TABLE 2

Comparison of IC₅₀s for milk thistle constituents and extracts under IC₅₀ shift experimental design

Values represent the estimate ± S.E. from nonlinear regression using WinNonlin (version 5.3).

Constituent/Extract	Enzyme Source
Constituent/Extract	HLMs			HIMs			rCYP3A4
	IC₅₀		Fold Change	IC₅₀		Fold Change	IC₅₀		Fold Change
	− NADPH^a	+ NADPH^b	Fold Change	− NADPH	+ NADPH	Fold Change	− NADPH	+ NADPH	Fold Change
	μM			μM			μM
Silybin A	120 ± 4.8	28 ± 3.1	4.3	100 ± 6.9	23 ± 1.7	4.3	53 ± 2.0	1.6 ± 0.2	33
Silybin B	140 ± 5.7	19 ± 2.1	7.4	100 ± 3.8	27 ± 1.9	3.7	63 ± 3.2	1.4 ± 0.2	45
Silibinin	120 ± 5.7	14 ± 2.2	8.6	67 ± 7.9	15 ± 3.0	4.5	45 ± 2.8	1.2 ± 0.2	38
Silychristin	26 ± 3.3	52 ± 5.2	0.5	25 ± 4.2	72 ± 7.7	0.3	N.D.	N.D.	N.D.
Isosilybin B	78 ± 6.2	30 ± 3.3	2.6	54 ± 3.3	23 ± 2.3	2.3	N.D.	N.D.	N.D.
Silymarin	95 ± 12	28 ± 4.5	3.4	29 ± 2.7	7.0 ± 0.8	4.1	N.D.	N.D.	N.D.

N.D., not determined.
↵^a NADPH was absent during the primary incubation.
↵^b NADPH was present during the primary incubation.