地西泮、苯巴比妥、普萘洛尔、和西咪替丁对大鼠肝微粒体安定氧化代谢的影响

研究地西泮、苯巴比妥、普萘洛尔和西咪替丁对地西泮氧化代谢的影响及其药酶蛋白的初步分析，应用HPLC，SDS－聚丙烯酰胺凝胶电泳和薄层扫描测定地西泮及其代谢物，并对大鼠肝微粒体和酶蛋白进行分离和含量测定，结果表明地西泮，普萘洛尔和西咪替丁使肝微粒体中P－450含量明显降低，地西泮和普萘洛尔明显抑制地西泮C3－羟化活性，大剂量普萘洛尔尚能抑制地西泮N－脱甲基，苯巴比妥明显诱导P－450生成，增强地西泮N－脱甲基和C3－羟化酶活性及分子量为51，000和59，000的电泳蛋白带，而地西泮，普萘洛尔则呈抑制作用，并发现，地西泮N－脱甲基酶活性和分子量为59，000蛋白含量呈线性相关（P＜0．05），而C3－羟化酶活性则与51，000蛋白含量呈线性相关（P＜0．01），因此地西泮C3－羟化代谢可能与51，000的P－450酶蛋白有关，而N－脱甲基代谢则可能与59，000的P－450酶蛋白有关。     

丹红注射液对大鼠肝微粒体5种CYP亚型酶活性的影响

摘要目的研究丹红注射液对5种细胞色素P450亚型酶活性的影响,为临床合理用药提供参考。方法采用大鼠体外肝微粒体孵育法,分别以非那西丁、甲苯磺丁脲、右美沙芬、氯唑沙宗、睾酮为CYP1A2、CYP2C9、CYP2D6、CYP2E1、CYP3A4的探针药物,在大鼠肝微粒体孵育体系中孵育,用高效液相色谱（HPLC）法测定相应的代谢产物,比较空白对照组和丹红注射液低、中、高剂量组之间探针药物代谢率的差异,评价丹红注射液对各亚型酶活性的影响。结果在体外肝微粒体孵育体系中,丹红注射液低剂量组中CYP1A2 和CYP2C9活性与空白对照组相比,差异无统计学意义（P＞0.05）;中和高剂量组中CYP1A2和CYP2C9活性与空白对照组相比降低,差异有统计学意义（P＜0.05或P＜0.01）;丹红注射液低、中、高剂量组中CYP2D6、CYP2E1、CYP3A4的活性与空白对照组相比,差异无统计学意义（P＞0.05）。丹红注射液对大鼠肝微粒体CYP1A2酶活性的半数抑制浓度（IC50）和抑制常数（Ki）分别为0.54%和0.226%。结论丹红注射液对大鼠肝微粒体CYP1A2酶活性有抑制作用,且为混合型抑制;对CYP2C9有弱抑制作用;对CYP2D6、CYP2E1、CYP3A4酶活性无明显影响。     

灯盏花素注射液对大鼠体外肝微粒体细胞色素P450酶活性的影响

摘 要 目的:研究灯盏花素注射液对大鼠肝微粒体CYP1A2、CYP2C9、CYP2D6、CYP2E1和CYP3A1/2 五个亚型酶活性的影响。方法: 采用大鼠肝微粒体体外孵育法,选用非那西丁（CYP1A2）、甲苯磺丁脲（CYP2C9）、右美沙芬（CYP2D6）、氯唑沙宗（CYP2E1）和睾酮（CYP3A1/2）作为5个亚型酶的探针药物,孵育系统中加入不同浓度的灯盏花素注射液,用HPLC法测定5个亚型酶探针药物代谢产物的生成量,比较空白对照组与不同浓度灯盏花素注射液给药组探针药物的活性,反映灯盏花素注射液对5个亚型酶活性的影响。结果:大鼠肝微粒体体外孵育系统中,灯盏花素注射液对大鼠CYP3A1/2的IC₅₀为29.40μg·ml^-1,K_i为37.78 μg·ml^-1;对CYP1A2、CYP2C9、CYP2D6和CYP2E1的IC₅₀＞200 μg·ml^-1。结论:灯盏花素注射液对大鼠体外肝微粒体CYP3A1/2有弱的抑制作用,对CYP1A2、CYP2C9、CYP2D6和CYP2E1活性无明显影响。     

