. 2017 Oct 5;8:699. doi: 10.3389/fphar.2017.00699

Table 2.

Kinetic parameters of estrogen metabolism by MCF-7 cells in the presence of genistein and daidzein.

Inhibitor	E2		E1-S		E2-S		E2-G

	V_max (fmol/10⁶ cells/h)	K_m (nM)	V_max (fmol/10⁶ cells/h)	K_m (nM)	V_max (fmol/10⁶ cells/h)	K_m (nM)	V_max (fmol/10⁶ cells/h)	K_m (nM)
Control	464.5 ± 39.2	95.4 ± 14.0	26.8 ± 2.3	88.3 ± 11.3	18.3 ± 0.7	95.9 ± 5.4	5.52 ± 0.37	92.7 ± 9.0
1 μM genistein	463.3 ± 39.7	87.1 ± 13.4	19.1 ± 2.0^∗	84.1 ± 12.9	13.5 ± 0.6^∗	98.2 ± 4.5	4.13 ± 0.34^∗	91.3 ± 10.9
5 μM genistein	520.7 ± 32.9	95.2 ± 10.5	4.28 ± 0.42^∗	91.6 ± 12.9	2.19 ± 0.07^∗	96.8 ± 4.5	2.84 ± 0.20^∗	106.4 ± 10.3
10 μM genistein	543.9 ± 31.6^∗	93.8 ± 9.51	2.58 ± 0.25^∗	93.9 ± 13.3	1.04 ± 0.07^∗	97.8 ± 9.8	2.16 ± 0.06^∗	106.3 ± 9.1
1 μM daidzein	488.2 ± 36.4	96.4 ± 12.4	17.1 ± 1.4^∗	102.6 ± 11.5	11.9 ± 0.9^∗	101.2 ± 10.8	4.83 ± 0.27^∗	98.0 ± 7.8
5 μM daidzein	508.7 ± 22.7	95.6 ± 7.39	6.43 ± 0.28^∗	104.4 ± 14.3	2.64 ± 0.22^∗	102.8 ± 11.9	3.99 ± 0.18^∗	100.4 ± 6.6
10 μM daidzein	543.5 ± 32.9^∗	96.8 ± 10.1	4.20 ± 0.47^∗	105.7 ± 16.5	1.35 ± 0.11^∗	98.6 ± 11.9	2.63 ± 0.32^∗	105.6 ± 18.3

Cells were incubated with increasing concentrations of the soy isoflavones genistein and daidzein and 10 to 100 nM E1 as hormone precursor for 48 h. All data represent the means ± SD of four independent biological replicates. Values in bold and marked with an asterisk (^∗) are significantly different in comparison to the control values (P < 0.05).