TABLE 1.

Kinetic parameters of esculetin (ET) and 4-methylesculetin (4-ME) glucuronidation obtained from recombinant UGT1A6 and UGT1A9 and human liver and intestinal microsomes (HLM and HIM)

Kinetic parameters were obtained using simple Michaelis-Menten models as described in Materials and Methods.

Compounds	Kinetic Parameters	UGT1A6	UGT1A9	HLM	HIM
ET	Km (µM)	185.59	134.75	134.19	189.33
	Vmax (nmol/min/mg)	127.40	19.23	72.61	30.45
	CL(Vmax/Km, ml/min/mg)	0.69	0.14	0.54	0.16
	R2	0.9823	0.9775	0.9833	0.9738
	AIC	40.98	14.05	29.53	26.69
4-ME	Km (µM)	172.51	25.20	117.81	129.12
	Vmax (nmol/min/mg)	24.70	0.99	69.91	3.88
	CL(Vmax/Km, ml/min/mg)	0.14	0.04	0.59	0.03
	R2	0.9824	0.9793	0.9879	0.9918
	AIC	15.21	−41.49	34.75	−26.16

AIC, Akaike’s information criterion.