HPLC法测定大鼠肝微粒体中睾酮的含量

目的:建立以高效液相色谱法测定大鼠肝微粒体中细胞色素P4503A4(CYP3A4)探针底物睾酮含量的方法。方法:色谱柱为Ultimate-XB C18,流动相为水-乙腈(50∶50),内标为地西泮,流速为1.0mL·min-1,检测波长为245nm,柱温为30℃,进样量为20μL。结果:睾酮生物样品检测浓度的线性范围为10.0～200.0μmo·lL-1(r=0.9995);低、中、高浓度的平均方法回收率分别为86.15%、103.10%、97.48%,平均相对回收率为111.15%、107.24%、100.78%,日内RSD分别为3.92%、2.46%、2.82%,日间RSD分别为2.98%、1.34%、2.41%。结论:本方法简便快速、灵敏度高、重复性好,可用于大鼠肝微粒体中CYP3A4活性的测定及相关研究应用。     

乌头碱在豚鼠和小鼠肝微粒体细胞色素氧化酶中的代谢作用研究

目的:研究乌头碱(AC)在豚鼠和小鼠体外肝微粒体中代谢产物的差异。方法:优化2个种属肝微粒体与AC的P450反应体系,应用高效液相色谱-高分辨质谱联用(HPLC-HRMS)和超高相液相色谱-多级质谱(UPLC-MS/MS)法测定AC在2种肝微粒体中的细胞色素氧化酶(CYP)代谢产物。结果:AC在2种肝微粒体中均代谢产生8种代谢产物,其中6种为CYP代谢产物;脱甲基、脱乙基、脱氢和氧化反应是其主要代谢特征。结论:乌头碱在豚鼠和小鼠体外肝微粒体中的CYP主要代谢途径相同。     

奥美拉唑在大鼠肝微粒体中的酶促反应动力学研究

目的研究奥美拉唑在大鼠肝微粒体中的酶促反应动力学。方法采用高效液相色谱法测定奥美拉唑在体外代谢系统中的产物5’-羟基奥美拉唑,并用Eadie-Hofstee作图法分析数据,计算酶促反应动力学参数最大反应速率(Vmax)、米氏常数(Km)。结果在体外代谢系统中,奥美拉唑生成5’-羟基奥美拉唑的Vmax为2010nmol/(min.mgprotein)、Km为50.3μmol/L。结论本分析方法符合方法学验证的要求,体外代谢常数准确,可满足奥美拉唑体外代谢的研究。     

Effects of Diethyl Phthalate and Other Plasticizers on Laurate Hydroxylation in Rat Liver Microsomes

Diethyl phthalate (DEP) is used in pharmaceutical coatings, cosmetics, and plastic films to wrap foods. There is a health concern associated with the exposure to certain phthalate esters because they belong to a class of compounds referred to as peroxisome proliferators which have been shown to increase the incidence of liver tumors when administered to rats. In this study, we have compared DEP to four other commonly used plasticizers, 2-diethylhexyl phthalate (DEHP), dibutyl phthalate (DBP), 2-diethylhexyl adipate (DEHA), and acetyltributyl citrate (ATBC), for their ability to induce the cytochrome P450-mediated fatty acid -hydroxylation system, which is one of the initial cellular responses when animals are treated with peroxisome proliferators. The administration of DEHP, DBP, and DEHA to rats increased the specific activity of laurate 12-hydroxylase from 2.8 ± 1.1 in control rats to 30.3 ± 11.6, 14.5 ± 4.1, and 9.7 ± 1.9 nmol 12-hydroxylaurate formed/min/nmol P450, respectively. In contrast, laurate 12-hydroxylase activity in DEP-and ATBC-treated rats were 4.4 ± 1.2 and 4.4 ± 1.0 nmol 12-hydroxylaurate formed/min/nmol P450, respectively. In addition, whereas DEHP increased peroxisomal palmitoyl-CoA oxidation 6-fold, DEP increased this activity only 1.3-fold. Two protein bands, at 51 and 52 kDa, were found to increase 6- to 12-fold in microsomes of DEHP-, DBP-, and DEHA-treated rats, but these bands were increased only 2-fold in DEP- or ATBC-treated rats.     

