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Updated: Apr 30, 2026

Mass Spectrometry and Luminogenic-based Approaches to Characterize Phase I Metabolic Competency of In Vitro Cell Cultures
Published on: March 28, 2017
In vitro microsomal hepatic metabolism of antiasthmatic prototype LASSBio-448
Isabelle Karine Costa Nunes, Luzineide Wanderley Tinoco, Helvecio Martins-Junior
1Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude, Bloco B, sala 14, Rio de Janeiro, RJ, Brazil, 21941-971. lidia@lassbio.icb.ufrj.br.
Abstract:
In this paper, the in vitro microsomal hepatic metabolism of the antiasthmatic prototype LASSBio-448 and the structural identification of its major phase I metabolites were described. Incubation with pooled rat liver microsomes converted LASSBio-448 to the following major metabolites: O-demethyl-LASSBio-448 (M1) and 3,4-dihydroxyphenyl- LASSBio-448 (M2). These metabolites were formed by the dealkylation step of 3,4-dimethoxyphenyl and 1,3- benzodioxole subunits, respectively, in agreement with the in silico prediction using MetaSite Program. The development of a reproducible analytical methodology for the major metabolites by using HPLC-MS showed that both reactions require NADPH generating system and appeared to be catalyzed by cytochrome P450 (CYP). The identification of which isoenzyme was involved in the oxidative metabolism of LASSBio-448 was carried out by pre-incubations with the selective inhibitors sulfaphenazole (CYP2C9), quinidine (CYP2D6), furafylline (CYP1A2), p-nitrophenol (CYP2E1), ticlopidine (CYP2C19) and ketoconazole (CYP3A4). CYP1A2, CYP2C19 and CYP3A4 were demonstrated to be involved in the oxidative biotransformation of LASSBio-448.
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