Table 2.

Liver and kidney microsome stability and activity

	Remaining After 50 min, μM				PTBA Measured After 50 min, μM
Compound	Liver +	Liver −	Kidney +	Kidney −	Liver +	Liver −	Kidney +	Kidney −
PTBA	8.0	8.1	8.6	8.9	N/A	N/A	N/A	N/A
UPHD25	ND	ND	ND	ND	5.1	7.2	3.2	5.1
UPHD36	0.8	6.8	5.9	13*	0.4	0.5	0.2	0.3
UPHD186	0.37	0.37	0.18	0.18	2.4	6.8	2.1	5.4

Compounds (10 μM) were incubated with liver or kidney microsomes ± NADPH, as indicated. Concentrations of the parent compound and PTBA were determined after 50-min incubation by LC-MS using standard curves. Intact UPHD25 could not be detected using electrospray ionization in positive or negative modes. Experiment was repeated 3 times with similar results.

^*Concentration within expected error for the calculation.