绿豆衣提取物对大鼠肝微粒体CYP3A4活性的影响

摘 要 目的：研究绿豆衣提取物（MBSC）对大鼠肝微粒体中细胞色素P450 （CYP）3A4酶活性的影响。方法: 采用高效液相色谱法,以咪达唑仑为CYP3A4探针药物,建立检测咪达唑仑代谢产物1 羟基咪达唑仑在大鼠肝微粒体孵育体系中浓度的方法,对体外肝微粒体孵育体系中孵育时间、肝微粒体量、孵育时间进行优化,以优化后的条件先后评价绿豆衣提取物对CYP3A4活性的影响及其潜在作用机制。结果: MBSC初提物可显著抑制CYP3A4酶活性,其活性仅为对照组的38.14%（P<0.05）,且IC50值为489.7 μg·ml^-1,抑制机制为竞争 非竞争性抑制。结论: 绿豆衣提取物在体外对大鼠CYP3A4酶的活性具有抑制作用,尚需进一步应用体内模型评价其对CYP3A4活性的影响。     

高效液相色谱法同时测定人血浆1'-羟基咪达唑仑与咪达唑仑含量

目的建立同时检测1’-羟基咪达唑仑和咪达唑仑血药浓度的高效液相色谱法。方法采用Zirchrom 反相柱(Kromasil C18， 250 mm×4.6 mm，5 μm)；柱温：40 ℃；流动相：醋酸铵水溶液-甲醇(35∶65，V/V)；流速：1.5 mL·min^-1，样品经碱化提取分离后，流动相溶解，在220 nm波长处检测，内标：地西泮溶液。结果1’-羟基咪达唑仑和咪达唑仑分别在0.005 ～0.100和0.01 ～0.20 μg·mL^-1范围内线性关系良好，最低检测浓度分别为0.002和0.003 μg·mL^-1。萃取回收率均＞95%，日内和日间RSD均＜5%。结论该方法专一性强、灵敏度高、简单可靠，可用于研究体内CYP3A4酶的活性。     

高效液相色谱法检测人肝微粒体CYP3A活性

目的：测定普罗帕酮和N 去丙基普罗帕酮的比值以表达人肝微粒体中CYP3A的活性。方法：以1 mg·mL 1微粒体蛋白浓度37℃孵育普罗帕酮1 h，以HPLC测定普罗帕酮和N 去丙基普罗帕酮的含量。结果： 普罗帕酮和N 去丙基普罗帕酮的线性方程分别为Y＝0.452 0X＋0.003 029(r＝0.999 7)；Y＝1.137 3X＋0.012 740(r＝0.998 5)。结论：N 去丙基普罗帕酮与普罗帕酮的最大比值为1.54，CYP3A具有饱和性。     

高效液相色谱法测定咪达唑仑注射液的含量

目的研究HPLC法测定咪达唑仑注射液的方法及条件.方法色谱柱Diamonsil C18,流动相为磷酸盐缓冲液(pH7.3)-甲醇-乙腈(36∶30∶34),检测波长219 nm.结果咪达唑仑在4.14～82.80 mg·L-1范围内线性关系良好,其回归方程为Y=2.1476X+0.03560,r=0.999 9,平均回收率为99.9%.结论本法操作简便、结果准确,可作为该制剂的定量分析方法.     

高效液相色谱法测定术前儿童口服复方氯胺酮的血药浓度

目的测定儿童口服复方氯胺酮的血药浓度并探讨血药浓度与药效学的关系。方法用高效液相方法测定用药后不同时点氯胺酮(KET)、咪达唑仑(MZ)、阿托品(AT)的血药浓度;观察药物显效时间、镇静止痛效果。结果KET的tmax=(30±15)min,Cmax=(633±121)ng·mL-1;MZ的tmax=(30±15)min,Cmax=(105±35)ng·mL-1。患儿服药(10±4)min,血中可测到KET、MZ的含量;(30±20)min达峰;未检测到AT。结论复方氯胺酮口服液起效时间与其血药浓度高峰期相近。     

