title: Identification and characterization of in vitro and in vivo metabolites of steroidal alkaloid veratramine.
abstract: Veratramine, a steroidal alkaloid originating from Veratrum nigrum L., has demonstrated distinct anti-tumor and anti-hypertension effects, however, its metabolism has rarely been explored. The objective of the current study was to provide a comprehensive investigation of its metabolic pathways. The in vitro metabolic profiles of veratramine were evaluated by incubating it with liver microsomes and cytosols. The in vivo metabolic profiles in plasma, bile, urine and feces were monitored by UPLC-MS/MS after oral (20 mg/kg) and i.v. (50 µg/kg) administration in rats. Meanwhile, related P450s inhibitors and recombinant P450s and SULTs were used to identify the isozymes responsible for its metabolism. Eleven metabolites of veratramine, including seven hydroxylated, two sulfated and two glucuronidated metabolites, were characterized. Unlike most alkaloids, the major reactive sites of veratramine were on ring A and B instead of on the amine moiety. CYP2D6 was the major isozyme mediating hydroxylation, and substrate inhibition was observed with a Vmax , Ki and Clint of 2.05 ± 0.53 nmol/min/mg, 33.08 ± 10.13 µ m and 13.58 ± 1.27 µL/min/mg. SULT2A1, with Km , Vmax and Clint values of 19.37 ± 0.87 µ m, 1.51 ± 0.02 nmol/min/mg and 78.19 ± 8.57 µL/min/mg, was identified as the major isozyme contributing to its sulfation. In conclusion, CYP2D6 and SULT2A1 mediating hydroxylation and sulfation were identified as the major biotransformation for veratramine.
authors.affiliation: Technology Laboratory Center, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China.|School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR.
authors.forename: Chunming
authors.initials: C
authors.lastname: Lyu
authors.affiliation: Center for Chinese Medical Therapy and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Zhou
authors.affiliation: School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Rehabilitation, Changzheng Hospital Affiliated to Second Military Medicine University, Shanghai, 200003, PR China.
authors.forename: Shen
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Center for Chinese Medical Therapy and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Kou
authors.affiliation: Center for Chinese Medical Therapy and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China.
authors.forename: Hai
authors.initials: H
authors.lastname: Wei
authors.affiliation: Technology Laboratory Center, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
authors.affiliation: School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zuo
mesh_terms: D000818:Animals; D015239:Arylsulfotransferase / Q000378:metabolism*; D001646:Bile / Q000737:chemistry; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D014704:Veratrum Alkaloids / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine
chemical_list: D007527:Isoenzymes; D014704:Veratrum Alkaloids; D003577:Cytochrome P-450 Enzyme System; D015239:Arylsulfotransferase; C009649:veratramine
keywords: CYP2D6; SULT2A1; hydroxylation; sulfation; veratramine