HPLC法测定大鼠肝微粒体中6-羟基氯唑沙宗的含量

目的：建立高效液相色谱法测定大鼠肝微粒体中6-羟基氯唑沙宗的含量.方法：采用Diamonsil C18柱（200 mm×215;4.6 mm,5 μm）,以甲醇-水-磷酸（45：55：0.1）为流动相,流速1.0 ml·min^-1,检测波长为296 nm.结果：6-羟基氯唑沙宗浓度在0.5 - 25 μmol·L^-1 范围内呈现良好的线性关系（r=0.999 1）,方法回收率为92.57% - 98.72%,提取回收率为76.38%-82.25%,日内、日间精密度RSD〈9%.结论：该方法可靠、准确、重复性好,可用于大鼠肝微粒体中6-羟基氯唑沙宗的含量测定及体外代谢研究.     

Potential Beneficial Metabolic Interactions Between Tamoxifen and Isoflavones via Cytochrome P450-mediated Pathways in Female Rat Liver Microsomes

PURPOSE: This study aims to evaluate a cytochrome P450-based tamoxifen-isoflavone interaction and to determine the mechanisms responsible for inhibitory effects of isoflavones (e.g., genistein) on the formation of alpha-hydroxytamoxifen. METHODS: Metabolism studies were performed in vitro using female rat liver microsomes. The effects of genistein and an isoflavone mixture on tamoxifen metabolism and the inhibition mechanism were determined using standard kinetic analysis, preincubation, and selective chemical inhibitors of P450. RESULTS: Metabolism of tamoxifen was saturable with Km values of 4.9+/-0.6, 14.6+/-2.2, 25+/-5.9 microM and Vmax values of 34.7+/-1.4, 297.5+/-19.2, 1867+/-231 pmol min(-1) mg(-1) for a-hydroxylation, N-desmethylation, and N-oxidation, respectively. Genistein (25 microM) inhibited alpha-hydroxylation at 2.5 microM tamoxifen by 64% (p < 0.001) but did not affect the 4-hydroxylation, N-desmethylation, and N-oxidation. A combination of three (genistein, daidzein, and glycitein) to five isoflavones (plus biochanin A and formononetin) inhibited tamoxifen alpha-hydroxylation to a greater extent but did not decrease the formation of identified metabolites. The inhibition on alpha-hydroxylation by genistein was mixed-typed with a Ki, value of 10.6 microM. Studies using selective chemical inhibitors showed that tamoxifen alpha-hydroxylation was mainly mediated by rat CYP1A2 and CYP3A1/2 and that genistein 3'-hydroxylation was mainly mediated by rat CYP1A2, CYP2C6 and CYP2D1. CONCLUSIONS: Genistein and its isoflavone analogs have the potential to decrease side effects of tamoxifen through metabolic interactions that inhibit the formation of a-hydroxytamoxifen via inhibition of CYP1A2.     

Effect of Water-miscible Organic Solvents on CYP450-mediated Metoprolol and Imipramine Metabolism in Rat Liver Microsomes

