Fig 1.
Structures of chemotypes 1a and 2a and their respective deuterated forms examined in this study.
Table 1.
Steep gradient for LC/MS analysis.
Table 2.
Shallow gradient for LC/MS analysis.
Fig 2.
Snapshots of docked 1a to the active site of CYP3A4 (Panels A and B), and 2a to the active sites of CYP 3A4 and CYP 2C19 (Panels C and D respectively).
Panels A and B show two discrete binding modes for compound 1a in the active site of CYP3A4 with either the pyrimidino-piperidine ring (Panel A), or the N-ethyl (Panel B) in proximity to the putative heme iron-oxo species. The arrows in Panels C and D show the N- and O-methyl groups of 2a. Panel C shows the binding of 2a to the active site of CYP3A4 with both methyl groups in similar proximity to the putative oxidant in CYP3A4, and Panel D shows the preferred binding mode with CYP2C19, where the O-methyl group of 2a is in proximity to the putative oxidant.
Fig 3.
UV (300–400 nm) chromatograms for the metabolism of 1a in human liver microsomes and recombinant cytochromes 3A4, 2C9, 2C19, 2D6, and 1A2.
Fig 4.
Scheme for metabolites of 1a observed with human liver microsomes.
Table 3.
Activities of recombinant human cytochrome P450 isoforms towards compounds 1a and 2a.
Fig 5.
UV (300–400 nm) chromatograms for the metabolism of 2a in human liver microsomes and recombinant cytochromes 3A4, 2C9, 2C19, 2D6, and 1A2.
Fig 6.
Scheme for metabolites of 2a observed with human liver microsomes.
Table 4.
Kinetic deuterium isotope effect on intrinsic clearance for deuterated forms of 1a with human liver microsomes and recombinant CYP3A4.
Table 5.
Percentage of primary oxidative metabolites from deuterated forms of 1a with r-CYP3A4.
Fig 7.
Extracted ion chromatograms for primary oxidative metabolites of 1a and its various deuterated forms with r-CYP3A4.
Table 6.
Kinetic deuterium isotope effect on intrinsic clearance for deuterated forms of 2a with human liver microsomes, r-CYP3A4 and r-CYP2C19.
Fig 8.
Extracted ion chromatograms for primary oxidative metabolites of 2a and its various deuterated forms (shown in Fig 1) with r-CYP2C19.
Fig 9.
Extracted ion chromatograms for primary oxidative metabolites of 2a and its various deuterated forms (shown in Fig 1) with r-CYP3A4.