右旋黄皮酰胺在大鼠肝微粒体中的代谢转化

目的：研究黄皮酰胺的主要代谢途径,为进一步研究黄皮酰胺代谢的立体选择性打下基础。方法：用大鼠肝微粒体体外温孵法对右旋黄皮酰胺((+)-clausenamide)进行温孵,用硅胶柱色谱、制备TLC分离纯化代谢产物并通过光谱分析鉴定其结构。结果：分离得到5个代谢产物CM1,CM3,CM4,CM5及CM6,其结构分别鉴定为6-羟基,4-羟基,4,6-二羟基,4-苯环邻位羟基,4,7-苯环间位-二羟基黄皮酰胺。结论：黄皮酰胺的代谢主要发生羟化或双羟化,CM3是其主要代谢产物,量较少的CM4,CM6为其进一步代谢产生的双羟基代谢产物;另2个代谢产物CM1,CM5产生的量也较少;CM2未分离得到,但通过HPLC分析知其为右旋黄皮酰胺的微量代谢产物。     

抗焦虑新药AF-5及其代谢物在人肝微粒体体外温孵体系中代谢研究

目的研究一类抗焦虑新药AF-5及其代谢物(I,II)在人肝微粒体体外温孵体系中代谢情况.方法自制人肝微粒体,用Lowry法测定酶活性为8.79mg·mL^-1.以此配制人肝微粒体体外温孵体系,加入药物,温孵后,提取分离,GC-MS测定.结果鉴定了AF-5在人肝微粒体体外温孵体系中的两个主要代谢物,并阐明了其体外代谢途径为AF-5的4位首先氧化为羟基,然后氧化成羰基.结论AF-5在体外人肝微粒体温孵体系中,100min后完全代谢成羟基代谢物I及羰基代谢物II,以羟基代谢物为主要代谢产物.AF-5代谢物I在人肝微粒体温孵体系中,可转化为代谢物II,而代谢物II在人肝中则不再代谢.     

氯代正丁苯酞在大鼠肝微粒体中的代谢研究

用大鼠肝微粒体体外温孵方法进行了氯代正丁苯酞(CBP)代谢转化研究,优化了温孵体系的组成,建立了反相HPLC-DAD在线同时分离检测CBP及其4个体外代谢产物的分析方法,并比较了在苯巴比妥(PB)与3-甲基胆蒽(3-MC)诱导的微粒体中代谢差别。利用TLC、柱色谱与制备HPLC分离纯化了3个主要代谢产物,并进行了NMR,MS,UV等光谱鉴定,确定了其主要代谢产物为γ-羟基氯代正丁苯酞与β-羟基氯代正丁苯酞及它们的立体异构体。     

布洛芬离体肝代谢中对映体间的相互作用

目的研究布洛芬离体肝代谢中对映体之间的相互作用。方法用家兔肝匀浆质与单纯的R(- ) 或S(+) 布洛芬以及两对映体以不同比例的混合物 ,加入必要的辅助因子进行离体肝手性转化代谢试验 ,利用立体选择性HPLC法测定各对映体以及中间产物硫酯的质量浓度。结果布洛芬手性转化代谢由R(- ) 型向S(+) 型单向进行 ,在S(+) 布洛芬的存在下 ,R(- ) 布洛芬的转化量减少 ,中间产物硫酯的生成量减少。结论S(+) 布洛芬在一定程度上抑制手性转化的进行     

左旋黄皮酰胺在大鼠肝微粒体中的代谢转化研究

用大鼠肝微粒体体外温孵法进行了左旋黄皮酰胺[(-)-clausenamide]代谢转化研究,优化了温孵体系,建立了反相HPLC-DAD同时分离检测左旋黄皮酰胺及其体外代谢产物的分析方法。用硅胶低压柱色谱、制备TLC及制备HPLC分离纯化了两个代谢产物并进行了光谱鉴定。结果表明,两个代谢物分别确定为6-和5-位羟基取代的黄皮酰胺。     