The catalytic activity of cytochrome P450 enzymes is known to be affected by presence of organic solvents in in vitro assays. However, these effects tend to be variable and depend on the substrate and CYP450 isoform in question. In the present study, we have investigated effect of ten water miscible organic solvents (methanol, ethanol, propanol, isopropanol, acetone, acetonitrile, dimethylsulphoxide, dimethylformamide, dioxane and PEG400) on water soluble substrates of CYP450, metoprolol and imipramine, at 0, 0.1, 0.25, 0.5, 0.75 and 1% v/v concentration in rat liver microsomes. Organic solvents studied had a concentration dependent inhibitory effect on the metoprolol and imipramine metabolism activity. Metoprolol metabolism was found to be more susceptible to the organic solvents, almost all the ten solvents had more or less inhibitory effect compared to imipramine metabolism. Except acetone, PEG400 and dimethylsulphoxide, all solvents had ~50% inhibition of total metoprolol metabolism activity, while in case of imipramine metabolism activity, only n-propanol, isopropanol and PEG400 had ~50% inhibition at 1% v/v. Interestingly, methanol, dimethylsulphoxide and acetonitrile had negligible effect on the imipramine metabolism (less than 10% inhibition at 1% v/v) while, total metoprolol metabolism activity was substantially inhibited by these solvents (MeOH 52%, DMSO 29% and ACN 47% at 1% v/v). In both cases, dioxane was found to be the most inhibitory solvent (~90% inhibition at 1% v/v).     

HPLC法测定大鼠肝微粒体中洛伐他汀含量的方法学研究

目的:考察测定大鼠肝微粒体中洛伐他汀含量的方法学。方法:采用高效液相色谱法,内标为地西泮,色谱柱为Ulti-mateXB-C18,流动相为乙腈-水(70∶30),流速为1.0mL·min-1,检测波长为238nm,柱温为30℃,进样量为20μL。结果:大鼠肝微粒体中洛伐他汀检测浓度的线性范围为2.5～40μmol·L-1(r=0.9983),低、中、高浓度洛伐他汀溶液的日内RSD分别为5.44%、2.89%、2.83%,日间RSD分别为5.48%、1.84%、1.91%,方法回收率分别为(109.24±3.28)%、(104.82±5.92)%、(102.17±1.92)%,绝对回收率分别为(104.65±2.93)%、(113.72±6.25)%、(101.92±1.89)%。结论:方法学考察结果表明,本方法简单易行、灵敏度高,可用于肝微粒体中洛伐他汀的含量测定。     

葛根素及葛根提取物在大鼠肝微粒体内代谢动力学研究

为了研究葛根素单体和葛根提取物中的葛根素在大鼠肝微粒体中的代谢是否存在差异,建立微粒体孵育体系。采用高效液相色谱法测定葛根素在肝微粒体代谢系统中的含量,并应用GraphPad Prism 5.0软件分析数据,计算酶促反应动力学参数。在体外代谢系统中,葛根素单体的酶促反应动力学参数K_m为(0.93±0.17)μmol/L,V_(max)为(93.59±2.82) nmol/min·mg,CL_(int)(V_(max)/K_m)为(100.6±1.07) mL/min·mg;葛根提取物中葛根素的相应的动力学参数分别为(1.02±0.09)μmol/L,(22.48±1.53) nmol/min·mg和(22.04±1.72) mL/min·mg。葛根素单体和葛根提取物中的葛根素在大鼠肝微粒体的代谢存在明显的差异,葛根素单体的代谢速度快于葛根提取物中的葛根素的代谢速度。结果提示中药提取物中的其它成分可影响有效成分单体的代谢过程。     

大黄酸对大鼠肝细胞色素P4503A酶活性的抑制

（1. ［摘要］目的研究大黄酸对大鼠肝微粒体细胞色素P450 3A（CYP3A）酶活性的影响。方法在体外大鼠肝微粒体孵育体系中加入底物睾酮和不同浓度的大黄酸,采用高效液相色谱仪测定睾酮的羟基化代谢产物6β羟基睾酮的含量,计算CYP3A酶活性来反映大黄酸对CYP3A酶的抑制效果。结果大鼠肝微粒体孵育体系中,大黄酸对CYP3A酶活性有抑制作用,其半数抑制浓度（IC50）和Ki值分别为36.74,20.73 μmol&#8226;L 1。结论在大鼠肝微粒体体外孵育系统中,大黄酸对CYP3A酶具有抑制作用。     

