Table 1.

Results of the fluorescence competitive binding assays and molecular docking analysis of the investigated compounds with G protein–coupled estrogen eceptor 1 (GPER).

Compounds	${\text{IC}}_{50}$ ($\mathrm{\mu }\mathrm{M}$)	RBA (%)	OH position	Hydrogen bond	Hydrogen bond residue position
${\mathrm{E}}_2$	0.3	100.0	—	Asn276	TM6
${\mathrm{\alpha }\text{-}\mathrm{E}}_2$	NA	—	—	—	—
G1	0.6	51.7	—	Asn276	TM6
G15	2.1	13.8	—	—	—
BDE-003	NA	—	—	—	—
2ʹ-OH-BDE-003	20.0	1.3	ortho	Gln138, Ser134	TM3
BDE-007	NA	—	—	—	—
2ʹ-OH-BDE-007	NA	—	ortho	—	—
3ʹ-OH-BDE-007	2.6	10.0	meta	Gln138, Glu218	TM3, TM5
BDE-028	NA	—	—	—	—
2ʹ-OH-BDE-028	NA	—	ortho	—	—
3ʹ-OH-BDE-028	3.0	8.7	meta	Glu218	TM5
BDE-047	NA	—	—	—	—
3-OH-BDE-047	12.0	2.2	meta	Ser134	TM3
5-OH-BDE-047	NA	—	meta	—	—
6-OH-BDE-047	NA	—	ortho	—	—
BDE-049	NA	—	—	—	—
4ʹ-OH-BDE-049	2.8	9.3	para	His282	TM6
BDE-085	NA	—	—	—	—
6-OH-BDE-085	NA	—	ortho	—	—
BDE-099	NA	—	—	—	—
6ʹ-OH-BDE-099	NA	—	ortho	—	—
5ʹ-OH-BDE-099	1.3	20.0	meta	Glu275	TM6
BDE-100	NA	—	—	—	—
5ʹ-OH-BDE-100	NA	—	meta	—	—
3-OH-BDE-100	3.6	7.2	meta	—	—
BDE-154	NA	—	—	—	—
3ʹ-OH-BDE-154	1.3	20.0	meta	Ser134	TM3
BDE-180	NA	—	—	—	—
6-OH-BDE-180	4.8	5.4	ortho	His307, Phe208	TM7, EL2
BDE-187	NA	—	—	—	—
4-OH-BDE-187	6.2	4.2	para	Phe208	EL2
BDE-201	NA	—	—	—	—
4ʹ-OH-BDE-201	5.3	4.9	para	—	—

Note: —, no information was collected at that particular examination point; ${\mathrm{\alpha }\text{-}\mathrm{E}}_2$, $17\mathrm{\alpha }\text{-estradiol}$; Asn, asparagine; BDE, bromodiphenyl ether; ${\mathrm{E}}_2$, $17\mathrm{\beta }\text{-estradiol}$; EL, extracellular loop; G1, GPER agonist; G15, GPER antagonist; Gln, glutamine; Glu, glutamic acid; His, histidine; ${\text{IC}}_{50}$, concentration of a ligand required to displace half of the probes from the receptors; NA, not achieved; OH-BDE, hydroxylated bromodiphenyl ether; Phe, phenylalanine; RBA (relative binding affinity): ratio between ${\text{IC}}_{50}$ of ${\mathrm{E}}_2$ and compounds; Ser, serine; TM, transmembrane helix.