. Author manuscript; available in PMC: 2009 Oct 1.

Published in final edited form as: Drug Metab Dispos. 2008 Jul 24;36(10):2104–2112. doi: 10.1124/dmd.108.021857

Table 1.

Kinetic parameters of isoliquiritigenin glucuronidation by human liver microsomes (HLM) and recombinant UGT enzymes.

Enzyme	Metabolite	K_m or S₅₀	V_max	CL_int	K_si

		(µM)	(nmol/min/mg protein)	(µL/min/mg protein)	(µM)
HLM	MG4 ^a	2.84 ± 0.42	0.25 ± 0.01	88.0	168.34 ± 39.52
	MG5 ^a	8.42 ± 1.21	1.47 ± 0.11	174.6	143.53 ± 31.36
UGT1A1	MG4 ^a	2.98 ± 0.80	1.01 ± 0.16	338.9	10.89 ± 2.92
	MG5 ^a	4.30 ± 0.47	1.77 ± 0.08	411.6	189.1 ± 36.0
UGT1A9	MG4 ^b	8.59 ± 1.43	0.14 ± 0.01	16.3
	MG5 ^c	3.15 ± 0.24	0.86 ± 0.02	273.0
UGT1A10	MG4 ^b	25.75 ± 1.28	2.13 ± 0.04	89.3
	MG5 ^b	26.15 ± 2.25	0.57 ± 0.02	21.8

Each value represents Mean ± Std. Error (N = 3)

^a)

Substrate inhibition

^b)

Michaelis-Menten

^c)

Hill equation (n = 1.20 ± 0.08)