2018 DMPK research progress in China / 药学学报

This paper summarizes research progresses of Chinese scholars in the field of drug metabolism and pharmacokinetics (DMPK) in 2018. Chinese scholars focused on drug metabolizing enzymes and transporters, and carried out studies on the mechanisms of drug metabolism and transport of active molecules. Topics of research included regulatory mechanisms of drug metabolizing enzymes or transporters, and their implications in drug development and disease etiology or progression. Here, we summarized studies on drug toxicity based on drug metabolism or transport, rational drug use in the clinic, drug metabolism mediated by intestinal flora, metabolism of traditional Chinese medicines, and new technologies or models in DMPK. In recent years, the research focus of drug metabolism in China has transformed from serving for new drug discovery and rational use, to innovation driven and mechanism oriented research. The domestic research topics and technology utilization are gradually aligning with the international conventions.

Epigenetics-based regulation of uptake drug transporter expression is a new approach for cancer drug resistance intervention / 医学研究生学报

Drug resistance is a key factor for poor clinical efficacy of chemotherapy. One of the important reasons for drug resistance is the abnormal expression of drug metabolizing enzymes and drug transporters, which results in the decrease of drug concentration in cancer cells. In this paper, the mechanism of abnormal uptake transporter expression in tumors is analyzed from aspects of drug metabolism enzymes and transporters and tumor drug resistance, drug epigenetics and drug resistance, and potential targets of renal cancer drug resistance, such as OCT2. It is proposed that the regulation of uptake drug transporter expression in tumors by epigenetic mechanism is a new way to reverse drug resistance in tumors.

The metabolism and hepatotoxicity of ginkgolic acid (17 : 1) in vitro / 中国天然药物

Pharmacological activities and adverse side effects of ginkgolic acids (GAs), major components in extracts from the leaves and seed coats of Ginkgo biloba L, have been intensively studied. However, there are few reports on their hepatotoxicity. In the present study, the metabolism and hepatotoxicity of GA (17 : 1), one of the most abundant components of GAs, were investigated. Kinetic analysis indicated that human and rat liver microsomes shared similar metabolic characteristics of GA (17 : 1) in phase I and II metabolisms. The drug-metabolizing enzymes involved in GA (17 : 1) metabolism were human CYP1A2, CYP3A4, UGT1A6, UGT1A9, and UGT2B15, which were confirmed with an inhibition study of human liver microsomes and recombinant enzymes. The MTT assays indicated that the cytotoxicity of GA (17 : 1) in HepG2 cells occurred in a time- and dose-dependent manner. Further investigation showed that GA (17 : 1) had less cytotoxicity in primary rat hepatocytes than in HepG2 cells and that the toxicity was enhanced through CYP1A- and CYP3A-mediated metabolism.

The metabolism and hepatotoxicity of ginkgolic acid (17 : 1) in vitro / 中国天然药物

Pharmacological activities and adverse side effects of ginkgolic acids (GAs), major components in extracts from the leaves and seed coats of Ginkgo biloba L, have been intensively studied. However, there are few reports on their hepatotoxicity. In the present study, the metabolism and hepatotoxicity of GA (17 : 1), one of the most abundant components of GAs, were investigated. Kinetic analysis indicated that human and rat liver microsomes shared similar metabolic characteristics of GA (17 : 1) in phase I and II metabolisms. The drug-metabolizing enzymes involved in GA (17 : 1) metabolism were human CYP1A2, CYP3A4, UGT1A6, UGT1A9, and UGT2B15, which were confirmed with an inhibition study of human liver microsomes and recombinant enzymes. The MTT assays indicated that the cytotoxicity of GA (17 : 1) in HepG2 cells occurred in a time- and dose-dependent manner. Further investigation showed that GA (17 : 1) had less cytotoxicity in primary rat hepatocytes than in HepG2 cells and that the toxicity was enhanced through CYP1A- and CYP3A-mediated metabolism.

