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黄芩苷在动物体内的吸收和代谢研究

Study on the Absorption and Metabolism of Baicalin in Animals

【作者】 邢杰

【导师】 钟大放; 陈笑艳;

【作者基本信息】 沈阳药科大学 , 药物分析学, 2005, 博士

【摘要】 黄芩苷为黄芩素的7-O-葡萄糖醛酸结合物,属于黄酮类化合物,是黄芩的主要有效成分,在临床上主要用于抗菌消炎和抗感染。黄芩苷可通过水解产生苷元黄芩素,亦具有抗炎和抗变态反应等多方面的作用。对黄芩苷体内的药代药动研究表明,黄芩苷在动物体内主要经历葡萄糖醛酸化和甲基化两条主要的代谢途径;可能由于检测手段的限制,关于黄芩苷在动物体内的吸收程度报道间差异较大,但多数研究认为,黄芩苷类似于其他黄酮类化合物,存在吸收差的问题,并认为黄芩苷只有通过肠茵群水解为黄芩素后才被吸收。近年来,随着国际上对黄芩药材的逐渐开发利用,对黄芩苷的研究以及认识也需进一步深入,有必要对黄芩苷的体内过程以及吸收机理进行再研究。这对正确评价动物实验数据并外推至人体,指导临床合理用药有重要意义。 本论文拟采用多种检测手段 (液相色谱,气相色谱一质谱联用以及液相色谱-质谱联用技术),系统研究黄芩苷在动物体内的代谢过程和动力学过程,确定研究黄芩苷代谢和动力学合理的动物模型,阐明黄芩苷的吸收机理及与抗生素等抗菌制剂合用所产生可能的相互作用,阐明肝肠循环在黄芩苷吸收过程中的作用,为黄芩苷的剂型设计,为其他黄酮类化合物的结构改造提供依据和新思路,为临床合理用药提供参考。 一、黄芩苷在不同动物体内的代谢 以大鼠、犬、金黄地鼠、豚鼠、家兔以及人为实验对象,研究了黄芩苷及其苷元在动物体内的代谢途径,确定或推测了各代谢物的结构,阐明了黄芩苷代谢在动物及人体间的种属差异和种属相似性。在受试动物体内,共检测到8种代谢物,经与对照品或经酶水解后与对照品比较多级质谱及色谱信息,鉴定或推测为黄芩苷M1、黄芩苷的异构体6-O-葡萄糖醛酸结合物M2,6-O-葡萄糖-7-O-葡萄糖醛酸结合物M3、6-O-,7-O-葡萄糖醛酸结合物M4,6-OCH3-7-O-葡萄糖醛酸结合物M5、葡萄糖结合物M6、黄芩苷苷元黄芩素M7和6-OCH3-黄芩素M8。结果表明,黄芩苷在受试动物体内经历相似的代谢途径,主要与葡萄糖结合、与葡萄糖醛酸结合、甲基化和水解等代谢过程。其中,与葡萄糖结合为新发现的代谢途径,此代谢途径与葡萄糖醛酸化程度存在一定的种属差异。苷元黄芩素在各动物体内具有与黄芩苷相同的代谢途径。大鼠作为本论文的动物实验模型在代谢方面与人具有种属相似性。 黄芩苷及其代谢物在排泄方面表现出一定的选择性,胆汁和尿样中葡萄糖醛酸结合物和甲基化结合物的水平较高,无相应的苷元黄芩素和甲基化苷元,而粪

【Abstract】 Baicalin (baicalein 7-O-β-glucopyranuronoside, BG) is a bioactive flavonoid isolated from the root of Scutellaria baicalensis George, a medicinal herb that has been used since ancient times to treat inflammation, fever and allergic diseases. Baicalin was readily hydrolyzed by β-glucuronidase to free aglycone baicalein, which has similar pharmacology effects to baicalin. In previous studies on the metabolism, baicalin underwent two main metabolic pathways including glucuronidation and methylation. Due in part to difficulties in establishing a sensitive and specific assay for baicalin and its metabolites, the absorption data of baicalin differed with each other. Most studies suggested that the absorption of baicalin was poor because of its low hydrophilicity, which was always encountered in study of other flavonoids, and baicalin has been found absorbed from the gastrointestinal tract as its aglycone after the hydrolysis of intestinal bacteria. In recent years, baicalin has attracted increasing interest due to its various beneficial biological activities to human health, which made it necessary to further study the metabolism, disposition and pharmacokinetics of baicalin to elucidate its biological effects. It is important for rational evaluation of animal data as well as extrapolation to humans, and for guiding clinical use.The thesis aimed to investigate the fate of baicalin in vivo by applying liquid chromatography-mass spectrometry technique (LC/MS~n) with the aid of HPLC/UV and GC/MS, to establish the rational animal model for the study, to evaluate the contribution of enterohepatic recirculation to absorption, and to reveal the absorption mechanism of baicalin. It would offer some references and inspirations for drug design and dosage form modification.1. Baicalin metabolism in lab animalsThe metabolic profiles of BG and its aglycone in rats, dogs, golden hamsters, Guinea pigs, rabbit and human were investigated. The metabolites were identified and the species differences were interpreted among animals and humans. Totally 8 metabolites were measured in the tested animals, and were identified as baicalin (M1), baicalein 6-O-β-glucopyranuronoside glucuronide (M2), baicalein 6-O-glucoside-7-O-β-glucopyranuronoside (M3), baicalein 6,7-di-O-β-glucopyranuronoside (M4),

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