concentration (C(max)) and 3.4-fold higher area under the curve (AUC).
    European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences 01/2013; · 2.61 Impact Factor
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    ABSTRACT: Objectives  The aim of the study was to prepare and to characterize two polymorphs of lornoxicam, a water-insoluble non-steroidal anti-inflammatory drug, which has thus far received no exploration of its polymorphs. Methods  Form I and form II of lornoxicam were prepared by recrystallization and characterized by X-ray powder diffractometry (XRPD), thermal analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. The solubility and dissolution of both polymorphs were also determined and compared to provide the basis for polymorph selection in formulation. Key findings  The crystal structures of the two polymorphs were established by the experimental XRPD patterns. Form I was demonstrated to be triclinic with two kinds of intermolecular hydrogen bonds, while form II was orthorhombic with two kinds of intramolecular hydrogen bonds. The morphologies of form I and form II were observed to be rectangle and approximately oval, respectively. Conclusions  Form II had the significantly higher solubility and dissolution and would be the suitable polymorph for the preparation of oral and injectable dosage forms of lornoxicam.
    The Journal of pharmacy and pharmacology. 01/2013; 65(1):44-52.
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    ABSTRACT: Using a newly developed strategy whose key step is the regioselective propargylation of hydroxyxanthone substrates, 99 structurally diverse Garcinia natural product-like xanthones based on gambogic acid were designed and synthesized and their in vitro antitumor activity was evaluated. A set of 40 related compounds was chosen for determination of their physicochemical properties including polar surface area, log D7.4, aqueous solubility and permeability at pH 7.4. In the light of the in vitro antitumor activity and the physicochemical properties, 2 compounds were advanced into in vivo efficacy experiments. The antitumor activity of compound 112, administered po, showed more potent in vivo oral antitumor activity than gambogic acid.
    Journal of Medicinal Chemistry 11/2012; · 5.61 Impact Factor
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    ABSTRACT: Gambogic acid (GA), a natural product, was identified as a promising antitumor agent. To further explore the structureactivity relationship of GA and discover novel GA derivatives as antitumor agents, 19 novel GA derivatives modified at C(34) were synthesized and evaluated against A549, BGC-823, U251, HepG2, and MB-231 cancer cell lines by cellular assays. Among them, 15 compounds were found to be more potent than GA against some cancer cell lines. Notably, compound 3 possessed potent inhibitory activities against five cell lines with IC(50) values ranging between 0.24 and 1.09 μM. Compounds 9 and 18 were seven to eightfold more active than GA against A549 cell line. Chemical modification at C(34) of GA by introducing of hydrophilic aliphatic amines resulted in increased activity and improved drug-like properties. These findings will enhance our understanding of the SAR of GA and can lead to the discovery of novel GA derivatives as potential antitumor agents.
    Chemistry & Biodiversity 10/2012; 9(10):2295-308. · 1.81 Impact Factor
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    ABSTRACT: Adefovir dipivoxil (AD) is a bis(pivaloyloxymethyl) prodrug of adefovir with chemical stability problem. It undergoes two degradation pathways including hydrolysis and dimerization during storage. Pharmaceutical cocrystallization exhibits a promising approach to enhance aqueous solubility as well as physicochemical stability. In this study we attempted to prepare and investigate the physiochemical properties of AD cocrystals, which were formed with two coformers having different acidity and alkalinity (weakly acidic saccharin (SAC) and weakly basic nicotinamide (NCT)). The presence of different coformer molecules along with AD resulted in altered physicochemical properties. AD-SAC cocrystal showed great improvement in solubility and chemical stability, while AD-NCT did not. Several potential factors giving rise to different solid-state properties were summarized. Different coformers resulted in different cocrystal formation, packing style and hydrogen bond formation. This study could provide the coformer selection strategy based on degradation pathways for some unstable drugs in pharmaceutical cocrystal design.
