花椒毒素在小肠中的吸收机制研究

花椒毒素(Xanthotoxin,Xan)是一个具有强光敏性的呋喃香豆素类化合物.临床上通常口服花椒毒素后结合长波紫外光照射来治疗中重度银屑病病人,即补骨脂素光化学疗法.但是口服花椒毒素后血药浓度和达峰时间个体差异较大,给部分病人造成严重的不良反应或治疗的失败[1].因此,本文研究不同浓度的Xan在Caco-2单层细胞模型和大鼠肠灌流模型中的吸收情况,并对Xan肠吸收机制进行了探讨,从而为改进补骨脂素光化学疗法提供有用信息.     

水飞蓟素肠溶聚乳酸-羟基乙酸共聚物纳米粒在大鼠在体肠灌流模型及Caco-2细胞模型中的吸收研究

目的:研究水飞蓟素肠溶聚乳酸-羟基乙酸共聚物(PLGA)纳米粒在大鼠在体肠灌流模型及结肠腺癌Caco-2细胞模型中的吸收特性。方法:采用高效液相色谱法测定水飞蓟素含量,考察水飞蓟素混悬液、水飞蓟素PLGA纳米粒和水飞蓟素肠溶PLGA纳米粒在大鼠在体肠灌流模型十二指肠、空肠、回肠和结肠的吸收速率常数(Ka)和表观吸收系数(Kapp)及其含低、中、高质量浓度(20、40、60μg/m L)水飞蓟素时在Caco-2细胞模型中的表观渗透系数(Papp)。结果:与水飞蓟素混悬液比较,水飞蓟素PLGA纳米粒和水飞蓟素肠溶PLGA纳米粒在十二指肠、空肠、回肠和结肠的Ka、Kapp均增加(P<0.05);与对应浓度水飞蓟素混悬液比较,含低、中、高质量浓度水飞蓟素的肠溶PLGA纳米粒和PLGA纳米粒在Caco-2细胞模型中的双向Papp均增加(P<0.05),其中水飞蓟素的肠溶PLGA纳米粒与PLGA纳米粒间差异无统计学意义(P>0.05)。结论:水飞蓟素肠溶PLGA纳米粒可有效增加水飞蓟素肠内吸收及Caco-2细胞摄取和跨膜转运速率。     

T2毒素在原位灌流大鼠小肠中的吸收和代谢动力学

应用原位肠灌流标本研究了T2毒素在大鼠小肠中的吸收和代谢功力学,T2毒素对小肠标本进行血管灌流时消除半衰期为46.9 min.主要代谢产物HT2毒素的生成半衰期为12.9 min.当T2毒素由十二指肠注射后再进行灌流时,可同时发生吸收前和吸收后的小肠代谢转化,并主要以HT2,3’-OHHT2等代谢产物的形式吸收,此时毒素在小肠中的吸收和消除半衰期分别为33.0和25.6 min,实验结果表明肠道也是代谢消除T2毒素的主要器官,尤其在消化道中毒时,毒素将经历显著的肠道首过代谢.     

姜黄素在Caco-2细胞模型中的吸收机制研究

目的 测定姜黄素透过Caco-2单细胞层的浓度,研究其吸收特征.方法 用Caco-2细胞单层模型来考察时间、浓度、不同药物酮康唑、维拉帕米、胡椒碱对姜黄素吸收的影响.采用液相色谱-质谱联用(LC-MS)法,测定姜黄素浓度并计算其表观渗透系数(Papp).结果 不同浓度姜黄素在90 min之前Papp大小顺序为:180 ＞240 ＞300 μg/ml;与对照组比较,胡椒碱,低浓度酮康唑,维拉帕米对姜黄素的吸收均呈不同程度的促进作用(P＜0.05).结论 姜黄素的吸收具有明显的高浓度饱和现象,且不呈线性变化,初步判定其吸收为主动吸收机制;促进姜黄素吸收的原因可能与酮康唑抑制Ⅰ相代谢酶CYP450 3A4和1A2酶的活性;胡椒碱抑制姜黄素Ⅱ相代谢酶-葡萄糖醛酸苷酶;维拉帕米抑制药物外排性转运蛋白-P-糖蛋白的活性有关.     

