Table 1. In Vitro Competitive Binding Assay.

	compound	TR-FRETa ERα	RBAb ERα	TR-FRETa ERβ	RBAb ERβ
		IC50 [nM]	[%]	IC50 [nM]	[%]
thioxo-quinazolinones	15	4.01 ± 1.90	8.2	12.6 ± 4.8	5.9
	16	1.41 ± 0.46	23.4	0.82 ± 0.07	110
	17	4.63 ± 1.74	7.1	18.5 ± 4.8	4.0
	18	4.23 ± 1.12	7.8	6.81 ±1.86	10.9
5-methoxybenzimidazole	31	2.75 ± 1.33	12.0	4.88 ± 2.65	15.2
	32	4.11 ± 1.88	8.0	3.01 ± 4.00	24.7
	34	2.22 ± 0.76	14.9	5.26 ± 3.10	14.1
	36	1.56 ± 0.63	21.1	7.84 ± 0.25	9.5
	38	2.61 ± 2.25	12.6	5.22 ± 0.65	14.3
5-hydroxybenzimidazole	39	1.45 ± 0.37	22.8	1.99 ± 0.88	37.4
	40	2.72 ± 1.12	12.1	3.78 ± 1.54	19.7
	41	1.62 ± 0.50	20.4	2.84 ± 1.31	26.2
	42	1.28 ± 0.58	25.7	3.81 ± 2.35	19.5
	43	3.41 ± 2.07	9.7	7.8 ± 2.30	9.5
references	E2	0.33 ± 0.19	100	1.02 ± 0.50	100
	GW7604	5.35 ± 1.39	6.2	3.77 ± 1.06	27.1
	fulvestrant	2.85 ± 0.83	11.6	10.2 ± 2.5	10.0
	4-OHT	2.24 ± 0.89	14.7	1.68 ± 1.00	60.7

^aDisplacement of fluorescent-labeled E2 from the LBD of ERα or ERβ by heterodimeric compounds and references.

^bRelative binding affinity (RBA) compared to E2 (100%).