吡喹酮在大环内酯类抗生素和糖皮质激素诱导的大鼠肝微粒体中的代谢

我们的结果表明，只有经细胞色素P－450ⅢA1同功酶特异的诱导剂（红霉素和地塞米松）处置过的大鼠肝微粒体能显著地代谢吡喹酮（PQT），高铁氧化钾能破坏细胞色素P－450Fe(Ⅱ）－代谢物的复合物，使细胞色素P－450ⅢA1同功酶的活性恢复。因此，当微粒体和PQT的温孵体系中加入高铁氰化钾时，PQT在经多剂红霉素处置后的微粒体中的代谢速率进一步增加，而乙酰螺旋霉素诱导的细胞色素P－450并不形成复合物，因此，高铁氰化钾不影响PQT在经乙酰螺旋霉素处置后的微粒体中的代谢。三乙酰竹桃霉素作为细胞色素P－450ⅢA1的特异抑制剂，能抑制PQT在地塞米松处置过的肝微粒体内的代谢速率53％，以上结果表明，大鼠肝细胞色素P－450ⅢA1同功酶参与PQT在大鼠肝微粒体内的代谢。     

葛根素对人肝微粒体中细胞色素P450酶活性的影响

目的:研究葛根素对人肝微粒体中细胞色素P450 1A2(CYP1A2)、CYP3A4、CYP2C9、CYP2C19、CYP2D6、CYP2E1酶活性的影响.方法:分别以咖啡因、咪达唑仑、甲苯磺丁脲、氯唑沙宗、美托洛尔、美芬妥因为探针药,利用HPLC方法测定探针药与相应代谢产物的浓度,研究葛根素在人肝微粒体孵化体系中对CYP1A2、CYP3A4、CYP2C9、CYP2E1、CYP2D6、CYP2C19酶活性的影响.结果:在人肝微粒体反应体系中,0.1,0.2,0.4,0.8mmol·L-1葛根素使咖啡因的代谢产物的生成分别降低了(31±15)%(P＜0.01),(43±8)%(P＜0.05),(48±6)%(P＜0.05),(49±4)%(P＜0.05),0.05,0.1,0.2,0.4,0.8mmol·L-1葛根素使美托洛尔的代谢产物生成分别降低了(25±7)%(P＜0.01),(33±4)%(P＜0.05),(40±9)%(P＜0.01),(46±5)%(P<0.01),(72±9)%(P＜0.01);而对甲苯磺丁脲、美芬妥因、咪达唑仑和氯唑沙宗的代谢产物没有明显影响.结论:在人肝微粒体反应体系中,葛根素(0.1 mmol·L-1)对CYP1A2和CYP2D6酶活性有较明显的抑制作用;且随着葛根素浓度的增高,对这两种酶活性的抑制作用也随之增强,而对CYP2C9、CYP2C19、CYP3A4和CYP2E1酶活性没有影响.     

On the Aromatic Hydroxylation of Amphetamine in Rat Liver Microsomes and Perfused Liver Preparations: Effects of Long-term Administration

Abstract The liver microsomal p-hydroxylation of amphetamine to parahydr-oxyamphetamine (pOHA) was dependent on NADP and inhibited by carbon monoxide indicating the involvement of cytochrome P-450. SKF 525-A, fenfluramine and desmethylimipramine were the most effective inhibitors of this pathway of amphetamine metabolism. Repeated administration of phenobarbital resulted in reduced p-hydroxylation of amphetamine in vitro. Chronic administration of amphetamine reduced the microsomal p-hydroxylation of amphetamine without apparent changes in the cytochrome P-450 levels or in the activity of NADPH-cytochrome c reductase. The aromatic hydroxylation of aniline and the demethylation of ethylmorphine was not affected by this treatment. However, the 455 nm complex formed during the microsomal metabolism of N-hydroxy-amphetamine was increased by the long-term administration of amphetamine. These results indicate some pecularities of the in vitro hydroxylation of amphetamine by rat liver microsomes. Amphetamine disappeared from the perfusate of the perfused liver at the same rate in rats given a single dose of amphetamine and in rats given amphetamine orally for four weeks. The excretion of pOHA and its conjugate increased at 60 and 90 min. and 30, 60 and 90 min. respectively in the perfusate of the same experiment as compared to the controls. The total excretion of radioactive amphetamine metabolites at the end of the perfusion was increased in the perfusate and reduced in the bile compared to the control experiment.     