川楝子中的柠檬苦素成分研究

为研究川楝子的化学成分, 利用硅胶柱色谱及制备型高效液相色谱等方法对川楝子的乙酸乙酯提取物进行分离纯化, 得到3个柠檬苦素类化合物, 根据理化性质及一维和二维核磁共振谱鉴定其结构分别为: 24, 25, 26, 27-tetranorapotirucalla-(apoeupha)-1α-tigloyloxy-3α, 7α-dihydroxyl-12α-acetoxyl-14, 20, 22-trien-21, 23-epoxy-6, 28-epoxy (1)、nimbolinin B (2) 和trichilinin D (3)。其中化合物1为新化合物, 化合物2为首次从川楝子中分离得到。     

千层纸素A在Caco-2细胞模型中的吸收机制研究

目的研究千层纸素A在Caco-2细胞模型中的吸收机制。方法 MTT实验考察千层纸素A在Caco-2细胞中的安全浓度范围,再利用Caco-2细胞单层模型研究千层纸素A的双向转运机制,以转运量及表观渗透系数(Papp)为指标,考察时间、浓度、pH和P-gp抑制药维拉帕米对其吸收的影响。结果千层纸素A在Caco-2细胞模型中的转运与时间和浓度呈正相关;并受pH值影响,P-gp抑制药维拉帕米对其转运无影响,从单层细胞层顶端(AP)到基底端(BL)的转运与基底端到顶端的转运大致相同。结论千层纸素A在Caco-2细胞模型中的吸收是被动转运。     

姜黄素在Caco-2细胞模型中的吸收机制研究

目的测定姜黄素透过Caco-2单细胞层的浓度,研究其吸收特征。方法用Caco-2细胞单层模型来考察时间、浓度、不同药物酮康唑、维拉帕米、胡椒碱对姜黄素吸收的影响。采用液相色谱-质谱联用(LC-MS)法,测定姜黄素浓度并计算其表观渗透系数(Papp)。结果不同浓度姜黄素在90 min之前Papp大小顺序为:180>240>300μg/ml;与对照组比较,胡椒碱,低浓度酮康唑,维拉帕米对姜黄素的吸收均呈不同程度的促进作用(P<0.05)。结论姜黄素的吸收具有明显的高浓度饱和现象,且不呈线性变化,初步判定其吸收为主动吸收机制;促进姜黄素吸收的原因可能与酮康唑抑制Ⅰ相代谢酶CYP450 3A4和1A2酶的活性;胡椒碱抑制姜黄素Ⅱ相代谢酶—葡萄糖醛酸苷酶;维拉帕米抑制药物外排性转运蛋白—P-糖蛋白的活性有关。     

体外Caco-2细胞模型在药物吸收中的应用进展

目的:介绍Caco-2细胞模型的特征及其在药物吸收中的应用.方法:分析国内外近期相关文献,对Caco-2细胞模型在药物吸收动力学中的研究进行概述.结果:Caco-2细胞模型用于药物动力学研究,可预测药物在体内的吸收和代谢.结论:体外Caco-2细胞模型在药物吸收过程的研究中有重要意义.     

Caco-2细胞模型——药物吸收研究的有效“工具”

吸收过程是决定口服药物生物利用度的重要因素 ,然而很多药物的吸收机制还不明确。Caco 2细胞模型是目前最好的体外吸收模型 ,在药物的吸收过程及吸收机制的研究方面有广泛的应用 ,尤其在中药吸收研究方面 ,Caco 2细胞模型的应用成为目前的热点。另外 ,Caco 2细胞模型在药物代谢方面也有应用。因此 ,Caco 2细胞模型将成为药物吸收研究的重要手段 ,有助于加快新药筛选和开发的速度。     

