Table 1. ERα binding affinity of PBP derivatives.

Entry	Binding affinity IC50 (nM)
4-OHT	5.6
PBP	7.3
PBP-C2	40
PBP-C4	87
PBP-C6	168
PBP-C8	400
PBP-C10	NA a
PBP-C12	NA a
PBP-tam	313
PBP-NH2	78
PBP-NC6	78
PBP-NC8	2.4
PBP-NC10	4.9
PBP-NC12	4.9
PBP-NC16	20

^aNo activity at 1 μM.