Synthesis and Biological Properties of a 1‐(6‐Aziridinylhexyl)‐2‐phenylindole, a Potential Fluorescence Label for Estrogen Receptors

2-Phenylindole derivative 8, linked to aziridine by a hexamethylene spacer group, was synthesized and tested. It binds to the estrogen receptor with an RBA-value of 4.0 (estradiol = 100). In vitro, it shows a selective cytostatic activity in hormone-dependent MCF-7 breast cancer cells (41% T/C at 10(-6) M). In vivo, it exerts a strong estrogenic effect. The binding to the estrogen receptor is largely reversible.