Methods. The intestinal absorption and metabolism of W and OA as well as the potential interactions among B, Wand OA were investigated at in vitro, in situ and in vivo levels. Various models were employed including Caco-2 cell monolayer model, in vitro enzymatic kinetics study, rat in situ single-pass intestinal perfusion model and in vivo pharmacokinetic study in rats. / Purpose. Scutellariae baicalensis Georgi is a medicinal plant widely distributed in Asia. Its dried root, Radix Scutellariae (RS), has been extensively used in Chinese and Japanese medicine. Six flavones including baicalein (B), wogonin (W), oroxylin A (OA) and their corresponding glucuronic acid conjugates (BG, WG, OAG) are the major bioactive components in RS. Our previous studies on B revealed an extensive first-pass metabolism during its absorption. Hence, it is expected that W and OA which have the similar structures as B, may share similar absorption and metabolic pathways as B. The present project aims to (1) establish an assay method for better quality control of RS; (2) provide further biopharmaceutic characterizations ofW and OA in RS; (3) investigate the potential pharmacokinetic interactions among B, Wand OA. / Results. Similar to B, Wand OA showed favorable permeability in both the Caco-2 cell and the rat in situ single-pass perfusion models. However, they experienced extensive first-pass metabolism, mainly in the form of glucuronidation. Intracellularly formed WG and OAG could be effluxed to both the apical side (lumen side) and basolateral side (mesenteric blood side) mainly by MRPs, which was confirmed by inhibition transport studies in Caco-2 cells and transfected MDCK cells. The glucuronidation rate of OA was higher than that of W, which was observed by enzymatic kinetics studies by sub-cellular fractions with intrinsic clearances (Vmax/K m, mul/min/mg) of 456 to 4170 for W and 509∼5038 for OA. UGT 1A9 was the most potent metabolic enzyme for hepatic glucuronidation, while UGTs 1A8 and 1AlO were responsible for the intestinal glucuronidation of W and OA. The in vivo rat pharmacokinetics studies showed that W and OA may be readily absorbed and extensively metabolized with no parent compound detectable in blood after oral administration of W and OA. A new metabolite of W was identified to be the glucuronic acid conjugate at 5-0H of W. After co-administration of B, W and OA, decreased formation of BG, WG and OAG was observed in in vitro enzymatic kinetics study. Further studies in absorption models of Caco-2 cell monolayer and rat in situ single-pass intestinal perfusion demonstrated the enhancement in absorption of B, W and OA and decrease of BG, WG and OAG after the co-administration of B, W and OA. The ultimate pharmacokinetics interaction study revealed that glucuronides were the predominant form in systemic circulation and the AUC of OAG significantly increased after co-administration of B, Wand OA. Conclusion: Similar to B, Wand OA may be well absorbed followed by extensive first-pass metabolism, which was mediated by various UGT isozymes. During absorption, the intracellularly formed WG and OAG were mainly effluxed by MRPs to both the lumen and mesenteric blood side of the intestine. Both in vitro and in situ models indicated that interactions among B, W and OA would lead to decreased glucuronidation and increased absorption of parent flavones. Due to extensive metabolism in vivo, only glucuronides appeared in systemic circulation after co-administration of B, W and OA in rats. The resulted increased systemic exposure of OAG indicated that the co-administration might lead to the enhancement of bioavailability for the studied flavones in the form of glucuronides. / Li, Chenrui. / Adviser: Zuo Zhong. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 201-236). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Conclusion. The present results indicate that, baicalein with optimal dosage of 30 muM suppressed collagen deposition in AngII stimulated SHR CF cultures. In animal model of hypertension, high dose of baicalein feeding for 12 week showed optimal antifibrotic effect in hypertensive hearts. (Abstract shortened by UMI.) / For in-vivo study, comparing to control group, HW/BW (x1000) of SHR was significantly reduced in 12 weeks-high dose baicalein and (-0.78+/-0.23, p=0.014) 12 weeks-Valsartan group (-0.71+/-0.22, p=0.021), however, no significant change was observed in the LW/BW ratio. / In Blood pressure control, no effects on attenuation of SBP were observed after 4 weeks and 12 weeks daily administration of baicalein, only 12 weeks feeding of Valsartan significantly down-regulated the systolic blood pressure by -19.25+/-10.09 mmHg, p=0.049. / In the in-vivo study, SHR was used as a model of genetic hypertension. The objectives were: firstly, to determine the efficacy of baicalein in the prevention of myocardial fibrosis (interstitial fibrosis) in SHR, & compared with WKY rats as normal controls. Secondly, to determine if over-expression of pro-collagen I (and III, if any) gene in the ventricles could be normalized by baicalein. Thirdly, to determine if left ventricular hypertrophy in SHR is improved by baicalein. Furthermore, to determine if blood pressure and blood biochemistry parameters (plasma level of brain natriuretic peptides (BNP), and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) level could be alternated by baicalein. Besides, to determine the body weight (BW), heart weight to body ratio (HW/BW), liver weight to body weight ratio (LW/BW), serum AST and ALT level could be alternated by baicalein. Finally to evaluate by echocardiography if there are changes of ivss and ivsd in SHR after administration of baicalein. / Keywords. baicalein, wogonin, collagen, cardiac fibrosis, hypertension / Objectives. In the in-vitro study, cardiac fibroblast