【作者】 李见春；

【导师】 陈飞虎；

【作者基本信息】 安徽医科大学 ， 药理学， 2010， 博士

【摘要】 汉黄芩素（wogonin），5,7-二羟基-8-甲氧基黄酮（C16H12O5）为唇形科植物黄芩Scutellaria baicalensis Georgi的干燥根中的一种主要活性成分，现代药理研究表明：汉黄芩素具有抗氧化、抗菌、抗炎、抗病毒、抗肿瘤、神经保护等多种作用，目前越来越受到人们的广泛关注。本文通过对其生物药剂学与药物动力学的系统研究，以明确其吸收机制及提高其生物利用度的方法，阐明发生药物相互作用的潜力，拟为该药的剂型设计和临床用药提供理论指导。1.汉黄芩素肠吸收机理的研究通过Caco-2细胞和大鼠在体单向肠灌流这两种吸收模型对汉黄芩素的肠吸收特征及吸收动力学进行了研究，两种方法都显示汉黄芩素的肠吸收主要以被动扩散方式吸收，其膜转运过程受pH、温度和4%BSA的影响（P<0.01）；药物的分泌不受P-gp抑制剂维拉帕米（VRP）、胞饮抑制剂金刚烷胺、能量代谢抑制剂2，4-二硝基苯酚（DNP）和多药耐药抑制剂MK571的影响（P>0.05），与大鼠在体胃、肠吸收同为被动过程；汉黄芩素在大鼠胃及各肠段均有吸收，但消化道上段的吸收优于下段，符合制成速释、胃漂浮制剂的基本条件。2.汉黄芩素在Beagle犬体内的生物利用度研究利用溶剂法制备汉黄芩素固体分散体（汉黄芩素:PVP K30=1:5），通过体外溶出度、差示热分析、X-射线衍射等方法确定汉黄芩素在固体分散体中以无定形方式存在；LC-MS/MS内标法测定汉黄芩素固体分散体给药后Beagle犬体内的血药浓度，汉黄芩素在犬体内吸收快，消除慢，其绝对生物利用度约为4.0%，但与原料药相比，生物利用度提高了约679.9%；利用LC/MSn/DAD技术对给药后的Beagle犬血浆进行分析，认为汉黄芩素的葡萄糖醛酸结合物为其主要代谢产物；与固体分散体比较，汉黄芩素盐溶液的相对生物利用度为81.3%；以β-葡萄糖醛酸酶酶解后总的汉黄芩素计算，其Cmax约为血浆中游离汉黄芩素的12倍以上，AUC(0-∞)则超过30倍，MRT(0-t)显著延长（8.38±3.14）v.s.（3.39±1.25）h。3.汉黄芩素对大鼠肝P450同工酶和mdr1的影响汉黄芩素盐溶液大鼠连续灌胃给药7d（10、30、90mg/kg，qd），各剂量组P450酶含量均有下降趋势，与正常组比较，大剂量组（90mg/kg）显示有统计学差异（P<0.05）。而CYP1A1的表达水平明显下降（低剂量P<0.05，中、高剂量P<0.01），CYP2E1、CYP3A1及mdr1mRNA表达水平则未见明显影响。本文通过研究汉黄芩素在Caco-2细胞和大鼠在体单向肠灌流这两种吸收模型中的吸收特征，并考察其固体分散体、精氨酸盐溶液在Beagle犬体内的生物利用度，发现在研究剂量范围内，汉黄芩素在两种模型中均具有较好的吸收参数，但口服后绝对生物利用度却很低，故认为，汉黄芩素口服给药绝对生物利用度低的主要原因与其溶解度低及体内较强的II相代谢有关。固体分散体、精氨酸盐溶液相对于原料药能显著提高汉黄芩素的相对生物利用度，Beagle犬给药后体内的主要代谢产物为汉黄芩素与葡萄糖醛酸的结合物；大鼠灌胃给药对P450酶含量有一定的影响并可使CYP1A1的表达水平明显下降，提示汉黄芩素长期用药应注意肝功能的变化，并应避免与CYP1A1的抑制剂同时应用。更多还原