High-Performance Liquid Chromatographic Analysis of Dipyrone Metabolites to Study Their Formation in Human Liver Microsomes

Pharmaceutical Research -     

探针药物法评价厚朴酚、和厚朴酚对大鼠肝微粒体中CYP450酶的抑制作用

目的 研究厚朴中的主要成分厚朴酚、和厚朴酚对CYP450酶的7种亚型酶活性的影响,预测可能的药物间相互作用,为中药的临床应用提供理论依据。方法 采用Cocktail探针方法,将厚朴酚、和厚朴酚和CYP450酶7种亚型的特异性探针底物：甲苯磺丁脲（CYP2C）、香豆素（CYP2A6）、右美沙芬（CYP2D6）、氯唑沙宗（CYP2E1）、睾酮（CYP3A）、非那西丁（CYP1A2）、安非他酮（CYP 2B6）与大鼠肝微粒体进行孵化反应,结合UPLC-MS/MS的多反应监测技术,测定对应的7种代谢产物（4-羟基甲苯磺丁脲、7-羟基香豆素、右啡烷、6-羟基氯唑沙宗、6β-羟基睾酮、对乙酰氨基酚和羟基丙酮）的峰面积,通过与对照组比较,确定厚朴酚、和厚朴酚对以上7种酶活性的影响,计算相应的IC₅₀,评价是否有抑制作用。结果 厚朴酚、和厚朴酚对大鼠肝微粒体中的4种亚型酶（CYP2C、CYP2D6、CYP2E1和CYP2B6）活性均有抑制作用,且随化合物浓度和预温育时间增加而增加机械抑制;另外3种亚型酶（CYP2A6、CYP3A4和CYP1A2）则不呈现此抑制规律。结论 厚朴在与以上4种酶（CYP2C、CYP2D6、CYP2E1、CYP2B6）代谢的药物联合用药时,易产生药物相互作用,抑制药物代谢。本研究也为中药厚朴的临床应用以及新药研发提供重要的数据支持。     

Glucuronidation of Entacapone, Nitecapone, Tolcapone, and Some Other Nitrocatechols by Rat Liver Microsomes

Purpose. Nitrocatechol COMT inhibitors are a new class of bioactive compounds, for which glucuronidation is the most important metabolic pathway. The objective was to characterize the enzyme kinetics of nitrocatechol glucuronidation to improve the understanding and predicting of the pharmacokinetic behavior of this class of compounds. Methods. The glucuronidation kinetics of seven nitrocatechols and 4-nitrophenol, the reference substrate for phenol UDP-glucuronosyltrans-ferase activity, was measured in liver microsomes from creosote-treated rats and determined by non-linear fitting of the experimental data to the Michaelis-Menten equation. A new method that combined densitometric and radioactivity measurement of the glucuronides separated by HPTLC was developed for the quantification. Results. Apparent K_m values for the nitrocatechols varied greatly depending on substitution pattern being comparable with 4-nitrophenol (0.11 mM) only in the case of 4-nitrocatechol (0.19 mM). Simple nitrocatechols showed two-fold V_max values compared with 4-nitrophenol (68.6 nmol min^–1 mg^–1), while all disubstituted catechols exhibited much lower glucuronidation rate. V_max/K_m values were about 10 times higher for monosubstituted catechols compared to disubstituted ones. The kinetic parameters for COMT inhibitors were in the following order: K_m nitecapone >> entacapone > tolcapone; V_max nitecapone > entacapone > tolcapone; V_max/K_m tolcapone > nitecapone > entacapone. Conclusions. Nitrocatechols can in principle be good substrates of UGTs. However, substituents may have a remarkable effect on the enzyme kinetic parameters. The different behaviour of nitecapone compared to the other COMT inhibitors may be due to its hydrophilic 5-substituent. The longer elimination half-life of tolcapone in vivo compared to entacapone could not be explained by glucuronidation kinetics in vitro.     

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。