利福平减弱NAPQI耗竭谷胱甘肽的HPLC分析

目的进一步研究小鼠肝微粒体温孵体系中利福平（RFP）减弱对乙酰氨基酚（APAP）毒性中间产物N-乙酸-对苯醌亚胺（NAPQI）耗竭谷胱甘肽（GSH）的保护作用。方法制备小鼠肝微粒体，体外温孵，HPLC测定APAP、RFP及相关代谢产物浓度变化。结果10．8％APAP（10μg／ml）温孵1h后代谢，分别加入RFP和GSH，23．0％、28．2％的APAP温孵1h代谢。RFP（50μg／ml）温孵1h后没明显变化，而在加入APAP温孵1h后开始减少，醌式利福平（QRFP）大量产生。结论RFP和GSH一样加速了APAP代谢，却减弱了APAP毒性中间产物致GSH耗竭的作用，RFP的结构中有两个酚羟基，很可能具有清除对乙酰氨基酚毒性中间产物的可能。     

甲基莲心碱在大鼠肝微粒体CYP450系统中的代谢特征

目的研究甲基莲心碱(Nef)在大鼠肝微粒体系的代谢特性,探明参与Nef代谢的CYP450亚酶种类及其在Nef代谢中的作用。方法应用CYP3A特异性诱导剂地塞米松(DEX)、CYP2B诱导剂苯巴比妥(PB)、CYP1A诱导剂β-萘黄酮(β-NF)分别对W istar大鼠进行在体诱导,建立肝微粒体温孵及NADPH再生体系,HPLC紫外检测法测定Nef及其代谢产物。观察Nef代谢消失率与代谢特征,研究上述各诱导剂和CYP3A特异性抑制剂三乙酰竹桃霉素(TAO)对Nef体外代谢的影响。结果Nef在大鼠微粒体系代谢呈饱和现象;温孵液中代谢产物生成的量与底物Nef的浓度具有良好的相关性(r=0.993);Nef在DEX、PB诱导组大鼠肝微粒体温孵液中的生物转化较对照组明显加快(P<0.01),DEX组又较PB组的Nef药物代谢率差异有显著性(P<0.01),而β-NF组未显现诱导作用,其药物代谢率分别为:DEX组80.6%±9.5%;PB组61.5%±6.7%;β-NF组20.7%±1.5%;对照组19.9%±1.6%;TAO呈量效依赖性抑制Nef在肝微粒体温孵液中的代谢。结论研究结果提示Nef具有酶促动力学代谢特性;CYP3A及CYP2B是介导Nef在大鼠体内生物转化的CYP450亚酶,其中主要参与Nef代谢的为CYP3A。     

左旋和右旋吡喹酮在人和大鼠肝微粒体内的代谢

左旋吡喹酮[(-)PQT]在人和大鼠肝微粒体中人谢生成产物[M];在[M]色谱峰处,右旋吡喹酮[(+)PQT]无明显代谢物生成.人肝微粒体代谢(?)-PQT生成MI的K_m和V_(max)分别为58±s13μmol·L~1和1.3±s 0.6 nmol·mg~1·min~1·RF.在人肝微粒体中,(?)与(+)PQT原药消除的K_m和V_(max)比值分别为0.86±s 0.28和1.5±s 0.5;(-)-和(+)PQT人肝内在清除率分别为1.3±s 0.5和0.7±s0.3 ml·h~1·mg~1,(-)-/(+)PQT的比值平均为1.8±s 0.5(-)与(-)-PQT在大鼠肝微粒体中消除速率的比值为1.83±s 0.27,结果说明PQT对映异构体在人和大鼠肝微粒体内代谢表现较严格的立体选择性     

去氢土莫酸在大鼠体外肝微粒体体系中的生物转化研究

目的:研究中药茯苓中主要化学成分之一的去氢土莫酸在大鼠肝微粒体中的生物转化.方法:用大鼠肝微粒体体外温孵法进行去氢土莫酸的生物转化,优化了温孵体系;高效液相色谱法检测和制备原形化合物去氢土莫酸及其生物转化产物,核磁共振波谱法和质谱法确定生物转化产物的结构.结果:去氢土莫酸在苯巴比妥诱导的大鼠肝微粒体药物代谢酶作用下,产生2个转化产物,分别为土莫酸和去氢茯苓酸.结论:去氢土莫酸可被苯巴比妥诱导的大鼠肝微粒体药物代谢酶转化为土莫酸和去氢茯苓酸.     

