基于肠道菌群和代谢组学研究化滞柔肝颗粒治疗非酒精性脂肪肝的作用机制

目的 探讨化滞柔肝颗粒治疗非酒精性脂肪肝（nonalcoholic fatty liver disease,NAFLD）的作用机制。方法 高脂饮食饲养8周构建大鼠NAFLD模型,化滞柔肝颗粒ig给药4周。半自动生化分析仪测定大鼠血脂相关指标;油红O染色观察肝脏组织病理变化;Illumina Miseq测序平台对V3～V4可变区进行扩增和测序,超高效液相色谱串联质谱（UPLCMS/MS）开展血浆代谢组学研究,并结合Spearman进行肠道菌群与代谢组学之间的关联分析。结果 与模型组相比,化滞柔肝颗粒中、高剂量组可显著降低大鼠体质量（P<0.05、0.01）和血清总胆固醇（totalcholesterol,TC）、三酰甘油（triacylglycerol,TG）水平（P<0.01）,升高高密度脂蛋白（high-density lipoprotein cholesterol,HDL-C）水平（P<0.05、0.01）。此外,化滞柔肝颗粒高剂量组还可显著降低大鼠低密度脂蛋白（low-density lipoprotein cholesterol,LDL-C）水平（P<0...     

基于网络药理学和16SrDNA测序的当归六黄汤合煎与单煎治疗阴虚甲亢作用的差异研究

目的 探讨当归六黄汤的抗阴虚甲亢作用,阐释传统汤剂合煎和单煎的差异。方法 运用网络药理学方法,筛选当归六黄汤的主要活性成分和治疗阴虚甲亢疾病的相关靶点,并对交集靶点进行蛋白质-蛋白质相互作用（protein-protein interaction,PPI）网络分析、基因本体（gene ontology,GO）功能和京都基因与基因组百科全书（Kyoto encyclopedia of genes and genomes,KEGG）通路富集分析,构建药材-成分-靶点-通路网络;进一步进行实验验证,构建阴虚甲亢大鼠模型,评价当归六黄汤合煎和单煎对阴虚甲亢大鼠体质量、粪便含水率及相关血清学指标的影响;利用16S rDNA测序技术,揭示合煎和单煎对大鼠肠道微生物群落多样性的影响。结果 筛选获得当归六黄汤方中102个活性成分,检索出与阴虚甲亢有关靶点116个。富集分析获得871条GO条目和158条KEGG相关条目（P<0.05）,其中生物过程（biological process,BP）675条、细胞组分（cellular component,CC）77条、分子功能（molecular fu...     

四君子汤非多糖功效组分的体外人源肠、肝微粒体代谢研究

目的 对四君子汤非多糖组分的主要活性成分进行人源肠、肝微粒体中的代谢过程研究,明确其在肠、肝中的代谢轮廓及代谢差异,为其临床应用提供科学证据。方法 应用Acquity UPLC I-class/VION IMS QTOF技术分析四君子汤非多糖组分中主要活性成分（异甘草苷、甘草素、甘草酸、甘草次酸、人参皂苷Rb₁、人参皂苷CK、白术内酯III）在人源肠、肝微粒体孵育体系下的代谢产物以及代谢转化途径。结果 甘草酸、甘草次酸在人源肠、肝微粒体中均以I相代谢为主;而甘草素、异甘草苷、人参皂苷Rb₁、人参皂苷CK则以肠II相代谢为主。白术内酯III在肠、肝微粒体中代谢均不显著,而四君子汤非多糖功效组分中其他化合物在肠微粒体中代谢速度均比在肝微粒体中更快。此外,甘草皂苷、人参皂苷主要进行脱糖基反应;异甘草苷以脱糖、羟基化等反应为主;甘草素则以葡萄糖醛酸结合为主;白术内酯III则主要发生水解、羟基化反应。结论 阐明了四君子汤非多糖组分中主要活性成分在人体肠道及肝脏中的代谢轮廓及代谢差异,为后续进行四君子汤非多糖功效组分的药效研究提供了数据支持,也为中药复方的功效组分研究提供了思路和策略。     

In Vitro Evaluation of Dexamethasone-β-D-Glucuronide for Colon-Specific Drug Delivery