culture was prepared from neonatal SHR and WKY rats. The objectives were multi-fold: firstly, to determine over-expression of pro-collagen I mRNA (and III, if any) in cardiac fibroblasts cultures could be normalized by baicalein and wogonin after AngII activation. Secondly, to evaluate the efficacy of baicalein and wogonin on the suppression of total collagen protein production in cardiac fibroblasts cultures after AngII activation. Thirdly, to evaluate the mechanism (in protein level) of baicalein and wogonin on regulating collagen deposition in cardiac fibroblasts after AngII activation. Furthermore, to determine if there were any effects on cytotoxicity and membrane integrity of baicalein and wogonin towards cardiac fibroblasts cultures. Finally, to determine the optimal concentration of baicalein and wogonin for the above actions in-vitro. / Results. For in-vitro study, incubation of AngII resulted in significant up-regulation of COL-I and COL-III mRNA and total collagen protein production. Addition of either baicalein or wogonin significantly suppressed the mRNA synthesis and total collagen protein in CF with an optimal dosage of 30 muM. No effects on viability and membrane integrity were observed on baicalein and wogonin towards cardiac fibroblasts cultures. / Kong, Kam Chuen Ebenezer. / Advisers: Cheuk-Man Yu; Gabriel W. K. Yip. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0242. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 176-204). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

Acute colitis was induced by exposing male SD rats to 4% DSS in drinking water for 8 days. Rats were divided into four groups as follows: DSS group---DSS-induced colitis; DSS + SRE group---SRE, 100 mg/kg/day in addition to DSS; Ctr + SRE group---SRE alone; and Ctr group---sham control group. The colon damage was elucidated by macroscopic, histological, electrophysiological and biochemical assessment. Orally administered SRE significantly reduced the colonic damage in all four aspects. However, baicalein did not show similar effect in the same experiment. / In summary, our finding indicated that both SRE and its major flavonoid, baicalein, could stimulate chloride secretion in human colonic T84 cells and mucosa freshly isolated from human colon. Although SRE was effective in treating acute DSS-induced ulcerative colitis, baicalein is unlikely the active anti-inflammatory component of SRE. Nevertheless, the results demonstrated that this TCM has a scientific basis for its effectiveness. Our data support further evaluation of the therapeutic potential of SRE for the treatment of IBD. / In TCM, Scutellariae radix and Coptidis Rhizoma (CR) derived compounds have been frequently used for gastroenteritis and secretory diarrhea. Our laboratory findings suggested that the major flavonoid component of SR, baicalein, stimulates chloride secretion in rat distal colon, probably via CFTR activation (Ko et al., 2002). In contrast, limited information about the cellular mechanism of chloride secretion induced by SR in human colonic epithelia is available. Therefore, the effect of Scutellariae radix extract (SRE) on electrolyte transport in a human colonic epithelial cell line, T84, was examined using the short-circuit current (ISC) technique. Results demonstrated that SRE stimulated a Cl--dependent secretion across T84 cells, probably via both Ca2+- and cAMP-mediated pathway. / On the other hand, the cellular mechanism of baicalein-induced Cl - secretion in T84 cells was further investigated. It was found that the secretory mechanisms involve protein kinase A (PKA)-, adenylate cyclase (AC)- and luminal cAMP-dependent Cl- channels, most likely cystic fibrosis transmembrane conductance regulator (CFTR) and serosal 293B-sensitive K + channels. However, the action of baicalein cannot be solely explained by its cAMP-elevating effect. In addition, the effect of baicalein could be potentiated by the inhibition of mitogen-activated protein kinase (MAPK) and phosphoinositide-3 kinase (PI3K). Furthermore, it was found that inhibition of protein kinase C (PKC) delta limited the baicalein-induced chloride secretion. / Our laboratory has found that baicalein (Ko et al., 2002 and Yue et al., 2003) stimulates chloride secretion in rat distal colon and human colonic T84 cells. As it is known that responses in the animal model or the cell line may not completely reflect the in vivo physiology, it is important to study the above responses in human colon. With scarce supply of freshly isolated human colonic mucosa, the results showed that the effect of SRE and baicalein on ion transport in human samples is similar to that obtained in T84 cell line and rat model. / Scutellariae radix (SR) is the dry root of Scutellariae baicalensis Georgi (Huangqin). SR has been employed for centuries as a traditional Chinese medicine (TCM) for various purposes. It contains a large amount of flavonoids such as baicalein, baicalin, and wogonin, which possess a number of beneficial bioactivities including anti-oxidant, anti-bacterial and anti-inflammatory, etc. / Ulcerative colitis (UC), an inflammatory bowel disease (IBD), has been known for more than half a century. Recent studies have shown that two flavonoids derived from SR, baicalein and wogonin, might alleviate the symptoms of IBD. Moreover, SR is the major component of Hange-shasshin-to (HST), one of the Chinese herbal formulas, which has been reported to suppress the pathogenesis of IBD. The above scientific background led us to examine the effect of SRE administration on DSS-induced colitis in rats in a way to evaluate new treatments potentially applicable to UC in humans. / Chung, Ho Lam. / "August 2007." / Adviser: W. H. Ko. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0925. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.