去氢厄弗酚在小鼠肝微粒体中代谢产物及CYP450酶亚型的鉴定

目的建立去氢厄弗酚(DHE)小鼠体外肝微粒体孵育方法,鉴定DHE在小鼠肝微粒体中的代谢产物及参与DHE代谢的CYP450酶亚型。方法采用UPLC-Q-TOF-MS/MS分析鉴定DHE在体外肝微粒体共温孵后的代谢产物,筛选7种CYP450酶亚型,并通过特异性化学抑制剂法,鉴别参与DHE代谢的主要CYP450酶亚型。结果在体外肝微粒体共温孵后,检测到4个代谢产物;所筛选的7种CYP450酶亚型中,CYP1A2、CYP2C8和CYP2D2对DHE体外肝微粒体代谢的参与度较高。结论在肝脏中,有多种代谢酶亚型参与DHE的代谢,表明DHE在临床上不易与其他药物产生相互作用。     

大鼠肝微粒体温孵体系中（＋）,（—）—黄皮酰胺及其代谢产物的LC—MS分析

目的：建立黄皮酰胺及其代谢产物的ＨＰＬＣ－ＥＳＩ－ＭＳ在线检测分析方法,并对未分离得到的微量代谢产物进行分析确证,探索ＬＣ－ＭＳ在代谢转化研究中的应用。方法：利用柱后补偿技术,采用正离子检测对大鼠肝微体中（＋）,（－）－黄皮酰胺及其代谢产物进行ＨＰＬＣ－ＥＳＩ－ＭＳ分析,根据ＭＳ的碎片信息检测主要的代谢产物,特别是对未分离得到的代谢产物的结构碎片进行分析,确定其结构。结果：除检测出主要已知代谢产物     

右旋和左旋黄皮酰胺在大鼠体内代谢转化的研究

目的　研究黄皮酰胺在大鼠体内的代谢转化途径。方法　收集ip给药后大鼠的尿液、粪便及血液进行分析,寻找已知的代谢产物并通过HPLC-DAD和HPLC-MS分析寻找未知的代谢产物,确定大鼠体内的主要代谢途径。并通过比较(+),(-)-黄皮酰胺代谢的差异,初步研究其代谢转化的立体选择性。结果　HPLC分析发现,大鼠肝微粒体中所分离得到的6个主要代谢产物均在体内存在,(+),(-)-黄皮酰胺的代谢有明显的差异,根据MS碎片信息确定了一个新的代谢产物的结构,即N-去甲黄皮酰胺。结论　手性黄皮酰胺主要在肝脏中发生羟基化代谢反应,并有明显的立体选择性。     

五味子醇甲在大鼠肝微粒体内的代谢动力学和性别差异

体外研究五味子醇甲(schizandrin，SZ)在大鼠肝微粒体内的代谢动力学和性别差异。制备正常雌、雄大鼠肝微粒体，与SZ共同温孵，以高效液相色谱法测定SZ及其代谢产物。SZ在雄鼠肝微粒体内代谢反应的最大速率V_max、米氏常数K_m和清除率Cl_int分别为(21.88±2.30) μmol·L^-1·min^-1·mg^-1(protein)，(389.00±46.26) μmol·L^-1和(0.056 3±0.000 7) min·mg^-1(protein)；在雌鼠肝微粒体内代谢反应的最大速率V_max、米氏常数K_m和清除率Clint_{分别为(0.61±0.07) μmol·L^-1·min^-1·mg^-1(protein)，(72.64±13.61) μmol·L^-1和(0.008 4±0.000 8) min·mg^-1(protein)，雌、雄鼠肝微粒体内SZ的主要代谢物不同，分别为7,8-顺二羟基五味子醇甲(M1)和7,8-顺二羟基-2-去甲基五味子醇甲(M2b)。酮康唑、奎尼丁和奥芬得林对SZ的在雌、雄大鼠肝微粒体内代谢均有不同程度的抑制作用，西咪替丁对其在雄鼠肝微粒体内的代谢也有一定的抑制作用。SZ在雌、雄大鼠肝微粒体中代谢动力学及代谢产物存在明显的性别差异，这种差异可能主要是由CYP3A和CYP2C11在大鼠肝微粒体内的性别差异引起的。}     