Induction study of CYP3A2 in male rats by zolmitriptan / 药学学报

In our preliminary studies, we observed zolmitriptan (ZOL) treatment led to induction of CYP3A2 in male not female rats. To figure out the reason is of great significance for drug-drug interactions and personalized administration. Since growth hormone (GH) is known as the major mechanistic determinant of sexually-dimorphic gene expression like CYP3A2 in rat liver, the impacts of ZOL on both plasma GH levels in non monosodium glutamate (MSG)-treated rats and CYP3A2 expression in GH depleted MSG-treated rats were studied. ZOL was shown to partially suppress GH levels in both genders. Furthermore, CYP3A2 protein and mRNA level declined in male not female MSG-treated rats. In order to study the possible molecular events involved in the depression of GH and gender-selective induction on rat CYP3A2 by ZOL, the mRNA and protein level (whole protein and nuclear protein) of hepatocyte nuclear factor 4α (HNF4α) was investigated. Nuclear accumulation of HNF4α was observed in the normal male not female rat liver tissue following ZOL treatment. However, this kind of nuclear translocation did not occur in rat hepatocytes and MSG-treated rats. These findings demonstrated CYP3A2 inducibility by ZOL was gender-selective. GH and HNF4α may play an important role in CYP3A2 induction.

Personalized dosing from perspective of pharmacogenomics of drug metabolizing enzymes and transporters / 药学学报

Pharmacogenomics is defined as research into the relationship between inherited genetic variations in drug metabolizing enzymes, transporters and targets and individual variations in person's response to drugs (fate of drug in human body, safety and efficacy). Personalized dosing is pharmacogenomics-based therapeutic regimen tailored to other individual characteristics. This article summarizes the progress in clinical application of personalized dosing from the perspective of pharmacogenomics of drug metabolizing enzymes and transporters, and proposes to draw attention to key scientific issues (e.g., the effect of multi-genes and non-genetic factors on drug effects, the integration of therapeutic drug monitoring and pharmacogenomics); meanwhile, bottle necks in the clinical application and corresponding strategies are proposed.

Mechanism for ginkgolic acid (15 : 1)-induced MDCK cell necrosis: Mitochondria and lysosomes damages and cell cycle arrest / 中国天然药物

Ginkgolic acids (GAs), primarily found in the leaves, nuts, and testa of ginkgo biloba, have been identified with suspected allergenic, genotoxic and cytotoxic properties. However, little information is available about GAs toxicity in kidneys and the underlying mechanism has not been thoroughly elucidated so far. Instead of GAs extract, the renal cytotoxicity of GA (15 : 1), which was isolated from the testa of Ginkgo biloba, was assessed in vitro by using MDCK cells. The action of GA (15 : 1) on cell viability was evaluated by the MTT and neutral red uptake assays. Compared with the control, the cytotoxicity of GA (15 : 1) on MDCK cells displayed a time- and dose-dependent manner, suggesting the cells mitochondria and lysosomes were damaged. It was confirmed that GA (15 : 1) resulted in the loss of cells mitochondrial trans-membrane potential (ΔΨm). In propidium iodide (PI) staining analysis, GA (15 : 1) induced cell cycle arrest at the G0/G1 and G2/M phases, influencing on the DNA synthesis and cell mitosis. Characteristics of necrotic cell death were observed in MDCK cells at the experimental conditions, as a result of DNA agarose gel electrophoresis and morphological observation of MDCK cells. In conclusion, these findings might provide useful information for a better understanding of the GA (15 : 1) induced renal toxicity.

Screening and verifying potential NTCP inhibitors from herbal medicinal ingredients using the LLC-PK1 cell model stably expressing human NTCP / 中国天然药物

NTCP is specifically expressed on the basolateral membrane of hepatocytes, participating in the enterohepatic circulation of bile salts, especially conjugated bile salts, to maintain bile salts homeostasis. In addition, recent studies have found that NTCP is a functional receptor of HBV and HDV. Therefore, it is important to study the interaction between drugs and NTCP and identify the inhibitors/substrates of NTCP. In the present study, a LLC-PK1 cell model stably expressing human NTCP was established, which was simple and suitable for high throughput screening, and utilized to screen and verify the potential inhibitors of NTCP from 102 herbal medicinal ingredients. The results showed that ginkgolic acid (GA) (13 : 0), GA (15 : 1), GA (17 : 1), erythrosine B, silibinin, and emodin have inhibitory effects on NTCP uptake of TCNa in a concentration-dependent manner. Among them, GA (13 : 0) and GA (15 : 1) exhibited the stronger inhibitory effects, with IC50 values being less than 8.3 and 13.5 μmol·L(-1), respectively, than the classical inhibitor, cyclosporin A (CsA) (IC50 = 20.33 μmol·L(-1)). Further research demonstrated that GA (13 : 0), GA (15 : 1), GA (17 : 1), silibinin, and emodin were not substrates of NTCP. These findings might contribute to a better understanding of the disposition of the herbal ingredients in vivo, especially in biliary excretion.