Dexamethasone--D-glucuronide is a potential prodrug for colonic delivery of the antiinflammatory corticosteroid dexamethasone. Previous studies [T. R. Tozer et al., Pharm. Res. 8:445–454 (1991)] indicated that a glucoside prodrug of dexamethasone was susceptible to hydrolysis in the upper gastrointestinal tract. Resistance of dexamethasone--D-glucuronide to hydrolysis in the upper gastrointestinal tract was therefore assessed. Conventional, germfree, and colitic rats were used to examine enzyme levels along the gastrointestinal tract to compare the stability of two model substrates (p-nitrophenyl--D-glucoside and --D-glucuronide) and to evaluate the prodrug dexamethasone--D-glucuronide. Hydrolytic activity was examined in the luminal contents, mucosa, and underlying muscle/connective tissues in all three types of rats. Enzymatic activity (-D-glucosidase and -D-glucuronidase) was greatest in the lumen of cecum and colon of conventional rats. In contrast, germ-free rats exhibited relatively high levels of -D-glucosidase activity (about 80% of total activity in the conventional rats) in the proximal small intestine (PSI) and the distal small intestine (DSI). Rats with induced colitis (acetic acid) showed reduced levels of luminal -D-glucuronidase activity in the large intestine; however, -D-glucosidase activity was relatively unchanged relative to that of the conventional rat. Mucosal -D-glucuronidase activity was significantly lower in the colitic rats compared with that in the conventional animals. Despite reduced luminal levels of -D-glucuronidase activity in the colitic rats, there was still a sharp gradient of activity between the small and the large intestines. Permeability of the glucoside and glucuronide prodrugs of dexamethasone through a monolayer of Caco-2 cells was relatively low compared to that of dexamethasone. The results indicate that dexamethasone--D-glucuronide should be relatively stable and poorly absorbed in the upper gastrointestinal tract. Once the compound reaches the large intestine, it should be hydrolyzed to dexamethasone and glucuronic acid. Specificity of colonic delivery in humans should be even greater due to lower levels of -D-glucuronidase activity in the small intestine compared with that in the laboratory rat.     

Evidence for an Interaction Between the β-Blocker Pafenolol and Bile Salts in the Intestinal Lumen of the Rat Leading to Dose-Dependent Oral Absorption and Double Peaks in the Plasma Concentration–Time Profile

Pafenolol is a -blocker with unusual oral absorption properties. The blood concentration–time profile exhibits two peaks, and the bioavailability is low and dose dependent because of incomplete and nonlinear intestinal uptake. We addressed the question whether the intestinal absorption of pafenolol was affected by bile depletion in the gut lumen of rats. Further, the hypothesis that variable gastric emptying accounts for double peaks in blood was tested by duodenal administration of pafenolol. Following intraduodenal administration to rats with intact bile secretion, double peaks were observed in the blood concentration–time curve. The bioavailability was 6.8 ± 0.7% for the low dose (1 µmol/kg) and increased significantly to 28 ± 10% following the high duodenal dose (25 µmol/kg). These blood concentration–time profiles exclude interrupted gastric emptying as cause of the twin peaks. In bile duct-cannulated rats the intestinal absorption of the low dose (1 µmol/kg) was still poor (F = 10.7 ± 5.5%) and the blood concentration–time profile contained two peaks. Following administration of a high duodenal dose (25 µmol/kg) to rats with an almost bile-free small intestine, the absorption rate increased and the double-peak phenomenon disappeared in five of seven rats, while the bioavailability increased significantly, to 62 ± 27%. These results suggest that the low bioavailability of pafenolol is due to a complexation between bile and pafenolol in the gut lumen, preventing intestinal uptake in the major part of the small intestine. Further, such complex formation in the intestinal lumen may be the underlying mechanism of the double peaks observed in the blood concentration–time profile.     

Mechanism of Intestinal Absorption of Ranitidine and Ondansetron: Transport Across Caco-2 Cell Monolayers

We have investigated the transport of ranitidine and ondansetron across the Caco-2 cell monolayers. The apparent permeability coefficients (P _app) were unchanged throughout the concentration range studied, indicating a passive diffusion pathway across intestinal mucosa. No metabolism was observed for ranitidine and ondansetron during the incubation with Caco-2 cell monolayers. P _app values for ranitidine and ondansetron (bioavailability of 50 and 100% in humans, respectively) were 1.03 ± 0.17 × 10^–7 and 1.83 ± 0.055 × 10^–5 cm/sec, respectively. The P _app value for ranitidine was increased by 15- to 20-fold in a calcium-free medium or in the transport medium containing EDTA, whereas no significant change occurred with ondansetron, indicating that paracellular passive diffusion is not rate determining for ondansetron. Uptake of ondansetron by Caco-2 cell monolayers was 20- and 5-fold higher than that of ranitidine when the uptake study was carried out under sink conditions and at steady state. These results suggest that ranitidine and ondansetron are transported across Caco-2 cell monolayers predominantly via paracellular and transcellular pathways, respectively.