    International Journal of Pharmaceutics 09/2012; 438(1-2):327-35. · 3.99 Impact Factor
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    ABSTRACT: The natural product gambogic acid exhibits high potency in inhibiting cancer cell lines. Rational medicinal modifications on gambogic acid will improve its physicochemical properties and drug-like characters. To investigate the structure-activity relationship of gambogic acid and also to find rational modification position on its chemical skeleton, we designed, synthesized, and characterized 16 derivatives of gambogic acid that were modified at C(39). The structure-activity relationships (SARs) were discussed. The anti-proliferation data were accquired through MTT (=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assays of A549, BGC823, U251, HepG2, and MDA-MB-231 cancer cell lines. Most of the synthesized compounds showed strong inhibitory effects. The SAR study revealed that derivatives with aliphatic amino moieties at C(39) were more potent than those with other substituents. The C(39) position can undergo different kinds of chemical modifications without leading to loss of activity. Compounds 4 and 6 can serve as potential lead compounds for further development of new anticancer drugs.
    Chemistry & Biodiversity 08/2012; 9(8):1579-90. · 1.81 Impact Factor
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    ABSTRACT: The aim of the study was to characterize the biopharmaceutics classification system (BCS) category of apigenin (AP) using intrinsic dissolution rate (IDR) and rat intestinal permeability, and to investigate the intestinal absorption mechanism of AP in rats. In the present investigation, equilibrium solubility and intrinsic dissolution rate (IDR) of AP were estimated in phosphate buffers. Effective intestinal permeability (P(eff)) of AP was determined using single-pass intestinal perfusion (SPIP) technique in four segments (duodenum, jejunum, ileum and colon) of rat intestine at three concentrations (10, 50 and 100 μg/ml). The aqueous solubility of AP in tested phosphate buffers was very poor with maximum solubility of 2.16 μg/ml at pH 7.5. The IDR of AP was very low with a value of 0.006 mg/min/cm(2). The minimum and maximum P(eff)s determined by SPIP were 0.198×10(-4) and 0.713×10(-4) cm/s at jejunum and duodenum site, respectively. In addition, the concentration-dependent permeability behavior was observed in the duodenum and jejunum, which suggested that AP was transported by both passive and active carrier-mediated saturable mechanism in these two intestinal segments. However, the observed concentration-independent permeability behavior in ileum and colon indicated primarily passive transport mechanism of absorption of AP in the last two intestinal segments. AP was classified as class II drug of the BCS due to its low solubility and high intestinal permeability. AP could be well absorbed in the whole intestine with the main absorption site at duodenum. The absorption of AP in four intestinal segments exhibited different transport mechanisms.
    International Journal of Pharmaceutics 07/2012; 436(1-2):311-7. · 3.99 Impact Factor
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    ABSTRACT: In order to explore the detailed structure-activity relationship (SAR) around xanthone scaffold bearing hydroxyl and prenyl moieties, twenty-nine natural and non-natural hydroxylated and prenylated xanthones have been synthesized and evaluated for their in vitro anti-proliferative activities against five human cancer cell lines, including HepG2 (hepatocelluar carcinoma), HCT-116 (colon carcinoma), A549 (lung carcinoma), BGC823 (gastric carcinoma) and MDAMB- 231 (breast carcinoma). The SAR analysis revealed that the anti-proliferative activity of the xanthones is substantially influenced by the position and number of attached hydroxyl and prenyl groups, and the presence of hydroxyl group ortho to the carbonyl function of xanthone scaffold contributes significantly to their cytotoxicity. The new prenylated xanthone 20 with a relatively simple structure, namely 1,3,8-trihydroxy-2-prenylxanthone, was found to exhibit potent antitumor activities comparable to α-mangostin against all the five cancer cell lines. Further mechanistic studies suggested that compound 20 induces apoptosis and causes cell cycle arrest at S phase in HepG2 cells. These results have highlighted compound 20 as a new potential lead candidate for future development of novel potent broad-spectrum antitumor agents.
    Medicinal chemistry (Shāriqah (United Arab Emirates)) 07/2012; 8(6):1012-25. · 1.64 Impact Factor
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    ABSTRACT: ZCVI(4)-2 was a novel nitric oxide-releasing glycosyl derivative of oleanolic acid that displayed strong cytotoxicity selectively against human hepatocellular carcinoma in vitro and in vivo. In this study, ZCVI(4)-2 was characterized by FT-IR spectroscopy, differential scanning calorimetry, powder X-ray diffractometry, Raman spectroscopy, hygroscopicity and stability. A high performance liquid chromatography method was also established for the quantitative determination of solubility and additional stability profile of ZCVI(4)-2. ZCVI(4)-2 was found to be an amorphous and stable solid with low solubility of less than 10 μg/mL. Based on the solubilization tests that included methods of cosolvency and micellization, the solution mixture of 5% Solutol HS-15, 5% 1, 2-propylene glycol and 5% anhydrous ethanol was determined to be the system for the preparation of the ZCVI(4)-2 early injection solution. The effect of pH, temperature, light and injectable isotonic glucose or NaCl solution on ZCVI(4)-2 injection was also investigated. Good stability was observed at all testing conditions. Under the conditions studied, the NO-releasing rate and amount of ZCVI(4)-2 from the early injection solution in rat plasma demonstrated a promising therapeutic efficacy while maintaining a good safety profile.