Simultaneous determination of madecassoside, asiaticoside and their aglycones in Centella asiatica (L.) urban extracts by RP-HPLC / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To establish a HPLC method for simultaneous determination of four major constituents (madecassoside, asiaticoside, madecassic acid and asiatic acid) in Centella asiatica (L.) urban extracts.</p><p><b>METHODS</b>The analysis was performed on an Agilent 1100 HPLC system with a ZORBAX Eclipse XDB-C8 column (4.6 mm×150 mm, 5μm). The four major constituents were separated with gradient mobile phase that consists of 1mmol/L potassium dihydrogen phosphate and acetonitrile at the detection wavelength of 205 nm.</p><p><b>RESULTS</b>The four major constituents all had good linear response in the determination ranges (R(2)≥0.9998). The average recoveries (n=9) were 97.4%, 93.7%, 97.5% and 99.8% with RSDs of 3.4%, 1.4%, 4.7% and 4.4%, respectively.</p><p><b>CONCLUSION</b>The developed method is sensitive and has good reproducibility, which can be used as a reference for quality control of Centella asiatica (L.) urban extracts.</p>

Determination of enantiomeric impurity of timolol maleate in bulk substances and eye drops / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To determine the enantiomeric impurity contents of domestic timolol maleate in bulk drugs and eye drops.</p><p><b>METHODS</b>Enantiomer impurity of timolol was assayed by chiral high performance liquid chromatography. The chromatographic conditions were as follows:chiralcel OD chiral column (4.6 mm ×150 mm, 5μm), detection wavelength:297 nm, mobile phase:hexane-isopropanol-diethylamine (480:20:1), column temperature:25 ℃, flow rate:1.0 ml/min, sample injection volume:5 μl.</p><p><b>RESULTS</b>The resolution between R- and S-timolol was more than 4. The enantiomeric impurity contents were less than 0.67% on average in two batches of timolol maleate bulk drugs, and 0.31% on average in three batches of timolol maleate eye drops.</p><p><b>CONCLUSION</b>Enantiomeric impurity contents in each batch of products all meet European Pharmacopoeia criteria, which can be used as references in Chinese Pharmacopoeia criteria.</p>

Enantiomeric separation and impurity determination of valaciclovir hydrochloride / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To determine the contents of L-enantiomer impurity in valaciclovir hydrochloride.</p><p><b>METHODS</b>Valaciclovir enantiomers were separated and determined by using chiral high performance liquid chromatography. Chromatographic conditions were as follows:CROWNPAK(®) CR(+) chiral column (4 mm×150 mm, 5 μm), detection wavelength:254 nm, mobile phase:water-methanol-perchloric acid (19:1:0.1), flow rate:0.75 ml/min, sample injection volume:10 μl.</p><p><b>RESULTS</b>D-valaciclovir was completely separated from L-enantiomer impurity. The contents of L-enantiomer impurity were 0.65%-2.62% on average in 8 batches of valaciclovir hydrochloride.</p><p><b>CONCLUSION</b>Enantiomeric impurity contents in each batch of products were all meet criteria of United States Pharmacopeia, which can be used in criteria of Chinese Pharmacopeia as references.</p>

Expression of human glutathione S-transferase A1, P1 and T1 in Escherichia coli / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct the vectors of human glutathione S-transferase A1 (GSTA1), P1 (GSTP1), T1(GSTT1) genes and express in Escherichia coli (E. coli).</p><p><b>METHODS</b>Human GSTA1, GSTP1 and GSTT1 gene whole length cDNAs were amplified by RT-PCR and then subcloned into pET-28a(+) vectors. The proteins were expressed in E. coli BL21(DE3). After purified by Ni2+ affinity chromatography, the enzymatic activities of GSTs were measured with 1-chloro-2,4 -dinitrobenzene (CDNB) as substrate.</p><p><b>RESULTS</b>The correct GSTA1, GSTP1 and GSTT1 genes were cloned. And soluble GSTA1, GSTT1, GSTP1 proteins were expressed in E.coli. After purification, GSTA1, GSTT1 and GSTP1 showed good enzymatic activities, which were 17.55, 0.02, 18.75 μmol·min-1·mg-1, respectively.</p><p><b>CONCLUSION</b>The expression plasmids for GSTA1, GSTT1 and GSTP1 have been constructed and the recombinant proteins are expressed successfully.</p>

Establishment of in vitro evaluation model for CYP2B6 induction and its application to screen inducers among TCMs / 药学学报

