title: Identification of cytochrome P450 1A2 as enzyme involved in the microsomal metabolism of Huperzine A.
abstract: Huperzine A is a reversible and selective cholinesterase inhibitor approved for the treatment of Alzheimer's disease. To identify which cytochrome P450 (CYP) isoenzymes are involved in the metabolism of Huperzine A, an in vitro study was performed with rat liver microsomes and immunoinhibition and chemical inhibition methods. Huperzine A metabolism was analyzed with high-performance liquid chromatography (HPLC) and expressed as Huperzine A disappearance rate. Result showed that 76.2% of Huperzine A metabolism was inhibited by CYP1A2 antibody and 17.8% by CYP3A1/2 antibody. Inhibitory effects produced by CYP2C11 and 2E1 antibodies were minor. The CYP1A2 substrate phenacetin showed an inhibitory effect of 70.3%. In conclusion, Huperzine A metabolism in rat liver microsomes is mediated primarily by CYP1A2, with a probable secondary contribution of CYP3A1/2. CYP2C11 and 2E1 are likely not involved in Huperzine A metabolism.
authors.affiliation: State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institute for Biological Science, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Xiaochao
authors.initials: X
authors.lastname: Ma
authors.forename: Haixue
authors.initials: H
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Xin
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.forename: Zenghong
authors.initials: Z
authors.lastname: Tu
mesh_terms: D000470:Alkaloids; D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D002110:Caffeine / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D019388:Cytochrome P-450 CYP1A2 / Q000276:immunology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010615:Phenacetin / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012717:Sesquiterpenes / Q000378:metabolism*
chemical_list: D000470:Alkaloids; D000906:Antibodies; D004791:Enzyme Inhibitors; D012717:Sesquiterpenes; C050426:huperzine A; D002110:Caffeine; D019388:Cytochrome P-450 CYP1A2; D010615:Phenacetin