    Archives of Pharmacal Research 07/2012; 35(7):1177-86. · 1.54 Impact Factor
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    ABSTRACT: Gambogic acid (GA, 1), the most prominent representative of Garcinia natural products, has been reported to be a promising anti-tumor agent. In order to further explore the structure-activity relationship of GA and discover novel GA derivatives as anti-tumor agents, 17 novel C-37 modified derivatives of GA were synthesized and evaluated for their in vitro anti-tumor activities against A549, HCT-116, BGC-823, HepG2 and MCF-7 cancer cell lines. Among them, 11 compounds were found to be more potent than GA against some cancer cell lines. Notably, compound 8 was almost 5–10 folds more active than GA against A549 and BGC-823 cell lines with the IC50 values of 0.12 µmol·L−1 and 0.57 µmol·L−1, respectively. Chemical modification at C-37 position of GA by introducing of hydrophilic amines could lead to increased activity and improved drug-like properties. These findings will enhance our understanding of the structure-activity relationship (SAR) of GA and lead to the discovery of novel GA derivatives as potential anti-tumor agents.
    Chinese Journal of Chemistry 05/2012; 30(5). · 0.92 Impact Factor
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    ABSTRACT: Inspired by the therapeutic potential of the simplified caged xanthones, we have developed a chemical strategy for synthesizing novel aza-caged Garcinia analogues through a regioselective Claisen/Diels-Alder cascade reaction. The origin of regioselectivity has been explained using the DFT method. We have further evaluated the cell proliferation and IKKβ inhibitory activities of these compounds and studied their binding mode with IKKβ by molecular docking. The results suggested that the aza-caged scaffold provides a suitable modification site and the introduction of a hydrophobic moiety leads to improvement in the cytotoxicity and IKKβ inhibitory activity. The aza-caged compound 6c exhibited an IC(50) value of 2.68, 2.10, 8.02 μM against the HepG2, A549 cells and IKKβ, respectively. Mechanism studies with 6c showed that the aza-caged compounds induce apoptosis and cell cycle S phase arrest in A549 cells.
    Organic & Biomolecular Chemistry 03/2012; 10(16):3288-99. · 3.57 Impact Factor
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    ABSTRACT: Gambogic acid (GA, 1), the most prominent member of Garcinia natural products, has been reported to be a promising anti-tumor agent. Previous studies have suggested that the planar B ring and the unique 4-oxa-tricyclo[4.3.1.03,7]dec-2-one caged motif were essential for anti-tumor activity. To further explore the structure-activity relationship (SAR) of caged Garcinia xanthones, two new series of B-ring modified caged GA analogues 13a–13e and 15a–15e were synthesized utilizing a Claisen/Diel-Alder cascade reaction. Subsequently, these compounds were evaluated for their in vitro anti-tumor activities against A549, MCF-7, SMMC-7721 and BGC-823 cancer cell lines by MTT assay. Among them, 13b–13e exhibited micromolar inhibition against several cancer cell lines, being approximately 2–4 fold less potent in comparison to GA. SAR analysis revealed that the peripheral gem-dimethyl groups are essential for maintaining anti-tumor activity and substituent group on C1 position of B-ring has a significant effect on potency, while modifications at C-2, C-3 and C-4 positions are relatively tolerated. These findings will enhance our understanding of the SAR of Garcinia xanthones and lead to the development of simplified analogues as potential anti-tumor agents.