This paper is to report the development of a high-throughput in vitro system to screen hPXR/CAR mediated CYP2B6 drug inducers, and the application of it into the quick determination of induction activity toward CYP2B6 by various commonly used traditional Chinese medicines (TCMs) extract. Dual reporter gene assays were performed. The hPXR/CAR expression vectors and the reporter vector pGL3-CYP2B6-Luc involved in the distal and proximal promoters of CYP2B6 were co-transfected into HepG2 cells. Relative luciferase activities in cell lysate were analyzed after 48 h treatment of blank vehicle or drugs to determine the induction activity toward CYP2B6 by various commonly used TCMs extract. The positive hPXR/hCAR activators rifampicin and CITCO were applied to make sure that the reporter gene model was successfully established. Then 5 kinds of commonly used TCM extracts and 1 herbal compound were successfully investigated, some were found to activate hPXR or hCAR and therefore have the potential to induce CYP2B6 enzyme. This is the first domestic article to report the hCAR3-mediated CYP2B6 induction model and the establishment of a reporter gene system for hPXR/CAR-mediated CYP2B6 induction can be an effective and systemic in vitro method to investigate the drug inducers of CYP2B6 and to explain the mechanism involved.

CYP2D6*1, CYP2D6*10 co-expressed with CYPOR in Bac-to-Bac expression system and activity determination / 药学学报

CYP2D6 is an important drug-metabolizing enzyme. The polymorphism of CYP2D6 leads to metabolism difference and the different reactions of drugs in the individuals and different races are normal phenomenon in clinical medication. CYP2D6*10 is an important subtype in Asian people and 51.3% Chinese are classified with this subtype. To obtain recombinant active CYP2D6*1/CYP2D6*10 in baculovirus system by optimizing coexpression with CYPOR, and detect their activity to catalyze dextromethorphan, three recombinants pFastBac-CYP2D6*1, pFastBac-CYP2D6*10 and pFastBac-CYPOR were constructed and transformed into DH10Bac cell to obtain the recombinant Bacmid-CYPOR, Bacmid-CYP2D6*1 and Bacmid-CYP2D6*10. And then the recombinant CYP2D6*1 and CYP2D6*10 virus were obtained by transfecting Sf9. Then homogenate protein activity was determined with dextromethorphan as substrate. The multiple of infection (MOI) and its ratio of recombinant CYP2D6 virus to CYPOR virus were adjusted by detecting the activity of the homogenate protein. The Km and Vmax are 26.67 +/- 2.71 micromol x L(-1) (n=3) and 666.7 +/- 56.78 pmol x nmol(-1) (CYP2D6) x min(-1) (n=3) for CYP2D6*1 to catalyze dextromethaphan. The Km and Vmax are 111.36 +/- 10.89 micromol x L(-1) (n=3) and 222.2 +/- 20.12 pmol x nmol(-1) (CYP2D6) x min(-1) (n=3) for CYP2D6*10 to catalyze dextromethorphan. There is significant difference between CYP2D6*1 and CYP2D6*10 for Vmax and Km (P < 0.01). The clearance ratio of CYP2D6*1 is 25.0 and the clearance ratio of CYP2D6*10 is 2.0. The expressed CYP2D6*1 and CYP2D6*10 are useful tools to screen the metabolism profile of many xenobiotics and endobiotics in vitro, which are benefit to understand individual metabolism difference.

Determination of quercetin metabolism in UGT1A3 cDNA-expressing cells by RP-HPLC / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To develop a RP-HPLC method for the determination of quercetin in UGT1A3 cDNA-transfected cells.</p><p><b>METHODS</b>The lysate of cells transfected with human recombinant uridine 5-diphosphate glucuronosyltransferases UGT1A3 cDNA was co-incubated with quercetin, the reaction was terminated with acetonitrile, and luteolin was used as internal standard. The determination was performed on a C(1) reversed phase column with a mobile phase of methanol-0.1% formic acid (V/V) at a flow rate of 1.0 ml/min. The gradient elution was as follows: 0 - 25 min (30:70-80:20, methanol:0.1% formic acid), > 25-25.5 min (80:20), >25.5-27 min (80:20-30:70), > 27-30 min (30:70). A UV-VIS detector was operated at 368 nm.</p><p><b>RESULT</b>The standard curve was linear over the concentration range of 5-200 μmol/L (r = 0.9999). The limit of detection was 1.25 μmol/L(S/N ≥ 3), and the limit of quantification was 5 μmol/L (S/N >10, RSD = 6.99%). The method afforded recoveries of 99.1%-103.5%, and precisions for inter- and intra-assay were < 2.5% and < 8%, respectively. In addition, kinetic analysis indicated that the K(m), V(max) and CL(int) (V(max)/K(m)) values for quercetin glucuronide were (62.95 ± 13.16) μ mol/L, (284.50 ± 24.35)nmol*min⁻¹*g⁻¹ and 4.52 ml*min⁻¹*g⁻¹, respectively.</p><p><b>CONCLUSION</b>The method established is accurate and simple and suitable for the determination of quercetin in UGT1A3 cDNA-expressed cells.</p>

