{"id":{"repo_id":"sask","oai_identifier":"oai:harvest.usask.ca:10388/ETD-2012-11-777"},"canonical_url":"https://search.dev.ndltd.org/etd/sask/oai:harvest.usask.ca:10388/ETD-2012-11-777","repository":{"repo_id":"sask","name":"University of Saskatchewan","base_url":"https://harvest.usask.ca/server/oai/request"},"display":{"title":"The Comparison of Rat and Human Intestinal and Hepatic Glucuronidation of Enterolactone Derived from Flaxseed Lignans","abstract":"The mammalian lignan, enterolactone (EL), is a gut microbe metabolite of plant lignan secoisolariciresinol diglucoside (SDG), which is most abundant in flaxseed. Numerous epidemiological, experimental and clinical studies suggest the protective effects of EL against various chronic diseases such as cancer, cardiovascular disease, and inflammation. However, EL’s oral bioavailability is low and highly variable due to extensive first-pass metabolism, especially glucuronidation, which results in the large amount of glucuronide metabolites but low levels of free EL in human plasma. Hepatocytes and enterocytes express UDP-glucuronosyltransferases (UGT), the enzymes responsible for the conjugation of glucuronic acid to EL. To better understand the contribution of liver and intestine to the first-pass glucuronidation, I conducted an in vitro enzyme kinetic analysis of EL glucuronidation using hepatic and intestinal microsomal fractions from both human and rat. An intrinsic clearance (CLint) value was calculated using the substrate depletion approach. In addition to monitoring substrate depletion, high-pressure liquid chromatography (HPLC) analysis allowed detection of EL glucuronides, which were further substantiated by LC-MS. EL monoglucuronide was identified in rat and human intestinal and liver microsomes. Enzyme kinetic studies indicated the extent of hepatic microsomal glucuronidation exceeded intestinal glucuronidation in both human and rat, while the human liver CLint value was slightly higher than that of rat liver. The CLint value generated in human intestinal microsomes was only one third of the value of human liver, whereas, the CLint of rat jejunum or colon was one-twentieth of rat liver, suggesting the human intestine makes a greater contribution to EL glucuronidation than rat intestine. These results suggest that both liver and intestine contribute to EL glucuronidation and the human intestine may exert a greater influence on the first-pass glucuronidation of EL than rat intestine, thereby significantly decreasing EL’s oral bioavailability. The rat might underestimate the extent of intestinal metabolism of EL relative to human.","abstract_html":"The mammalian lignan, enterolactone (EL), is a gut microbe metabolite of plant lignan secoisolariciresinol diglucoside (SDG), which is most abundant in flaxseed. Numerous epidemiological, experimental and clinical studies suggest the protective effects of EL against various chronic diseases such as cancer, cardiovascular disease, and inflammation. However, EL’s oral bioavailability is low and highly variable due to extensive first-pass metabolism, especially glucuronidation, which results in the large amount of glucuronide metabolites but low levels of free EL in human plasma. Hepatocytes and enterocytes express UDP-glucuronosyltransferases (UGT), the enzymes responsible for the conjugation of glucuronic acid to EL. To better understand the contribution of liver and intestine to the first-pass glucuronidation, I conducted an in vitro enzyme kinetic analysis of EL glucuronidation using hepatic and intestinal microsomal fractions from both human and rat. An intrinsic clearance (CLint) value was calculated using the substrate depletion approach. In addition to monitoring substrate depletion, high-pressure liquid chromatography (HPLC) analysis allowed detection of EL glucuronides, which were further substantiated by LC-MS. EL monoglucuronide was identified in rat and human intestinal and liver microsomes. Enzyme kinetic studies indicated the extent of hepatic microsomal glucuronidation exceeded intestinal glucuronidation in both human and rat, while the human liver CLint value was slightly higher than that of rat liver. The CLint value generated in human intestinal microsomes was only one third of the value of human liver, whereas, the CLint of rat jejunum or colon was one-twentieth of rat liver, suggesting the human intestine makes a greater contribution to EL glucuronidation than rat intestine. These results suggest that both liver and intestine contribute to EL glucuronidation and the human intestine may exert a greater influence on the first-pass glucuronidation of EL than rat intestine, thereby significantly decreasing EL’s oral bioavailability. The rat might underestimate the extent of intestinal metabolism of EL relative to human.","abstract_has_math":false,"creators":["Lin, Chaojie"],"institution":"University of Saskatchewan","degree_name":"Master of Science (M.Sc.)","degree_level":"Masters","degree_discipline":"Pharmacy","degree_department":null,"school":null,"contributors":[],"advisors":["Alcorn, Jane","Krol, Ed"],"committee_chairs":[],"committee_members":["Olkowski, Andrew","Remillard, Fred","Weber, Lynn"],"year":2012,"date_issued":"2012-12-03","date_published":"2012-12-03","updated_at":"2026-07-24T04:27:08Z","subjects":["enterolactone, flaxseed, glucuronidation, intestine, liver, lignan"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/10388/ETD-2012-11-777","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Alcorn, Jane","Krol, Ed"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Olkowski, Andrew","Remillard, Fred","Weber, Lynn"]},{"key":"dc:creator","label":"Author","values":["Lin, Chaojie"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2013-01-03T22:34:33Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2013-01-03T22:34:33Z"]},{"key":"dc:date.issued","label":"Date","values":["2012-12-03"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Pharmacy"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (M.Sc.)"