Table 2.

Binding affinity of the coregulator SRC3 to ERα and ERβ complexes with E2 and BEs expressed as RCA values

BE	ERα		ERβ		β/α
	EC50 (nM)	RCA	EC50 (nM)	RCA
E2	0.13 ± 0.004	[100]	0.12 ± 0.002	[100]	[1.0]
Genistein	1.1 ± 0.1	11.30 ± 0.7	0.20 ± 0.01	61 ± 0.9	5.4
Daidzein	14.2 ± 1.1	0.88 ± 0.05	0.22 ± 0.02	54.4 ± 2.1	61.8
S-equol	16.7 ± 0.6	0.73 ± 0.01	0.18 ± 0.01	78.5 ± 4.2	108.0
R-equol	33.9 ± 1.8	0.36 ± 0.008	0.33 ± 0.1	43 ± 2.1	119.0
(±)-Equol	25.9 ± 4.2	0.47 ± 0.02	0.25 ± 0.11	56 ± 4.2	119.0
Biochanin A	88.8 ± 6.4	0.14 ± 0.02	0.26 ± 0.01	46.7 ± 1.5	334.0
Formononetin	ND	ND	0.53 ± 0.02	22.9 ± 1.7	—
Liquiritigenin	2.2 ± 0.4	4.60 ± 0.5	0.13 ± 0.01	88.9 ± 6.7	19.3

RCA = (EC_{50 E2}/EC_{50 BE}) × 100. β/α = RCA_ERβ/RCA_ERα. ND, not detectable.