五味子甲素对大鼠肝微粒体CYP3A活性的影响

目的：通过体外药物代谢实验探讨五味子甲素对CYP3A活性的影响。方法：以大鼠肝微粒体为载体,选取咪达唑仑（MDZ）作为药物“探针”,建立高效液相色谱（HPLC）检测方法,体外给药测定五味子甲素对MDZ的IC50值以及相关酶动力学参数。结果：孵育体系内源性物质不干扰测定,方法快捷、稳定、灵敏度高。在肝微粒中,五味子甲素对MDZ的IC50浓度为6．26μmol／mL,相关酶动力学参数：Km=15．77μmol／L,K1=5．50μmol／mL。结论：五味子甲素对大鼠肝微粒体CYP3A活性具有抑制作用,其抑制作用为混合型,即：非竞争与反竞争抑制。     

雷公藤多苷对大鼠与人肝微粒体CYP3A酶活性的体外抑制作用

目的:建立液相色谱-串联质谱(LC-MS/MS)法测定大鼠和人肝微粒体中1′-羟基咪达唑仑的含量,研究雷公藤多苷对体外大鼠与人肝微粒体细胞色素P45(0CYP)3A酶活性的抑制作用。方法:将不同质量浓度的雷公藤多苷(0.5、1.0、2.0、5.0、10.0、50.0、100.0μg/ml)分别与大鼠和人肝微粒体(0.4 mg/ml)共同孵育20 min后终止反应,采用LC-MS/MS法测定孵育液中咪达唑仑的代谢产物1′-羟基咪达唑仑的浓度以评价CYP3A酶活性并计算酶活性抑制率,采用Graph Pad Prism 5.0软件进行拟合并计算半数抑制浓度(IC50)。色谱柱为Agilent Eclipse XBD-C18,流动相为水-甲醇(梯度洗脱),流速为0.3 ml/min,柱温为30℃,进样量为2μl。采用电喷雾电离(ESI),定量离子为m/z 342.01→324.1(1′-羟基咪达唑仑)、m/z 383.01→337.2(内标氯雷他定)。结果:1′-羟基咪达唑仑检测浓度在0.01~3μmol/L范围内与其和内标物峰面积比值呈良好线性关系;精密度试验RSD均小于10%,提取回收率为97.92%~101.65%,方法回收率为96.70%~104.10%,稳定性试验RSD均小于10%。雷公藤多苷对大鼠和人微粒体中CYP3A的IC50分别为(48.610±1.32)μg/ml和(4.754±1.12)μg/ml;在0.5~100.0μg/ml范围内雷公藤多苷对CYP3A酶活性有抑制作用,且与质量浓度呈正相关。结论:所建立的LC-MS/MS法可用于检测大鼠和人肝微粒体中1′-羟基咪达唑仑的含量。雷公藤多苷对体外大鼠和人肝微粒体药物代谢酶CYP3A均存在抑制作用,且对人肝微粒体CYP3A的抑制作用明显强于大鼠。     

高效液相色谱法测定大鼠血浆中咪达唑仑含量

目的建立检测大鼠血浆中咪达唑仑质量浓度的高效液相色谱法。方法取大鼠20只,一次性给予尾静脉注射咪达唑仑10mg／kg,分别于给药后0rain,5min,10min,20min,30min,1h,1．5h,2h,4h,6h时眼内眦取血,采用高效液相色谱法检测其血药浓度。采用DiamonsilC。8柱（250mm×4．6mm,5μm）,流动相为乙腈-水（62：38）,流速1．0mL／min,检测波长225nm,柱温30℃,进样量20此。结果咪达唑仑的保留时间为6．7rain,回归方程为y=0．0752X一0．0042（r=0．9999,n=7）,检测质量浓度的线性范围为0．1。30mg／L。低、中、高3种质量浓度血浆样品的绝对回收率分别为（109．84-4．54）％,（101．6±3．28）％和（104．9±4．30）％;日内RSD分别为2．86％,4．38％,3．54％,日间RSD分别为3．25％,3．17％,3．14％;咪达唑仑血浆样品-40℃保存3d及反复冻融3次,性质稳定,血浆样品处理后放置4h对测定无影响。20只大鼠血浆样品中咪逸唑仑的平均质量浓度为（8．78±2．18）mg／L。结论该方法简便、准确、灵敏度高、重现性好,可用于大鼠血浆中咪达唑仑浓度的测定。     