LC-MS测定雷公藤甲素及其在Caco-2细胞上的转运特征

目的：建立体外模拟体内肠道细胞的Caco-2细胞Transwell模型,以此研究雷公藤甲素在Caco-2细胞模型上的跨膜转运特征。方法：采用聚酯碳酸酯膜连续培养Caco-2细胞21天,形成致密的单层细胞模型。然后对影响雷公藤甲素在Caco-2细胞模型上转运特征的因素包括浓度、时间及跨膜转运蛋白（P-糖蛋白,多药耐药蛋白,乳腺癌耐药蛋白）进行考察;同时采用LC-MS对溶液中的雷公藤甲素的含量进行测定。结果：雷公藤甲素主要以主动转运的方式进行吸收,且随着时间和药物浓度的增加,转运量明显增加。结论：雷公藤甲素在Caco-2细胞上转运存在一定的浓度及时间依赖性,且P-gp介导雷公藤甲素在Caco-2细胞上转运。     

左旋紫草素肠道转运及Caco-2细胞转运特性

目的研究左旋紫草素肠道及Caco-2细胞转运特征及其机制。方法应用翻转肠囊法和Caco-2细胞模型考察时间、浓度对左旋紫草素转运吸收特性的影响,应用P-糖蛋白抑制剂维拉帕米对左旋紫草素转运吸收机制进行研究,采用HPLC法测定左旋紫草素的浓度,计算其表观渗透系数(Papp)。结果在Caco-2细胞模型,随浓度增加和时间延长,左旋紫草素的累积转运量逐渐增加;加用维拉帕米后,使AP侧到BL侧的表观渗透系数Papp(AP→BL)显著增加,而从BL侧到AP侧的表观渗透系数Papp(BL→AP)显著降低。在翻转肠囊模型,100μmol·L-1左旋紫草素中加入维拉帕米后Papp显著增加。结论左旋紫草素的转运存在被动转运和主动转运2种形式,P糖蛋白参与主动转运过程;该药经肠道吸收中等,加入维拉帕米可能促进吸收。     

Kinetic modelling of the intestinal transport of sarafloxacin. Studies in situ in rat and in vitro in Caco-2 cells

The absorption kinetics of sarafloxacin, as a model of fluoroquinolone structure, were studied in the rat small intestine and in Caco-2 cells. The objective of the study was to investigate the mechanistic basis of the drug's intestinal transport in comparison with other members of the fluoroquinolone family and to apply a mathematical modelling approach to the transport process. In the rat small intestine, sarafloxacin showed dual mechanisms of intestinal absorption with a passive diffusional component and an absorptive carrier-mediated component. The characteristics of the animal study design made it suitable for population analysis, thus allowing the accurate estimation of transport parameters and their inter and intra-individual variances. The transport system in the rat model was ATP-dependent, as sodium azide was able to decrease the absorption rate constant in a concentration-dependent fashion. The inhibition mechanism of sodium azide was modelled based on its ATP depletion capacity. The rationale of this approach was to consider the inhibitor-carrier interaction as a concentration- dependent response. This interaction was accurately described by a non-competitive mechanism. In Caco-2 cells, sarafloxacin showed a concentration dependent permeability in both directions apical to basal, and basal to apical. The permeability values and ratios of permeability values at different concentrations suggested the presence of two carriers (absorption and efflux carriers). The passive diffusion component in both systems was compared to that predicted by the absorption–partition correlation, previously established for two series of fluoroquinolones. The discrepancy between the experimental and predicted value suggested the presence of an efflux mechanism similar to that already described for other fluoroquinolones. The differences and similarities of the in situ and the in vitro results are discussed as well as the usefulness of the modelling approach.     