Metabolism of prostaglandin E analogs in guinea pig and rat liver microsomes

Tritium-labelled 16,16-dimethyl-PGE2, 9-methylene-PGE2 (9-deoxo-16,16-dimethyl-9-methylene-prostaglandin E2) and tetranor-9-methylene-PGE2 were incubated with guinea pig liver microsomes. All three compounds were converted to omega-oxidized products in yields of a few per cent. In addition, from incubations with 9-methylene-PGE2 and tetranor-9-methylene-PGE2 were also obtained metabolites with the methylene group transformed into a dihydrodiol. In a comparative study with rat liver microsomes, it was found that these converted tetranor-9-methylene-PGE2 in a 50 per cent yield to omega-oxidized products. Finally, 20.000 X G supernatants from guinea pig and rat liver were compared with respect to omega-oxidation. The rat liver 20.000 X G supernatant was found to convert the substrate to the same extent as washed microsomes. By contrast, the guinea pig liver 20.000 X G supernatant was considerably more efficient than washed microsomes.     

Metabolism of prazepam by rat liver microsomes: stereoselective formation and N-dealkylation of 3-hydroxyprazepam

The metabolism of prazepam (7-chloro-1-(cyclopropylmethyl)-1,3-dihydro-2H-1, 4-benzodiazepin-2-one) (PZ) was studied using liver microsomes prepared from untreated, phenobarbital (PB)-treated, and 3-methylcholanthrene (3MC)-treated male Sprague-Dawley rats. Relative rates of PZ metabolism by liver microsomes prepared from rats were PB-treated greater than untreated greater than 3MC-treated. Metabolites of PZ were separated by normal phase high performance liquid chromatography and the relative amounts of major metabolites were found to be N-desalkylprazepam (also known as N-desmethyldiazepam and nordiazepam) greater than 3-hydroxy-PZ (3-OH-PZ) greater than oxazepam. Enantiomers of 3-OH-PZ were resolved by high performance liquid chromatography on an analytical column packed with Pirkle's chiral stationary phase, (R)-N-(3,5-dinitrobenzoyl)phenylglycine covalently bonded to spherical particles of gamma-aminopropylsilanized silica. 3-OH-PZ formed in the metabolism of PZ by liver microsomes prepared from rats was found to have 3R/3S enantiomer ratios of 84:16 (untreated), 85:15 (PB-treated), and 84:16 (3MC-treated), respectively. Relative rates of N-dealkylation of PZ by three rat liver microsomal preparations were PB-treated greater than untreated greater than 3MC-treated. N-Dealkylation of 3-OH-PZ by rat liver microsomes was substrate enantioselective; the 3S-enantiomer was N-dealkylated faster than the 3R-enantiomer. The results indicated that both C3-hydroxylation of PZ and N-dealkylation of 3-OH-PZ catalyzed by rat liver microsomes were stereoselective, resulting in the formation of a 3-OH-PZ highly enriched in the 3R-enantiomer.     

