Flavin-containing monooxygenase isoform specificity for the N-oxidation of tamoxifen determined by product measurement and NADPH oxidation

Development of a CD‐MEKC method for investigating the metabolism of tamoxifen by flavin‐containing monooxygenases and the inhibitory effects of methimazole, nicotine and DMXAA

“…It has been noted that calculated K m values are well above the plasma concentration of TAM . In literature the K m value was reported as 43 μM for human FMO1 and 1.2 mM for mouse FMO1 . As K m values vary depending on the origin of the FMO1 enzyme and the method conditions, the K m for TAM cannot be compared exactly with the K m values from other studies.…”

Human Flavin-Containing Monooxygenase 3 on Graphene Oxide for Drug Metabolism Screening

“…Benzydamine is a nonsteroidal anti-inflammatory drug that has been mainly used as a marker substrate of hFMO3, and its N-oxidation is usually referred to as an indicator of hFMO3 catalytic activity. Tamoxifen is an antiestrogenic drug widely used in breast cancer therapy and chemoprevention that is also N-oxygenated by hFMO3 to its N -oxide. , The calculation of apparent kinetic parameters for the N-oxidation of these two drugs was performed by electrocatalysis followed by HPLC separation of the products. Reaction rate values were estimated after the quantification of the product formed during the electrocatalysis experiment and corrected by subtraction of the relevant controls (Figure A and B).…”

“…Apparent kinetic values obtained for hFMO3 in the presence of GO were compared with previously published data for both benzydamine ,,, and tamoxifen , and are reported in Table . Regarding benzydamine catalysis, our results are generally in good agreement with previously published data, especially the calculated K ′ M values (∼50–60 μM).…”

Flavin‐Containing Monooxygenase 3 Polymorphic Variants Significantly Affect Clearance of Tamoxifen and Clomiphene

“…to eliminate the precipitated protein. A 100‐μl sample of each resulting supernatant was subsequently analysed by HPLC according to the previously published methods . Reaction mixtures in the absence of hFMO3, tamoxifen and/or NADPH were used as controls, and the metabolites were identified by comparison with commercially available synthetic standards.…”