Transport of Pregabalin in Rat Intestine and Caco-2 Monolayers

Purpose. The purpose of this study was to determine if the intestinal transport of pregabalin (isobutyl --aminobutyric acid, isobutyl GAB A), a new anticonvulsant drug, was mediated by amino acid carriers with affinity for large neutral amino acids (LNAA). Methods. Pregabalin transport was studied in rat intestine and Caco-2 monolayers. An in vitro Ussing/diffusion chamber model and an in situ single-pass perfusion model were used to study rat intestinal transport. An in vitro diffusion chamber model was used to evaluate Caco-2 transport. Results. In rat ileum, pregabalin transport was saturable and inhibited by substrates of intestinal LNAA carriers including neurontin (gabapentin), phenylalanine, and proline. Weak substrates of intestinal LNAA carriers (-alanine, --aminobutyric acid, and methyl aminoisobutyric acid) did not significantly change pregabalin transport. In Caco-2 mono-layers that showed a high capacity for phenylalanine transport, pregabalin transport was concentration- and direction-independent and equivalent in magnitude to the paracellular marker, mannitol. The in vitro and in situ rat ileal permeabilities of the LNAA carrier-mediated compounds neurontin, pregabalin, and phenylalanine correlated well with the corresponding in vivo human oral absorption. Conclusions. The transport of pregabalin was mediated by LNAA carriers in rat ileum but not in Caco-2 monolayers. Caco-2 was not an appropriate model for evaluating the in vivo human oral absorption of pregabalin and neurontin.     

Caco-2细胞模型在药物体外研究中的应用

Caco-2细胞模型是一种筛选药物离体口服特性的模型,已广泛用于评价药物在小肠的吸收特性和各种转运机制的研究.现综述Caco-2细胞单层模型的基本特点及其在药物的小肠吸收、代谢以及高通量筛选等方面的应用.     

尼莫地平大鼠在体肠吸收动力学

目的研究尼莫地平在大鼠各肠段的吸收动力学特征。方法采用大鼠在体肠段灌流实验 ,主要从吸收部位、药物浓度、pH值等 3方面对尼莫地平的肠段吸收特性进行研究。结果尼莫地平在大鼠肠道内无特定吸收部位 ,各肠段吸收速率常数按十二指肠、空肠、结肠、回肠顺序依次下降 ,吸收速率常数分别为 0 0 6 87、0 0 6 2 0、0 0 5 97、0 0 4 89h-1。在 4 8～ 14 3μmol·L-1浓度内药物吸收量与浓度呈线性关系 ;在 pH 5 0～ 7 4内药物吸收不受 pH值影响。 结论尼莫地平在大鼠全肠段均有吸收 ,吸收符合一级动力学特征 ,吸收机制为被动扩散 ,适于制备日服 1次缓释给药系统     

利用人源Caco-2细胞单层模型研究罂粟碱、N-甲基四氢罂粟碱和头花千金藤碱在人肠道的吸收

研究罂粟碱(papaverine，PAP)、N-甲基四氢罂粟碱(laudanosine，LAU)和头花千金藤碱(cepharanthine，CEP)在人小肠的吸收。利用人源结肠腺癌细胞系Caco-2细胞单层模型研究PAP、LAU和CEP由绒毛面(AP侧)到基底面(BL侧)、BL侧到AP侧两个方向的转运过程。应用HPLC-UV对上述3个生物碱进行定量分析，计算转运参数和表观渗透系数，并与易吸收性对照药普萘洛尔和难吸收性对照药阿替洛尔进行比较。PAP、LAU和CEP由AP侧到BL侧的表观渗透系数(P_app)分别为(3.524±0.223)×10^-5、(2.821±0.050)×10^-5和(6.524±0.052)×10^-5 cm·s^-1；由BL侧到AP侧的P_app分别为(5.095±0.508)×10^-5、(2.646±0.146)×10^-5和(5.495±0.036)×10^-5 cm·s^-1，与在Caco-2细胞单层模型上呈良好吸收的阳性对照药普萘洛尔基本一致。PAP、LAU和CEP的P_{app A→B}/P_{app B→A}分别为0.69、1.07和1.19；PAP外流是摄取的1.45倍。PAP、LAU和CEP可以通过小肠上皮细胞被动吸收进入体内，属于良好吸收的药物。在三者的吸收转运过程中，油/水分配系数起着关键性的作用。PAP在Caco-2细胞单层模型中的转运可能存在外流机制。     

