title: Metabolic fate of combretastatin A-1: LC-DAD-MS/MS investigation and biological evaluation of its reactive metabolites.
abstract: Combretastatin A-1, an antineoplastic agent characterized by a remarkable cytotoxicity and a strong antitubulinic activity, is currently under investigation in phase I clinical trials. Yet a comprehensive metabolic study of CA-1 in human and animal models has so far not been reported in the literature. We have therefore investigated, through LC-UV and LC-MS analysis the in vitro/in vivo metabolism of CA-1, have synthesized its reactive quinone metabolite Q1, and have evaluated its cytotoxic and antitubulinic activities. In vitro CA-1 metabolism was studied in rat and human liver microsomes in the presence of the nucleophilic trapping agent GSH were performed while urine samples of the CA-1-treated rats were analyzed to establish the in vivo metabolic pathways. The metabolite Q1, that was synthesized in good yield using a polymer supported oxidant, displayed a significant cytotoxicity but was devoid of significant antitubulinic activity. Finally the chemical interaction of Q1 and the other combretastatin quinone metabolites with sulphydryl groups of tubulin was measured by Ellman's method: the results suggested the haptenization of the tubulin through the formation of a covalent bond.
authors.affiliation: Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale A. Avogadro, Largo Donegani 2, 28100 Novara, Italy. silvio.aprile@unipmn.it
authors.forename: Silvio
authors.initials: S
authors.lastname: Aprile
authors.forename: Roberta
authors.initials: R
authors.lastname: Zaninetti
authors.forename: Erika
authors.initials: E
authors.lastname: Del Grosso
authors.forename: Armando A
authors.initials: AA
authors.lastname: Genazzani
authors.forename: Giorgio
authors.initials: G
authors.lastname: Grosa
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013267:Stilbenes / Q000493:pharmacokinetics*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D013267:Stilbenes; C063690:combretastatin A-1