title: 9-Glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine Is the Major Pyrrolic Glutathione Conjugate of Retronecine-Type Pyrrolizidine Alkaloids in Liver Microsomes and in Rats.
abstract: Retronecine-, otonecine-, and heliotridine-type pyrrolizidine alkaloids (PAs) are all reported to be hepatotoxic. These PAs are suggested to be metabolized to the corresponding electrophilic dehydropyrrolizidine alkaloids (dehydro-PAs) and subsequently conjugated with macromolecules, such as glutathione (GSH). In the present study, a total of five glutathione conjugates, named M1-M5, were detected in rat and human liver microsomal incubations with three retrornecine-type PAs (isoline, retrorsine, or monocrotaline) in the presence of glutathione, and were chemically synthesized. M1 and M3 were unambiguously identified as a pair of epimers of 7-glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (7-GSH-DHP), and M4 and M5 were epimers of 7,9-diglutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (7,9-diGSH-DHP). M2, an extremely unstable conjugate, was proposed to be 9-glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (9-GSH-DHP). It was the most abundant among the five GSH conjugates, and the finding corrects the mistake that 7-GSH-DHP is the predominant GSH conjugate derived from dehydro-PAs. Similar patterns in glutathione conjugate profile were observed in the bile of rats treated with the PAs. This is the first study to describe 9-GSH-DHP as a major pyrrolic GSH conjugate of retronecine-type PAs, providing insight into the interactions of dehydro-PAs with biomolecules.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 501 Haike Road, Shanghai, China.
authors.forename: Meixia
authors.initials: M
authors.lastname: Chen
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 501 Haike Road, Shanghai, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 501 Haike Road, Shanghai, China.
authors.forename: Dafang
authors.initials: D
authors.lastname: Zhong
authors.affiliation: Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology and Hepatology, Department of Pediatrics, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Shuijie
authors.initials: S
authors.lastname: Shen
authors.affiliation: Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology and Hepatology, Department of Pediatrics, University of Washington , Seattle, Washington 98195, United States.|Key Laboratory of Structure-Based Drug Design & Discovery of Ministry of Education, Shenyang Pharmaceutical University , Shenyang, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 501 Haike Road, Shanghai, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005978:Glutathione / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D011758:Pyrroles / Q000032:analysis* / Q000737:chemistry; D011763:Pyrrolizidine Alkaloids / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D053719:Tandem Mass Spectrometry
chemical_list: C091658:7-glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine; C000611823:9-glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine; D011758:Pyrroles; D011763:Pyrrolizidine Alkaloids; C014795:retronecine; D005978:Glutathione