Metabolism of roquinimex in mouse and rat: an in vitro/in vivo comparison

1. In vitro studies with roquinimex, an immuno-modulator, in liver microsomes from mouse and rat were conducted to evaluate the primary metabolism and compare the metabolite pattern as well as the rate of metabolism with the in vivo pharmacokinetics of the compound in these two species. 2. In the presence of NADPH, roquinimex was metabolized to six primary metabolites (R1-6) by liver microsomes from mouse and rat. The formation of these metabolites was qualitatively similar in both species, and was greatly enhanced by pretreatment with PCN, an inducer of cytochrome P4503A. 3. The identification of the R1-6 demonstrated that roquinimex had been hydroxylated and demethylated. Hydroxylation at different sites of the quinoline moiety was the dominating reaction in both species. 4. Comparison of the resulting microsomal intrinsic clearance of 0.3 micromol mg(-1) protein min(-1) in mouse liver microsomes, versus 0.03 micromol mg(-1) protein min(-1) in rat liver microsomes demonstrated that the mouse possesses about a 10-fold greater metabolic capacity for roquinimex than the rat. 5. The in vivo pharmacokinetics of roquinimex demonstrated a 7-fold higher clearance in mouse than in the rat (82 ml h(-1) kg(-1) in mouse, 10.6 ml h(-1) kg(-1) in rat), which is in concordance with the in vitro findings.     

Positional metabolism of benzo(a)pyrene in rat placenta and maternal liver. Comparison of induction effects

The biotransformation of [14C]benzo(a)pyrene (BP) was studied in vitro in the presence of microsomes prepared from isolated labyrinth and basal zone tissues of the rat placenta, as well as from maternal liver. Pregnant rats, day 14 of gestation, received beta-naphthoflavone (beta NF; 15 mg/kg, ip) or 3-methyl-cholanthrene (3MC; 30 mg/kg, ip). On day 15, placentae were dissected and microsomes were incubated with 17 microM [14C]BP and 2 mM NADPH. Metabolites formed in the incubation flasks were extracted and separated by HPLC utilizing a reverse phase column. Only trace BP metabolism occurred in basal zone microsomes from control, beta NF-, or 3MC-pretreated animals, as well as in labyrinth microsomes from control animals. In contrast, the preadministration of beta NF and 3MC increased labyrinth microsomal BP metabolism by 10- to 15-fold. Labyrinth and maternal liver microsomes from beta NF- and 3MC-treated animals actively converted BP to eight separate metabolites which co-chromatographed primarily with quinones and phenols. The overall formation of BP diol and phenolic metabolites by labyrinth microsomes was appreciably less than was observed for liver preparations. The very low activity of BP-4,5-oxide hydrolase in labyrinth microsomes compared to liver may in part explain the low level of formation of BP diols in placental microsomes. Labyrinth microsomes catalyzed the covalent binding of [3H]BP to calf thymus DNA, and this activity increased 5-fold following beta NF pretreatment. A comparison of induced tissues indicates that the amount of DNA binding in labyrinth microsomes is more extensive than would be expected by the level of total BP metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolism of lovastatin by rat and human liver microsomes in vitro

The metabolism of lovastatin (Mevacor) was examined using isolated microsomes derived from the livers of normal and phenobarbital-treated rats and from human liver samples. Incubation of lovastatin with rat liver microsomes resulted in the formation of several polar metabolites of lovastatin. The metabolites were isolated by HPLC and identified by NMR and mass spectrometry. One fraction consisted of a 2:1 mixture of 6-hydroxy-lovastatin and the rearrangement product delta 4,5-3-hydroxy lovastatin. Addition of a trace of acid to this mixture resulted in the formation of a single aromatized product, the desacyl-delta 4a,6,8-dehydro analog of lovastatin. Another microsomal metabolite was determined to be the delta 4,8a,1-3-hydroxy-lovastatin derivative. The chromatographic pattern of metabolites produced from lovastatin by human liver microsomes was similar to that obtained with rat liver microsomes. Metabolism of lovastatin by rat liver microsomes was both time and concentration dependent; optimal microsomal metabolism occurred with 0.1 mM lovastatin, whereas higher lovastatin concentrations inhibited the reaction. The open acid form of lovastatin was poorly metabolized by both the rat and the human liver microsomes.