    Chinese Journal of Chemistry 01/2012; 30(1). · 0.92 Impact Factor
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    ABSTRACT: VI-16, a newly synthesized flavonoid, has a hydroxy substitution at C5 position, a methoxyl substitution at C5 position, and a piperazine substitution at C7 position. Here, we firstly investigated the potential antitumor effect of VI-16 in HepG2 human hepatocarcinoma cells. The MTT assay showed that VI-16 inhibited HepG2 cell growth in a concentration- and time-dependent manner. To further investigate whether apoptosis induction contributed to the antitumor effects of VI-16, DAPI staining and Annexin-V/PI double staining were performed in our tests. The data showed that VI-16 could induce apoptotic cell death in HepG2 cells. Moreover, mechanistic studies revealed that VI-16-induced apoptosis was a caspase-dependent process by decreasing the expression of pro-caspase-3. The changes in the expression of caspase-8, capsase-9, Bax and bcl-2 after VI-16 treatment suggested that the mitochondrial pathway was involved in the apoptosis induced by VI-16. Furthermore, VI-16 could significantly increase the loss of mitochondrial membrane potential and the expression of p53. Taken together, these results demonstrated that apoptosis induced by VI-16 might be one of the mechanisms by which VI-16 acts as a preventive antitumor drug against human hepatoma.
    Oncology Reports 12/2011; 27(3):873-9. · 2.30 Impact Factor
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    ABSTRACT: Spray-dried emulsion (SDE) was prepared and characterized to improve the intestinal absorption and oral bioavailability of ZLR-8, a nitric oxide-releasing derivative of diclofenac, currently under preclinical development. The intestinal absorption of ZLR-8 was characterized by single pass intestinal perfusion technique to obtain its absorption and permeability parameters. SDE of ZLR-8 was prepared and characterized by particle size measurements and in-vitro release study. Accurate and precise RP-HPLC methods for the detection of ZLR-8 and its metabolite diclofenac were constructed to perform the bioavailability study. It was demonstrated that ZLR-8 was absorbed in the whole intestine, of which the duodenum segment exhibited the largest absorption ability. ZLR-8 can be classified into BCS Class 2. SDE significantly enhanced the intestinal absorption rate of ZLR-8 in duodenum and jejunum but had indistinctive effect on permeability. All concentrations of ZLR-8 in rat plasma was lower than the limit of detection. A bicompartment model gave the best fit to the plasma diclofenac concentration-time curves. Calculated on AUC(0-12h) , the mean relative bioavailability of SDE was 105.4-fold that of ZLR-8 suspension. SDE significantly improved the intestinal absorption of ZLR-8 and resulted in a dramatic improvement in its bioavailability.
    The Journal of pharmacy and pharmacology. 12/2011; 63(12):1531-8.
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    ABSTRACT: The aim of the study was to investigate the potential of oral and pulmonary nanocrystal to enhance the bioavailability of baicalein, a bioactive flavonoid isolated from the root of Scutellaria baicalensis Georgi. So far, the nano-sized delivery system of baicalein and its pulmonary delivery have received no exploration. In the present investigation, the baicalein nanocrystal was prepared by anti-solvent recrystallization followed by high pressure homogenization. In vitro characterization was performed including particle size and distribution, Zeta potential, dissolution, scanning electron microscopy, differential scanning calorimetry and X-ray powder diffractometry. It was indicated that no crystalline change was observed after nanocrystal preparation. The baicalein nanocrystal containing only trace of stabilizer exhibited a significantly enhanced dissolution of baicalein. In vivo test was also carried out in rats and pharmacokinetic parameters of the baicalein crystal and the baicalein nanocrystal after gavage and pulmonary administration were compared, based on the simultaneous determination of baicalein and baicalin by high performance liquid chromatography. The mean relative bioavailability of oral baicalein nanocrystal was 1.67-fold that of oral baicalein crystal. The pulmonary baicalein nanocrystal had rapid and extensive absorption and had almost identical pharmacokinetic parameters to intravenous baicalein injection.
    International Journal of Pharmaceutics 08/2011; 420(1):180-8. · 3.99 Impact Factor

Publication Stats

81 Citations
72.32 Total Impact Points

Institutions

  • 2013–2014
    • Nanjing University of Traditional Chinese Medicine
      • Department of Traditional Chinese Medicine
      Nan-ching, Jiangsu Sheng, China
    • The Chinese University of Hong Kong
      • Department of Pharmacy
      Hong Kong, Hong Kong
  • 2011–2014
    • China Pharmaceutical University
      • • School of Traditional Chinese Medicine
      • • School of Pharmacy
      Nan-ching-hsü, Jiangxi Sheng, China