以睾酮为探针的HPLC法测定CYP3A1酶活性的方法学研究

目的:建立以睾酮为探针测定大鼠CYP3A1酶活性的方法。方法:采用高效液相色谱法,以咪达唑仑为内标,样品用乙酸乙酯萃取后重溶进样,进行睾酮特异代谢物6-β-羟基睾酮(6-β-OHT)浓度测定的方法学研究。色谱柱为HypersilBDSC18,流动相为甲醇-Na2HPO4水溶液(pH8.25)(60:40),流速为1mL.min-1,检测波长为254nm。结果:6-β-OHT检测浓度线性范围为1.25～100μg.mL-1(r=0.9998),最低定量限为1.25μg.mL-1;萃取回收率为83.9%～87.4%(RSD≤8.82%),相对回收率为100.4%～103.4%(RSD≤7.05%);平均日内、日间RSD均<10%;样本室温放置4h稳定性良好。结论:所建立的方法快速、简便、重复性好,适用于体外定量测定睾酮及其代谢物6-β-OHT,也可用于体外评估CYP3A1酶的活性。     

大鼠肝微粒体中CYP2C9酶的活性及动力学研究

目的 以双氯芬酸为探针药,建立HPLC测定大鼠肝微粒体CYP2C9酶活性的方法,并对其进行动力学考察。方法 采用Agilent ZORBAX SB-C18色谱柱;流动相为乙腈-水-0.1%三氟乙酸,梯度洗脱;流速为1 mL·min^-1;柱温30 ℃;检测波长为278 nm。大鼠肝微粒体加入双氯芬酸钠孵育30 min后,用盐酸和乙酸乙酯终止反应,加入内标地西泮,涡旋后高速离心,取上层有机相吹干复溶进样检测;以Lineweaver-Burk作图计算Km和Vmax。结果 双氯芬酸、4-羟基双氯芬酸和内标分离良好且无内源性干扰。4-羟基双氯芬酸浓度在0.05-10 μmol·L^-1内线性关系良好（r=0.999 8）,定量下限为0.05 μmol·L^-1;日内、日间精密度均〈10%,回收率〉75%。动力学考察表明选择盐酸和乙酸乙酯作为终止试剂效果良好,测得大鼠肝微粒体中双氯芬酸羟化反应的Km为26.87 μmol·L^-1,Vmax为2.359 nmol·min^-1·mg^-1 pro。结论 该方法稳定,结果能准确反映CYP2C9酶的活性,可用于相关动力学研究。     

HPLC法测定利多卡因及其代谢产物估算人肝微粒体CYP3A的活性

目的　以利多卡因 (LDC)与其代谢产物的比值估算人肝微粒体中CYP3A的活性。方法　以 1 0g·L- 1微粒体蛋白浓度 3 7℃孵育利多卡因 60min ,以HPLC测定利多卡因及其代谢产物单乙基甘氨二甲基苯酰胺 (MEGX)和甘氨二甲基苯酰胺 (GX)的含量。结果　LDC、MEGX和GX的标准曲线方程分别为 ^Y =0 2 93 4X -0 0 0 5661(r =0 9997)、^Y =0 7913X -0 0 0 8916(r =0 9993 )和 ^Y =0 6799X -0 0 0 7770 (r =0 9985)。体外孵育的最佳条件为 2 0mg·L- 1的LDC在浓度为 1 0 g·L- 1的微粒体中 ,孵育 60min ,代谢产物与利多卡因的平均比值为 3 2 8。结论　(MEGX +GX) /LDC可用来估算人肝微粒体CYP3A的活性。     

五味子甲素对大鼠肝微粒体CYP3A活性的影响

目的：通过体外药物代谢实验探讨五味子甲素对CYP3A活性的影响。方法：以大鼠肝微粒体为载体,选取咪达唑仑（MDZ）作为药物“探针”,建立高效液相色谱（HPLC）检测方法,体外给药测定五味子甲素对MDZ的IC50值以及相关酶动力学参数。结果：孵育体系内源性物质不干扰测定,方法快捷、稳定、灵敏度高。在肝微粒中,五味子甲素对MDZ的IC50浓度为6．26μmol／mL,相关酶动力学参数：Km=15．77μmol／L,Ki=5．50μmol／mL。结论：五味子甲素对大鼠肝微粒体CYP3A活性具有抑制作用,其抑制作用为混合型,即：非竞争与反竞争抑制。     

