In Vitro And In Vivo Metabolism Of Emodin

Emodin is the main anthraquinone component in commonly used traditional Chinese medicines such as Polygonum multiflorum and Polygonum cuspidatum.In order to fully understand the ADME(absorption,distribution,metabolism,excretion)process of emodin in vivo,the oral bioavailability of emodin was firstly investigated in this thesis,and then the metabolism of emodin in blood,urine,feces and bile was investigated.identification of emodin and its metabolites in rat heart,liver,spleen,lung and kidney,followed by quantification of emodin and its metabolites in urine,feces and bile excretion,and finally The main liver drug enzymes involved in emodin metabolism were further identified by the method of in vitro liver microsome incubation.Objective: To clarify the ADME process of emodin in vivo and the main liver drug enzymes involved in emodin metabolism.Methods: 1.Absorption: Emodin was injected into the tail vein of rats/administered,and plasma was collected at different time points.The drug concentration of emodin in plasma was determined by UHPLC-MS/MS method,and the drug-time curve was drawn and the pharmacokinetics was calculated.Oral bioavailability data of emodin were obtained.2.Metabolism: Rat plasma,urine,bile,and feces were collected,wherein the plasma was precipitated with four times the amount of methanol,and the urine and bile were extracted and diluted with twice the amount of methanol.Identification of emodin metabolites in plasma,urine,bile,and feces by ultra-high performance liquid phase-quadrupole-electrostatic orbitrap mass spectrometry(UHPLC-Q-Orbitrap MS).3.Tissue distribution: Rats were given emodin,and five tissues of heart,liver,spleen,lung and kidney were harvested at different time points.After tissue homogenization and pretreatment,UHPLC-MS/MS was used to determine emodin and Tissue distribution of its metabolites.4.Excretion: Rats were administered emodin,feces,urine and bile were collected in different time periods,and the cumulative excretion of emodin and its metabolites for 48 hours was determined.5.In vitro metabolism: using liver microsome incubation method,the specific inhibitors of five metabolic enzymes CYP1A2,CYP2E1,UGT1A1,UGT1A9 and UGT1B7 are α-naphthoflavone(AN)and sodium diethyldithiocarbamate,respectively.(SD),pazopanib(PAZ),flunilic acid(NA),fluconazole(FLU),and the metabolic types of emodin were studied by inhibiting the corresponding enzymes.Results: 1.Absorption: The area under the curve(AUC0-4 h)of the mean plasma concentration of emodin in rats at 0-24 h after intravenous injection was 194.887 ng/m L;oral administration in rats was 0-48 The AUC0-48 h of h was 2025.798 ng/m L.According to the bioavailability formula,the oral bioavailability of emodin was 3.197±0.714%.2.Metabolism:A total of 18 metabolites of emodin were found in plasma,urine,bile and feces,including phase I hydroxylated metabolites and phase II glucuronide and sulfate metabolites,namely ω-hydroxyemodin,2-Hydroxyemodin,4-Hydroxyemodin,5-Hydroxyemodin,Emodin-8-Oglucuronic acid,Emodin-1-O-glucuronic acid,Emodin-3-O-glucuronic acid,Emodin-8-Osulfate,Emodin-1-O-sulfate,Emodin-3-O-sulfate,etc.3.Tissue distribution: The drug concentration of pro-emodin in liver and kidney is higher than that in heart,spleen and lung;the hydroxylated and glucuronidated metabolites of emodin have higher tissue distribution in kidney tissue.4.Excretion: About 56% of emodin is directly excreted in the feces without being absorbed,glucuronidated emodin is mainly excreted through urine and bile,and hydroxyemodin is mainly excreted through urine and feces.5.In vitro liver microsome incubation experiment of emodin: CYP1A2 can metabolize emodin to generate ω-hydroxyemodin and 2-hydroxyemodin,CYP2E1 can only metabolize emodin to generate ω-hydroxyemodin,UGT1A1,UGT1A9,UGT2B7 three isoform enzymes Both can metabolize emodin to generate emodin-3-O-glucuronic acid,among which UGT1A1 has a stronger metabolism.Conclusion: The low oral bioavailability of emodin is related to its extensive metabolism after entering the body.Emodin mainly undergoes hydroxylation and glucuronidation metabolism in vivo.The main liver drug enzymes involved in emodin metabolism are CYP1A2,2E1,UGT1A1,1A9 and 2B7.The tissue distribution of emodin is mainly concentrated in the kidney.