【Abstract】 Wogonin,5,7-dihydroxy-8-methoxyflavone, is one of the major bioactive flavonoidaglycones isolated from the root of Scutellaria baicalensis Georgi (Fam. Labiatae). In recentyears, wogonin has attracted substantial interest as it possesses antioxidant, antibiosis,anti-inflammatory, anti-hepatitis B virus, cancer-preventive and anticonvulsant effects. Themain objectives of this research were to investigate and clarify the biopharmaceutics andpharmacokinetics characteristics of wogonin, in order to guide design of dosage forms andclinical medication.1. Investigation on the intestinal absorption mechanism of wogoninCaco-2cell and single pass intestine perfusion (SPIP) model were used toinvestigate the intestinal absorption kinetics of wogonin. Wogonin was absorbedthrough the epithelia mostly by paracellular pathway. Temperature, pH and BSAaffected its member transport significantly (P<0.01). Inhibitor of P-gp, pinocytosis, cellmetabolism and multi-drug resistance had not influence on wogonin efflux frombasolateral side to apical side (P>0.05). Wogonin can be absorbed by stomach and different position of rat intestine, and the extent of absorption of upper gastrointestinalis superior to that of below gastrointestinal, which provide a theoretical basis for quickrelease forms or intragastric floating drug delivery system of wogonin.2. Investigation on the bioavailability of wogonin in Beagle dogsWogonin solid dispersions were prepared by the solvent method, and characterizeby methods including dissolution, differential scanning calorimetry and power X-raydiffractometry. The bioavailability assessment in Beagle dogs were assayed byLC-MS/MS. It was indicated that wogonin existed in the solid dispersions at amorphousform and that it possibly interacted with PVP K30via hydrogen bond when the ratio ofdrug to the carrier was1:5. Wogonin plasma concentration versus time curve in Beagledogs showed that the solid dispersion approach was associated with a significantdecrease in tmaxand an evident increase in Cmaxcompared to raw substance wogonin.The absolute bioavailability of wogonin solid dispersion was4%, and comparing to rawsubatance wogonin, the relative bioavalability of wogonin in the solid dispersions was679.9%. The major metabolite wogonin-7β-D-glucuronide (W-7-G) in Beagle dogplasma was confirmed by LC/MSn/DAD technology. Comparing to wogonin soliddispersions, the relative bioavalability of arginine-wogonin solution was81.3%. Theconcentration of W-7-G in dog expressed as wogonin equivalent was twelve times tothat of free wogonin in dog plasma, AUC(0-∞)was amplified to thirty times and MRT(0-t)was extended to2.5times.3. Effects of wogonin administrated by oral on liver microsomal cytochrome P450isoenzyme and mdr1in ratsTo evaluate the induction/inhibition action of wogonin on P450isoenzyme andmdr1in rats, the P450content and mRNA level expression of CYP1A1, CYP2E1,CYP3A1, mdr1a and mdr1b in rat liver after oral administration of wogonin wasanalysed. Male SD rats (n=36) were randomly divided into six groups and givendifferent compounds. P450content in liver microsomes was mearsured by Dual-Beam Spectrophotometric method and mRNA level expression of CYP1A1, CYP2E1,CYP3A1, mdr1a and mdr1b were assayed with RT-PCR. Oral administration ofwogonin at high dose(90mg/kg) can cause significant declined in the content of P450inrat liver, and at low dose(>10mg/kg) can cause decrease significantly in the mRNAlevel expression of CYP1A1.In the present study, the absorption of features in Caco-2cell and SPIP model ofwogonin and the bioavalability of wogonin solid dispersions and arginine-wogonin inBeagle dogs were investigated, which showed that the oral bioavability of wogonin waslow although it had good absorption characters. The reasons were that it suffered poordissolution and strong second-phase metabolism to produce conjugated metabolitewogonin-7-beta-glucuronide under the action of UDP-glucuronytransferase. It deservesto investigate some bioactive on the conjugated substance. Oral administration ofwogonin at high dose can cause significant difference in the content of P450in rat liver,and all given doses can cause decrease significantly in the mRNA level expression ofCYP1A1, which suggested that liver function should be pay attention during long termtreatment with wogonin and avoid combine with the inhibitor of CYP1A1in clinical.更多还原