高效液相色谱法测定鼠肝微粒体中CYP1A2酶的活性及动力学考察

目的:建立以非那西丁为探针的高效液相色谱-紫外检测的实验方法,测定大鼠肝微粒体中CYP1A2酶活性并对其进行动力学考察。方法:采用Shimadzu Shim-Pack VP-ODS柱(150 mm×4.6 mm,5μm),流动相为:100 mmol·L-1磷酸二氢钠缓冲液(pH 4.3)和乙腈,梯度洗脱,流速为1.0 mL·min-1,柱温为室温,检测波长245 nm。非那西丁与大鼠肝微粒体在37℃温孵60 min,加入冰甲醇终止,12000 r.min-1离心10 min,取上清进行HPLC分析,以Lineweaver-Burk作图计算Vmax与Km值。结果:非那西丁、对乙酰氨基酚及其内标间乙酰氨基酚三者分离良好且无内源性干扰。对乙酰氨基酚最低检测限50 nmol·L-1,线性范围0.1～10μmol·L-1。日内日间精密度均小于10%。回收率大于75%。动力学考察表明选择甲醇作为终止试剂效果较好,非那西丁在0.2 mg·mL-1大鼠肝微粒体体系中孵育60 min,测得动力学参数Vmax为0.21 nmol·min-1.mgprotein-1,Km为20.39μmol·L-1。结论:该方法稳定,结果能准确地反映CYP1A2酶的活性,可以用于相关动力学研究。     

HPLC-RF测定小鼠肝微粒体中CYP2A5的酶活性

目的 以香豆素为探针底物建立测定小鼠肝微粒体中CYP2A5酶活性的方法.方法 用Waters Symmetry C18柱;流动相为0.1％醋酸-乙腈=70∶ 30;流速为1.0 mL·min-1,柱温30℃,Ex=340 nm,Em =458 nm.香豆素与小鼠肝微粒体在37℃孵育20 min,加入含内标的冰乙腈终止,4℃、12000 r·min-1离心15 min,取上清液,用HPLC测定其代谢产物7-羟基香豆素的含量,以GraphPad Prism 5.0作图计算酶动力学参数.结果 7-羟基香豆素与内标两者分离良好.7-羟基香豆素的检测限为2nmol · L-1(S/N≥3),线性范围为8～ 800 nmol·L-.日内日间精密度RSD小于5％,回收率为91.3％～101.4％.香豆素羟化反应的Km为2.15 μmol·L-1;Vmax为9.74 pmol·(min·mg protein)-1.结论 该方法稳定可靠,灵敏度高,适于体外CYP2A5酶活性的测定.     

大鼠肝细胞色素P4503A活性测定及其孵育条件的优化

目的:测定大鼠肝微粒体中细胞色素P4503A(CYP3A)的活性,并对其体外孵育条件进行优化。方法:采用1’-羟基咪哒唑仑的生成量表示肝中CYP3A的活性,高效液相色谱法测定肝微粒体中1’-羟基咪哒唑仑的浓度,用单因素试验法对其体外孵育条件进行优化,用线性Lineweaver-Burk双倒数作图法研究肝CYP3A酶促动力学。结果:1’-羟基咪哒唑仑在18.20~1 820.00μg.L-1范围内线性关系良好;体外优化的孵育条件为5μmol.L-1咪哒唑仑、0.102mg肝微粒体、孵育15min;肝CYP3A酶促动力学参数Km为1.67μmol.L-1,Vmax为95.15pmol.min-1.mg-1。结论:HPLC法操作简便、灵敏、快速,适用于肝微粒体中1’-羟基咪哒唑仑的浓度测定,肝CYP3A孵育条件及其酶促动力学研究为研究经CYP3A代谢的药物相互作用及其他物质对CYP3A酶的影响提供理论依据。     

Determination of UDP-glucuronosyltransferase UGT1A6 activity in human and rat liver microsomes by HPLC with UV detection