Chiral separation of fluvastatin enantiomers with in vitro cellular method / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To establish a chiral separation method for determination of fluvastatin enantiomer with in vitro cellular model.</p><p><b>METHODS</b>The determination was performed on Chiralpak AD column (4.6 mm × 250 mm); and the phase consisted of hexane-isopropanol-trifluoroacetic acid (90:10:0.1) at a flow rate of 0.5 ml/min with UV detection of 239 nm.</p><p><b>RESULT</b>The standard curve was linear over the concentration range of 20 μmol/L-300 μmol/L (r² = 0.9993, r² = 0.9997). The recovery for this assay was (99.4 ± 0.8)%, precision for inter-assay and intra-assay was <10 %.</p><p><b>CONCLUSION</b>The normal-phase HPLC chiral separation method was accurate and suitable for study on the stereoselectivity of fluvastatin with in vitro cellular model.</p>

The role of ADME evaluation in translation research of innovative drug / 药学学报

New Chemical Entities (NCEs) development is a systematic long-term project that involves multiple disciplines. The translation research will help to build an advanced R&D system from the basic laboratory research, preclinical studies and clinical evaluation to clinical application of drug, for the purpose of shortening the R&D cycle and accelerate the launch of new drugs. In new drug R&D and its clinical application, drug disposition (absorption, distribution, metabolism, excretion, ADME) properties are important criteria for assessing drug-likeness of candidates. ADME evaluation of NCEs plays an important role in the translation research throughout innovative drug R&D process. Therefore, ADME evaluation at the early stage of drug design and development will be helpful to improve the success rate and reduce costs, and further access to safe, effective drugs.

Induction of rat hepatic cytochrome P-450 3A by zolmitriptan mediated with pregnane X receptor / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate whether pregnane X receptor (PXR) is involved in the induction of rat hepatic cytochrome P450 3A1/2 by zolmitriptan.</p><p><b>METHODS</b>The induction effects of zolmitriptan were investigated in three concentrations (100 micromol L(-1)), 50 micromolL(-1)) and 10 micromol L(-1))) using luciferase report gene method based on PXR. Pregnenolone-16 alpha-carbonitrile (PCN) was used as the positive control and the solvent DMSO as the negative control.</p><p><b>RESULT</b>Compared with the negative groups, the positive and high level zolmitriptan groups exhibited a significant induction effect on CYP 3A1, the activity increased to 1.93 and 1.96 times, respectively (P<0.05). The positive, middle level and low level zolmitriptan groups exhibited a significant induction effect on CYP 3A2, the activity increase to 2.51, 2.10 and 1.63 times, respectively (P<0.01, <0.05 ).</p><p><b>CONCLUSION</b>Zolmitriptan can significantly induce CYP 3A2 in low and middle concentrations and induce CYP 3A1 in high concentration.PXR is involved in the induction of CYP 3A1/2 by zolmitriptan.</p>

Cultivation of Students' Comprehensive Abilities in Independence Experiment and Practice / 中华医学教育探索杂志

This article introduces the independent experiment and social investigation activities in the course of medication analy- sis set up for strengthening students' comprehensive abilities.These activities create a good study atmosphere for enhancing stu- dents' ability to do research and their humanistic qualities.

Enatiomeric separation of beta-blocking agents and analogs / 浙江大学学报·医学版

OBJECTIVE: To evaluate enantiomeric separation methods for beta-blocking agents and analogs. METHODS: Enantiomeric separation of racemates of 11 beta-blocking agents and their analogs was performed using chiral stationary phases and 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC). RESULTS: These beta -blocker racemates were separated into enantiomers in one or several chormatographic states such as propranolol, bisoprolol, metoprolol, celiprolol, carvedilol, sotalol, propafenone, ephedrine, and zomitriptan. Temperature had a significant effect on the resolution of the drugs when using chiralcel OD. Lower temperatures were associated with higher resolutions. CONCLUSION: When separating beta-blocking agents and their analogs, Chiralcel OD, Chiralpak AD, Chiral stationary phases and GITC chiral derivative reagents have complementary functions.