蜕皮甾酮在Caco-2细胞模型中的摄取和跨膜转运研究

目的以Caco-2细胞单层模型,首次研究了蜕皮甾酮的口服吸收与转运特性。方法采用普通Caco-2细胞模型、表达活性CYP3A4酶的Caco-2细胞模型,分别从AP→BL方向和BL→AP方向研究蜕皮甾酮的摄取和跨膜转运规律。结果蜕皮甾酮在2种模型中的表观渗透系数(Papp)在0.1×10-6～1×10-6cm.s-1之间,药物吸收情况为1%～10%;在4 h的实验过程中,4种浓度蜕皮甾酮的ER值均小于1.5。结论研究表明,蜕皮甾酮主要以被动扩散的方式被细胞摄取和转运,其跨膜转运特性未受到CYP3A4-介导机制的影响。     

Intestinal transport of HDND-7, a novel hesperetin derivative,in in vitro MDCK cell and in situ single-pass intestinal perfusion models

1.?Hesperetin (HDND) possesses extensive bioactivities, however, its poor solubility and low bioavailability limit its application. HDND-7, a derivative of HDND, has better solubility and high bioavailability. In this study, we investigated the intestinal absorption mechanisms of HDND-7.

2.?MDCK cells were used to examine the transport mechanisms of HDND-7 in vitro, and a rat in situ intestinal perfusion model was used to characterize the absorption of HDND-7. The concentration of HDND-7 was determined by HPLC.

3.?In MDCK cells, HDND-7 was effectively absorbed in a concentration-dependent manner in both directions. Moreover, HDND-7 showed pH-dependent and TEER-independent transport in both directions. The transport of HDND-7 was significantly reduced at 4?°C or in the presence of NaN3. Furthermore, the efflux of HDND-7 was apparently reduced in the presence of MRP2 inhibitors MK-571 or probenecid. However, P-gp inhibitor verapamil had no effect on the transport of HDND-7. The in situ intestinal perfusion study indicated HDND-7 was well-absorbed in four intestinal segments. Furthermore, MRP2 inhibitors may slightly increase the absorption of HDND-7 in jejunum.

4.?In summary, all results indicated that HDND-7 might be absorbed mainly by passive diffusion via transcellular pathway, MRP2 but P-gp may participate in the efflux of HDND-7.     

Absorption and cleavage of enalapril,a carboxyl ester prodrug,in the rat intestine: in vitro,in situ intestinal perfusion and portal vein cannulation models

In recent years prodrug strategy has been used extensively to improve the pharmacokinetic properties of compounds exhibiting poor bioavailability. Mechanistic understanding of the absorption and the role of intestine and liver in the activation of oral prodrugs is crucial. Enalapril, a carboxyl ester prodrug, is reported to be metabolized by human carboxylesterase‐1 (CES1) but not by carboxylesterase‐2 (CES2) to its active metabolite enalaprilat. Further, it has been reported that the small intestines of both rat and human contain mainly CES2. The objective of this work was to understand whether enalapril remains unchanged as it is absorbed through the intestine into the portal circulation. This was evaluated using different intestinal preparations, an in situ intestinal perfusion experiment and a portal vein cannulated rat model. No turnover of enalapril was seen with commercial rat intestinal S9 and microsomes, but reasonable turnover was observed with freshly prepared rat intestinal and mucosal homogenate and S9. In the intestinal perfusion study, both enalapril and enalaprilat were observed in the mesenteric plasma with the data suggesting 32% hydrolysis of enalapril in the intestine. In the portal vein cannulated rat, about 51% of enalapril absorbed into intestine was converted to enalaprilat. Overall, it was demonstrated that even though enalapril has been shown to be a specific substrate for CES1, it is converted to enalaprilat to a significant extent in the intestine. Such experimental techniques can be applied by other scientific groups who are working on prodrugs to determine the region and extent of activation. Copyright © 2015 John Wiley & Sons, Ltd.