A simple and sensitive method for the determination of UDP-glucuronosyltransferase UGT1A6 activity using 4-methylumbelliferone (4-MU) and 4-nitrophenol (4-NP) as substrates in human and rat liver microsomes by high-performance liquid chromatography (HPLC) with uv detection is reported. The method was validated for the determination of 4-methylumbelliferyl beta-D-glucuronide (4-MUG) and 4-nitrophenyl beta-D-glucuronide (4-NPG) with respect to specificity, linearity, detection limit, recovery, stability, precision and accuracy. There was no interference from matrix and non-enzymatic reactions. Calibration curves for 4-MUG and 4-NPG are linear from 0.5 to 500 microM. Average recoveries ranged from 98 to 100% in spiked liver microsomes samples. 4-MUG and 4-NPG were stable at 4 degrees C for at least 72 h in spiked liver microsomes samples. The method was found to be more sensitive than previous methods using a spectrophotometer, a spectrofluorometer and HPLC. The detection limit for 4-MUG and 4-NPG (signal-to-noise ratio of 3) was 14 and 23 nM, respectively. The intra- and inter-day precision (relative S.D. (RSD)) and accuracy (relative mean error (RME)) was <5 and 9%, respectively. The intra- and inter-day reproducibility (RSD) of UGT1A6 enzyme assay in liver microsomes was <6%. With this improved sensitivity, the kinetics of UGT activities toward 4-MU and 4-NP in human and rat liver microsomes could be determined more precisely. In addition, the method could determine the non-inducible, and 3-methylcholanthrene- and phenobarbital-inducible activities of UGT1A6 in rat liver microsomes under the same assay conditions. Therefore, this method is applicable to in vivo and in vitro studies on the interaction of xenobiotic chemicals with UGT1A6 isoform in mammals using small amounts of biological samples.     

CYP3A4 activity in four different animal species liver microsomes using 7-benzyloxyquinoline and HPLC/spectrofluorometric determination

Some microplate-based direct assays with different fluorometric substrates have been developed, among which 7-benzyloxyquinoline (BOQ) has demonstrated the highest degree of selectivity for CYP3A subfamily. In our study, we firstly developed and validated an efficient, fast and cheap HPLC/spectrofluorometric analytical method to quantify 7-hydroxyquinoline (BOQ metabolite). Secondly, BOQ oxidation rate (1.95 +/- 0.24 microM/mg protein/min) was compared to that of midazolam (MDZ) (1.4 +/- 0.21 microM/mg protein/min), an other specific CYP3A probe. However, the difference did not reach statistically significance (test of Sign; p = 0.125, two tailed). Thirdly, the potential use of BOQ in other species than the rat (mouse, dog and monkey) was studied. The highest BOQ activity was observed in rat microsomes (3.75 micromol/mg protein/min) with lower P450 content (0.3 nmol/mg protein) compared to other species. Finally, the effect of CYP3A enzymes-selective inhibitor ketoconazole on the dealkylation of BOQ in control and dexamethasone (DM)-treated rat microsomes was studied. Ketoconazole inhibition potency was greater in control (IC(50) approximately 21.6 microM) compared to DM induced (IC(50) approximately 32.3 microM) microsomes. At concentrations greater than that considered to be enzyme-selective (e.g., 10-30 microM), ketoconazole inhibitory activity did not rise significantly, and at the maximal concentration tested (1,000 microM) a nearly similar inhibition (76%) was observed than that at 50 microM concentration (68.2%).     

CYP3A catalyses schizandrin biotransformation in human,minipig and rat liver microsomes

1. Schizandrin is recognized as the major absorbed effective constituent of Fructus schisandrae, which is extensively applied in Chinese medicinal formula. The present study aimed to profile the phase I metabolites of schizandrin and identify the cytochrome P450 (CYP) isoforms involved.

2. After schizandrin was incubated with human liver microsomes, three metabolites were isolated by high-performance liquid chromatography (HPLC) and their structures were identified to be 8(R)-hydroxyl-schizandrin, 2-demethyl-8(R)-hydroxyl-schizandrin, 3-demethyl-8(R)-hydroxyl-schizandrin, by liquid chromatography-mass spectrometry (LC-MS), ¹H-nuclear magnetic resonance (NMR), and ¹³C-NMR, respectively. A combination of correlation analysis, chemical inhibition studies, assays with recombinant CYPs, and enzyme kinetics indicated that CYP3A4 was the main hepatic isoform that cleared schizandrin. Rat and minipig liver microsomes were included when evaluating species differences, and the results showed little difference among the species.

3. In conclusion, CYP3A4 plays a major role in the biotransformation of schizandrin in human liver microsomes. Minipig and rat could be surrogate models for man in schizandrin pharmacokinetic studies. Better knowledge of schizandrin’s metabolic pathway could provide the vital information for understanding the pharmacokinetic behaviours of schizandrin contained in Chinese medicinal formula.