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Saskatchewan"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["enterolactone, flaxseed, glucuronidation, intestine, liver, lignan"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10388/ETD-2012-11-777"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The mammalian lignan, enterolactone (EL), is a gut microbe metabolite of plant lignan secoisolariciresinol diglucoside (SDG), which is most abundant in flaxseed. Numerous epidemiological, experimental and clinical studies suggest the protective effects of EL against various chronic diseases such as cancer, cardiovascular disease, and inflammation. However, EL’s oral bioavailability is low and highly variable due to extensive first-pass metabolism, especially glucuronidation, which results in the large amount of glucuronide metabolites but low levels of free EL in human plasma. Hepatocytes and enterocytes express UDP-glucuronosyltransferases (UGT), the enzymes responsible for the conjugation of glucuronic acid to EL. To better understand the contribution of liver and intestine to the first-pass glucuronidation, I conducted an in vitro enzyme kinetic analysis of EL glucuronidation using hepatic and intestinal microsomal fractions from both human and rat. An intrinsic clearance (CLint) value was calculated using the substrate depletion approach. In addition to monitoring substrate depletion, high-pressure liquid chromatography (HPLC) analysis allowed detection of EL glucuronides, which were further substantiated by LC-MS. EL monoglucuronide was identified in rat and human intestinal and liver microsomes. Enzyme kinetic studies indicated the extent of hepatic microsomal glucuronidation exceeded intestinal glucuronidation in both human and rat, while the human liver CLint value was slightly higher than that of rat liver. The CLint value generated in human intestinal microsomes was only one third of the value of human liver, whereas, the CLint of rat jejunum or colon was one-twentieth of rat liver, suggesting the human intestine makes a greater contribution to EL glucuronidation than rat intestine. These results suggest that both liver and intestine contribute to EL glucuronidation and the human intestine may exert a greater influence on the first-pass glucuronidation of EL than rat intestine, thereby significantly decreasing EL’s oral bioavailability. The rat might underestimate the extent of intestinal metabolism of EL relative to human."]},{"key":"dc:title","label":"Title","values":["The Comparison of Rat and Human Intestinal and Hepatic Glucuronidation of Enterolactone Derived from Flaxseed Lignans"]}]}],"canonical_facts":{"dc:contributor.advisor":["Alcorn, Jane","Krol, Ed"],"dc:contributor.committeemember":["Olkowski, Andrew","Remillard, Fred","Weber, Lynn"],"dc:creator":["Lin, Chaojie"],"dc:date.accessioned":["2013-01-03T22:34:33Z"],"dc:date.available":["2013-01-03T22:34:33Z"],"dc:date.issued":["2012-12-03"],"dc:description.abstract":["The mammalian lignan, enterolactone (EL), is a gut microbe metabolite of plant lignan secoisolariciresinol diglucoside (SDG), which is most abundant in flaxseed. Numerous epidemiological, experimental and clinical studies suggest the protective effects of EL against various chronic diseases such as cancer, cardiovascular disease, and inflammation. However, EL’s oral bioavailability is low and highly variable due to extensive first-pass metabolism, especially glucuronidation, which results in the large amount of glucuronide metabolites but low levels of free EL in human plasma. Hepatocytes and enterocytes express UDP-glucuronosyltransferases (UGT), the enzymes responsible for the conjugation of glucuronic acid to EL. To better understand the contribution of liver and intestine to the first-pass glucuronidation, I conducted an in vitro enzyme kinetic analysis of EL glucuronidation using hepatic and intestinal microsomal fractions from both human and rat. An intrinsic clearance (CLint) value was calculated using the substrate depletion approach. In addition to monitoring substrate depletion, high-pressure liquid chromatography (HPLC) analysis allowed detection of EL glucuronides, which were further substantiated by LC-MS. EL monoglucuronide was identified in rat and human intestinal and liver microsomes. Enzyme kinetic studies indicated the extent of hepatic microsomal glucuronidation exceeded intestinal glucuronidation in both human and rat, while the human liver CLint value was slightly higher than that of rat liver. The CLint value generated in human intestinal microsomes was only one third of the value of human liver, whereas, the CLint of rat jejunum or colon was one-twentieth of rat liver, suggesting the human intestine makes a greater contribution to EL glucuronidation than rat intestine. These results suggest that both liver and intestine contribute to EL glucuronidation and the human intestine may exert a greater influence on the first-pass glucuronidation of EL than rat intestine, thereby significantly decreasing EL’s oral bioavailability. The rat might underestimate the extent of intestinal metabolism of EL relative to human."],"dc:identifier.uri":["https://hdl.handle.net/10388/ETD-2012-11-777"],"dc:language.iso":["eng"],"dc:subject":["enterolactone, flaxseed, glucuronidation, intestine, liver, lignan"],"dc:title":["The Comparison of Rat and Human Intestinal and Hepatic Glucuronidation of Enterolactone Derived from Flaxseed Lignans"],"thesis:degree_discipline":["Pharmacy"],"thesis:degree_level":["Masters"],"thesis:degree_name":["Master of Science (M.Sc.)"],"thesis:institution_name":["University of Saskatchewan"]},"updated_at":"2026-07-24T04:27:08Z"}